The Project Gutenberg eBook of An introduction to the study of mammals living and extinct
This ebook is for the use of anyone anywhere in the United States and
most other parts of the world at no cost and with almost no restrictions
whatsoever. You may copy it, give it away or re-use it under the terms
of the Project Gutenberg License included with this ebook or online
at www.gutenberg.org. If you are not located in the United States,
you will have to check the laws of the country where you are located
before using this eBook.
Title: An introduction to the study of mammals living and extinct
Author: William Henry Flower
Richard Lydekker
Release date: April 23, 2025 [eBook #75947]
Language: English
Original publication: London: Adam and Charles Black, 1891
Credits: Tim Lindell, Carlo Traverso, BnF/Gallica and the Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images generously made available by The Internet Archive)
*** START OF THE PROJECT GUTENBERG EBOOK AN INTRODUCTION TO THE STUDY OF MAMMALS LIVING AND EXTINCT ***
AN INTRODUCTION TO THE STUDY OF MAMMALS
AN INTRODUCTION
TO THE STUDY OF
MAMMALS
LIVING AND EXTINCT
BY
WILLIAM HENRY FLOWER
C.B., F.R.S., D.C.L., LL.D., P.Z.S., F.L.S., F.G.S., &c.
DIRECTOR OF THE NATURAL HISTORY DEPARTMENTS, BRITISH MUSEUM
AND
RICHARD LYDEKKER
B.A., F.G.S., F.Z.S., &c.
[Illustration: THE WOOLLY OPOSSUM]
LONDON: ADAM AND CHARLES BLACK
MDCCCXCI
PREFACE
One of the greatest difficulties experienced by all who undertake a
work of this nature, not professing to be an exhaustive treatise on
the subject with which it deals, is to determine the amount of detail
desirable to be introduced to meet the requirements of the ordinary
student, without rendering it too bulky or costly for general use. The
experience of those who endeavour to profit by the book can alone decide
how far the authors have succeeded in this respect. It will be observed
that in many instances certain better-known or more interesting members
of the class have been described at considerable length, while it has
been necessary to treat others with much greater brevity.
With regard to the references to the literature of the various groups
treated of, it has been the endeavour of the authors to make a selection
of such memoirs and works as are likely to prove most valuable to the
student for the amount of original information which they contain, and
more especially of those giving full bibliographical data up to the
time of their publication, the repetition of which has been considered
unnecessary.
In a few instances new generic terms have been introduced to replace
some which were already occupied; these have been proposed by Mr.
Lydekker, and should be quoted as his.
The work is based largely upon the article “Mammalia,” together with
forty shorter articles, written by the senior of the two authors for
the ninth edition of the Encyclopædia Britannica. The account of the
orders Rodentia, Insectivora, and Chiroptera contributed to the article
“Mammalia” by Dr. G. E. Dobson, F.R.S., as well as the articles “Mole,”
“Shrew,” and “Vampyre,” by the same writer, the articles “Marmot,”
“Mouse,” “Opossum,” “Phalanger,” “Rat,” “Squirrel,” “Stoat,” “Vole,” and
others, by Mr. Oldfield Thomas, and likewise the article “Ape,” by Dr.
St. G. Mivart, F.R.S., have also been made use of to a greater or less
extent. The best thanks of the authors are due to these three gentlemen
for freely permitting the incorporation of their own work in the present
volume.
Mr. Lydekker undertook the task of arranging the various articles in
their proper sequence, selecting from these such portions as seemed
suitable, filling up the gaps, and adding new matter where necessary; a
large amount of this new matter treating of the extinct forms, and also
of the group Artiodactyla.
The subsequent revision, both before being sent to the printers, and also
when passing through the press, has been made by both authors, who are
thus jointly responsible for the whole work.
The illustrations are to a great extent those prepared for the various
articles in the Encyclopædia, but many have been added—some drawn
expressly for the work, and some borrowed from other publications. For
most of the latter the authors take this opportunity of expressing their
thanks to the Publication Committee of the Zoological Society of London,
as well as to the individual writers in whose works they first appeared.
The authors have further much pleasure in acknowledging the ready and
obliging way in which Mr. Oldfield Thomas has, throughout the progress of
the work, placed his extensive knowledge of the group of animals of which
it treats at their disposal.
LONDON, _March_ 1891.
CORRIGENDA.
Page 280, _for_ Chæropsis _read_ Chœropsis.
Page 292, _for_ Chæropotamidæ and Chæropotamus _read_ Chœropotamidæ and
Chœropotamus.
Page 590, _for_ Pæcilogale _read_ Pœcilogale.
=Transcriber’s Note:= The corrections have been applied.
CONTENTS
PAGE
CHAPTER I
INTRODUCTORY REMARKS 1
Use of term mammals, 1; Characters of mammals, 2;
Development of young, 3; Size of mammals, 4; Uses and
products of mammals, 4.
CHAPTER II
GENERAL ANATOMICAL CHARACTERS 7
I. Tegumentary Structures 7
Hair, 7; Colour, 8; Scales, etc., 11; Nails, claws, and
hoofs, 12; Odour-secreting glands, 12.
II. Dental System 13
Teeth, 13; Structure of teeth, 13; Development of teeth, 15;
Forms of teeth, 17; Succession of teeth, 19; Arrangement,
homologies, and notation of teeth, 21; Dental formulæ,
25; Modifications of teeth in relation to function, 28;
Taxonomy, 30; Trituberculism, 30.
III. The Skeleton 33
Definition, 33; Axial skeleton, 34; Skull, 34; Vertebral
column, 39; Cervical vertebræ, 41; Dorsal vertebræ, 42;
Lumbar vertebræ, 42; Sacral vertebræ, 43; Caudal vertebræ,
43; Sternum, 44; Ribs, 44; Appendicular skeleton, 46;
Anterior limb, 46; Shoulder-girdle, 46; Brachium and
Antebrachium, 47; Manus, 48; Carpus, 48; Metacarpus and
Phalanges, 49; Posterior limb, 50; Pelvic girdle, 50; Thigh
and Leg, 51; Pes, 52.
IV. The Digestive System 53
General considerations, 53; Mouth, 54; Salivary glands, 55;
Stomach, 57; Intestinal canal, 59; Liver, 60.
V. Circulatory, Absorbent, Respiratory, and Urinary Systems 63
Blood, 63; Heart, 63; Lymphatic vessels, 65; Ductless
glands, 65; Nostrils, 66; Trachea, 67; Larynx, 67;
Diaphragm, 67; Lungs, 68; Air-sacs, 68; Urinary Organs, 69;
Bladder, 69.
VI. Nervous System and Organs of Sense 69
Brain, 69; Nerves, 71; Sense of touch, 72; Taste and smell,
72; Sight, 72; Hearing, 73.
VII. Reproductive Organs 74
Testes, 74; Penis, 74; Ovaries and oviduct, 75; Mammary
glands, 75; Secondary sexual characters, 76; Placenta, 76.
CHAPTER III
ORIGIN AND CLASSIFICATION OF THE MAMMALIA 82
Origin, 82; Classification, 84; Table of orders and
families, 88.
CHAPTER IV
GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION 93
I. Geographical Distribution 93
Zoological regions, 96; Palæarctic region, 97; Ethiopian
region, 98; Oriental region, 100; Celebes, 102; Nearctic
region, 102; Neotropical region, 103; Aquatic mammals, 104.
II. Geological Distribution 107
Sequence of strata, 107; Mesozoic mammals, 109;
Multituberculata, 109; Polyprotodont types, 113; Tertiary
mammals, 115.
CHAPTER V
THE SUBCLASS PROTOTHERIA OR ORNITHODELPHIA 117
General characters, 117. _Family_ ORNITHORHYNCHIDÆ, 119;
_Ornithorhynchus_, 119. _Family_ ECHIDNIDÆ, 124; _Echidna_,
125; _Proechidna_, 126; Fossil species, 127.
CHAPTER VI
THE SUBCLASS METATHERIA OR DIDELPHIA 128
General characters, 128; Distribution, 131; Classification,
131.
_Suborder_ POLYPROTODONTIA 133
_Family_ DIDELPHYIDÆ, 133; _Chironectes_, 134; _Didelphys_,
135. _Family_ DASYURIDÆ, 136; _Subfamily_ Dasyurinæ, 136;
_Thylacinus_, 136; _Sarcophilus_, 137; _Dasyurus_, 138;
_Phascologale_, 139; _Sminthopsis_, 139; _Antechinomys_,
139; _Subfamily_ Myrmecobiinæ, 140; _Myrmecobius_, 140.
_Family_ PERAMELIDÆ, 141; _Perameles_, 142; _Peragale_, 143;
_Chœropus_, 143.
_Suborder_ DIPROTODONTIA 144
_Family_ PHASCOLOMYIDÆ, 144; _Phascolomys_, 145;
_Phascolonus_, 146. _Family_ PHALANGERIDÆ, 147; _Subfamily_
Tarsipedinæ, 148; _Tarsipes_, 148; _Subfamily_ Phalangerinæ,
149; _Phalanger_, 149; _Trichosurus_, 150; _Pseudochirus_,
151; _Petauroides_, 152; _Dactylopsila_, 152; _Petaurus_,
153; _Gymnobelideus_, 154; _Dromicia_, 154; _Distœchurus_,
155; _Acrobates_, 155; _Subfamily_ Phascolarctinæ,
155; _Phascolarctus_, 156. EXTINCT PHALANGEROIDS, 157;
_Thylacoleo_, 157. _Family_ MACROPODIDÆ, 158; _Subfamily_
Hypsiprymnodontinæ, 162; _Hypsiprymnodon_, 162;
_Triclis_, 162; _Subfamily_ Potoroinæ, 162; _Potorous_,
163; _Bettongia_, 163; _Caloprymnus_, 164; _Æpyprymnus_,
164; _Subfamily_ Macropodinæ, 164; _Lagostrophus_, 165;
_Dendrolagus_, 165; _Dorcopsis_, 166; _Lagorchestes_, 166;
_Onychogale_, 166; _Petrogale_, 167; _Macropus_, 167;
Extinct genera, 170. EXTINCT FAMILIES, 171; _Diprotodon_,
171; _Nototherium_, 171.
CHAPTER VII
THE SUBCLASS EUTHERIA AND THE ORDER EDENTATA 173
General characters and classification of Eutheria, 173.
ORDER EDENTATA 176
_Family_ BRADYPODIDÆ, 179; _Bradypus_, 181; _Cholœpus_, 182;
_Nothropus_, 183. _Family_ MEGATHERIIDÆ, 183; _Megatherium_,
185; _Scelidotherium_ and _Mylodon_, 188; _Promegatherium_,
189. _Family_ MYRMECOPHAGIDÆ, 190; _Myrmecophaga_, 190;
_Tamandua_, 192; _Cycloturus_, 193. _Family_ DASYPODIDÆ,
194; _Subfamily_ Chlamydophorinæ, 196; _Chlamydophorus_,
196; _Subfamily_ Dasypodinæ, 197; _Dasypus_, 197; _Xenurus_,
198; _Priodon_, 198; _Tolypeutes_, 199; _Subfamily_
Tatusiinæ, 200; _Tatusia_, 200; Extinct genera, 201.
_Family_ GLYPTODONTIDÆ, 202. _Family_ MANIDÆ, 204; _Manis_,
204; _Palæomanis_, 208. _Family_ ORYCTEROPODIDÆ, 208;
_Orycteropus_, 208. Bibliography, 211.
CHAPTER VIII
THE ORDERS SIRENIA AND CETACEA 212
ORDER SIRENIA 212
_Family_ MANATIDÆ, 215; _Manatus_, 215. _Family_ HALICORIDÆ,
220; _Halicore_, 220. _Family_ RHYTINIDÆ, 221; _Rhytina_,
221. EXTINCT SIRENIANS, 222; _Halitherium_, 222; Other
forms, 223. Bibliography, 224.
ORDER CETACEA 225
_Suborder_ MYSTACOCETI 234
_Family_ BALÆNIDÆ, 234; _Balæna_, 236; _Neobalæna_, 241;
_Rhachianectes_, 241; _Megaptera_, 241; _Balænoptera_, 242;
Extinct genera, 245.
_Suborder_ ARCHÆOCETI 246
_Family_ ZEUGLODONTIDÆ, 246; _Zeuglodon_, 246.
_Suborder_ ODONTOCETI 247
_Family_ PHYSETERIDÆ, 247; _Subfamily_ Physeterinæ, 248;
_Physeter_, 248; _Cogia_, 250; Extinct physeteroids, 251;
_Subfamily_ Ziphiinæ, 251; _Hyperoödon_, 252; _Ziphius_,
254; _Mesoplodon_, 254; _Berardius_, 256; _Choneziphius_,
257. _Family_ SQUALODONTIDÆ, 257; _Squalodon_, 257.
_Family_ PLATANISTIDÆ, 257; _Platanista_, 258; _Inia_, 259;
_Pontoporia_, 259; Fossil forms, 259. _Family_ DELPHINIDÆ,
260; _Monodon_, 260; _Delphinapterus_, 262; _Phocæna_,
263; _Cephalorhynchus_, 266; _Orcella_, 267; Orca, 267;
_Pseudorca_, 268; _Globicephalus_, 268; _Grampus_, 270;
_Feresia_, 270; _Lagenorhynchus_, 270; _Delphinus_, 271;
_Tursiops_, 271; _Prodelphinus_, 271; _Steno_, 271;
_Sotalia_, 272. Bibliography, 272.
CHAPTER IX
THE ORDER UNGULATA 273
UNGULATA VERA 275
_Suborder_ ARTIODACTYLA 275
SUINA, 278. _Family_ HIPPOPOTAMIDÆ, 278; _Hippopotamus_,
278. _Family_ SUIDÆ, 281; _Sus_, 281; _Babirusa_, 287;
_Phacochœrus_, 288. _Family_ DICOTYLIDÆ, 289; _Dicotyles_,
289; _Hyotherium_, etc., 291. EXTINCT TRANSITIONAL
ARTIODACTYLES, 292; Chœropotamidæ, 292; Anthracotheriidæ,
292; _Merycopotamus_, 293; Cotylopidæ, 293; Anoplotheriidæ,
293; Cænotheriidæ, 294; Dichodontidæ, 294. TYLOPODA, 295.
_Family_ CAMELIDÆ, 295; _Camelus_, 296; _Auchenia_, 298;
Extinct Cameloids, 303. TRAGULINA, 305. _Family_ TRAGULIDÆ,
305; _Tragulus_, 305; _Dorcatherium_, 306; Extinct
Traguloids, 306. PECORA, 307; Antlers, 308; Horns, 310;
Teeth, 310; Stomach, 312. _Family_ CERVIDÆ, 313; _Subfamily_
Moschinæ, 314; _Moschus_, 314; _Subfamily_ Cervinæ, 316;
Plesiometacarpalia, 316; _Cervulus_, 316; _Elaphodus_,
318; _Cervus_, 319; Telemetacarpalia, 323; _Rangifer_,
324; _Alces_, 326; _Cervalces_, 327; _Capreolus_, 327;
_Hydropotes_, 328; _Cariacus_, 329; _Pudua_, 330; Extinct
genera, 330. _Family_ GIRAFFIDÆ, 330; _Giraffa_, 331;
Allied extinct types, 332. _Family_ ANTILOCAPRIDÆ, 333;
_Antilocapra_, 333. _Family_ BOVIDÆ, 334; _Alcelaphus_, 334;
_Connochætes_, 336; _Cephalophus_, 338; _Tetraceros_, 338;
_Neotragus_, 338; _Nanotragus_, 339; _Pelea_, 339; _Cobus_,
339; _Cervicapra_, 340; _Antilope_, 340; _Æpyceros_,
341; _Saiga_, 341; _Pantholops_, 341; _Gazella_, 341;
_Hippotragus_, 343; _Oryx_, 343; _Addax_, 345; _Boselaphus_,
345; _Tragelaphus_, 346; _Strepsiceros_, 347; _Oreas_, 348;
Extinct types, 348; _Rupicapra_, 349; _Nemorhædus_, 350;
_Haploceros_, 351; _Budorcas_, 351; _Capra_, 352; _Ovis_,
354; _Ovibos_, 357; _Bos_, 360.
_Suborder_ PERISSODACTYLA 368
_Family_ TAPIRIDÆ, 370; _Tapirus_, 370; _Palæotapirus_, 373.
_Family_ LOPHIODONTIDÆ, 373. _Family_ PALÆOTHERIIDÆ, 375.
_Family_ EQUIDÆ, 376; _Protohippus_, 380; _Hipparion_, 380;
_Equus_, 381. _Family_ RHINOCEROTIDÆ, 402; _Rhinoceros_,
402; Extinct types, 411. _Families_ LAMBDOTHERIIDÆ,
CHALICOTHERIIDÆ, and TITANOTHERIIDÆ, 412. _Family_
MACRAUCHENIIDÆ, 414. _Family_ PROTEROTHERIIDÆ, 414.
SUBUNGULATA 414
_Suborder_ HYRACOIDEA 415
_Family_ HYRACIDÆ, 415; _Hyrax_, 417; _Dendrohyrax_, 418.
_Suborder_ PROBOSCIDEA 418
_Family_ ELEPHANTIDÆ, 423; _Elephas_, 424; _Mastodon_, 431.
_Family_ DINOTHERIIDÆ, 435; _Dinotherium_, 435.
_Suborder_ AMBLYPODA 436
_Uintatherium_, 436; _Coryphodon_, 437.
_Suborder_ CONDYLARTHRA 438
_Suborder_ TOXODONTIA 439
_Nesodon_, 439; _Toxodon_, 439; _Typotherium_, 440.
_Group_ TILLODONTIA 441
Bibliography of Ungulates 442
CHAPTER X
THE ORDER RODENTIA 443
_Suborder_ SIMPLICIDENTATA 448
_Section_ SCIUROMORPHA, 448. _Family_ ANOMALURIDÆ, 449;
_Anomalurus_, 449. _Family_ SCIURIDÆ, 450; _Sciurus_,
450; _Rhithrosciurus_, 452; _Xerus_, 452; _Tamias_,
452; _Pteromys_ and _Sciuropterus_, 453; _Eupetaurus_,
454; Extinct genera, 454; _Arctomys_, 454; _Cynomys_,
455; _Spermophilus_, 456; Extinct genera, 457. _Family_
HAPLODONTIDÆ, 457; _Haplodon_, 457. _Family_ CASTORIDÆ,
457; _Castor_, 457. _Section_ MYOMORPHA, 459. _Family_
MYOXIDÆ, 459; _Myoxus_, 459; _Eliomys_, 459; _Graphiurus_,
459; _Claviglis_, 460; _Muscardinus_, 460. _Family_
LOPHIOMYIDÆ, 460; _Lophiomys_, 460. _Family_ MURIDÆ, 461;
_Hydromys_, 461; _Xeromys_, 461; _Platacanthomys_, 462;
_Gerbillus_, 462; _Pachyuromys_, 462; _Mystromys_, 462;
_Otomys_ and _Dasymys_, 462; _Malacomys_, 462; _Phlœomys_,
462; _Dendromys_, 463; _Cricetus_, 463; _Holochilus_,
464; _Sigmodon_, 464; _Rhithrodon_ and _Ochetodon_,
464; _Neotoma_, 464; _Hypogeomys_, 465; _Nesomys_, 465;
_Brachytarsomys_, 465; _Hallomys_, 465; _Eliurus_, 465;
_Phenacomys_, 466; _Arvicola_, 466; _Synaptomys_, 467;
_Myodes_, 467; _Cuniculus_, 470; _Fiber_, 470; _Neofiber_,
472; _Ellobius_, 472; _Siphneus_, 472; _Deomys_, 473;
_Mus_, 473; _Nesocia_, 475; _Golunda_, 476; _Uromys_,
476; _Chiruromys_, 476; _Hapalotis_, 476; _Mastacomys_,
476; _Acanthomys_, 476; _Echinothrix_, 477; _Typhlomys_,
477; _Cricetomys_ and _Saccostomus_, 477; _Pithechirus_,
477. _Family_ SPALACIDÆ, 477; _Spalax_, 477; _Rhizomys_,
477; _Bathyergus_, 478; _Georychus_ and _Myoscalops_,
478; _Heterocephalus_, 478. _Family_ GEOMYIDÆ, 478;
_Geomys_, 478; _Thomomys_, 478; _Dipodomys_, 479;
_Perognathus_ and _Heteromys_, 479. _Family_ DIPODIDÆ,
479; _Sminthus_, 479; _Zapus_, 480; _Dipus_, 480;
_Alactaga_, 480; _Platycercomys_, 480; _Pedetes_, 480.
_Section_ HYSTRICOMORPHA, 480. _Family_ OCTODONTIDÆ,
480. _Ctenodactylus_, 481; _Pectinator_, 481; _Octodon_,
481; _Habrocoma_, 482; _Schizodon_, 482; _Ctenomys_,
482; _Spalacopus_, 482; _Petromys_, 482; _Myopotamus_,
482; _Capromys_, 482; _Aulacodus_, 483; _Plagiodon_,
483; _Loncheres_ and _Echinomys_, 483; _Mesomys_, 483;
_Dactylomys_, 483; _Cercomys_, 483; _Carterodon_, 484;
Fossil forms, 484. _Family_ THERIDOMYIDÆ, 484. _Family_
HYSTRICIDÆ, 484; _Erethizon_, 484; _Synetheres_, 485;
_Chætomys_, 486; _Hystrix_, 486; _Atherura_, 487; _Trichys_,
487. _Family_ CHINCHILLIDÆ, 487; _Chinchilla_, 487;
_Lagidium_ and _Lagostomus_, 488; Extinct genera, 488.
_Family_ CASTOROIDIDÆ, 488; _Castoroides_, 488. _Family_
DASYPROCTIDÆ, 488; _Dasyprocta_, 488; _Cælogenys_, 489.
_Family_ DINOMYIDÆ, 489; _Dinomys_, 489. _Family_ CAVIIDÆ,
489; _Cavia_, 489; _Dolichotis_, 490; _Hydrochœrus_, 490;
Extinct genera, 491.
_Suborder_ DUPLICIDENTATA 491
_Family_ LAGOMYIDÆ, 491; _Lagomys_, 491. _Family_ LEPORIDÆ,
492; _Lepus_, 492.
CHAPTER XI
THE ORDER CARNIVORA 496
_Suborder_ CARNIVORA VERA 497
_Section_ ÆLUROIDEA, 501. _Family_ FELIDÆ, 502; _Felis_,
502; _Cynælurus_, 523; Extinct genera, 523. _Family_
VIVERRIDÆ, 525; _Cryptoprocta_, 525; _Viverra_, 526;
_Fossa_, 527; _Genetta_, 528; _Prionodon_, 530; _Poiana_,
531; _Paradoxurus_, 532; _Arctogale_, 533; _Hemigale_,
533; _Arctictis_, 534; _Nandinia_, 534; _Cynogale_, 534;
_Herpestes_, 535; _Helogale_, 537; _Bdeogale_, 537;
_Cynictis_, 537; _Rhinogale_, 537; _Crossarchus_, 537;
_Suricata_, 538; _Galidictis_, _Galidea_, and _Hemigalidea_,
538; _Eupleres_, 538; Extinct genera, 539. _Family_
PROTELEIDÆ, 539; _Proteles_, 539. _Family_ HYÆNIDÆ, 540;
_Hyæna_, 540. _Section_ CYNOIDEA, 544. _Family_ CANIDÆ, 544;
_Canis_, 546; _Lycaon_, 553; _Icticyon_, 553; _Otocyon_,
554; Extinct genera, 555. _Section_ ARCTOIDEA, 556. _Family_
URSIDÆ, 557; _Ursus_, 557; _Melursus_, 560; _Æluropus_, 560;
Extinct genera, 561. _Family_ PROCYONIDÆ, 562; _Ælurus_,
562; _Procyon_, 564; _Bassaris_, 566; _Bassaricyon_, 566;
_Nasua_, 566; _Cercoleptes_, 567. _Family_ MUSTELIDÆ, 567;
_Lutra_, 567; Extinct Otters, 570; _Latax_, 570; _Mephitis_,
572; _Conepatus_, 574; _Arctonyx_, 574; _Mydaus_, 575;
_Meles_, 575; _Taxidea_, 576; _Mellivora_, 576; _Helictis_,
578; _Ictonyx_, 579; _Galictis_, 579; _Mustela_, 579;
Extinct Mustelines, 590; _Pœcilogale_, 590; _Lyncodon_, 590;
_Gulo_, 591.
_Suborder_ PINNIPEDIA 592
_Family_ OTARIIDÆ, 593; _Otaria_, 593. _Family_ TRICHECHIDÆ,
596; _Trichechus_, 597. _Family_ PHOCIDÆ, 600; _Halichœrus_,
601; _Phoca_, 601; _Monachus_, 604; _Ogmorhinus_, 605;
_Lobodon_, 605; _Pœcilophoca_, 605; _Ommatophoca_, 605;
_Cystophora_, 605; _Macrorhinus_, 606; Extinct seals, 606.
_Suborder_ CREODONTA 606
_Hyænodontidæ_, 608; _Proviverridæ_, 608; _Arctocyonidæ_ and
_Mesonychidæ_, 609.
CHAPTER XII
THE ORDER INSECTIVORA 610
_Suborder_ DERMOPTERA 614
_Family_ GALEOPITHECIDÆ, 614; _Galeopithecus_, 614.
_Suborder_ INSECTIVORA VERA 616
_Family_ TUPAIIDÆ, 617; _Tupaia_, 617; _Ptilocercus_,
618; Extinct genera, 618. _Family_ MACROSCELIDIDÆ, 618;
_Macroscelides_, 618; _Rhynchocyon_, 618. _Family_
ERINACEIDÆ, 619; _Gymnura_, 619; _Erinaceus_, 620;
Extinct genera, 621; _Family_ SORICIDÆ, 621; _Sorex_,
622; _Soriculus_, 624; _Notiosorex_, 624; _Blarina_, 624;
_Crossopus_, 625; _Myosorex_, 625; _Crocidura_, 626;
_Diplomesodon_, 626; _Anurosorex_, 626; _Chimarrogale_, 626;
_Nectogale_, 627; Fossil Soricidæ, 627. _Family_ TALPIDÆ,
628; _Myogale_, 628; _Urotrichus_, 629; _Uropsilus_,
629; _Scalops_, 630; _Scapanus_, 630; _Condylura_, 630;
_Scaptonyx_, 630; _Talpa_, 630; Extinct genera, 634.
_Family_ ADAPISORICIDÆ, 634. _Family_ POTAMOGALIDÆ, 634;
_Potamogale_, 635; _Geogale_, 635. _Family_ SOLENODONTIDÆ,
635; _Solenodon_, 636; _Centetes_, 637; _Hemicentetes_,
637; _Ericulus_, 638; _Microgale_, 638; _Oryzorictes_, 638;
_Chrysochloris_, 639. EXTINCT TYPES, 640. Bibliography, 640.
CHAPTER XIII
THE ORDER CHIROPTERA 641
_Suborder_ MEGACHIROPTERA 650
_Family_ PTEROPODIDÆ, 650; _Epomophorus_, 650; _Pteropus_,
651; _Xantharpyia_, 652; _Boncia_, 653; _Cynopterus_, 653;
_Harpyia_, 653; _Cephalotes_, 653; _Pteralopex_, 654;
_Notopteris_, 654; _Eonycteris_, 654; _Carponycteris_ and
_Melonycteris_, 654; _Nesonycteris_, 655; _Callinycteris_,
655; _Trygenycteris_, 655.
_Suborder_ MICROCHIROPTERA 655
_Section_ VESPERTILIONINA, 655. _Family_ RHINOLOPHIDÆ,
656; _Rhinolophus_, 656; _Hipposiderus_, 657; _Anthops_,
657; _Rhinonycteris_ and _Triænops_, 658; _Cœlops_, 658;
_Megaderma_, 658. _Family_ VESPERTILIONIDÆ, 660; _Plecotus_,
660; _Synotus_, 661; _Otonycteris_, 661; _Nyctophilus_, 661;
_Antrozous_, 661; _Vesperugo_, 661; _Chalinolobus_, 662;
_Scotophilus_, 662; _Nycticejus_, 663; _Atalapha_, 663;
_Harpyiocephalus_, 663; _Vespertilio_, 663; _Cerivoula_,
664; _Natalus_, 664; _Miniopterus_, 664; _Thyroptera_,
665; _Myxopoda_, 665; Fossil Vespertilionidæ, 665.
_Section_ EMBALLONURINA, 666. _Family_ EMBALLONURIDÆ, 666;
_Furipterus_ and _Antorphochilus_, 666; _Emballonura_, 667;
_Coleüra_, 667; _Rhynchonycteris_, 667; _Saccopteryx_,
667; _Taphozous_, 667; _Diclidurus_, 668; _Noctilio_,
668; _Rhinopoma_, 669; _Chiromeles_, 669; _Molossus_,
670; _Nyctinomus_, 670; _Mystacops_, 671. _Family_
PHYLLOSTOMATIDÆ, 672; _Chilonycteris_, 672; _Mormops_,
672; _Lonchorhina_, _Otopterus_ and _Dolichophyllum_, 673;
_Vampyrus_, etc., 673; _Desmodus_, 677; _Diphylla_, 678.
CHAPTER XIV
THE ORDER PRIMATES 680
_Suborder_ LEMUROIDEA 682
_Family_ LEMURIDÆ, 683; _Indris_, 684; _Propithecus_,
684; _Avahis_, 686; _Lemur_, 687; _Hapalemur_, 689;
_Lepidolemur_, 689; _Chirogaleus_, 689; _Galago_, 690;
_Nycticebus_, 691; _Loris_, 692; _Perodicticus_, 693.
_Family_ TARSIIDÆ, 694; _Tarsius_, 694. _Family_ CHIROMYIDÆ,
694; _Chiromys_, 695. EXTINCT LEMUROIDS, 696.
_Suborder_ ANTHROPOIDEA 699
_Family_ HAPALIDÆ, 709; _Hapale_, 710; _Midas_, 710.
_Family_ CEBIDÆ, 711; _Mycetes_, 711; _Pithecia_, 712;
_Uacaria_, 712; _Callithrix_, 713; _Chrysothrix_, 714;
_Nyctipithecus_, 714; _Ateles_, 715; _Eriodes_, 715;
_Lagothrix_, 716; _Cebus_, 717. _Family_ CERCOPITHECIDÆ,
718; _Cynocephalus_, 719; _Theropithecus_, 722;
_Cynopithecus_, 722; _Macacus_, 722; _Cercocebus_, 723;
_Cercopithecus_, 724; _Nasalis_, 725; _Semnopithecus_, 726;
_Colobus_, 727; Extinct genera, 727. _Family_ SIMIIDÆ,
728; _Hylobates_, 728; _Simia_, 731; _Gorilla_, 734;
_Anthropopithecus_, 736. _Family_ HOMINIDÆ, 739; _Homo_,
740. Classification of the varieties of Man, 743.
AN INTRODUCTION TO THE STUDY OF MAMMALS LIVING AND EXTINCT
CHAPTER I
_INTRODUCTORY REMARKS_
Mammalia (French, _Mammifères_; German, _Säugethiere_) is the name
invented by Linnæus (from the Latin _mamma_), and now commonly used by
zoologists, for one of the five great classes of vertebrated animals,
which, though the best known and undoubtedly the most important group
of the animal kingdom, has never received any generally accepted
vernacular designation in our language. The unity of structure of the
animals composing this class, and their definite demarcation from other
vertebrates, were not recognised until comparatively modern times,
and hence no word was thought of to designate what zoologists now
term a mammal. The nearest equivalents in common use are “beast” and
“quadruped,” both of which, however, cover a different ground, since they
are often used to include the larger four-footed reptiles, and to exclude
certain undoubted mammals, as Man, Bats, and Whales.
The limits of the class as now understood by zoologists are perfectly
well defined, and, although certain forms still existing on the earth
(but not those mentioned above as excluded by the popular idea) are
of exceedingly aberrant structure, and exhibit several well-marked
characters connecting them with the lower vertebrated groups, common
consent retains them in the class with which the great proportion of
their characters ally them, and hitherto no traces of any species showing
still more divergent or transitional characters have been discovered.
There is thus an interval, not bridged over by any known forms, between
mammals and other vertebrates; although recent discoveries have shown
evidence of a more or less marked affinity between the most generalised
mammals and a peculiar group of extinct reptiles known as the Anomodontia
(or Theromora), which are themselves nearly related to the equally
extinct Labyrinthodont amphibians of the Palæozoic and Mesozoic epochs.
In the gradual order of evolution of living beings, mammals, taken
altogether, are certainly the highest in organisation, as, with the
possible exception of birds, they were the last to appear on the
earth’s surface. But, as in speaking of all other large and greatly
differentiated groups, this expression must not be understood in too
limited a sense. The tendency to gradual perfection for their particular
station in life, which all groups manifest, leads to various lines of
specialisation, or divergence from the common or general type, which
may or may not take the direction of elevation. A too complex and
sensitive condition of organisation may in some circumstances of life be
disadvantageous, and modification may then take place in a retrograde
direction. Thus in mammals, as in other classes, there are low as well as
high forms, but by any tests that can be applied—especially those based
on the state of development of the central nervous system—it will be seen
that the average exceeds that of any other class; that the class contains
many species far excelling those of any other in perfection of structure,
and especially one form which is unquestionably the culminating point yet
arrived at amongst organised beings.
With regard to the time of the first appearance of mammals upon
the earth, the geological record is provokingly imperfect. At the
commencement of the Tertiary period they were abundant, and already
modified into most of the leading types at present existing. It was at
one time thought that they first came into being at this date, but the
discovery of more or less fragmentary remains of numerous and generally
small species has revealed the existence of some forms of the class at
various periods throughout almost the whole of the age of the deposition
of the Secondary or Mesozoic rocks. This subject will be reverted to
later on.
It hardly need be said that mammals are vertebrated animals, and possess
all the characteristics common to the members of that division of the
animal kingdom. They are separated from the _Ichthyopsida_ (fishes and
amphibians), and agree with the _Sauropsida_ (reptiles and birds), in
the possession during their development of an amnion and allantois, and
in never having external branchiæ or gills. They differ from reptiles
and resemble birds in being warm-blooded, and having a heart with four
cavities and a complete double circulation. They differ from both birds
and reptiles in the red corpuscles of the blood being non-nucleated
and, with very few exceptions, circular in outline; in the lungs being
freely suspended in a thoracic cavity, separated from the abdomen by a
complete muscular partition—the diaphragm—which is the principal agent
in inflating the lungs in respiration; in having but one aortic arch,
which curves over the left bronchus; in the skin being more or less
clothed with hair; in the greater perfection of the commissural system of
the cerebral hemispheres, which has either a complete corpus callosum,
or an incomplete one associated with a very large anterior commissure;
in having no syrinx or inferior vocal organ, but a complete larynx at
the upper end of the trachea; in having a mandible of which each ramus
(except in very early developmental conditions) consists of a single bone
on each side, articulating to the squamosal without the intervention of
a quadrate bone; in having a pair of laterally placed occipital condyles
instead of one median one; and in the very obvious character of the
female being provided with mammary glands, by the secretion of which the
young (usually produced alive, although in the lowest forms by means of
externally hatched eggs) are nourished for some time after birth.
In common with all vertebrated animals, mammals never have more than
two pairs of limbs; as the larger number live ordinarily on the surface
of the earth, in the great majority of the class both pairs are
well-developed and functional, and adapted for terrestrial progression.
Mammals are, however, by no means limited to this situation. Thus some
species spend the greater part of their lives beneath the surface, their
fore limbs being specially modified for burrowing; others, again, are
habitually arboreal, their limbs being fitted for climbing or hanging
to boughs of trees; some are as aerial as birds, the fore limbs being
developed into wings of a special character; while in others which are as
aquatic as fishes, the limbs assume the form of fins or paddles. In many
of the latter the hinder extremities are either completely suppressed,
or present only in a rudimentary state. In no known mammal are the fore
limbs absent.
The hinder extremity of the axis of the body is usually prolonged into
a tail, which may be a mere pendent appendage, or may be modified to
perform various functions, as grasping boughs in climbing, or even
gathering food, in the case of the prehensile-tailed Monkeys and
Opossums, swimming in the Cetacea, and acting as a flap to drive away
troublesome insects from the skin in the Ungulata.
The state of development of the young at the time of birth varies greatly
in the different groups. Thus among the Marsupials where there is no
connection during intra-uterine life between the circulatory systems
of the parent and the fœtus, the young are born in an exceedingly
imperfectly developed condition. For their protection the mother, in
a large number of cases, has a special pouch enclosing the mammæ, into
which the young are transferred at birth, and in which they remain till
they are well developed. Among the higher, or Placental types, however,
where a connection exists between the maternal and fœtal circulations
previous to birth, the young are always born in a much more highly
developed state than among the Marsupials, although we meet with great
variations in this respect. In those forms which habitually live in
holes, like many Rodents, the young are always very helpless at birth;
and the same is also true of many of the Carnivora, which are well able
to defend their young from attack. In the great order of Ungulate,
or Hoofed Mammals, where in the majority of cases defence from foes
depends upon fleetness of foot, or upon huge corporeal bulk, the young
are born in a very highly developed condition, and are able almost at
once to run by the side of the parent. This state of relative maturity
at birth reaches its highest development in the Cetacea, where it is
evidently associated with the peculiar conditions under which these
animals pass their existence. In the Primates, however, we again find
the young produced in a more or less helpless condition, and requiring
a long period before they attain their full development, this being
more especially the case with those higher forms which approximate in
structure to man.
In point of size mammals vary to a greater extent than the existing
members of any one class of animals, and include the largest living
inhabitants of the earth. The extremes of size are marked on the one
hand by the whale known as Sibbald’s Rorqual, which attains a length of
eighty feet and a weight of nearly as many tons, and on the other by the
Pigmy-Shrew and the minute Harvest-mouse, which can climb a stem of wheat.
Of all the living creatures inhabiting our globe, mammals are by far
the most important in their economic uses, since, in addition to being
the only animals capable of labour for human benefit, they furnish the
greater portion of the animal food of many races of man, and likewise a
large amount of their clothing. In these respects the Ungulates hold the
first place.
As regards employment for labour, with the exception of the Dogs used
for sleighing by the Esquimaux, and those which among some European
nations draw light carts, all the mammals in general use are Ungulates.
Of the first importance are the Horses and Asses, which are employed
as beasts of draught or burden over nearly the whole globe. Among many
nations, however, cattle, as represented by the true Oxen, the Buffalos,
and the Yaks of Tibet, occupy a still more important position, while in
the highlands of Tibet, Sheep are largely used for carrying burdens. In
other regions, again, the place of the Horse and the Ass is taken by the
Camels, which are peculiarly fitted for traversing parched and arid
deserts, while in the Andes we find the Llamas serving the same office.
In Lapland and other parts of the northern regions the Reindeer is the
main agent employed in draught. Lastly, we must not omit to mention the
Indian Elephant, which, from its vast strength, is so useful in transport
through the wilder parts of its native country.
As regards food, we again find the Ungulates, and more especially the
Artiodactyle division, taking the foremost place; and in this connection
we have only to mention, among animals kept in a domestic condition,
Swine, Cattle, Sheep, and Goats—the three latter affording not only their
flesh, but also milk and its resulting cheese and butter. To many races,
however, Mares and Camels are the chief milk producers, while the Laps
make use of the milk of the Reindeer. The Rodents, as represented by
Hares and Rabbits, occupy a minor position as furnishers of food.
In relation to clothing, the Ungulates are likewise of paramount
importance, as exemplified by the wool of the Sheep, which is so valuable
on account of its peculiar property of felting. Furs, however, are
mostly yielded by mammals of other orders, among which the Fur-seals are
perhaps the most important at the present day. Many other Carnivores
yield valuable furs, among which may be mentioned Bears, Foxes, Raccoons,
Skunks, Minks, Otters, and Ermines. Of less importance are certain
Rodents, such as the Squirrels, Rabbits, Hares, etc., while the hair of
the Beaver was formerly much sought after for the manufacture of hats.
Returning to the Ungulates, we may notice the importance of horse-hair,
the employment of camel’s hair for brushes, and the many uses of the
bristles of the pig. Some of the Monkeys yield fur which has been
extensively used. Leather, again, is almost exclusively supplied by
mammals, and mainly by the Ungulates.
Three other important products, namely horn, buck’s-horn, and ivory, are
likewise obtained solely from the same great order. Horn, as we shall
notice in the sequel, is the sheath covering the bony horn-cores of the
Oxen, while buck’s-horn is the commercial term applied to the antlers of
the Deer, which are largely used for knife-handles and other purposes.
True ivory is the product of the two species of Elephant; but other kinds
of ivory are obtained from the teeth of the Sperm Whale and the tusks
of the Walrus and Hippopotamus, the latter kind having been extensively
employed some years ago for artificial teeth. For many purposes the place
of ivory is taken by bone, this being mostly obtained from Ungulates.
The bones of Camels are of an especially firm texture and good colour,
and are largely employed in India for inlaying. Other important uses of
bones are in the form of bone-dust as manure, and also as a source of
phosphoric acid. The horns of the African Rhinoceros and the hide of the
Hippopotamus are occasionally manufactured into small canes or whips.
Horns and hoofs are also largely employed in the manufacture of glue.
Formerly the so-called whalebone, or more properly baleen, was much
used, especially to form the ribs of umbrellas and in stiffening ladies’
apparel, but the gradual destruction of the Right Whales, its only source
of supply, has largely restricted its use of late years.
The Cetacea are also of great economical importance from the abundance
of oil yielded by the thick layer of blubber underlying the skin.
Large quantities of valuable oil are also furnished by the Walrus and
the Seals. Spermaceti, which was at one time extensively used in the
manufacture of candles, is obtained from a large cavity in the head
of the Sperm Whale or Cachalot, and also from the _Hyperoödon_ or
Bottle-nosed Whale.
The nature of ambergris, a peculiar substance found floating on the
surface of the sea and employed in perfumery, was long a matter of
controversy; but it appears to be an intestinal concretion of the Sperm
Whale. Other substances of more importance to the perfumer are musk, the
product of the Musk-Deer of the Himalaya, and civet, which is obtained
from the so-called Civet Cat and other allied Carnivores. A secretion of
the Beaver has also been used in perfumery and in medicine.
CHAPTER II
GENERAL ANATOMICAL CHARACTERS
I. TEGUMENTARY STRUCTURES
_Hair._—The external surface of the greater number of members of the
class is thickly clothed with a peculiarly modified form of epidermis,
commonly called hair. This consists of hard, elongated, slender,
cylindrical or tapering, filiform, unbranched masses of epidermic
material, growing from a short papilla sunk at the bottom of a follicle
in the derm or true skin. Such hairs upon different parts of the same
animal, or upon different animals, assume various forms, and are of
various sizes and degrees of rigidity,—as seen in the delicate soft
velvety fur of the Mole, the stiff bristles of the Pig, and the spines
of the Hedgehog and Porcupine, all modifications of the same structures.
Each hair is composed usually of a cellular pithy internal portion,
containing much air, and a denser or more horny cortical part. In some
animals, as Deer, the substance of the hair is almost entirely composed
of the medullary or cellular substance, and it is consequently very
easily broken; in others the horny part prevails almost exclusively, as
in the bristles of the Wild Boar. In the Three-toed Sloth (_Bradypus_)
the hairs have a central horny axis and a pithy exterior. Though
generally nearly smooth, or but slightly scaly, the surface of some hairs
is strongly imbricated, notably so in some Bats; while in the Two-toed
Sloth (_Cholœpus_) the hairs are longitudinally grooved or fluted.
Though usually more or less cylindrical or circular in section, hairs
are often elliptical or flattened, as in the curly-haired races of men,
the terminal portion of the hair of Moles and Shrews, and conspicuously
in the spines of the Rodents _Xerus_ and _Platacanthomys_. Hair having
a property of mutual cohesion or “felting,” which depends upon a
roughened scaly surface and a tendency to curl, as in domestic Sheep (in
which animal this property has been especially cultivated by selective
breeding), is called “wool.”
In a large number of mammals hairs of one kind only are scattered pretty
evenly over the surface; but in many there are two kinds, one longer,
stiffer, and alone appearing on the surface, and the other shorter,
finer, and softer, constituting the under fur, analogous to the down
of birds. This under fur, or _pashm_ as it is called by the natives
of Kashmir, is especially abundant in the mammals inhabiting the cold
plateau of Tibet and the adjacent regions. In many cases hairs of a
different character from those of the general surface grow in special
regions, forming ridges or tufts on the median dorsal or ventral surface
or elsewhere. The tail is very often completed in this way by variously
disposed elongated hairs. The margins of the eyelids are almost always
furnished with a special row of stiffish hairs, called _cilia_ or
eyelashes; and in most mammals specially modified hairs, constituting
the _vibrissæ_ or whiskers, and endowed, through the abundant nerve
supply of their basal papillæ, with special tactile powers, grow from
the lips and cheeks. In some mammals the hairy covering is partial and
limited to particular regions; in others, as the Hippopotamus and the
Sirenia, though scattered over the whole surface, it is extremely short
and scanty; but in none is it reduced to so great an extent as in the
Cetacea, in which it is limited to a few small bristles confined to the
neighbourhood of the lips and nostrils, and often only present in the
young or even fœtal condition.
Some kinds of hairs, as those of the mane and tail of the Horse, appear
to persist throughout the lifetime of the animal; but more generally,
as in the case of the body hair of the same animal, they are shed and
renewed periodically, generally annually. Many mammals have a longer
hairy coat in winter, which is shed as summer comes on; and some few,
which inhabit countries covered in winter with snow, as the Arctic Fox,
Variable Hare, and Ermine, undergo a complete change of colour in the
two seasons, being white in winter, and gray or brown in summer. The
several species of Cape Mole (_Chrysochloris_), the Desmans or Water
Moles (_Myogale_), and _Potamogale velox_, are remarkable as being the
only mammals whose hair reflects those iridescent tints so common in the
feathers of tropical birds.
The principal and most obvious purpose of the hairy covering is to
protect the skin against external influences, especially cold and damp.
Its function in the hairless Cetacea is supplied by the specially
modified and thickened layer of adipose tissue beneath the skin, called
“blubber.”
_Colour._—From the consideration of hair we are easily led to that of
colour. As a general rule, bright and primary colours are absent in
the class; but among the Baboons we find brilliant patches of scarlet
or blue on some of the bare portions of the body, and one of the South
American Monkeys (_Brachyurus_) has its whole face of a bright crimson.
The most general colours are various shades of gray, brown, and tawny,
with a frequent tendency to whiteness of the ventral surface of the
body; but among the Squirrels, and more especially those provided with
a parachute for flying, we find brilliant russets, passing into orange
and red. Dark brown or black is also not very uncommon, as in the Bears
and the Sable Antelope of South Africa. Entirely white mammals are rare,
and mostly characteristic of the polar regions, or of countries having
a long and snowy winter. An entirely white Bat (_Diclidurus albus_)
occurs, however, in South America. In the large majority of mammals that
exhibit a varied coloration, the upper and most exposed parts of the
surface present the richest and darkest colours, the under parts being
pale or often quite white. The Ratels, Gluttons, _Ælurus_, Hamsters,
and some others are exceptions to this rule. A large number of mammals
having a ground colour of gray, tawny, or dun are marked by stripes or
spots, which are generally of a darker hue than the ground colour, as in
many Carnivora, but more rarely are lighter, as in the Fallow and Axis
Deer and several species of Antelope. These stripes very generally run
transversely to the axis of the body, as in the Tasmanian Thylacine, the
Tiger, and the Zebra; but they may be longitudinal, as in several of
the Civet family. There has been considerable discussion as to whether
the striped or the spotted is the more primitive type of coloration;
but no very conclusive arguments have been brought forward in favour of
either view. It is, however, manifest that in several groups of mammals
there is a tendency to lose the spots, and more rarely the stripes, and
to assume a uniform colour. Thus the young of nearly all the species of
Deer are spotted, whereas the adults of only the Fallow and Axis Deer
are so marked. The same is true of most of the Pigs; and the young of
the Malayan and American Tapirs are marked by light-coloured stripes and
spots on a dark ground. In like manner the young of the Lion and the
Puma exhibit distinct spots which disappear with advancing age. In most
of our domestic horses of various shades of bay and brown we may detect
“dappling” on the under hair when the outer coat has been removed, which
is not apparent on the surface of the latter. Many varieties of the Ass
and the Horse also exhibit a tendency to the presence of stripes on the
legs, which would seem to indicate a descent from a striped Zebra-like
type.
A peculiar feature, which is, however, common to many other groups of
animals, is the tendency to what is known as melanism, or the production
of black or dark individuals or races of particular species, due to an
excess of pigment in the skin and hair. Thus we may have black Leopards
and Jaguars, black Wolves, and black Rabbits.
The opposite to melanism, and of more frequent occurrence, is albinism—a
condition in which the pigment or colouring matter usually present in
the tissues constituting the external coverings of the body, and which
gives them their characteristic hue, is absent. When it occurs the hair
is of an opaque white, the claws, hoofs, etc., of a pale horn-colour,
and the skin and eyes pink, in consequence of the colour of the blood
which circulates through them being no longer concealed by the stronger
hues of the pigments. An animal in this condition is called an _albino_.
In complete albinism there is a total absence of pigment throughout the
system. This condition occurs occasionally as an individual peculiarity
among wild animals of many kinds; but it has never been perpetuated among
them in distinct races or species. The disadvantage of absence of pigment
in the eye, causing a certain amount of intolerance of light, is probably
sufficient to account for this. Several races of true albinos, as White
Ferrets, Rabbits, Rats, and Mice, have, however, been established under
the protection of man, and in them this abnormal condition is propagated
from generation to generation.
Partial albinism—a condition in which the absence of pigment is limited
to portions of the surface, or, at all events, does not extend to the
eyes—is much more common as an individual variation both in domestic and
in wild animals. It is possible that the artificial conditions incident
to domestication increase the tendency to its occurrence; but, whether
this be so or not, it certainly becomes perpetuated more frequently among
domesticated than among wild animals. This may be accounted for partly
by its proving of no disadvantage to them, and partly by the frequent
selection by man of animals of such colour in preference to others. The
result is that there is no completely domestic animal of which white
races do not exist. On the other hand, to most wild animals even partial
albinism seems to be a disadvantage in the struggle for existence, since,
except in the case of species inhabiting lands continually covered with
snow, it renders them more conspicuous objects both to their enemies and
their prey, and hence it is rarely perpetuated. In northern regions,
however, a large proportion of species are regularly and normally of a
white colour, either, as the Polar Bear, all the year through, or, as the
Ermine or Stoat, Arctic Fox, and Alpine Hare, during the winter season.
The coloration in these cases is obviously protective, as it is also to a
great extent in many other instances throughout the class.
Among conspicuously coloured mammals, it has been observed that the
vertical black and tawny stripes of the Tiger harmonise so well with the
brown and green grasses of its native jungle as to render the animal
almost invisible when lying among them; while the dappled hide of the
Giraffe is said to agree equally well with the chequered splashes of
light and shade in the clumps of tall mimosas among which it feeds. The
uniformly tawny hue of the Lion accords well with the prevailing tint
of its native desert; and any one who has seen an Elephant or Buffalo in
the deep shades of an Indian forest will realise how perfectly adapted is
their dull, slaty colour to concealment in such a spot. The dun colour
of the Wild Ass of India is equally well suited to the sandy deserts
of Kutch; it is also stated that the brilliant stripes of the Zebras
of Africa are arranged in such proportion as exactly to match the pale
tint which arid ground possesses when seen by moonlight.[1] The most
remarkable instance of protective coloration is, however, to be found in
the Sloths of South America, in which the coarse gray hairs so closely
resemble a mass of lichenous growth that it is almost impossible to
distinguish these animals when at rest from the gnarled and lichen-clad
boughs from which they suspend themselves. This resemblance is increased
by the fact that the hairs actually develop a growth of lichens upon
themselves. That the sombre coloration of these animals has been produced
to harmonise with their present surroundings seems to be evident by the
circumstance that when the long hair is plucked off the under fur is seen
to present a bold alternation of black and yellow stripes, which may
probably be regarded as the original primitive coloration of this group.
_Scales, etc._—True scales, or flat imbricated plates of horny material,
covering the greater part of the body, so frequently occurring in
reptiles, are found only in one family of mammals, the _Manidæ_ or
Pangolins; but these are also associated with hairs growing from the
intervals between the scales, or on the parts of the skin not covered
by them. Similarly, imbricated epidermic productions form the covering
of the under surface of the tail of the flying Rodents of the genus
_Anomalurus_; and flat scutes, with the edges in apposition, and not
overlaid, clothe both surfaces of the tail of the Beaver, Rats, and
others of the same order, and also of some Insectivores and Marsupials.
The Armadillos alone have an ossified exoskeleton, composed of plates
of true bony tissue, developed in the derm or corium, and covered with
scutes of horny epidermis. Other epidermic appendages are the horns of
Ruminants and Rhinoceroses,—the former being elongated, tapering, hollow
caps of hardened epidermis of fibrillated structure, fitting on and
growing from conical projections of the frontal bone, and always arranged
in pairs, while the latter are of similar structure, but solid and
without any internal bony support, and (in all existing species) situated
in the median line. Callosities, or bare patches covered with hardened
and thickened epidermis, are found covering the pads under the soles of
the feet and undersurfaces of the toes of nearly all mammals, upon the
ischial tuberosities of many Apes, the sternum of Camels, on the inner
side of the limbs of the _Equidæ_, the grasping under surface of the
tail of the prehensile-tailed Monkeys, etc. The greater part of the skin
of both species of one-horned Asiatic Rhinoceros is immensely thickened
and stiffened by increase of the tissue both of the derm and epiderm,
constituting the well-known jointed “armour-plated” hide of those animals.
_Nails, Claws, and Hoofs._—With very few exceptions, the terminal
extremities of the digits of both limbs are more or less protected or
armed by epidermic plates or sheaths, constituting the various forms
of nails, claws, or hoofs. These are wanting in the Cetacea alone. A
perforated spur, with a special secreting gland in connection with it,
is found attached to the hind leg of the males of the three genera of
Monotremata, _Ornithorhynchus_, _Proechidna_, and _Echidna_.
_Odour-secreting Glands._—Besides the universally distributed sebaceous
glands connected with the pilose system, most mammals have special glands
situated in modified portions of the integument, often involuted to form
a shallow recess or a deep sac with a narrow opening, situated in various
parts of the surface of the body, and secreting odorous substances,
by the aid of which individuals appear to recognise one another, and
probably affording the principal means by which wild animals are able
to become aware of the presence of other members of the species, even
at great distances. Although the commencement of the modifications of
portions of the external covering for the formation of special secretions
may be at present difficult to understand, the principle of natural
selection will readily explain how such organs become fixed and gradually
increase in development in any species, especially as there would
probably be a corresponding modification and increased sensibility of the
olfactory organs. Such individuals as by the intensity and peculiarity
of their scent had greater power of attracting the opposite sex would
certainly be those most likely to leave descendants to inherit and in
their turn propagate the modification.
To this group of structures belong the suborbital gland or “crumen” of
Antelopes and Deer, the frontal gland of the Muntjac and of Bats of
the genus _Hipposiderus_, the submental gland of the Chevrotains and
of _Taphozous_ and some other Bats, the post-auditory follicle of the
Chamois, the temporal gland of the Elephant, the lateral glands of the
Musk-Shrew, the dorsal gland of the Peccary, the inguinal glands of
Antelopes, the preputial glands of the Musk-Deer and Beaver (already
alluded to in connection with the use made of their powerfully odorous
secretion in medicine and perfumery) and also of the Swine and Hare,
the anal glands of Carnivora, the perineal gland of the Civet (also of
commercial value), the caudal glands of the Fox and Goat, the gland on
the humeral membrane of Bats of the genus _Saccopteryx_, the post-digital
gland of the Rhinoceros, the interdigital glands of the Sheep and many
Ruminants, and numerous others. In some of these cases the glands are
peculiar to, or more largely developed in, the male; in others they are
found equally developed in both sexes.
II. DENTAL SYSTEM
The dental system of mammals may be considered rather more in detail
than space permits for some other portions of their structure, not only
on account of the important part it plays in the economy of the animals
of this class, but also for its interest to zoologists as an aid in the
classification and identification of species. Owing to the imperishable
nature of their tissues, teeth are preserved for an indefinite time, and
in the case of extinct species frequently offer the only indications
available from which to derive an idea of the characters, affinities,
and habits of the animals to which they once belonged. Hence even
their smallest modifications have received great attention from
comparative anatomists, and they have formed the subject of many special
monographs.[2]
Teeth are present in nearly all mammals, and are applied to various
purposes. They are, however, mainly subservient to the function of
alimentation, being used either in procuring food, by seizing and
killing living prey or gathering and biting off portions of vegetable
material, and more indirectly in tearing or cutting through the hard
protective coverings of food substances, as the husks and shells of nuts,
or in pounding, crushing, or otherwise mechanically dividing the solid
materials before swallowing, so as to prepare them for digestion in the
stomach. Certain teeth are also in many animals most efficient weapons of
offence and defence, and for this purpose alone, quite irrespective of
subserviency to the digestive process, are they developed in the male sex
of many herbivorous animals, in the females of which they are absent or
rudimentary.
Teeth belong essentially to the tegumentary or dermal system of organs,
and, as is well seen in the lower vertebrates, pass by almost insensible
gradations into the hardened spines and scutes formed upon the integument
covering the outer surface of the body; but in mammals they are more
specialised in structure and limited in locality. In this class they
are developed only in the gums or fibro-mucous membrane covering the
alveolar borders of the upper and lower jaws, or, in other words, the
premaxillary and maxillary bones and the mandible. In the process of
development, for the purpose of giving them that support which is needful
for the performance of their functions, they almost always become
implanted in the bone,—the osseous tissue growing up and moulding itself
around the lengthening root of the tooth, so that ultimately they become
apparently parts of the skeleton. In no mammal, however, does ankylosis
or bony union between the tooth and jaw normally take place, as in
many fishes and reptiles,—a vascular layer of connective tissue, the
alveolo-dental membrane, always intervening.[3] The presence of two or
more roots, frequently met with in the cheek-teeth of mammals, implanted
in corresponding distinct sockets of the jaw, is now peculiar to animals
of this class.[4]
_Structure._—The greater number of mammalian teeth when fully formed are
not simple and homogeneous in structure, but are composed of several
distinct tissues, which are enumerated below.
The _pulp_, a soft substance, consisting of a very delicate gelatinous
connective tissue, in which numerous cells are imbedded, and abundantly
supplied with blood-vessels and nerves, constitutes the central axis
of all the basal part of the tooth, and affords the means by which the
vitality of the whole is preserved. The nerves which pass into the pulp
and endow the tooth with sensibility are branches of the fifth pair of
cranial nerves. The pulp occupies a larger relative space, and performs
a more important purpose, in the young growing tooth than afterwards, as
by the calcification and conversion of its outer layers the principal
hard constituent of the tooth, the dentine, is formed. In teeth which
have ceased to grow the pulp occupies a comparatively small space, which
in the dried tooth is called the pulp-cavity. This communicates with the
external surface of the tooth by a small aperture at the apex of the
root, through which the branches of the blood-vessels and nerves, by
which the tooth receives its nutrition and sensitiveness, pass in to be
distributed in the pulp. In growing teeth the pulp-cavity is widely open,
while in advanced age it often becomes obliterated, and the pulp itself
entirely converted into bone-like material.
The _dentine_ or _ivory_ forms the principal constituent of the greater
number of teeth. When developed in its most characteristic form, it is
a very hard but elastic substance, white, with a yellowish tinge, and
slightly translucent. It consists of an organic matrix, something like,
but not identical with, that of bone, richly impregnated with calcareous
salts (chiefly calcium phosphate), these constituting in a fresh human
tooth 72 per cent of its weight. When subjected to microscopical
examination it is seen to be everywhere permeated by nearly parallel
branching tubes which run, in a slightly curving or wavy manner, in a
general direction from the centre towards the free surface of the tooth.
These tubes communicate by open mouths with the pulp-cavity, and usually
terminate near the periphery of the dentine by closed ends or loops,
though in Marsupials and certain other mammals they penetrate into the
enamel. They are occupied in the living tooth by soft gelatinous fibrils
connected with the cells of the pulp. A variety of dentine, permeated
by canals containing blood-vessels, met with commonly in fishes and
in some few mammals, as the _Megatherium_, is called vaso-dentine.
Other modifications of this tissue occasionally met with are called
osteodentine and secondary dentine,—the latter being a dentine of
irregular structure which often fills up the pulp-cavity of old animals.
The _enamel_ constitutes a thin investing layer, complete or partial, of
the outer or exposed and working surface of the dentine of the crown of
the teeth of most mammals. This is the hardest tissue met with in the
animal body, containing from 95 to 97 per cent of mineral substances
(chiefly calcium phosphate and some carbonate, with traces of fluoride).
Its ultimate structure consists of prismatic fibres, placed generally
with their long axes at right angles to the free surface of the tooth.
Enamel is easily distinguished from dentine with the naked eye by its
clear, bluish-white, translucent appearance.
The _cement_ or _crusta petrosa_ is always the most externally placed
of the hard tissues of which teeth are composed, as will be understood
when the mode of development of these organs is considered. It is often
only found as a thin layer upon the surface of the root; but sometimes,
as in the complex-crowned molar teeth of the Horse and Elephant, it is a
structure which plays a very important part, covering and filling in the
interstices between the folds of the enamel. In appearance, histological
structure, and chemical composition it is closely allied to osseous
tissue, containing lacunæ and canaliculi, though only when it is of
considerable thickness are Haversian canals present in it.
_Development._—The two principal constituents of the teeth, the dentine
and the enamel, are developed from the two layers of the mucous membrane
of the jaw—the dentine from the deeper or vascular, the enamel from the
superficial or epithelial layer. The latter dips down into the substance
of the gum, and forms the enamel-organ or germ, the first rudiment of the
future tooth, which is constantly present even in those animals in which
the enamel is not found as a constituent of the perfectly-formed tooth.
Below the mass of epithelial cells thus embedded in the substance of the
gum, and remaining connected by a narrow neck of similar structure with
the epithelium of the surface, a portion of the vascular areolar tissue
becomes gradually separated and defined from that which surrounds it,
and assumes a distinct form, which is that of the crown of the future
tooth,—a single cone in the case of simple teeth, or with two or more
eminences in the complex forms. This is called the dental papilla or
dentine germ, and by the gradual conversion of its tissue into dentine
the bulk of the future tooth is formed, the uncalcified central portion
remaining as the pulp. The conversion of the papilla into hard tissue
commences at the outer surface of the apex, and gradually proceeds
downwards and inwards, so that the form of the papilla exactly determines
the form of the future dentine, and no alteration either in shape or
size of this portion of the tooth, when once calcified, can take place
by addition to its outer surface. In the meanwhile, calcification of a
portion of the cells of the enamel-organ, which adapts itself like a cap
round the top of the dentinal papilla, and has assumed a somewhat complex
structure, results in the formation of the enamel-coating of the crown of
the tooth. While these changes are taking place the tissues immediately
surrounding the tooth-germ become condensed and differentiated into a
capsule, which appears to grow up from the base of the dental papilla,
and encloses both this and the enamel-germ, constituting the follicle
or tooth-sac. By the ossification of the inner layer of this follicle
the cement is formed. This substance, therefore, unlike the dentine,
increases from within outwards, and its growth may accordingly be the
cause of considerable modification of form and enlargement, especially
of the roots, of certain teeth, as those of Seals and some Cetacea. The
delicate homogeneous layer coating the enamel surface of newly-formed
teeth, in which cement is not found in the adult state, and known as
Nasmyth’s membrane, is considered by Tomes as probably a film of this
substance, too thin to exhibit its characteristic structure, though
by others it is believed to be derived from the external layer of the
enamel-organ. The homology of the teeth with the dermal appendages,
hairs, scales, and claws, has already been alluded to, and it will now
be seen that in both cases two of the primary embryonic layers are
concerned in their development—the mesoblast and epiblast—although in
very different proportions respectively. Thus in the hair or nail the
part derived from the epiblast forms the principal bulk of the organ, the
mesoblast only constituting the papilla or matrix. But in the tooth the
epiblastic portion is limited to the enamel, and is always of relatively
small bulk and often absent, while the dentine (the principal constituent
of the tooth) and the cement are formed from the mesoblast.
When more than one set of teeth occur in mammals, those of the second
set are developed in a precisely similar manner to the first, but the
enamel-germ, instead of being derived directly from an independent
part of the oral epithelium, is formed from a budding out of the neck
of the germ of the tooth succeeded. In the case of the true molars,
which have no predecessors, the germ of the first has an independent
origin, but that of the others is derived from the neck of the germ of
the tooth preceding it in the series. The foundations of the permanent
teeth are thus laid as it were almost simultaneously with those of their
predecessors, although they remain in many cases for years before they
are developed into functional activity.
Although the commencement of their formation takes place at an early
period of embryonic life, teeth are in nearly all mammals still concealed
beneath the gum at the time of birth. The period of eruption, or
“cutting” of the teeth as it is called, that is, their piercing through
and rising above the surface of the mucous membrane, varies much in
different species. In some, as Seals, the whole series of teeth appears
almost simultaneously; but more often there are considerable intervals
between the appearance of the individual teeth, the front ones usually
coming into place first, and those at the back of the mouth at a later
period.
_Forms of Teeth._—The simplest form of tooth may be exemplified on a
large scale by the tusk of the Elephant (Fig. 1, I.) It is a hard mass
almost entirely composed of dentine, of a conical shape at first, but
during growth becoming more and more cylindrical or uniform in width.
The enamel-covering, present on the apex in its earliest condition, soon
disappears, but a thin layer of cement covers the circumference of the
tooth throughout life. In section it will be seen that the basal portion
is hollow, and contains a large conical pulp, as broad at the base as the
tooth itself, and deeply imbedded in the bottom of a recess, or socket,
in the maxillary bone. This pulp continues to grow during the lifetime
of the animal, and at the same time is converted at its surface into
dentine. The tooth therefore continually elongates, but the use to which
the animal subjects it in its natural state causes the apex to wear away,
at a rate generally proportionate to the growth at the base, otherwise it
would become of inconvenient length and weight. Such teeth of indefinite
growth are said to be “rootless,” or to have “persistent pulps.”
[Illustration: FIG. 1.—Diagrammatic Sections of various forms of Teeth.
I. Incisor or tusk of Elephant, with pulp-cavity persistently open
at base. II. Human incisor during development, with root imperfectly
formed, and pulp-cavity widely open at base. III. Completely formed human
incisor, with pulp-cavity contracted to a small aperture at the end of
the root. IV. Human molar, with broad crown and two roots. V. Molar
of the Ox, with the enamel covering the crown deeply folded, and the
depressions filled up with cement. The surface is worn by use; otherwise
the enamel coating would be continuous at the top of the ridges. In all
the figures the enamel is black, the pulp white, the dentine represented
by horizontal lines, and the cement by dots.]
One of the corresponding front teeth of man (Fig. 2, II. and III.) may
be taken as an example of a very different condition. After its crown is
fully formed by calcification of the germ, the pulp, though continuing to
elongate, begins to contract in diameter; a neck or slight constriction
is formed; and the remainder of the pulp is converted into the root
(often, but incorrectly, called “fang”), a tapering conical process
imbedded in the alveolar cavity of the bone, and having at its extremity
a minute perforation, through which the vessels and nerves required to
maintain the vitality of the tooth enter the pulp-cavity, which is very
different from the widely open cavity at the base of the growing tooth.
When the crown of the tooth is broad and complex in character, instead of
having a single root, it may be supported by two or more roots, each of
which is implanted in a distinct alveolar recess or socket, and to the
apex of which a branch of the common pulp-cavity is continued (Fig. 1,
IV.) Such teeth are called “rooted teeth.” When they have once attained
their position in the jaw, with the neck a little way above the level
of the free margin of the alveolus, and embraced by the gum or tough
fibrovascular membrane covering the alveolar border, and having the root
fully formed, they can never increase in length or alter their position;
if they appear to do so in old age, it being only in consequence of
absorption and retrocession of the surrounding alveolar margins. If,
as often happens, their surface wears away in mastication, it is never
renewed. The open cavity at the base of the imperfectly developed tooth
(Fig. 1, II.) causes it to resemble the persistent condition of the
rootless tooth. The latter is therefore a more primitive condition,
the formation of the root being a completion of the process of tooth
development. Functionally it is, however, difficult to say that the one
is a higher form than the other, since they both serve important and
different purposes in the animal economy.
As is almost always the case in nature, intermediate conditions between
these two forms of teeth are met with. Thus some teeth, as the molars of
the Horse, and of many Rodents, are for a time rootless, and have growing
pulps producing very long crowns with parallel sides, the summits of
which may be in use and beginning to wear away while the bases are still
growing; but ultimately the pulp contracts, forms a neck and distinct
roots, and ceases to grow. The canine tusks of the Musk Deer and of the
Walrus have persistent pulps, and are open at their base until the animal
is of advanced age, when they close, and the pulp ceases to be renewed.
The same sometimes happens in the tusks of very old Boars.
The simplest form of the crown of a tooth is that of a cone; but this may
be variously modified. Thus it may be flattened, with its edges sharp
and cutting, and pointed at the apex, as in the laterally compressed
premolars of most Carnivora; or it may be chisel- or awl-shaped, with a
straight truncated edge, as in the human incisors; or it may be broad,
with a flat or rounded upper surface. Very often there is a more or less
prominent ridge encircling the whole or part of the base of the crown
just above the neck, called the cingulum, which serves as a protection to
the edge of the gum in masticating, and is most developed in flesh-eating
and insectivorous animals, in which the gums are liable to be injured by
splinters of bone or other hard fragments of their food. The form of the
crown is frequently rendered complex by the development upon its surface
of elevations or tubercules called cusps or cones, or by ridges usually
transverse, but sometimes variously curved or folded. When the crown
is broad and the ridges are greatly developed, as in the molars of the
Elephant, Horse, and Ox (Fig. 1, V.), the interspaces between them are
filled with cement, which supports them and makes a solid compact mass of
the whole tooth. When such a tooth wears away at the surface by friction
against the opposed tooth of the other jaw, the different density of
the layers of the substances of which it is composed—enamel, dentine,
and cement—arranged in characteristic patterns, causes them to wear
unequally, the hard enamel ridges projecting beyond the others, and thus
giving rise to a grinding surface of great mechanical advantage.
_Succession._—The dentition of all mammals consists of a definite set
of teeth, almost always of constant and determinate number, form,
and situation, and, with few exceptions, persisting in a functional
condition throughout the natural term of the animal’s life. In many
species these are the only teeth which the animal ever possesses,—the
set which is first formed being permanent, or, if accidentally lost,
or decaying in extreme old age, not being replaced by others. These
animals are called Monophyodont. But in the larger number of mammals,
certain of the teeth are preceded by others, which may be only of a
very transient, rudimentary, and functionless character (being in the
Seals, for example, shed either before or within a few days after
birth), or may be considerably developed, and functionally occupy the
place of the permanent teeth for a somewhat lengthened period, during
the growth and development of the latter and of the jaws. In all cases
these teeth disappear (by the absorption of their roots and shedding
of the crowns) before the frame of the animal has acquired complete
maturity, as evidenced by the coalescence of the epiphyses of the
osseous system. As these teeth are, as a general rule, present during
the period in which the animal is nourished by the milk of the mother,
the name of “milk-teeth” (French _dents de lait_, German _milchzähne_)
has been commonly accorded to them, although it must be understood that
the epoch of their presence is by no means necessarily synchronous with
that of lactation. Animals possessing such teeth are called Diphyodont.
No mammal is known to have more than two sets of teeth; and the definite
and orderly replacement of certain members of the series is a process
of quite a different nature from the indefinite succession which takes
place in all the teeth continuously throughout the lifetime of the lower
vertebrates.
When the milk-teeth are well developed, and continue in place during the
greater part of the animal’s growth, as is especially the case with the
Ungulata, and, though to a less degree, with the Primates and Carnivora,
their use is obvious, since taken all together they form structurally
a complete epitome on a small scale of the more numerous and larger
permanent set (see Fig. 3), and, consequently, are able to perform the
same functions, while time is allowed for the gradual maturation of
the latter, and especially while the jaws of the growing animal are
acquiring the size and strength sufficient to support the permanent
teeth. Those animals, therefore, that have a well-developed and tolerably
persistent set of milk-teeth may be considered to be in a higher state
of development, as regards their dentition, than those that have the
milk-teeth absent or rudimentary.
It is a very general rule that individual teeth of the milk and permanent
set have a close relationship to one another, being originally formed, as
mentioned above, in exceedingly near proximity, and with, at all events
so far as the enamel-germ is concerned, a direct connection. Moreover,
since the latter ultimately come to occupy the position in the alveolar
border temporarily held by the former, they are spoken of respectively as
the predecessors or successors of each other. But it must be understood
that milk-teeth may be present which have no successors in the permanent
series, and, what is far more general, permanent teeth may have no
predecessors in the milk series.
The complete series of permanent teeth of most mammals forms a complex
machine, with its several parts adapted for different functions,—the
most obvious structural modification for this purpose being an increased
complexity of the individual components of the series from the anterior
towards the posterior extremity of such series. Since, as has just been
said, the complete series of the milk teeth often presents structurally
and functionally a similar machine, but composed of fewer individual
members, and the anterior of which are as simple, and the posterior as
complex as those occupying corresponding positions in the permanent
series,—and since the milk-teeth are only developed in relation to
the anterior or lateral, never to the most posterior of the permanent
series,—it follows that the hinder milk-teeth are usually more complex
than the teeth of which they are the predecessors in the permanent
series, and represent functionally, not their immediate successors, but
those more posterior permanent teeth which have no direct predecessors.
This character is clearly seen in those animals in which the various
members of the molar series are well differentiated from each other in
form, as the Carnivora, and also in Man.
In animals which have two sets of teeth the number of those of the
permanent series which are preceded by milk-teeth varies greatly, being
sometimes, as in Marsupials and some Rodents, as few as one on each side
of each jaw, and sometimes including the larger portion of the series.
Although there are difficulties in some cases in arriving at a
satisfactory solution of the question, it is, on the whole, safest to
assume that when only one set of teeth is present, this corresponds to
the permanent teeth of the Diphyodonts. When this one set is completely
developed, and remains in use throughout the animal’s life, there can
be no question on this subject. When, on the other hand, the teeth are
rudimentary and transient, as in the Whalebone Whales, it is possible
to consider them as representing the milk series; but there are weighty
reasons in favour of the opposite conclusion.[5]
_Arrangement, Homologies, and Notation of Teeth._—The teeth of the two
sides of the jaws are always alike in number and character, except in
cases of accidental or abnormal variation, and in the one remarkable
instance of constant deviation from bilateral symmetry among mammals,
the tusks of the Narwhal (_Monodon_), in which the left is of immense
size, and the right rudimentary. In certain mammals, such as the Dolphins
and some Armadillos, which have a very large series of similar teeth,
not always constant in number in different individuals, there may be
differences in the two sides; but, apart from these, in describing the
dentition of any mammal, it is quite sufficient to give the number and
characters of the teeth of one side only. Since the teeth of the upper
and the lower jaws work against each other in masticating, there is a
general correspondence or harmony between them, the projections of one
series, when the mouth is closed, fitting into corresponding depressions
of the other. There is also a general resemblance in the number,
characters, and mode of succession of both series, so that, although
individual teeth of the upper and lower jaws may not be in any strict
sense of the term homologous parts, there is a great convenience in
applying the same descriptive terms to the one as are used for the other.
[Illustration: FIG. 2.—Upper and Lower Teeth of one side of the Mouth
of a Dolphin (_Lagenorhynchus_) as an example of the homodont type of
dentition. The bone covering the outer side of the roots of the teeth has
been removed to show their simple character.]
The simplest dentition as a whole is that of many species of Dolphin
(Fig. 2), in which the crowns are single-pointed, slightly curved cones,
and the roots also single and tapering, and all alike in form from the
anterior to the posterior end of the series, though it may be with
some slight difference in size, those at the two extremities of the
series being rather smaller than the others. Such a dentition is called
Homodont, and in the case cited, as the teeth are never changed, it is
also Monophyodont. Such teeth are adapted only for catching slippery
living prey, as fish.
In a very large number of mammals the teeth of different parts of the
series are more or less differentiated in character, and have different
functions to perform. The front teeth are simple and one-rooted, and
are adapted for cutting and seizing. They are called “incisors.” The
back- or cheek-teeth have broader and more complex crowns, tuberculated
or ridged, and are supported on two or more roots. They crush or grind
the food, and are hence called “molars.” Many animals have, between
these two sets, a tooth at each corner of the mouth, longer and more
pointed than the others, adapted for tearing or stabbing, or for fixing
struggling prey. From the conspicuous development of such teeth in the
Carnivora, especially the Dogs, they have received the name of “canines.”
A dentition with its component parts so differently formed that these
distinctive terms are applicable to them is called Heterodont. In most
cases, though by no means invariably, animals with Heterodont dentition
are also Diphyodont.
This general arrangement is extremely obvious in a considerable number of
mammals; and closer examination shows that, under very great modification
in detail, there is a remarkable uniformity of essential characters in
the dentition of a large number of members of the class belonging to
different orders and not otherwise closely allied; so much so indeed that
it has been possible (chiefly through the researches of Sir Richard Owen)
to formulate a common plan of dentition from which the others have been
derived by the alteration of some and suppression of other members of the
series, and occasionally, but very rarely, by addition. The records of
palæontology fully confirm this view, as by tracing back many groups now
widely separated in dental characters we find a gradual approximation to
a common type. In this generalised form of mammalian dentition (which is
best exemplified in the genera _Anoplotherium_ and _Homalodontotherium_)
the entire number of teeth present is 44, or 11 above and 11 below on
each side. Those of each jaw are placed in continuous series without
intervals between them; and, although the anterior teeth are simple and
single-rooted, and the posterior teeth complex and with several roots,
the transition between the two kinds is gradual.
In dividing and grouping such teeth for the purpose of description and
comparison, more definite characters are required than those derived
merely from form or function. The first step towards a classification
has been made by the observation that the upper jaw is composed of two
bones, the premaxilla and the maxilla, and that the suture between these
bones separates the three anterior teeth from the others. These three
teeth, then, which are implanted by their roots in the premaxilla,
form a distinct group, to which the name of “incisor” is applied. This
distinction is, however, not so important as it appears at first sight,
for, as mentioned when speaking of the development of the teeth, their
connection with the bone is only of a secondary nature, and, although it
happens conveniently for our purpose that in the great majority of cases
the segmentation of the bone coincides with the interspace between the
third and fourth tooth of the series, still, when it does not happen to
do so, as in the case of the Mole, we must not give too much weight to
this fact, if it contravenes other reasons for determining the homologies
of the teeth. The eight remaining teeth of the upper jaw offer a natural
division, inasmuch as the posterior three never have milk-predecessors;
and, although some of the anterior teeth may be in the same case, the
particular one preceding these three always has such a predecessor. These
three then are grouped apart as the “molars,” or, since some of the teeth
in front of them often have a molariform character, “true molars.” Of the
five teeth between the incisors and molars the most anterior, or that
which is usually situated close behind the premaxillary suture, almost
always, as soon as any departure takes place from the simplest and most
homogeneous type, assumes a lengthened and pointed form, and is the tooth
so developed as to constitute the “canine” or “laniary” tooth of the
Carnivora, the tusk of the Boar, etc. It is customary therefore to call
this tooth, whatever its size or form, the “canine.” The remaining four
are the “premolars” or “false molars.” This system of nomenclature has
been objected to as being artificial, and in many cases not descriptive,
the distinction between premolars and canine especially being sometimes
not obvious; but the terms are now in such general use, and are so
practically convenient—especially if, as it is best to do in all such
cases, we forget their original signification and treat them as arbitrary
signs—that it is not likely they will be superseded by any that have been
proposed as substitutes for them.
With regard to the lower teeth the difficulties are greater, owing to the
absence of any suture corresponding to that which defines the incisors
above; but since the number of the teeth is the same, the corresponding
teeth are preceded by milk-teeth, and in the large majority of cases it
is the fourth tooth of the series which is modified in the same way as
the canine (or fourth tooth) of the upper jaw, it is quite reasonable
to adopt the same divisions as with the upper series, and to call the
first three, which are implanted in the part of the mandible opposite
to the premaxilla, the incisors, the next the canine, the next four the
premolars, and the last three the molars. It may be observed that when
the mouth is closed, especially when the opposed surfaces of the teeth
present an irregular outline, the corresponding upper and lower teeth
are not exactly opposite, otherwise the two series could not fit into
one another; but as a rule the points of the lower teeth shut into the
interspaces in front of the corresponding teeth of the upper jaw. This
is seen very distinctly in the canine teeth of the Carnivora, and is a
useful guide in determining the homologies of the teeth of the two jaws.
Objections have certainly been made to this view, because, in certain
rare cases, the tooth which, according to it, would be called the lower
canine has the form and function of an incisor (as in Ruminants and
Lemurs), and on the other hand (as in _Cotylops_, an extinct Ungulate
from North America) the tooth that would thus be determined as the
first premolar has the form of a canine; but it should not be forgotten
that, as in all such cases, definitions derived from form and function
alone are quite as open to objection as those derived from position and
relation to surrounding parts, or still more so.
_Dental formulæ._—For the sake of brevity the complete dentition,
arranged according to these principles, is often described by the
following formula, the numbers above the line representing the teeth of
the upper, those below the line those of the lower jaw:—incisors ³⁻³⁄₃₋₃,
canines ¹⁻¹⁄₁₋₁, premolars ⁴⁻⁴⁄₄₋₄, molars ³⁻³⁄₃₋₃ = ¹¹⁻¹¹⁄₁₁₋₁₁; total
44. Since, however, initial letters may be substituted for the names of
each group, and it is quite unnecessary to give more than the numbers
of the teeth on one side of the mouth, the formula may be conveniently
abbreviated into—
_i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃ = ¹¹⁄₁₁; total 44.
The individual teeth of each group are always enumerated from before
backwards, and by such a formula as the following—
_i_ 1, _i_ 2, _i_ 3, _c_, _p_ 1, _p_ 2, _p_ 3, _p_ 4, _m_ 1, _m_ 2, _m_ 3
-------------------------------------------------------------------------
_i_ 1, _i_ 2, _i_ 3, _c_, _p_ 1, _p_ 2, _p_ 3, _p_ 4, _m_ 1, _m_ 2, _m_ 3
or more briefly—
1,2,3 1 1,2,3,4 1,2,3
_i_ ------ _c_ -- _p_ -------- _m_ -----.
1,2,3, 1, 1,2,3,4, 1,2,3
A special numerical designation is thus given by which each one can be
indicated. In mentioning any single tooth, such a sign as _m¹_⁄ will mean
the first upper molar, ⁄_m₁_ the first lower molar, and so on. The use of
such signs saves much time and space in description.[6]
It was part of the view of the founder of this system of dental notation
that, at least throughout the group of mammals whose dentition is
derived from this general type, each tooth has its strict homologue in
all species, and that in those cases in which fewer than the typical
number are present (as in all existing mammals except the genera _Sus_,
_Gymnura_, _Talpa_, and _Myogale_), the teeth that are missing can be
accurately defined. According to this view, when the number of incisors
falls short of three it is assumed that the absent ones are missing
from the outer and posterior end of the series. Thus, when there is
but one incisor present, it is _i_ 1; when two, they are _i_ 1 and
_i_ 2. Furthermore, when the premolars and the molars are below their
typical number, the absent teeth are missing from the fore part of the
premolar series, and from the back part of the molar series. If this were
invariably so, the labours of those who describe teeth would be greatly
simplified; but there are so many exceptions that a close scrutiny into
the situation, relations, and development of a tooth is required before
its nature can be determined, and in some cases the evidence at our
disposal is scarcely sufficient for the purpose. In other instances,
however, as among the Polyprotodont Marsupials, we have decisive evidence
to show that the missing premolar teeth are not those at the extremity of
the series.
[Illustration: FIG. 3.—Milk and Permanent Dentition of Upper (I.) and
Lower (II.) Jaw of the Dog (_Canis familiaris_), with the symbols by
which the different teeth are commonly designated. The third upper molar
(_m._3) is the only tooth wanting in this animal to complete the typical
heterodont mammalian dentition.]
The milk-dentition is expressed by a similar formula, _d_ for deciduous
or _m_ for milk being commonly prefixed to the letter expressive of
the nature of the tooth. Since the three molars, and almost invariably
the first premolar of the permanent series, have no predecessors, the
typical milk-dentition would be expressed as follows—_di_ ³⁄₃, _dc_
¹⁄₁, _dm_ ³⁄₃, = ⁷⁄₇, total 28. In a few Ungulates, however, such as
the Hyrax and Tapir, and in some instances the Rhinoceros and the
extinct _Palæotherium_, the whole of the four premolars are preceded
by milk-teeth; when we have the fullest development of cheek-teeth in
the whole of the Eutheria. The teeth which precede the premolars of the
permanent series are all called molars in the milk-dentition, although
as a general rule, in form and function they represent in a condensed
form the whole premolar and molar series of the adult. When there is
a marked difference between the premolars and molars of the permanent
dentition, the first milk-molar resembles a premolar, while the last has
the characters of the posterior true molar.
The dentition of all the members of the orders Primates, Carnivora,
Insectivora, Chiroptera, and Ungulata can clearly be derived from the
above-described generalised type. The same may be said of the Rodents,
and even the Proboscidea, though at least in the existing members of the
order with greater modification. It is also apparent in certain extinct
Cetacea, as _Zeuglodon_ and _Squalodon_, but it is difficult to find
any traces of it in existing Cetacea, Sirenia, or any of the so-called
Edentata. All the Marsupials, different as they are in their general
structure and mode of life, and variously modified as is their dentition,
present in this system of organs some deep-lying common characters
which show their unity of origin. The generalised type to which their
dentition can be reduced presents considerable resemblance to that of the
placental mammals, yet differing in details. It is markedly heterodont,
and susceptible of division into incisors, canines, premolars, and molars
upon the same principles. The whole number is, however, not limited to
forty-four. The incisors may be as numerous as five on each side above,
and they are almost always different in number in the upper and the lower
jaw. The premolars and molars are commonly seven, as in the placental
mammals, but their arrangement is reversed, as there are four true molars
and three premolars.
The larger number of incisive and molar teeth among the Marsupials
suggests that their additional teeth have disappeared in the Eutheria,[7]
and Mr. O. Thomas has endeavoured to construct a generalised dental
formula from which both the Marsupial and Eutherian modifications
may have been derived by the suppression of particular teeth. Thus
the hypothetical formula _i_ ¹,²,³,⁴,⁵⁄₁,₂,₃,₄,₅, _c_ ¹⁄₁, _p_
¹,²,³,⁴⁄₁,₂,₃,₄, _m_ ¹,²,³,⁴,⁵⁄₁,₂,₃,₄,₅, by the loss of the fifth
lower incisor, and of the second premolars (which we know to be those
which disappear in the Marsupials) and the fifth molars, will give _i_
¹,²,³,⁴,⁵⁄₁,₂,₃,₄,₀, _c_ ¹⁄₁, _p_ ¹,⁰,³,⁴⁄₁,₀,₃,₄, _m_ ¹,²,³,⁴⁄₁,₂,₃,₄;
or the formula of the Opossum (_Didelphys_), usually written _i_ ⁵⁄₄, _c_
¹⁄₁, _p_ ³⁄₃, _m_ ⁴⁄₄. Again, in the same formula the loss of the fourth
and fifth incisors in both jaws, and also of the fourth molars, gives us
_i_ ¹,²,³,⁰,⁰⁄₁,₂,₃,₀,₀, _c_ ¹⁄₁, _p_ ¹,²,³,⁴⁄₁,₂,₃,₄, _m_ ¹,²,³⁄₁,₂,₃,
or the formula of a typical Eutherian, like the Pig, which we generally
write as _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃. Such a generalised formula
will admit of modification into that of all existing, and a large number
of fossil Marsupials, but it is possible that some of the Mesozoic types
may have had more than four premolars, although there is no absolutely
decisive evidence that such was the case. The presence of seven or eight
true molars in some Mesozoic forms merely entails the addition of two or
three additional figures to the ideal generalised formula.
The milk-dentition of all known Marsupials, existing or extinct, is (if
not entirely absent) limited to a single tooth on either side of each
jaw, this being the predecessor of the last permanent premolar. And if
the view that the milk-dentition is an additional series grafted upon the
original permanent series be correct, it is evident that we have in this
single replacement the first stage of this additional development.
In very few mammals are teeth entirely absent. Even in the Whalebone
Whales their germs are formed in the same manner and at the same period
of life as in other mammals, and even become partially calcified, but
they never rise above the gums, and completely disappear before the birth
of the animal. In some species of the order Edentata, the true Anteaters
and the Pangolins, no traces of teeth have been found at any age. The
adult Monotremata are likewise devoid of teeth of the same structure
as those of ordinary mammals; but well-developed molars occur in the
young _Ornithorhynchus_, although no traces of teeth have hitherto been
detected in _Echidna_.
_Modifications of the Teeth in Relation to their Functions._—The
principal functional modifications noticed in the dentition of mammalia
may be roughly grouped as piscivorous, carnivorous, insectivorous,
omnivorous, and herbivorous, each having, of course, numerous variations
and transitional conditions.
The essential characters of a piscivorous dentition are best exemplified
in the Dolphins, and also (as modifications of the carnivorous type) in
the Seals. This type consists of an elongated, rather narrow mouth, wide
gape, with numerous subequal, conical, sharp-pointed, recurved teeth,
adapted simply to rapidly seize, but not to divide or masticate, active,
slippery, but not powerful prey. All animals which feed on fish as a
rule swallow and digest them entire, a process which the structure of
prey of this nature, especially the intimate interblending of delicate,
sharp-pointed bones with the muscles, renders very advantageous, and for
which the above-described type of dentition is best adapted.
The carnivorous type of dentition is shown in its most specialised
development among existing mammals in the _Felidæ_. The function being
here to seize and kill struggling animals, often of large size and great
muscular power, the canines are immensely developed, trenchant, and
piercing, and are situated wide apart, so as to give the firmest hold
when fixed in the victim’s body. The jaws are as short as is consistent
with the free action of the canines, so that no power may be lost. The
incisors are very small, so as not to interfere with the penetrating
action of the canines, and the crowns of the molar series are reduced
to scissor-like blades, with which to pare off the soft tissues from
the large bones, or to divide into small pieces the less dense portions
of the bones for the sake of nutriment afforded by the blood and marrow
they contain. The gradual modification between this and the two following
types will be noticed in their appropriate places.
In the most typical insectivorous animals, as the Hedgehogs and Shrews,
the central incisors are elongated, pointed, and project forwards, those
of the upper and lower jaw meeting like the blades of a pair of forceps,
so as readily to secure small active prey, quick to elude capture, but
powerless to resist when once seized. The crowns of the molars are
covered with numerous sharp edges and points, which, working against each
other, rapidly cut up the hard-cased insects into little pieces fit for
swallowing and digestion.
The omnivorous type, especially that adapted for the consumption of soft
vegetable substances, such as fruits of various kinds, may be exemplified
in the dentition of Man, of most Monkeys, and of the less modified Pigs.
The incisors are moderate, subequal, and cutting. If the canines are
enlarged, it is usually for other purposes than those connected with
food, and only in the male sex. The molars have their crowns broad,
flattened, and elevated into rounded tubercles. The name _Bunodont_, or
hillock-toothed, has been proposed for molars of this type, and will
frequently be found convenient.
In the most typically herbivorous forms of dentition, as seen in the
Horse and Kangaroo, the incisors are well developed, trenchant, and
adapted for cutting off the herbage on which the animals feed; the
canines are rudimentary or suppressed; the molars are large, with broad
crowns, which in the simplest forms have strong transverse ridges, but
may become variously complicated in the higher degrees of modification
which this type of tooth assumes.
Various forms of teeth of this type will be noticed among the Ungulates
and Rodents.
The natural groups of mammals, or those which in our present state of
knowledge we have reason to believe are truly related to each other, may
each contain examples of more than one of these modifications. Thus the
Primates have both omnivorous and insectivorous forms. The Carnivora show
piscivorous, carnivorous, insectivorous, and omnivorous modifications of
their common type of dentition. The Ungulata and the Rodentia have among
them the omnivorous and various modifications, both simple and complex,
of the herbivorous type. The Marsupialia exhibit examples of all forms,
except the purely piscivorous. Other orders, more restricted in number or
in habits, as the Proboscidea and Cetacea, naturally do not show so great
a variety in the dental structure of their members.
_Taxonomy._—In considering the taxonomic value to be assigned to the
modifications of teeth of mammals, two principles, often opposed to each
other, which have been at work in producing these modifications, must
be held in view:—(1) the type, or ancestral form, as we generally now
call it, characteristic of each group, which in most mammals is itself
derived from the still more generalised type described above; and (2)
variations which have taken place from this type, generally in accordance
with special functions which the teeth are called upon to fulfil in
particular cases. These variations are sometimes so great as completely
to mask the primitive type, and in this way the dentition of many animals
of widely different origin has come to present a remarkable superficial
resemblance, as in the case of the Wombat (a Marsupial), the Aye-Aye (a
Lemur), and the Rodents, or as in the case of the Thylacine and the Dog.
In all these examples indications may generally be found of the true
nature of the case by examining the earlier conditions of dentition;
for the characters of the milk-teeth or the presence of rudimentary
or deciduous members of the permanent set will generally indicate the
route by which the specialised dentition of the adult has been derived.
It is perhaps owing to the importance of the dental armature to the
well-being of the animal in procuring its sustenance, and preserving
its life from the attacks of enemies, that great changes appear to have
taken place so readily, and with such comparative rapidity, in the forms
of these organs—changes often accompanied with but little modification
in the general structure of the animal. Of this proposition the Aye-Aye
(_Chiromys_) among Lemurs, the Walrus among Seals, and the Narwhal
among Dolphins form striking examples; since in all these forms the
superficial characters of their dentition would entirely separate them
from the animals with which all other evidence (even including the mode
of development of their teeth) proves their close affinity.
[Illustration: FIG. 4.—Molar teeth of Mesozoic Mammals (enlarged).
Triconodont type—1, _Dromatherium_; 2, _Microconodon_; 3,
_Amphilestes_; 4, _Phascolotherium_; 5, _Triconodon_. Tritubercular
type—6, 7, _Spalacotherium_; 10, _Asthenodon_. Tubercular sectorial
type—8, _Amphitherium_; 9, _Peramus_; 11-13, _Amblotherium_; 14 (?)
_Amblotherium_. _pr_, Protocone; _hy_, hypocone; _pa_, paracone; _me_,
metacone, in the upper teeth; and protoconid, hypoconid, paraconid, and
metaconid in the lower. 6 and 15 are upper molars, and the rest lower
molars. (After Osborn.)]
_Trituberculism._—Recent researches, and more especially those of
Professors Cope and Osborn, tend to show that almost all of the extremely
different forms of tooth-structure found among Mammals may be traced to
one common type, in which the crown of each tooth carried three cusps,
and hence termed the _tritubercular_ type; these three cusps being
arranged in a triangle, with the apex directed inwardly in the upper
teeth (Fig. 4, ₆), and outwardly in the lower ones (Fig. 4, ₇). It is
further probable that this tritubercular type was itself derived from
a type of dentition in which the teeth were in the form of almost a
quite simple cone; such a presumably primitive type of dentition—being
apparently retained among some existing Edentates, like the Armadillos,
while it is possible that we should regard the dentition of the existing
Cetacea (Fig. 2) as a reversion to the same primitive type. None of
the Mesozoic mammals at present known exhibit this simple conical type
of teeth, although we have an approximation to it in the extremely
generalised genus _Dromatherium_. Starting then from this presumed simple
cone it appears that the teeth of _Dromatherium_ (Fig. 4, ₁) present the
first stage towards trituberculism, the crown of each tooth having one
main cone, with minute lateral cusps, and the root being grooved. In
the next or true Triconodont stage (Fig. 4, ₃₋₅) the crown has become
elongated antero-posteriorly, and consists of one central and two lateral
cones or cusps, while the root is divided. From this the transition is
easy to the tritubercular type, in which the three cusps, instead of
being placed in a line, are arranged in a triangle; the upper teeth
(Fig. 4, ₆) having one inner and two outer cusps, while the reverse
condition obtains in those of the lower jaw (Fig. 4, ₇). These three
cusps of the simple tritubercular tooth are collectively designated as
the primitive triangle; in the upper tooth the inner cusp is termed the
protocone, the antero-external one the paracone, and the postero-external
the metacone; the corresponding cusps of the lower tooth being named
protoconid, paraconid, and metaconid—the protoconid being here on the
outer side of the crown.
It is thus apparent that in the first, or haplodont type, as well as in
the triconodont type, the upper and lower molars are alike; while in
the simple tritubercular type they have a similar pattern, but with the
arrangement of the cusps reversed. This simple tritubercular type occurs
in the Mesozoic genus _Spalacotherium_ (Fig. 4, ₆ and ₇), and apparently
in the existing _Chrysochloris_; but in the majority of tritubercular
forms, while this primitive triangle forms the main portion of the
crown, other secondary cusps are added, the homologies of which in the
upper and lower teeth are somewhat doubtful. At the same time that we
have the addition of these secondary cusps we also find trituberculism
differentiating into a secodont and a bunodont series, according as to
whether the dentition becomes of a cutting or a crushing type.
Thus in the lower molars (Fig. 4, ₈ and ₉) we very frequently find the
three cusps of the primitive triangle elevated and connected by cross
crests, while there is an additional low posterior heel or talon, which
may be termed the hypoconid. This tubercular-sectorial sub-type, as it
is termed, is found in the lower molars of many Polyprotodont Marsupials
and Insectivores, and it also occurs in the lower carnassial teeth of the
true Carnivora. The presence of two cusps (inner and outer) to the talon
converts this modification into a quinquetubercular form; while, by the
suppression of one of the three primitive cusps, it develops into the
quadritubercular type of the bunodont series.
[Illustration: FIG. 5.—Diagram of two upper and two lower left
quadritubercular molars in mutual apposition. The cusps and ridges
of the upper molars in double lines, and those of the lower in black
lines. The lower molars are looked at from below, as if transparent.
_pr_, Protocone; _hy_, hypocone; _pa_, paracone; _me_, metacone; _ml_,
protoconule; _pl_, metaconule; _prd_, protoconid; _hyd_, hypoconid;
_pad_, paraconid; _med_, metaconid; _end_, entoconid. (After Osborn.)]
In the upper molars the primitive triangle in the secodont series may
remain purely tricuspid; but the addition of intermediate cusps, both in
the secodont and bunodont series, may give rise to a quinquetubercular
type; these intermediate cusps being respectively designated as the
protoconule and metaconule (Fig. 5, _ml_, _pl_). Finally, in the
bunodont series, the addition of a postero-internal cusp (Fig. 5, _hy_),
termed the hypocone, forms the sextubercular molar.
The following table exhibits, in a collective form, the names and
relations of all the above-mentioned cusps, and the letters by which they
are indicated in the figures:—
UPPER MOLARS.
Antero-internal cusp = protocone = _pr_.
Postero ” or 6th cusp = hypocone = _hy_.
Antero-external cusp = paracone = _pa_.
Postero ” ” = metacone = _me_.
Anterior intermediate cusp = protoconule = _ml_.
Posterior ” ” = metaconule = _pl_.
LOWER MOLARS.
Antero-external cusp = protoconid = _prd_.
Postero ” ” = hypoconid = _hyd_.
Antero-internal or 5th cusp = paraconid = _pad_.
Intermediate (or in quadritubercular
molars antero-internal) cusp = metaconid = _med_.
Postero-internal cusp = entaconid = _end_.
The common occurrence of trituberculism in the mammals of the earlier
geological epochs is, as remarked by Osborn, very significant of the
uniformity of molar origin. Thus, among the Mesozoic mammals (with the
exception of the group known as Multituberculata, in which the molars
are constructed on a different type), trituberculism occurs in the
great majority of the genera; while out of 82 species, belonging to
five different suborders from the Lowest or Puerco Eocene of the United
States, all but four exhibit this feature; and the same holds good for
the mammals of the corresponding European horizon. At the present day
trituberculism persists in the Lemuroidea, Insectivora, Carnivora, and
Marsupialia. In the Carnivora there is a tendency to lose the metaconid,
while in the bunodont molars of the Ungulata it is the paraconid that
disappears.
III. THE SKELETON.
_Definition._—The skeleton is a system of hard parts, forming a
framework which supports and protects the softer organs and tissues
of the body. It consists of dense fibrous and cartilaginous tissues,
portions of which remain through life in this state, but the greater
part is transformed during the growth of the animal into bone or osseous
tissue. This is characterised by a peculiar histological structure and
chemical composition, being formed mainly of a gelatinous basis, strongly
impregnated with salts of calcium, chiefly phosphate, and disposed in a
definite manner, containing numerous minute nucleated spaces or cavities
called lacunæ, connected together by delicate channels or canaliculi,
which radiate in all directions from the sides of the lacunæ. Parts
composed of bone are, next to the teeth, the most imperishable of all
the organs of the body, often retaining their exact form and internal
structure for ages after every trace of all other portions of the
organisation has completely disappeared, and thus, in the case of extinct
animals, affording the only means of attaining a knowledge of their
characters and affinities.[8]
In the Armadillos and their extinct allies alone is there an ossified
exoskeleton, or bony covering developed in the skin. In all other mammals
the skeleton is completely internal. It may be described as consisting
of an axial portion belonging to the head and trunk, and an appendicular
portion belonging to the limbs. There are also certain bones called
splanchnic, being developed within the substance of some of the viscera.
Such are the _os cordis_ and _os penis_ found in some mammals.
It is characteristic of all the larger bones of the mammalia that their
ossification takes its origin from several distinct centres. One near
the middle of the bone, and spreading throughout its greater portion,
constitutes the _diaphysis_, or “shaft,” in the case of the long
bones. Others near the extremities, or in projecting parts, form the
_epiphyses_, which remain distinct during growth, but ultimately coalesce
with the rest of the bone.
_Axial skeleton._—The axial skeleton consists of the skull, the vertebral
column (prolonged at the posterior extremity into the tail), the sternum,
and the ribs.
_Skull._—In the _skull_ of adult mammals, all the bones, except the
lower jaw, the auditory ossicles, and the bones of the hyoid arch, are
immovably articulated together, their edges being in close contact,
and often interlocking by means of fine denticulations projecting from
one bone and fitting into corresponding depressions of the other;
they are also held together by the investing periosteum, or fibrous
membrane, which passes directly from one to the other, and permits
no motion, beyond perhaps a slight yielding to external pressure.
In old animals there is a great tendency for the different bones to
become actually united by the extension of ossification from one to
the other, with consequent obliteration of the sutures. The cranium,
thus formed of numerous originally independent ossifications, which may
retain throughout life more or less of their individuality, or be all
fused together, according to the species, the age, or even individual
peculiarity, consists of a brain-case, or bony capsule for enclosing and
protecting the brain, and a face for the support of the organs of sight,
smell, and taste, and of those concerned in seizing and masticating the
food. The brain-case articulates directly with the anterior cervical
vertebra, by means of a pair of oval eminences, called condyles, placed
on each side of the large median foramen which transmits the spinal cord.
It consists of a basal axis, continuous serially with the axes or centra
of the vertebræ, and of an arch above, roofing over and enclosing the
cavity which contains the cephalic portion of the central nervous system
(see Fig. 6). The base with its arch is composed of three segments placed
one before the other, each of which is comparable to a vertebra with a
greatly expanded neural arch. The hinder or occipital segment consists
of the basioccipital, exoccipital, and supraoccipital bones; the middle
segment of the basisphenoid, alisphenoid, and parietal bones; and the
anterior segment of the presphenoid, orbitosphenoid, and frontal bones.
The axis is continued forwards into the mesethmoid, or septum of the
nose, around which the bones of the face are arranged in a manner so
extremely modified for their special purposes that anatomists who have
attempted to trace their serial homologies with the more simple portions
of the axial skeleton have arrived at very diverse interpretations.
The characteristic form and structure of the face of mammals is mainly
dependent upon the size and shape of (1) the orbits, a pair of cup-shaped
cavities for containing the eyeball and its muscles, which may be
directed forwards or laterally, placed near together or wide apart, and
may be completely or only partially encircled by bone; (2) the nasal
fossæ, or cavities on each side of the median nasal septum, forming the
passage for the air to pass between the external and the internal nares,
and containing in their upper part the organ of smell; (3) the zygomatic
arch, a bridge of bone for the purpose of muscular attachment, which
extends from the side of the face to the skull, overarching the temporal
fossa; (4) the roof of the mouth, with its alveolar margin for the
implantation of the upper teeth. The face is completed by the mandible,
or lower jaw, consisting of two lateral rami, articulated by a hinge
joint with the squamosal (a cranial bone interposed between the posterior
and penultimate segment of the brain-case, where also the bony capsule of
the organ of hearing is placed), each being composed of a single solid
piece of bone, and the two united together in the middle line in front,
at the symphysis,—which union may be permanently ligamentous or become
completely ossified. Into the upper border of the mandibular rami the
lower teeth are implanted.
[Illustration: FIG. 6.—Longitudinal and vertical section of the skull of
a Dog (_Canis familiaris_), with mandible and hyoid arch. _an_, Anterior
narial aperture; _MT_, maxillo-turbinal bone; _ET_, ethmo-turbinal;
_Na_, nasal; _ME_, ossified portion of the mesethmoid; _CE_, cribriform
plate of the ethmo-turbinal; _Fr_, frontal; _Pa_, parietal; _IP_,
interparietal; _SO_, supraoccipital; _ExO_, exoccipital; _BO_,
basioccipital; _Per_, periotic; _BS_, basisphenoid; _Pt_, pterygoid;
_AS_, alisphenoid; _OS_, orbitosphenoid; _PS_, presphenoid; _PI_,
palatine; _VO_, vomer; _Mx_, maxilla; _PMx_, premaxilla; _sh_, stylohyal;
_eh_, epihyal; _ch_, ceratohyal; _bh_, basihyal; _th_, thyrohyal; _s_,
symphysis of mandible; _cp_, coronoid process; _cd_, condyle; _a_, angle;
_id_, inferior dental canal. The mandible is displaced downwards, to show
its entire form; the * indicates the part of the cranium to which the
condyle is articulated.[9]]
In addition to the bones already mentioned as entering into the formation
of the cranium, there are many others, the most important of which may
be briefly noticed. The anterior extremity of the skull is formed by the
premaxillæ (Figs. 6, 7, _PMx_), which carry the incisors; behind them
are the maxillæ, in which all the remaining upper teeth are implanted.
Both the premaxillæ and maxillæ meet in a median suture on the palate,
where they form a floor to the nasal passage; this floor being continued
backwards by the plate-like palatines, at the hinder extremity of which
the posterior nares are usually situated. In a few instances, however,
as in certain Edentates and Cetaceans, the small pair of bones forming
the posterior continuation of the lateral borders of the palatines, and
known as the pterygoids (Fig. 6, _Pt_), likewise meet in the middle line
below the nasal passage, and thus cause the aperture of the posterior
nares to be situated near the occiput. On the upper, or frontal aspect of
the cranium the paired nasals roof over the nasal passage and fill the
interval left between the premaxilla and maxilla of either side. Behind
the nasals and maxillæ, the anterior part of the brain-case is formed
by the large paired frontals (Figs. 6, 7, _Fr_), behind which are the
parietals, which may be of still larger size, and form the greater part
of the brain-case. A median interparietal ossification (Fig. 6, _IP_)
may divide the parietals posteriorly, and is itself articulated with the
supraoccipital, to the lateral borders of which the parietals are also
joined. The squamosal (Fig. 7, _Sq_) forms the lateral wall of the hinder
part of the brain-case, and articulates superiorly with the parietal,
and posteriorly with the exoccipital. The glenoid cavity (Fig. 8), for
the reception of the articular condyle of the mandible, is formed by the
inferior portion of the squamosal, at the point where it gives off the
zygomatic process to form the hinder portion of the zygomatic arch. The
middle portion of that arch is formed by the jugal, or malar bone (Fig.
7, _Ma_), which articulates posteriorly with the zygomatic process of
the squamosal, and anteriorly with the maxilla. The jugal (as in Fig. 7)
may also articulate with a small bone situated on the anterior border
of the orbit known as the lachrymal. It is important to observe that
the zygomatic or temporal arch is a squamoso-maxillary one, and that an
arcade thus composed is found elsewhere only among the extinct Anomodont
reptiles, which have already been mentioned as showing signs of mammalian
affinity. The relative position occupied by the orbito- and alisphenoid
is sufficiently indicated in Fig. 7.
[Illustration: FIG. 7.—Side view of skull of Cape Jumping Hare (_Pedetes
caffer_). × ⅗ _PMx_, Premaxilla; _Mx_, maxilla, _Ma_, jugal or malar;
_Fr_, frontal; _L_, lachrymal; _Pa_, parietal; _Na_, nasal; _Sq_,
squamosal; _Ty_, tympanic; _ExO_, exoccipital; _AS_, alisphenoid; _OS_,
orbitosphenoid; _Per_, mastoid bulla.]
Wedged in between the squamosal and the bones of the occipital and
basisphenoidal region are the bones connected with the organ of hearing,
known as the periotic and tympanic. The position of the periotic, which
encloses the labyrinth or essential organ of hearing, is shown in Fig. 6.
The periotic is divided into a very dense antero-internal moiety known as
the petrosal, and a postero-external or mastoid portion (Fig. 8), which
appears on the outer wall of the brain-case. The tympanic is produced
horizontally outwards to form the external auditory meatus or tube of
the ear, while the inner and under surface is frequently dilated into a
shell-like auditory bulla (Fig. 8). The small bones of the internal ear
known as the malleus, incus, and stapes are contained in the membranous
_tympanic cavity_, which is situated in a space left among this group of
bones. Further mention of these bones is made below under the head of the
sense organs.
In the Carnivora and some other groups the foramina on the base of the
skull for the passage of blood-vessels and nerves are of considerable
taxonomic importance. The position of the more important of these
foramina is indicated in Fig. 8; but for details the reader may refer to
the work on the _Osteology of the Mammalia_ already mentioned. Attention
may, however, be particularly directed to the so-called alisphenoid
canal, the position of which is shown in Fig. 8, since this is a feature
of some importance in the classification of the Carnivora. This canal
is a short channel running horizontally forward from near the foramen
ovale through the alisphenoid, and opening anteriorly with the foramen
rotundum; it is traversed by the external carotid artery.
[Illustration: FIG. 8.—The right half of the hinder part of the base
of the cranium of the Wolf (_Canis lupus_). _c_, Condyloid foramen;
_l_, foramen lacerum posticum; _car_, carotid canal; _e_, eustachian
canal; _o_, foramen ovale; _a_, posterior, and _a′_, anterior aperture
of alisphenoid canal; _P_, paroccipital process of exoccipital; _m_,
mastoid process of periotic; _am_, external auditory meatus; _g_, glenoid
foramen, below which is the glenoid cavity for the condyle of the
mandible. (Flower, _Proc. Zool. Soc._, 1869, p. 25.)]
Only in those species, as Man and the smaller kinds of the Primates and
some other orders, in which the brain holds a large relative proportion
to the rest of the body, does the external form of the skull receive
much impress from the real shape of the cavity containing the brain.
The size and form of the mouth, and the modifications of the jaws for
the support of teeth of various shape and number, the ridges and crests
on the cranium for the attachment of the muscles necessary to put this
apparatus in motion, and outgrowths of bone for the enlargement of the
external surface required for the support of sense organs or of weapons,
such as horns or antlers (which outgrowths, to prevent undue increase
of weight, are filled with cells containing air), cause the principal
variations in the general configuration of the skull. These variations
are, however, only characteristically developed in perfectly adult
animals, and are in many cases more strongly marked in the male than the
female sex. Throughout all the later stages of growth up to maturity
the size and form of the brain-case remain comparatively stationary,
while the accessory parts of the skull rapidly increase and assume their
distinctive development characteristic of the species.
The hyoidean apparatus in mammals (Fig. 6) supports the tongue and
larynx, and consists of an inferior median portion termed the basihyal,
from which two pairs of half arches, or cornua, extend upwards and
outwards. The anterior is the more important, being connected with the
periotic bone of the cranium. It may be almost entirely ligamentous, but
more often has several ossifications, the largest of which is usually the
stylohyal. The posterior cornu (thyrohyal) is united at its extremity
with the thyroid cartilage of the larynx, which it suspends in position.
The median portion, or basihyal, is sometimes, as in the Howling Monkeys,
enormously enlarged and hollowed, admitting into its cavity an air-sac
connected with the organ of voice.
[Illustration: FIG. 9.—Anterior surface of Human thoracic vertebra
(fourth). _c_, Body or centrum; _nc_, neural canal; _p_, pedicle,
and _l_, lamina of the arch; _t_, transverse process; _az_, anterior
zygapophysis.]
_Vertebral Column._—The _vertebral column_ consists of a series of
distinct bones called vertebræ, arranged in close connection with each
other along the dorsal side of the neck and trunk, and in the median
line.[10] It is generally prolonged posteriorly beyond the trunk, to
form the axial support of the appendage called the tail. Anteriorly it
is articulated with the occipital region of the skull. The number of
distinct bones composing the vertebral column varies greatly among the
Mammalia, the main variation being due to the degree of elongation of
the tail. Apart from this, in most mammals the number is not far from
thirty, though it may fall as low as twenty-six (as in some Bats), or
rise as high as forty (_Hyrax_ and _Cholœpus_). The different vertebræ,
with some exceptions, remain through life quite distinct from each other,
though closely connected by means of fibrous structures which allow of
a certain, but limited, amount of motion between them. The exceptions
are the following:—(1) near the posterior part of the trunk, in nearly
all mammals which possess completely developed hinder limbs, two or more
vertebræ become ankylosed together to form the “sacrum,” or portion of
the vertebral column to which the pelvic girdle is attached; (2) in some
species of Whales and Armadillos there are constant ossific unions of
certain vertebræ of the cervical region.
[Illustration: FIG. 10.—Side view of the first lumbar vertebra of a Dog
(_Canis familiaris_). _s_, Spinous process; _az_, anterior zygapophysis;
_pz_, posterior zygapophysis; _m_, metapophysis; _a_, anapophysis; _t_,
transverse process.]
Although the vertebræ of different regions of the column of the same
animal or of different animals present great diversities of form, yet
there is a certain general resemblance among them, or a common plan on
which they are constructed, which is more or less modified by alteration
of form or proportions, or by the addition or suppression of parts to
fit them to fulfil their special purpose in the economy. An ordinary or
typical vertebra consists, in the first place, of a solid piece of bone,
termed the body or centrum (Fig. 9, _c_), of the form of a disk or short
cylinder. The bodies of contiguous vertebræ are connected together by
a very dense, tough, and elastic material called the “intervertebral
substance,” of peculiar and complex arrangement. This substance forms
the main, and in some cases the only, union between the vertebræ. Its
elasticity provides for the vertebræ always returning to their normal
relation to each other and to the column generally, when they have been
disturbed therefrom by muscular action. A process (_p_) arises on each
side from the dorsal surface of the body. These processes, meeting
in the middle line above, form an arch, surmounting a space or short
canal (_nc_). Since it contains the posterior prolongation of the great
cerebro-spinal nervous axis, or spinal cord, this space is called the
neural canal, and the arch the neural arch, in contradistinction to
another arch on the ventral surface of the body of the vertebræ, called
the hæmal arch. The latter is, however, never formed in mammals by
any part of the vertebra itself, but by certain distinct bones placed
more or less in apposition to it, namely the ribs in the thoracic, and
the “chevron bones” in the caudal region. In most cases the arch of
one vertebra is articulated with that of the next by distinct surfaces
with synovial joints, placed one on each side, called “zygapophyses”
(_az_, _pz_), but these are often entirely wanting when flexibility is
more needed than strength, as in the greater part of the caudal region
of long-tailed animals. In addition to the body and the arch, there
are certain projecting parts called processes, chiefly serving for the
attachment of the numerous muscles which move the vertebral column. Of
these two are single and median, viz. the spinous process, neural spine,
or neurapophysis (_s_), arising from the middle of the upper part of
the arch, and the hypapophysis from the under surface of the body. The
latter, however, is as frequently absent as the former is constant. The
other processes are paired and lateral. They are the transverse processes
(_t_), of which there may be two, an upper and a lower, in which case the
former is called, in the language of Owen (to whom we are indebted for
the terminology of the parts of vertebræ in common use), “diapophysis,”
and the latter “parapophysis.” Other processes less constantly present
are called respectively “metapophyses” (_m_) and “anapophyses” (_a_).
The vertebral column is divided for convenience of description into five
regions—the cervical, thoracic or dorsal, lumbar, sacral, and caudal.
This division is useful, especially as it is not entirely arbitrary,
and in most cases is capable of ready definition; but at the contiguous
extremities of the regions the characters of the vertebræ of one are
apt to blend into those of the next region, either normally or as
peculiarities of individual skeletons.
[Illustration: FIG. 11.—Anterior surface of sixth cervical vertebra
of Dog. _s_, Spinous process; _az_, anterior zygapophysis; _v_,
vertebrarterial canal; _t_, transverse process; _t′_, its inferior
lamella.]
_Cervical Vertebræ._—The _cervical_ region constitutes the most anterior
portion of the column, or that which joins the cranium. The vertebræ
which belong to it are either entirely destitute of movable ribs, or
if they have any these are small, and do not join the sternum. As a
general rule they have a considerable perforation through the base
of the transverse process (the vertebrarterial canal, Fig. 11, _v_);
or, as it is sometimes described, they have two transverse processes,
superior and inferior, which meet at their extremities to enclose a
canal. This, however, rarely applies to the last vertebra of the region,
in which only the upper transverse process is usually developed. The
transverse process, moreover, very often sends down near its extremity
a more or less compressed plate (inferior lamella), which, being
considered serially homologous with the ribs of the thoracic vertebræ
(though not developed autogenously), is often called the “costal” or
“pleurapophysial” plate. This is usually largest on the sixth, and
altogether wanting on the seventh vertebra. The first and second cervical
vertebræ, called respectively “atlas” and “axis,” are specially modified
for the function of supporting and permitting the free movements of the
head. They are not united together by the intervertebral substance, but
connected only by ordinary ligaments and synovial joints.
The cervical region in mammals presents the remarkable peculiarity that,
whatever the length or flexibility of the neck, the number of vertebræ
is the same, viz. seven, with the exception of the Manatee and Hoffman’s
Two-toed Sloth (_Cholœpus hoffmanni_), which both have but six, and
the Three-toed Sloth (_Bradypus tridactylus_), which has nine, though
in this case the last two usually support movable ribs, which are not
sufficiently developed to reach the sternum.
According to Parker there may occasionally be eight cervicals in the
Pangolins (_Manis_).
_Dorsal Vertebræ._—The _dorsal_ (or, as it would be more correctly
termed, _thoracic_) region consists of the vertebræ succeeding those of
the neck, which have ribs movably articulated to them. These ribs arch
round the thorax—the anterior one, and usually the greater number of
those that follow, being attached below to the sternum.
_Lumbar Vertebræ._—The _lumbar_ region consists of those vertebræ of
the trunk in front of the sacrum which bear no movable ribs. It may
happen that, as the ribs decrease in size posteriorly (the last being
sometimes more or less rudimentary), the step from the thoracic to
the lumbar region may be gradual and rather undetermined in a given
species; but most commonly this is not the case, and the distinction is
as well defined here as in any other region. As a general rule there
is a certain relation between the number of the thoracic and lumbar
vertebræ, the whole number being tolerably constant in a given group
of animals, and any increase of the one being at the expense of the
other. Thus in all known Artiodactyle Ungulata there are 19 dorso-lumbar
vertebræ; but these may consist of 12 dorsal and 7 lumbar vertebræ, or
13 dorsal and 6 lumbar, or 14 dorsal and 5 lumbar. The smallest number
of dorso-lumbar vertebræ in mammals occurs in some Armadillos, which
have but 14. The number found in Man, the higher Apes, and most Bats,
viz. 17, is exceptionally low; 19 prevails in the Artiodactyla, nearly
all Marsupials, and very many Rodents; 20 or 21 in Carnivora and most
Insectivora; and 23 in Perissodactyla. The highest and quite exceptional
numbers are in the Two-toed Sloth (_Cholœpus_) 27, and the Hyrax 30. The
prevailing number of rib-bearing vertebræ is 12 or 13, any variation
being generally in excess of these numbers.
_Sacral Vertebræ._—The _sacral_ region offers more difficulties of
definition. Taking the human “os sacrum” as a guide for comparison,
it is generally defined as consisting of those vertebræ between the
lumbar and caudal regions which are ankylosed together to form a single
bone. It happens, however, that the number of such vertebræ varies in
different individuals of the same or nearly allied species, especially
as age advances, when a certain number of the tail vertebræ generally
become incorporated with the true sacrum. Other suggested tests—as those
vertebræ which have a distinct additional (pleurapophysial) centre of
ossification between the body and the ilium, those to which the ilium
is directly articulated, or those in front of the insertion of the
ischiosacral ligaments—being equally unsatisfactory or unpractical, the
old one of ankylosis, as it is found to prevail in the average condition
of adults in each species, is used in the enumeration of the vertebræ in
the following pages. The Cetacea, having no iliac bones, have no part of
the vertebral column modified into a sacrum.
[Illustration: FIG. 12.—Anterior surface of fourth caudal vertebræ of
Porpoise (_Phocæna communis_). _s_, Spinous process; _m_, metapophysis;
_t_, transverse process; _h_, chevron bone.]
_Caudal Vertebræ._—The _caudal_ vertebræ are those placed behind the
sacrum, and terminating the vertebral column. They vary in number
greatly—being reduced to 5, 4, or even 3, in a most rudimentary
condition, in Man and in some Apes and Bats, and being numerous and
powerfully developed, with strong and complex processes, in many mammals,
especially among the Edentata, Cetacea, and Marsupialia. The highest
known number, 46, is possessed by the African Long-tailed Pangolin.
Connected with the under surface of the caudal vertebræ of many mammals
which have the tail well developed are certain bones formed more or less
like an inverted arch, called chevron bones, or by the French _os en V_.
These are always situated nearly opposite to an intervertebral space, and
are generally articulated both to the vertebra in front and the vertebra
behind, but sometimes chiefly or entirely either to one or the other.
In some of the Anomodont Reptiles and Labyrinthodont Amphibians these
chevrons are attached to the intercentra—or imperfect disks alternating
with the true centra—which suggests that they are primarily intercentral
elements which have been transferred to the edges of the centra by the
disappearance of the intercentra.
_Sternum._—The _sternum_ of mammals is a bone, or generally a series
of bones, placed longitudinally in the mesial line, on the inferior
or ventral aspect of the thorax, and connected on each side with the
vertebral column by a series of more or less ossified bars called “ribs.”
It is present in all mammals, but varies much in character in the
different groups. It usually consists of a series of distinct segments
placed one before the other, the anterior being called the presternum or
“manubrium sterni” of human anatomy, and the posterior the xiphisternum,
or xiphoid or ensiform process, while the intermediate segments, whatever
their number, constitute the mesosternum or “body.” In the Whalebone
Whales the presternum alone is developed, and but a single pair of ribs
is attached to it.
[Illustration: FIG. 13.—Human sternum and sternal ribs. _ps_, Presternum;
_ms_, mesosternum; _xs_, xiphisternum; _c_, point of attachment of
clavicle; 1 to 10, the cartilaginous sternal ribs.]
_Ribs._—The _ribs_ form a series of long, narrow, and more or less
flattened bones, extending laterally from the sides of the vertebral
column, curving downwards towards the median line of the body below, and
mostly joining the sides of the sternum. The posterior ribs, however,
do not directly articulate with that bone, but are either attached by
their extremities to the edges of each rib in front of them, and thus
only indirectly join the sternum, or else they are quite free below,
meeting no part of the skeleton. These differences have given rise to the
division into “true” and “false” ribs (by no means good expressions),
signifying those that join the sternum directly and those that do not;
and of the latter, those that are free below, are called “floating” ribs.
The portion of each rib nearest the vertebral column and that nearest
the sternum differ in their characters, the latter being usually but
imperfectly ossified, or remaining permanently cartilaginous. These are
called “costal cartilages,” or when ossified “sternal ribs.”
[Illustration: FIG. 14.—Sternum and strongly ossified sternal ribs of
Great Armadillo (_Priodon gigas_). _ps_, Presternum; _xs_, xiphisternum.]
In the anterior part of the thorax the vertebral extremity of each rib is
divided into two parts, “head” or “capitulum,” and “tubercle”; the former
is attached to the side of the body of the vertebra, the latter to its
transverse process; the former attachment corresponds to the interspace
between the vertebræ, the head of the rib commonly articulating partly
with the hinder edge of the body of the vertebra antecedent to that which
bears its tubercle. Hence the body of the last cervical vertebra usually
supports part of the head of the first rib. In the posterior part of the
series the capitular and tubercular attachments commonly coalesce, and
the rib is attached solely to its corresponding vertebra. The number of
pairs of ribs is of course the same as that of the thoracic vertebræ.
The circumstance that in some of the Anomodont reptiles and
Labyrinthodonts the capitula of the ribs articulate with the intercentral
elements of the vertebral column has suggested, as in the instance of
the chevron bones, that the intercentral capitular articulation of the
ribs of mammals is a feature directly inherited from those extinct types
by the gradual disappearance of the intercentra.
_Appendicular Skeleton._—The appendicular portion of the framework
consists, when completely developed, of two pairs of limbs, anterior and
posterior (Fig. 15).
[Illustration: FIG. 15.—Skeleton of Lion (_Felis leo_). _cd_, Caudal
vertebræ; _cp_, carpus; _cr_, coracoid process of scapula, _cv_, cervical
vertebræ; _d_, dorsal vertebræ; _fb_, fibula; _fm_, femur; _h_, humerus;
_il_, ilium; _isch_, ischium; _l_, lumbar vertebræ; _m_, metatarsus;
_mc_, metacarpus; _p_, patella; _pb_, pubis; _ph_, phalanges; _pv_,
pelvis; _r_, radius; _s_, sacral vertebræ; _sc_, scapula; _sk_, skull;
_tb_, tibia; _ts_, tarsus; _u_, ulna; _zy_, zygomatic arch.]
_Anterior Limb._—The anterior limb is present and fully developed in all
mammals, being composed of a shoulder girdle and three segments belonging
to the limb proper; viz. the upper arm or brachium, the forearm or
antebrachium, and the hand or manus.
_Shoulder-girdle._—The _shoulder_ or _pectoral girdle_ in the large
majority of mammals is in a rudimentary or rather modified condition,
compared with that in which it exists in other vertebrates. In the
Monotremata (_Ornithorhynchus_ and _Echidna_) alone is the ventral
portion, or coracoid, complete and articulated with the sternum below,
as in the Sauropsida; and in this group alone do we find an anterior
ventral element, apparently corresponding with the pre-coracoid of the
Anomodont reptiles, although generally known as the epi-coracoid. In
all other mammals the coracoid, though ossified from a distinct centre,
forms only a process, sometimes a scarcely distinct tubercle, projecting
from the anterior border of the glenoid cavity of the scapula. The
last-named cavity, which in the Monotremes is formed jointly by the
scapula and coracoid, receives the head of the humerus, or arm-bone. The
scapula is always well developed, and generally broad and flat (whence
its vernacular name “blade bone”), with a ridge called the “spine” on
its outer surface, which usually ends in a free curved process, the
“acromion.” As the scapula affords attachment to many of the muscles
which act upon the anterior limb, its form and the development of its
processes are greatly modified according to the uses to which the
member is put. Thus it is most reduced and simple in character in those
animals whose limbs are mere organs of support, as the Ungulates; and
most complex when the limbs are also used for grasping, climbing, or
digging. The development or absence of the clavicle or “collar-bone,”
an accessory bar which connects the sternum with the scapula and
steadies the shoulder-joint, has a somewhat similar relation, though
its complete absence in the Bears shows that this is not an invariable
rule. A complete clavicle is found in Man and all the Primates, in
Chiroptera, all Insectivora (except _Potamogale_), in many Rodents, in
most Edentates, and in all Marsupials, except _Perameles_. More or less
rudimentary clavicles (generally suspended freely in the muscles) are
found in the Cat, Dog, and most Carnivora, _Myrmecophaga_, and some
Rodents. Clavicles are altogether absent in most of the _Ursidæ_, all the
Pinnipedia, _Manis_ among Edentates, the Cetacea, Sirenia, Ungulates, and
some Rodents.
The Monotremes are peculiar in possessing a T-shaped interclavicle
like that of many reptiles, lying upon the sternum, and articulating
superiorly with the clavicles.
_Brachium and Antebrachium._—The proximal segment of the anterior or
pectoral limb proper contains a single bone, the humerus, and the second
segment two bones, the radius and the ulna, placed side by side, and
articulating with the humerus at their proximal, and with the carpus
at their distal extremity (Fig. 15). In their primitive and unmodified
condition these bones may be considered as placed one on each border of
the limb, the radius being preaxial or anterior, and the ulna postaxial
or posterior, when the distal or free end of the limb is directed
outwards, or away from the trunk. This is their position in the earliest
embryonic condition, and is best illustrated among adult mammals in the
Cetacea, where the two bones are fixed side by side and parallel to each
other. In the greater number of mammals the bones assume a very modified
and adaptive position, usually crossing each other in the forearm, the
radius in front of the ulna, so that the preaxial bone (radius), though
external (in the ordinary position of the limb) at the upper end, is
internal at the lower end; and the hand, being mainly fixed to the
radius, also has its preaxial border internal. In the large majority of
mammals the bones are fixed in this position, but in some few, as in Man,
a free movement of crossing and uncrossing—or pronation and supination,
as it is termed—is allowed between them, so that they can be placed in
their primitive parallel condition, when the hand (which moves with the
radius) is said to be supine, or they may be crossed, when the hand is
said to be prone.
The humerus frequently has a foramen piercing the inner border of the
distal extremity, known as the entepicondylar foramen, which corresponds
with a similar one found in the Anomodont reptiles. The hollow in the
head of the ulna for the reception of the head of the humerus is known as
the greater sigmoid cavity, and that for the head of the radius as the
lesser sigmoid cavity (Fig. 16). The term olecranon is applied to that
process of the ulna which forms the prominence of the elbow.
[Illustration: FIG. 16.—Outer aspect of the proximal extremity of the
right ulna of a Bear (_Ursus_). _a_, Anterior tubercle; _ol_, olecranon;
_b_, greater sigmoid cavity; _c_, lesser do.]
In most mammals walking on four limbs, in which the hand is permanently
prone, the ulna is much reduced in size, and the radius increased,
especially at the upper end; so that the articular surface of the latter,
instead of being confined to the external side of the trochlea of the
humerus, extends all across its anterior surface, and the two bones,
instead of being external and internal, are anterior and posterior. In
many hoofed or Ungulate mammals, and in Bats, the ulna is reduced to
little more than its upper articular extremity, and firmly ankylosed to
the radius—stability of these parts being more essential than mobility.
_Manus._—The terminal segment of the anterior limb is the hand or
manus. Its skeleton consists of three divisions: (1) the “carpus,” a
group of small, more or less rounded or angular bones with flattened
surfaces applied to one another, and, though articulating by synovial
joints, having scarcely any motion between them; (2) the “metacarpus,”
a series of elongated bones placed side by side, with their proximal
ends articulating by almost immovable joints with the carpus; (3) the
“phalanges” or bones of the digits, usually three in number to each,
articulating to one another by freely movable hinge-joints, the first
being connected in like manner to the distal end of the metacarpal bone
to which it corresponds.
[Illustration: FIG. 17.—Dorsal surface of the right manus of a Water
Tortoise (_Chelydra serpentina_). After Gegenbaur. U, Ulna; R, radius;
_u_, ulnare; _i_, intermedium; _r_, radiale; _c_, centrale; 1-5, the five
bones of the distal row of the carpus; _m¹_-_m⁵_, the five metacarpals.]
_Carpus._—To understand thoroughly the arrangement of the bones of the
carpus in mammals, it is necessary to study their condition in some of
the lower vertebrates. Fig. 17 represents the manus in one of its fullest
and at the same time most generalised forms, as seen in one of the Water
Tortoises (_Chelydra serpentina_). The carpus consists of two principal
rows of bones. The upper or proximal row contains three bones, to which
Gegenbaur has applied the terms _radiale_ (_r_), _intermedium_ (_i_), and
_ulnare_ (_u_), the first being on the radial or preaxial side of the
limb.[11] The lower or distal row contains five bones, called _carpale_
1, 2, 3, 4, and 5 respectively, commencing on the radial side. Between
these two rows, in the middle of the carpus, is a single bone, the
_centrale_ (_c_). In this very symmetrical carpus it will be observed
that the _radiale_ supports on its distal side two bones, _carpale_ 1
and 2; the _intermedium_ is in a line with the _centrale_ and _carpale_
3, which together form a median axis of the hand, while the _ulnare_ has
also two bones articulating with its distal end, viz. _carpale_ 4 and 5.
Each of the carpals of the distal row supports a metacarpal.
In the carpus of the Mammalia there are usually two additional bones
developed in the tendons of the flexor muscles, one on each side of the
carpus, which may be called the radial and ulnar sesamoid bones; the
latter, which is the more constant and generally larger, is commonly
known as the pisiform bone. The fourth and fifth carpals of the distal
row are always united into a single bone, and the centrale is very often
absent. As a general rule all the other bones are present and distinct,
though it not unfrequently happens that two may have coalesced to form a
single bone, or one or more may be altogether suppressed.
The following table shows the principal names in use for the various
carpal bones,—those in the second column being the terms generally
employed by English anatomists:—
_Radiale_ = Scaphoid = _Naviculare_.
_Intermedium_ = Lunar = _Semilunare_, _Lunatum_.
_Ulnare_ = Cuneiform = _Triquetrum_, _Pyramidale_.
_Centrale_ = Central = _Intermedium_ (Cuvier).
_Carpale_ 1 = Trapezium = _Multangulum majus_.
_Carpale_ 2 = Trapezoid = _Multangulum minus_.
_Carpale_ 3 = Magnum = _Capitatum_.
_Carpale_ 4 } = Uneiform = _Hamatum_, _Uncinatum_.
_Carpale_ 5 }
The radial and ulnar sesamoids are regarded by Bardeleben[12] as the
rudiments of a prepollex and a postminimus digit; the primitive number
of digits being thus supposed to have been seven. These bones have
been observed in all orders of mammals having five complete digits.
Occasionally, as in _Pedetes caffer_, the so-called prepollex consists
of two bones, of which the distal one bears a distinct nail-like horny
covering. In _Bathyergus maritimus_ the pisiform, or postminimus, is
likewise double; the two elements being regarded by their describer as
representing the carpal and metacarpal of the presumed seventh digit.
Similarly in the posterior limb the tibial sesamoid, and a fibular
ossification corresponding to the pisiform, are regarded as representing
a prehallux and a postminimus.
_Metacarpus and Phalanges._—The metacarpal bones, with the digits which
they support, are never more than five in number, and are described
numerically—first, second, etc., counting from the radial towards the
ulnar side. The digits are also sometimes named (1) the pollex, (2)
index, (3) medius, (4) annularis, (5) minimus. One or more may be in
a rudimentary condition, or altogether suppressed. If one is absent,
it is most commonly the first. Excepting the Cetacea, no mammals have
more than three phalanges to each digit, but they may occasionally have
fewer by suppression or ankylosis. The first or radial digit is an
exception to the usual rule, one of its parts being constantly absent,
since, while each of the other digits has commonly a metacarpal and
three phalanges, it has only three bones altogether; whether the missing
one is a metacarpal or one of the phalanges is a subject which has
occasioned much discussion, and has not yet been satisfactorily decided.
The terminal phalanges of the digits are usually specially modified to
support the nail, claw, or hoof, and are called “ungual phalanges.” In
walking, some mammals (as the Bears) apply the whole of the lower surface
of the carpus, metacarpus, and phalanges to the ground; to these the
term “plantigrade” is applied. Many others (as nearly all the existing
Ungulata) only rest on the last one or two phalanges of the toes, the
first phalanx and the metacarpals being vertical and in a line with the
forearm. These are called “digitigrade.” Intermediate conditions exist
between these two forms, to which the terms “phalangigrade” (as the
Camel) and “subplantigrade” (as in most Carnivora), are applied. When the
weight is borne entirely on the distal surface of the ungual phalanx,
and the horny structures growing around it, as in the Horse, the mode of
progression is called “unguligrade.”
In the Chiroptera the digits are enormously elongated, and support a
cutaneous expansion constituting the organ of flight. In the Cetacea the
manus is formed into a paddle, being covered by continuous integument,
which conceals all trace of division into separate digits, and shows no
sign of nails or claws. In the Sloths the manus is long and very narrow,
habitually curved, and terminating in two or three pointed curved claws
in close apposition with each other, and incapable, in fact, of being
divaricated; so that it is reduced to the condition of a hook, by which
the animal suspends itself to the boughs of the trees among which it
lives. These are only examples of the endless modifications to which the
distal extremity of the limb is subjected in adaptation to the various
purposes to which it is applied.
_Posterior Limb._—The posterior limb is constructed upon a plan very
similar to that of the anterior extremity. It consists of a pelvic girdle
and three segments belonging to the limb proper, viz. the thigh, the leg,
and the foot or pes (Fig. 15).
_Pelvic Girdle._—The pelvic girdle is present in some form in all
mammals, though in the Cetacea and the Sirenia it is in an exceedingly
rudimentary condition. In all mammals except those belonging to the
two orders just named, each lateral half of the pelvic girdle consists
essentially, like the corresponding part of the anterior limb, of a
flattened rod of bone crossing the long axis of the trunk, having an
upper or dorsal and a lower or ventral end. The upper end diverges from
that of the opposite side, but the lower end approaches, and, in most
cases, meets it, forming a symphysis, without the intervention of any
bone corresponding to the sternum. The pelvic girdle differs from the
shoulder girdle in being firmly articulated to the vertebral column, thus
giving greater power to the hinder limb in its function of supporting
and propelling the body. Like the shoulder girdle, it bears on its outer
side, near the middle, a cup-shaped articular cavity (“acetabulum”),
into which the proximal end of the first bone of the limb proper is
received. Each lateral half of the girdle is called the “os innominatum,”
or innominate bone, and consists originally of three bones which unite
at the acetabulum. The “ilium” or upper bone is that which articulates
with the sacral vertebræ. Of the two lower bones the anterior or “pubis”
unites with its fellow of the other side at the symphysis; the posterior
is the “ischium.” These lower elements form two bars of bone, united
above and below, but leaving a space between them in the middle, filled
only by membrane, and called the “thyroid” or “obturator” foramen. The
whole circle of bone formed by the two innominate bones and the sacrum
is called the pelvis. In the Monotremata and Marsupialia, a pair of
thin, flat, elongated ossifications called epipubic or marsupial bones
are attached to the fore part of the pubis, and project forward into the
muscular wall of the abdomen.
_Thigh and Leg._—The first segment of the limb proper has one bone, the
femur, corresponding with the humerus of the anterior limb. The second
segment has two bones, the tibia and fibula, corresponding with the
radius and ulna. These bones always lie in their primitive unmodified
position, parallel to each other, the tibia on the preaxial and the
fibula on the postaxial side, and are never either permanently crossed or
capable of any considerable amount of rotation, as in the corresponding
bones of the fore limb. In the ordinary walking position the tibia is
internal, and the fibula external. In many mammals the fibula is in a
more or less rudimentary condition, and it often ankyloses with the tibia
at one or both extremities. The patella or “knee-cap,” which is found
in an ossified condition in all mammals, with the exception of some of
the Marsupialia, is a large sesamoid bone developed in the tendon of the
extensor muscles of the thigh, where the tendon passes over the front of
the knee-joint, to which it serves as a protection. There are frequently
smaller ossicles, one or two in number, situated behind the femoral
condyles, called “fabellæ.” The processes for the attachment of muscles
near the upper end of the femur are termed trochanters; and the third
trochanter, found on the hinder aspect of the shaft of this bone in many
forms is of considerable taxonomic importance.
_Pes._—The terminal segment of the hind limb is the foot or pes. Its
skeleton presents in many particulars a close resemblance to that of
the manus, being divisible into three parts: (1) a group of short, more
or less rounded or square bones, constituting the tarsus; (2) a series
of long bones placed side by side, forming the metatarsus; and (3) the
phalanges of the digits or toes.
The bones of the tarsus of many of the lower Vertebrata closely resemble
both in number and arrangement those of the carpus, as shown in Fig. 17.
They have been described in their most generalised condition by Gegenbaur
under the names expressed in the first column of the following table. The
names in the second column are those by which they are generally known to
English anatomists, while in the third column some synonyms occasionally
employed are added.
_Tibiale (?)_ } = Astragalus[13] = _Talus_.
_Intermedium_ }
_Fibulare_ = Calcaneum = _Os calcis_.
_Centrale_ = Navicular = _Scaphoideum_.
_Tarsale_ 1 = Internal cuneiform = _Entocuneiforme_.
_Tarsale_ 2 = Middle cuneiform = _Mesacuneiforme_.
_Tarsale_ 3 = External cuneiform = _Ectocuneiforme_.
_Tarsale_ 4 } = Cuboid.
_Tarsale_ 5 }
The bones of the tarsus of mammals present fewer diversities of number
and arrangement than those of the carpus. The proximal row (see Fig.
18) always consists of two bones, namely the astragalus (_a_), which
probably represents the coalesced scaphoid and lunar of the hand, and the
calcaneum (_c_). The former is placed more to the dorsal side of the foot
than the latter, and almost exclusively furnishes the tarsal part of the
tibio-tarsal or ankle-joint. The calcaneum, placed more to the ventral
or “plantar” side of the foot, is elongated backwards to form a more or
less prominent tuberosity, the “tuber calcis,” to which the tendon of
the great extensor muscles of the foot is attached. The navicular bone
(_n_) is interposed between the proximal and distal row on the inner
or tibial side of the foot, but on the outer side the bones of the two
rows come into contact. The distal row, when complete, consists of four
bones, which, beginning on the inner side, are the three cuneiform bones,
internal (_c¹_), middle (_c²_), and external (_c³_), articulated to the
distal surface of the navicular, and the cuboid (_cb_), articulated with
the calcaneum. Of these the middle cuneiform is usually the smallest in
animals in which all five digits are developed; but when the hallux is
wanting the internal cuneiform may be rudimentary or altogether absent.
The three cuneiform bones support respectively the first, second, and
third metatarsals, and the cuboid supports the fourth and fifth; they
thus exactly correspond with the four bones of the distal row of the
carpus.
[Illustration: FIG. 18.—Bones of the right Human foot. _T_, Tarsus; _M_,
metatarsus; _Ph_, phalanges, _c_, calcaneum; _a_, astragalus; _cb_,
cuboid; _n_, navicular; _c¹_, internal cuneiform; _c²_, middle cuneiform;
_c³_, external cuneiform. The digits are indicated by Roman numerals,
counting from the tibial to the fibular side.]
In addition to these constant tarsal bones, there may be supplemental
or sesamoid bones: one situated near the middle of the tibial side of
the tarsus, largely developed in many Carnivora and Rodentia; another,
less frequent, on the fibular side; and a third, often developed in the
tendons of the plantar surface of the tarsus, is especially large in
Armadillos. There is also usually a pair of sesamoid bones on the plantar
aspect of each metatarso-phalangeal articulation. In the young of the
carnivorous genus _Crytoprocta_ there may be a second centrale, which
usually coalesces with the ectocuneiform.
The metatarsal bones never exceed five in number, and the phalanges
follow the same numerical rule as in the manus, never exceeding three in
each digit. Moreover, the first digit, counting from the tibial side, or
hallux, resembles the pollex of the hand in always having one segment
less than the other digits. As the function of the hind foot is more
restricted than that of the hand the modifications of its structure are
less striking. In the Cetacea and the Sirenia it is entirely wanting,
though in some existing members of the first-named order rudiments of
the bones of both the first and second segments of the limb have been
detected, and a femur is present in the Miocene Sirenian _Halitherium_.
IV. THE DIGESTIVE SYSTEM.
_General Considerations._—The search after the purpose which every
modification of structure subserves in the economy is always full of
interest, and, if conducted with due caution and sufficient knowledge of
all the attendant circumstances, may lead to important generalisations.
It must always be borne in mind, however, that adaptation to its special
function is not the only cause of the particular form or structure of an
organ, but that this form, having in all probability been arrived at by
the successive and gradual modification of some other different form from
which it is now to a greater or less degree removed, has other factors
besides use to be taken into account. In no case is this principle so
well seen as in that of the organs of digestion. These may be considered
as machines which have to operate upon alimentary substances in very
different conditions of mechanical and chemical combination, and to
reduce them in every case to the same or precisely similar materials;
and we might well imagine that the apparatus required to produce flesh
and blood out of coarse fibrous vegetable substances would be different
from that which had to produce exactly the same results out of ready-made
flesh or blood; and in a very broad sense we find that this is so. Thus,
if we take a large number of carnivorous animals, belonging to different
fundamental types, and a large number of herbivorous animals, and strike
a kind of average of each, we shall find that there is, pervading the
first group, a general style, if we may use the expression, of the
alimentary organs, different from that of the others. That is to say,
there is a specially carnivorous and a specially herbivorous modification
of these parts. But, if function were the only element which has guided
such modification, it might be inferred that, as one form must be
supposed to be best adapted in its relation to a particular kind of diet,
that form would be found in all the animals consuming such diet. But this
is far from being the case. Thus the Horse and the Ox, for instance—two
animals whose food in the natural state is precisely similar—are most
different as regards the structure of their alimentary canal, and the
processes involved in the preparation of that food. Again, the Seal and
the Porpoise, both purely fish-eaters, which seize, swallow, and digest
precisely the same kind of prey, in precisely the same manner, have a
totally different arrangement of the alimentary canal. If the Seal’s
stomach is adapted in the best conceivable manner for the purpose it has
to fulfil, why is not the Porpoise’s stomach an exact facsimile of it,
and _vice versâ_? We can only answer that the Seal and Porpoise belong to
different natural groups of animals, formed either on different primitive
types, or descended from differently constructed ancestors. On this
principle only can we account for the fact that, whereas, owing to the
comparatively small variety of the different alimentary substances met
with in nature, few modifications would appear necessary in the organs of
digestion, there is really endless variety in the parts devoted to this
purpose.
_Mouth._—The digestive apparatus of mammals, as in other vertebrates,
consists mainly of a tube with an aperture placed at or near either
extremity of the body,—the oral and the anal orifice,—and furnished with
muscular walls, the fibres of which are so arranged as by their regular
alternate contraction and relaxation to drive onwards the contents of
the tube from the first to the second of these apertures. The anterior
or commencing portion of this tube and the parts around it are greatly
and variously modified in relation to the functions assigned to them of
selecting and seizing the food, and preparing it by various mechanical
and chemical processes for the true digestion which it has afterwards
to undergo before it can be assimilated into the system. For this end
the tube is dilated into a chamber or cavity called the mouth, bordered
externally by the lips, which are usually muscular and prehensile, and
supported by a movable framework carrying the teeth; the structure and
modifications of which have been already described. The roof of the mouth
is formed by the palate, terminating behind by a muscular, contractile
arch, having in Man and some few other species a median projection
called the uvula, beneath which the mouth communicates with the pharynx.
The anterior part of the palate is composed of mucous membrane tightly
stretched over the flat or slightly concave bony lamina separating the
mouth from the nasal passages, and is generally raised into a series
of transverse ridges, which sometimes, as in Ruminants, attain a
considerable development. In the floor of the mouth, between the rami of
the mandible, and supported behind by the hyoidean apparatus, lies the
tongue; an organ the free surface of which, especially in its posterior
part, is devoted to the sense of taste, but which also, by its great
mobility (being composed almost entirely of muscular fibres), performs
important mechanical functions connected with masticating and procuring
food. Its modifications of form in different mammals are very numerous.
Between the long, extensile, vermiform tongue of the Anteaters, which
is essential to the peculiar mode of feeding of those animals, and the
short, sessile, and almost functionless tongue of the Porpoise, every
intermediate condition is found. Whatever the form, the upper surface
is always covered with numerous fine papillæ, in which the terminal
filaments of the gustatory nerve are distributed.
_Salivary Glands._—The fluid known as the saliva is secreted by an
extensive and complex system of glands discharging into the cavity of the
mouth (buccal cavity), the position and relation of some of which are
exhibited in the woodcut on the next page (Fig. 19).
[Illustration: FIG. 19.—Salivary Glands of the Genet. _A_, Right side
of the head dissected; _p_, parotid gland; _d_, Steno’s duct; _sm_,
submaxillary gland, traversed by the jugular veins (_jv_); _o_, aperture
of Steno’s duct. _B_, Part of the head with the lip drawn up to show
(_st.d_) aperture of Steno’s duct; _z.gl_, zygomatic gland; _o_, aperture
of do.; _z_, zygomatic arch (Mivart, _Proc. Zool. Soc._ 1882, p. 504.)]
This apparatus consists of small glands embedded in the mucous membrane
or submucous tissue lining the cavity of the mouth, which are of two
kinds (the follicular and the racemose), and of others in which the
secreting structure is aggregated in distinct masses removed some
distance from the cavity; other tissues besides the lining membrane being
usually interposed, and pouring their secretion into the cavity by a
distinct tube or duct, which traverses the mucous membrane. To the latter
alone the name of “salivary glands” is ordinarily appropriated, although
the distinction between them and the smaller racemose glands is only one
of convenience for descriptive purposes, their structure being more or
less nearly identical; and, since the fluids secreted by all become mixed
in the month, their functions are, at all events in great part, common.
Under the name of salivary glands are commonly included—(1) the “parotid”
(_p_), situated very superficially on the side of the head, below or
around the cartilaginous external auditory meatus, and the secretion of
which enters the mouth by a duct (often called Steno’s or Stenson’s)
which crosses the masseter muscle and opens into the upper and back part
of the cheek (Fig. 19); and (2) the “submaxillary” (_sm_), situated in
the neck, near or below the angle of the mandible, and sending a long
duct (Wharton’s) forwards to open on the forepart of the floor of the
cavity of the mouth, below the apex of the tongue. These are the most
largely developed and constant of the salivary glands, being met with
in various degrees of development in almost all animals of the class.
Next in constancy are (3) “the sublingual,” closely associated with the
last-named, at all events in the locality in which the secretion is
poured out; and (4) the “zygomatic” (_z.gl_), found only in some animals
in the cheek, just under cover of the anterior part of the zygomatic
arch, its duct entering the buccal cavity near that of the parotid.
The most obvious function common to the secretion of these various
glands, and to that of the smaller ones placed in the mucous membrane
of the lips, the cheeks, the tongue, the palate, and fauces, is the
mechanical one of moistening and softening the food, to enable it the
more readily to be tasted, masticated, and swallowed, though each kind of
gland may contribute in different manner and different degree to perform
this function. The saliva is, moreover, of the greatest importance in the
first stage or introduction to the digestive process, as it dissolves
or makes a watery extract of all soluble substances in the food, and
so prepares them to be further acted on by the more potent digestive
fluids met with subsequently in their progress through the alimentary
canal. In addition to these functions it seems now well established by
experiment that saliva serves in Man and many animals to aid directly
in the digestive process, particularly by its power of inducing the
saccharine transformation of amylaceous substances. As a general rule,
in mammals the parotid saliva is more watery in its composition, while
that of the submaxillaries, and still more the sublingual, contains
more solid elements and is more viscid;—so much so that some anatomists
consider the latter, together with the small racemose glands of the
cheeks, lips, and tongue, as mucous glands, retaining the name of
salivary only for the parotid. These peculiar properties are sometimes
illustrated in a remarkable degree, as, for example, the great secretion
of excessively viscid saliva which lubricates the tongue of the Anteaters
and Armadillos, associated with enormously developed submaxillary glands;
while, on the other hand, the parotids are of great size in those animals
which habitually masticate dry and fibrous food.
_Stomach._—After the preparation which the aliment has undergone in the
mouth,—the extent of which varies immensely in different forms, being
reduced almost to nothing in such animals as the Seals and Cetaceans,
which, to use the familiar expression, “bolt” their food entire, and
most fully carried out in the Ruminants, which “chew the cud,”—it is
swallowed, and carried along the œsophagus by the action of its muscular
coats into the stomach. In the greater number of mammals this organ is a
simple saccular dilatation of the alimentary canal, as in Figs. 20, 21,
but in others it undergoes remarkable modifications and complexities.
The lining of the stomach is thickly beset with tubular glands, which
are generally considered to belong to two different forms, recognisable
by their structure, and different in their function—the most numerous
and important secreting the gastric juice (the active agent in stomachic
digestion), and hence called “peptic” glands, while the others are
concerned only in the elaboration of mucus. The relative distribution
of these glands in different regions of the walls of the stomach varies
greatly in different animals, and in many species there are large tracts
of the mucous membrane which do not secrete a fluid having the properties
of gastric juice, but often constitute more or less distinct cavities
devoted to storing and perhaps softening or otherwise preparing the
food for digestion. Sometimes there is a great aggregation of glands
forming distinct thickened patches of the stomach wall, as in the Beaver
and Koala, or even collected in pyriform pouches with a common narrow
opening into the cavity, as in the Manatee and the curious African Rodent
_Lophiomys_. The action of the gastric fluid is mainly exerted upon the
nitrogenous elements of the food, which it dissolves and modifies so as
to render them capable of undergoing absorption, effected partly by the
blood-vessels of the stomach, although the greater part, passes through
the pylorus, an aperture surrounded by a circular muscular valve, into
the intestinal canal. Here it comes in contact with the secretion of a
vast number of small glands called the crypts of Lieberkuhn, somewhat
similar to those of the stomach; and also of several special glands of a
different character, namely, the small racemose, duodenal, or Brunner’s
glands, the pancreas, and the liver; the position of the ducts of the two
latter organs being indicated in Fig. 20.
[Illustration: FIG. 20.—Stomach and pancreas of the Genet. Posterior or
dorsal surface, _œ_, Œsophagus; _s_, pancreas; _pd_, pancreatic duct;
_bd_, biliary duct from the liver. (From Mivart, _Proc. Zool. Soc._ 1882,
p. 305.)]
_Intestinal Canal._—The intestinal canal varies greatly in relative
length and capacity in different animals, and it also offers manifold
peculiarities of form, being sometimes a simple cylindrical tube of
nearly uniform calibre throughout, but more often subject to alterations
of form and capacity in different portions of its course,—the most
characteristic and constant being the division into an upper and
narrower, and lower and wider portion, called respectively the small
and the large intestine, the former being divided quite arbitrarily and
artificially into duodenum, jejunum, and ileum, and the latter into
colon and rectum. One of the most striking peculiarities of this part
of the alimentary canal is the frequent presence of a diverticulum or
blind pouch, the _caput cæcum coli_, as it was first called, a name
generally abbreviated into “cæcum,” situated at the junction of the large
and the small intestine, a structure presenting an immense variety of
development, from the smallest bulging of a portion of the side wall of
the tube to a huge and complex sac, greatly exceeding in capacity the
whole of the remainder of the alimentary canal. It is only in herbivorous
animals that the cæcum is developed to this great extent, and among
these there is a curious complementary relationship between the size
and complexity of this organ and that of the stomach. Where the latter
is simple the cæcum is generally the largest, and _vice versâ_. Both
the cæcum and colon are often sacculated, a disposition caused by the
arrangement of the longitudinal bands of muscular tissue in their walls;
but the small intestine is always smooth and simple-walled externally,
though its lining membrane often exhibits various contrivances for
increasing the absorbing surface without adding to the general bulk of
the organ, such as the numerous small villi by which it is everywhere
beset, and the more obvious transverse, longitudinal, or reticulating
folds projecting into the interior, met with in many animals, of which
the “valvulæ conniventes” of Man form well-known examples.
[Illustration: FIG. 21.—Diagrammatic plan of the general arrangement of
the alimentary canal in a typical Mammal. _o_, Œsophagus; _st_, stomach;
_p_, pylorus; _s_, _s_, small intestine; (abbreviated); _c_, cæcum; _l_,
_l_, large intestine or colon, ending in _r_, the rectum.]
Besides the crypts of Lieberkuhn found throughout the intestinal canal,
and the glands of Brunner confined to the duodenum, there are other
structures in the mucous membrane, about the nature of which there is
still much uncertainty, called “solitary” and “agminated” glands; the
latter being more commonly known by the name of “Peyer’s patches.” These
were formerly supposed to be secretory organs, which discharged some
kind of fluid into the intestine, but are now more generally considered
to belong to that group of structures of somewhat mysterious function
of which the lymphatic and lacteal glands are members. The solitary
glands are found scattered irregularly throughout the whole intestinal
tract; the agminated, on the other hand, are always confined to the small
intestine, and are most abundant in its lower part. They are subject to
great variation in number and in size, and even in different individuals
of the same species, and also differ in character at different periods of
life, becoming atrophied in old age.
_Liver._—The distinct glands situated outside the walls of the intestinal
canal, but which pour their secretion into it, are the pancreas and the
liver. The latter is the more important on account of its size, if not on
account of the direct action of its secretion in the digestive process.
This large gland, so complex in structure and function, is well developed
in all mammals, and its secreting tube, the bile-duct, always opens into
the duodenum, or that portion of the canal which immediately succeeds
the stomach. It is situated on the right side of the abdomen in contact
with the diaphragm and the stomach, but varies greatly in relative size,
and also in form, in different groups of mammals. In most mammals a
gall-bladder, consisting of a pyriform diverticulum from the bile-duct,
is present, but in many this appendage is wanting, and it is difficult to
find the rationale of its presence or absence in relation to use or any
other circumstance in the animal economy.
The descriptions of the livers of various animals to be met with in
treatises or memoirs on comparative anatomy are very difficult to
understand for want of a uniform system of nomenclature. The difficulty
usually met with arises from the circumstance that this organ is divided
sometimes, as in Man, Ruminants, and the Cetacea, into two main lobes,
which have been always called respectively right and left, and in other
cases, as in the lower Monkeys, Carnivora, Insectivora, and several other
orders, into a larger number of lobes. Among the latter the primary
division usually appears at first sight tripartite, the whole organ
consisting of a middle, called “cystic” or “suspensory” lobe, and two
lateral lobes, called respectively right and left lobes. This introduces
confusion in describing livers by the same terms throughout the whole
series of mammals, since the right and left lobes of the Monkey or Dog,
for instance, do not correspond with parts designated by the same names
in Man and the Sheep. There are, moreover, conditions where neither the
bipartite nor the tripartite system of nomenclature will answer, so that
we should have considerable difficulty in describing them without some
more general system. In order to arrive at such a system it appears
desirable to consider the liver in all cases as primarily divided by the
umbilical vein (see Fig. 22, _u_) into two segments, right and left. This
corresponds with its development and with the condition characteristic
of the organ in the inferior classes of vertebrates. The situation of
this division can almost always be recognised in adult animals by the
persistence of some traces of the umbilical vein in the form of the round
ligament, and by the position of the suspensory ligament.
[Illustration: FIG. 22.—Diagrammatic plan of the inferior surface of
a multilobed liver of a Mammal. The posterior or attached border is
uppermost. _u_, Umbilical vein of the fœtus, represented by the round
ligament in the adult, lying in the umbilical fissure; _dv_, the ductus
venosus; _vc_, the inferior vena cava; _p_, the vena portæ entering the
transverse fissure; _llf_, the left lateral fissure; _rlf_, the right
lateral fissure; _cf_, the cystic fissure; _ll_, the left lateral lobe;
_lc_, the left central lobe; _rc_, the right central lobe; _rl_, the
right lateral lobe; _s_, the Spigelian lobe; _c_, the caudate lobe; _g_,
the gall-bladder.]
When the two main parts into which the liver is thus divided are entire,
as in Man, the Ruminants, and Cetacea, they may be spoken of as the
right and left lobes; when fissured, as the right and left segments
of the liver, reserving the term lobe for the subdivisions. This will
involve no ambiguity, for the terms right and left lobe will no longer
be used for divisions of the more complex form of liver. In the large
majority of mammals each segment is further divided by a fissure, more
or less deep, extending from the free towards the attached border, which
are called right and left lateral fissures (Fig. 22, _rlf_ and _llf_).
When these are more deeply cut than the umbilical fissure (_u_), the
organ has that tripartite or trefoil-like form just spoken of, but it
is easily seen that it is really divided into four regions or lobes,
those included between the lateral fissures being the right and left
central (_rc_ and _lc_) separated by the umbilical fissure, and those
beyond the lateral fissures on each side being the right and left lateral
lobes (_rl_ and _ll_). The essentially bipartite character of the organ
and its uniformity of construction throughout the class are thus not
lost sight of, even in the most complex forms. The left segment of the
liver is rarely complicated to any further extent, except in some cases
by minor or secondary fissures marking off small lobules, generally
inconstant and irregular, and never worthy of any special designation.
On the other hand, the right segment is usually more complex. The
gall-bladder, when present, is always attached to the under surface of
the right central lobe, sometimes merely applied to it, in other cases
deeply embedded in its substance. In many instances the fossa in which
it is sunk is continued to the free margin of the liver as an indent, or
even a tolerably deep fissure (_cf_). The portal fissure (_p_), through
which the portal vein and hepatic artery enter and the bile-duct emerges
from the liver, crosses the right central lobe transversely, near the
attached border of the liver. The right lateral lobe always has the
great vena cava (_vc_) either grooving its surface or tunnelling through
its substance near the inner or left end of its attached border; and a
prolongation of this lobe to the left, between the vein and the portal
fissure, sometimes forming a mere flat track of hepatic substance, but
more often a prominent tongue-shaped process, is the so-called “Spigelian
lobe” (_s_). From the under surface, of the right lateral lobe a portion
is generally partially detached by a fissure, and called the “caudate
lobe” (_c_). In Man this lobe is almost obsolete, but in most mammals it
is of considerable magnitude, and has very constant and characteristic
relations. It is connected by an isthmus at the left (narrowest or
attached) end to the Spigelian lobe, behind which isthmus the vena cava
is always in relation to it, channelling through or grooving its surface.
It generally has a pointed apex, and is deeply hollowed to receive the
right kidney, to the upper and inner side of which it is applied.
Considerations derived from the comparatively small and simple condition
of the liver of the Ungulata, compared with its large size and complex
form in the Carnivora, have led to the perhaps too hasty generalisation
that the first type is related to a herbivorous and the latter to a
carnivorous diet. The exceptions to such a proposition are very numerous.
The fact of the great difference between the liver of the Cetacea and
that of the Seals cannot be accounted for by difference of habits of
life, though it perhaps may be by difference of origin.[14]
V. CIRCULATORY, ABSORBENT, RESPIRATORY, AND URINARY SYSTEMS.
_Blood._—The blood of mammals is always red, and during the life of the
animal hot, having a nearly uniform temperature, varying within a few
degrees on each side of 100° Fahr. The corpuscles are, as usual in the
vertebrates, of two kinds: (1) colourless, spheroidal, nucleated, and
exhibiting amœboid movements; while (2) the more numerous, on which
depends the characteristic hue of the fluid in which they are suspended,
are coloured, non-nucleated, flattened, slightly biconcave discs, with
circular outline in all known species except the Camels and Llamas,
where they have the elliptical form characteristic of the red corpuscles
of nearly all the other vertebrates, though adhering to the mammalian
type in the absence of nucleus and relatively small size. As a rule they
are smaller as well as more numerous than in other classes, but vary
considerably in size in different species, and not always in relation
to the magnitude of the animal; a Mouse, for instance, having as large
corpuscles as a Horse. Within the limits of any natural group there is,
however, very often some such relation, the largest corpuscles being
found among the large species and the smallest corpuscles among the small
species of the group, but even to this generalisation there are many
exceptions. The transverse diameter of the red corpuscles in Man averages
¹⁄₃₂₀₀ of an inch, which is exceptionally large, and only exceeded by
the Elephant (¹⁄₂₇₄₅), and by some Cetacea and Edentata. They are also
generally large in Apes, Rodents, and the Monotremata, and small in the
Artiodactyles, least of all in the Chevrotains (_Tragulus_), being in _T.
javanicus_ and _meminna_ not more than ¹⁄₁₂₃₂₅.[15]
_Heart._—The heart of mammals consists of four distinct cavities,
two auricles and two ventricles. Usually the ventricular portion is
externally of conical form, with a simple apex, but in the Sirenia it is
broad and flattened, and a deep notch separates the apical portion of
each ventricle. A tendency to this form is seen in the Cetacea and the
Seals. It is characteristic of mammals alone among vertebrates that the
right auriculo-ventricular valve is tendinous like the left, consisting
of flaps held in their place by fibrous ends (_chordæ tendiniæ_) and
arising from projections of the muscular walls of the ventricular cavity
(_musculi papillares_). In the Monotremata a transition between this
condition and the simple muscular flap of the Sauropsida is observed. In
most of the larger Ungulates a distinct but rather irregular ossification
(_os cordis_) is developed in the central tendinous portion of the base
of the heart.
_Blood-vessels._—The orifices of the aorta and pulmonary artery are each
guarded by three semilunar valves. The aorta is single, and arches over
the left bronchial tube. After supplying the tissues of the heart itself
with blood by means of the coronary arteries, it gives off large vessels
(“carotid”) to the head and (“brachial”) to the anterior extremities. The
mode in which these vessels arise from the aorta varies much in different
mammals, and the study of their disposition affords some guide to
classification. In nearly all cases the right brachial and carotid have a
common origin (called the “innominate artery” in anthropotomy). The other
two vessels may come off from this, as is the rule in Ungulates, the
common trunk constituting the “anterior aorta” of veterinary anatomy; or
they may be detached in various degrees, both arising separately from the
aorta, as in Man, or the left carotid from the innominate and the left
brachial from the aorta, a very common arrangement; or the last two from
a common second or left innominate, as in some Bats and Insectivores.
The aorta, after giving off the intercostal arteries, passes through the
diaphragm into the abdomen, and, after supplying the viscera of that
cavity by means of the gastric, hepatic, splenic, mesenteric, renal,
and spermatic vessels, gives off in the lumbar region a large branch
(iliac) to each of the hinder extremities, which also supplies the
pelvic viscera, and is continued onwards in the middle line, greatly
diminished in size, along the under surface of the tail as the caudal
artery. In certain mammals, arterial plexuses, called _retia mirabilia_,
formed by the breaking up of the vessel into an immense number of small
trunks, which may run in a straight course parallel to one another
(as in the limbs of Sloths and Slow Lemurs), or form a closely packed
network, as in the intracranial plexuses of Ruminants, or a sponge-like
mass of convoluted vessels, as in the intercostals of Cetaceans, are
peculiarities of the vascular system the meaning of which is not in all
cases clearly understood. In the Cetacea they are obviously receptacles
for containing a large quantity of oxygenated blood available during the
prolonged immersion, with consequent absence of respiration, to which
these animals are subject.
The vessels returning the blood to the heart from the head and upper
extremities usually unite, as in Man, to form the single _vena cava
superior_ or precaval vein, but in some Insectivores, Chiroptera, and
Rodents, in the Elephant, and all Marsupials and Monotremes, the two
superior caval veins enter the right auricle without uniting, as in
birds. In Seals and some other diving mammals there is a large venous
sinus or dilatation of the inferior vena cava immediately below the
diaphragm. In the Cetacea the purpose of this is supplied by the immense
abdominal venous plexuses. As a rule the veins of mammals are furnished
with valves, but these are said to be altogether wanting in the Cetacea,
and in the superior and inferior cava, subclavian and iliac veins, the
veins of the liver (both portal and hepatic), heart, lungs, kidneys,
brain, and spinal cord of other mammals. Many of the veins within the
cranium are included in spaces formed by the separation of the laminæ of
the dura mater, and do not admit of being dilated beyond a certain size;
these are termed sinuses. The portal circulation in mammals is limited
to the liver, the portal vein being formed by the superior and inferior
mesenteric, the splenic, the gastro-epiploic, and the pancreatic veins.
The kidney is supplied solely by arterial blood, and its veins empty
their contents only into the inferior cava.
_Lymphatic Vessels._—The _absorbent_ or _lymphatic_ system of vessels is
very fully developed in the Mammalia. Its ramifications extend through
all the soft tissues of the body, and convey a colourless fluid called
lymph, containing nucleated corpuscles, and also, during the process of
digestion, the chyle, a milky fluid taken up by the lymphatics (here
called lacteals) of the small intestine, and pour them into the general
vascular system, where they mix with the venous blood. The lymphatic
vessels of the hinder extremities, as well as those from the intestinal
canal, unite in the abdomen to form the “thoracic duct,” the hinder
end or commencement of which has a dilatation called the _receptaculum
chyli_. This duct, which is of irregular size and sometimes double, often
dividing and uniting again in its course, or even becoming plexiform,
passes forwards close to the bodies of the thoracic vertebræ, and
empties itself, by an orifice guarded by a valve, into the great left
brachio-cephalic vein, having previously received the lymphatics from
the thorax and the left side of the head and left anterior extremity.
The lymphatics from the right side of the head and right anterior limb
usually enter by a small distinct trunk into the corresponding part
of the right brachio-cephalic vein. The duct, and also the principal
lymphatic vessels, are provided with valves.
Lymphatic glands, rarely met with in the Sauropsida, are usually
present in mammals, both in the general and in the lacteal system; the
latter being called “mesenteric glands.” They are round or oval masses,
situated upon the course of the vessels, which break up in them and
assume a plexiform arrangement, and then reunite as they emerge. No
structures corresponding to the pulsating “lymphatic hearts” of the lower
vertebrates have been met with in mammals.
_Ductless Glands._—Associated with the vascular and lymphatic systems
are certain bodies (the functions of which are not properly understood),
usually, on account of their general appearance, grouped together under
the name of “ductless glands.” The largest of these is the “spleen,”
which is single, and always placed in mammals in relation to the
fundus or left end of the stomach, to which it is attached by a fold
of peritoneum. It is dark-coloured and spongy in substance, and has a
depression or “hilus” on one side, into which the splenic artery, a
branch of the cœliac axis of the abdominal aorta, enters, and from which
the vein joining the portal system emerges. The spleen varies much in
size and form in different mammals, being relatively very small in the
Cetacea. It is sometimes almost spherical, but more often flattened,
oval, triangular, or elongated, and occasionally, as in Monotremes and
most Marsupials, triradiate. The “suprarenal bodies” or “adrenals” are
two in number, each situated either in contact with, or at a short
distance in front of the anterior extremity of the kidney. They are
abundantly supplied with nerves, and are much larger relatively in
early than in adult life. The “thyroid bodies,” of which there are
generally two, though in Man and some other species they are connected
by an isthmus passing across the middle line, are constant in mammals,
though only met with in a rudimentary condition, if at all, in other
vertebrates. They are situated in the neck, in contact with the sides of
the anterior extremity of the trachea. The “thymus” lies in the anterior
part of the thorax, between the sternum and the great vessels at the
base of the heart, and differs from the thyroid in being median and
single, and having a central cavity. It attains its greatest development
during the period in which the animal is nourished by its mother’s milk,
and then it diminishes, and generally disappears before full growth is
attained.
_Nostrils._—Mammals breathe occasionally through the mouth, but usually,
and in many cases exclusively, through the nostrils or _nares_. Those are
apertures, always paired (except in the toothed Cetacea, where they unite
to form a single external opening), and situated at the fore part of the
face, generally at or beneath the end of the muzzle, a median prominence
above the mouth. This is sometimes elongated to form a proboscis, to
the extremity of which the nostrils are carried, and which attains its
maximum of development in the Elephant. In the Cetacea the nostrils
are situated at a considerable distance behind the anterior end of the
face, upon the highest part of the head, and are called “blowholes,”
from the peculiar mode of respiration of those animals. The nostrils
are kept open by means of cartilages surrounding their aperture, which
many animals have the power of moving so as to cause partial dilatation
or contraction. In diving animals, as Seals and Cetacea, they can be
completely closed at will so as to prevent the entrance of water when
beneath the surface. The passage to which the nostrils lead is in most
mammals filled by a more or less complex sieve-like apparatus, formed
of the convoluted turbinal bones and cartilages, over which a moist,
vascular, ciliated mucous membrane is spread, which intercepts particles
of dust, and also aids in warming the inspired air before it reaches the
lungs. In the Proboscidea, in which these functions are performed by the
walls of the long tubular proboscis, this apparatus is entirely wanting.
_Trachea._—The narial passages have the organ of smell situated in
their upper part, and communicate posteriorly with the pharynx, and
through the glottis with the “trachea” or windpipe, a tube by which
the air is conveyed to and from the lungs. The permanent patency of
the trachea during the varied movements of the neck is provided for by
its walls being stiffened by a series of cartilaginous rings or hoops,
which in most mammals are incomplete behind. Having entered the thorax,
the trachea bifurcates into the two bronchi, one of which enters, and,
dividing dichotomously, ramifies through each lung. In some of the
Cetacea and Artiodactyla a third bronchus is given off from the lower
part of the trachea, above its bifurcation and enters the right lung.
_Larynx._—The upper end of the trachea is modified into the organ of
voice or “larynx,” the air passing through which to and from the lungs
is made use of to set the edges of the “vocal cords,” or fibrous bands
stretched one on each side of the tube, into vibration. The larynx is
composed of several cartilages, such as the “thyroid,” the “cricoid,”
and the “arytenoid” which are moved upon one another by muscles, and
suspended from the hyoidean arch. By alteration of the relative position
of these cartilages the cords can be tightened or relaxed, approximated
or divaricated, as required to modulate the tone and volume of the voice.
A median tongue-shaped fibro-cartilage at the top of the larynx, the
“epiglottis,” protects the “glottis,” or aperture by which the larynx
communicates with the pharynx, from the entry of particles of food during
deglutition. The form of the larynx and development of the vocal cords
present many variations in different members of the class, the greatest
modification from the ordinary type being met with in the Cetacea,
where the arytenoid cartilages and epiglottis are united in a tubular
manner, so as to project into the nasal passage, and, being grasped by
the muscular posterior margin of the palate, provide a direct channel
of communication from the lungs to the external surface. An approach to
this condition is met with in the Hippopotamus and some other Ungulates;
it is indeed so general as an abnormality, that Howes suggests that
an internarial epiglottis may have been a primitive feature common
throughout the class. Nearly all mammals have a voice, although sometimes
it is only exercised at seasons of sexual excitement. Some Marsupials
and Edentates appear to be quite mute. In no mammal is there an inferior
larynx, or “syrinx,” as in birds.
_Diaphragm._—The thoracic cavity of mammals differs from that of the
Sauropsida in being completely separated from the abdomen by a muscular
partition, the “diaphragm,” attached to the vertebral column, the ribs,
and the sternum. This is much arched, with the convexity towards the
thorax, so that when its fibres contract and it is flattened the cavity
of the thorax is increased, and when they are relaxed the cavity is
diminished.
_Lungs._—The lungs are suspended freely in the thorax, one on each side
of the heart, being attached only by the root, which consists of the
bronchus or air-tube and pulmonary arteries and veins by which the blood
is passed backwards and forwards between the heart and the lungs. The
remaining part of the surface of each lung is covered by serous membrane,
the “pleura”; and whatever the state of distension or contraction of the
chest-wall, is accurately in contact with it. Inspiration is effected
by the contraction of the diaphragm and by the intercostal and other
muscles elevating or bringing forward the ribs, and thus throwing the
sternum farther away from the vertebral column. As the surface of the
lung must follow the chest-wall, the organ itself is expanded, and air
rushes in through the trachea to fill all the minute cells in which the
ultimate ramifications of the bronchi terminate. In ordinary expiration
very little muscular power is expended, the elasticity of the lungs and
surrounding parts being sufficient to cause a state of contraction and
thus drive out at least a portion of the air contained in the cells,
when the muscular stimulus is withdrawn. The lungs are sometimes simple
externally, as in the Sirenia (where they are greatly elongated) and the
Cetacea, but are more often divided by deep fissures into one or more
lobes. The right lung is usually larger and more subdivided than the
left. It often has a small distinct lobe behind, wanting on the left
side, and hence called _lobulus azygos_.
_Air-sacs._—Most mammals have in connection with the air passages certain
diverticuli or pouches containing air, the use of which is not always
easy to divine. The numerous air sinuses situated between the outer and
inner tables of the bones of the head, represented in Man by the antrum
of Highmore and the frontal and sphenoidal sinuses, and attaining their
maximum of development in the Indian Elephant, are obviously for the
mechanical purpose of allowing expansion of the osseous surface without
increase of weight. They are connected with the nasal passages. The
Eustachian tubes pass from the back of the pharynx to the cavity of
the tympanum, into which and the mastoid cells they allow air to pass.
In the _Equidæ_ there are large post-pharyngeal air-sacs in connection
with them. The Dolphins have an exceedingly complicated system of
air-sacs in connection with the nasal passages just within the nostrils,
and the Tapirs, Rhinoceroses, and Horses have blind sacs in the same
situation. In the males of some Seals (_Cystophora_ and _Macrorhinus_)
large pouches, which the animal can inflate with air, and which are not
developed in the young animal or the female, arise from the upper part
of the nasal passages, and lie immediately under the skin of the face.
These appear analogous, although not in the same situation, to the gular
pouch of the male Bustard. The larynx frequently has membranous pouches
in connection with it, into which air passes. These may be lateral and
opening just above the vocal cords, when they constitute the _sacculi
laryngis_, found in a rudimentary state in Man, and attaining an enormous
development, so as to reach to the shoulders and axillæ, in some of the
Anthropoid Apes; or they may be median, opening in front either above or
below the thyroid and cricoid cartilages, as in the Howling and other
Monkeys, and also in the Whalebone Whales and Great Anteater.
_Urinary Organs._—The kidneys of mammals are more compact and definite
in form than in other vertebrates, being usually more or less oval,
with an indent on the side turned towards the middle line, from and
into which the vessels and ducts pass. They are distinctly divided into
a cortical secretory portion, composed mainly of convoluted tubes, and
containing the so-called Malpighian bodies; and a medullary excreting
portion, formed of straight tubes converging towards a papilla, embraced
by the commencement of the ureter or duct of the organ. The kidneys of
some mammals, as most Monkeys, Carnivores, Rodents, etc., are simple,
with a single papilla into which all the renal tubuli enter. In others,
as Man, there are many pyramids of the medullary portion, each with its
papilla, opening into a division (calyx) of the upper end of the ureter.
Such kidneys, either in the embryonic condition only, or throughout
life, are lobulated on the surface. In some cases, as in Bears, Seals,
and especially the Cetacea, the lobulation is carried further, the whole
organ being composed of a mass of renules, loosely united by connective
tissue, and with separate ducts, which soon join to form the common
ureter.
_Bladder._—In all mammals except the Monotremes the ureters terminate
by slit-like valvular openings in the urinary bladder. This receptacle
when filled discharges its contents through the single median urethra,
which in the male is almost invariably included in the penis, and in
the females of some species of Rodents, Insectivores, and Lemurs has a
similar relation to the clitoris. In the Monotremes, though the bladder
is present, the ureters do not enter into it, but join the urino-genital
canal some distance below it, with the orifice of the genital duct
intervening.
VI. NERVOUS SYSTEM AND ORGANS OF SENSE.
_Brain._—The brain of mammals shows a higher condition of organisation
than that of other vertebrates. The cerebral hemispheres have a greater
preponderance compared with other parts, especially to the so-called
optic lobes, or corpora quadrigemina, which are completely concealed by
them. The commissural system of the hemispheres is much more complex,
both fornix and corpus callosum being present in some form; and when the
latter is rudimentary, as in Marsupials and Monotremes, its deficiency
is made up for by the great size of the anterior commissure. The lateral
lobes of the cerebellum, wanting in lower vertebrates, are well developed
and connected by a transverse commissure, the pons Varolii. The whole
brain, owing especially to the size of the cerebral hemispheres, is
considerably larger relatively to the bulk of the animal than in other
classes, but it must be recollected that the size of its brain depends
upon many circumstances besides the degree of intelligence which an
animal possesses, although this is certainly one. Man’s brain is many
times larger than that of all other known mammals of equal bulk, and
even three times as large as that of the most nearly allied Ape. Equal
bulk of body is here mentioned, because, in drawing any conclusions
from the size of the brain compared with that of the entire animal, it
is always necessary to take into consideration the fact that in every
natural group of closely allied animals the larger species have much
smaller brains relatively to their general size than the smaller species,
so that, in making any effective comparison among animals belonging to
different groups, species of the same size must be selected. It may be
true that the brain of a Mouse is, as compared with the size of its
body, larger than that of a Man, but, if it were possible to reduce an
animal having the general organisation of a Man to the size of a Mouse,
its brain would doubtless be very many times larger; and conversely, as
shown by the rapid diminution of the relative size of the brain in all
the large members of the Rodent order, a Mouse magnified to the size of
a Man would, if the general rule were observed, have a brain exceedingly
inferior in volume. Although the brain of the large species of Whales is,
as commonly stated, the smallest in proportion to the bulk of the animal
of any mammal, this does not invalidate the general proposition that
the Cetacea have very large brains compared with terrestrial mammals,
like the Ungulata, or even the aquatic Sirenia, as may be proved by
placing the brain of a Dolphin by the side of that of a Sheep, a Pig, or
a Manatee of equal general weight. It is only because the universally
observed difference between the slower ratio of increase of the brain
compared with that of the body becomes so enormous in these immense
creatures that they are accredited with small brains.
The presence or absence of “sulci” or fissures on the surface of
the hemisphere, dividing it into “convolutions” or “gyri,” and thus
increasing the superficies of the cortical gray matter, as well as
allowing the pia mater with its nutrient blood-vessels to penetrate
into the cerebral substance, follow somewhat similar rules. The sulci
are related partly to the high or low condition of organisation of
the species, but also in a great degree to the size of the cerebral
hemispheres. In very small species of all groups, even the Primates, they
are absent, and in the largest species of groups so low in the scale as
the Marsupials and Edentates they are found. They reach their maximum of
development in the Cetacea.
The accompanying woodcut (Fig. 23) shows the principal parts of a
mammalian brain, as seen from the superior, lateral, and inner surfaces.
The sylvian fissure (_sf_) is one of the most constant of the sulci found
in the hemispheres.
[Illustration: FIG. 23.—Brain of the Genet (_Genetta tigrina_). A, From
above; B, from the right side; C, inner surface of right hemisphere;
_cc_, corpus callosum; _c.m.s_, calloso-marginal sulcus; _c_, notch
representing central sulcus of other forms; _d_, depression on superior
lateral gyrus of hemisphere; _hg_, hippocampal gyrus; _i_, inferior
lateral gyrus of hemisphere; _m_, middle lateral gyrus of do.; _s_,
superior lateral gyrus of do.; _os_, supraorbital sulcus of do.; _sf_,
sylvian fissure of do.; _ol_, olfactory lobes. The deeply convoluted part
behind the cerebral hemisphere is the cerebellum, below which lies the
medulla oblongata, or commencement of the spinal cord. (Mivart, _Proc.
Zool. Soc._ 1882, p. 516.)]
The researches of Palæontologists, founded upon studies of casts of the
interior of the cranial cavity of extinct forms, have shown that, in
many natural groups of mammals, if not in all, the brain has increased
in size, and also in complexity of surface foldings, with the advance
of time,—indicating in this, as in so many other respects, a gradual
progress from a lower to a higher type of development.
_Nerves._—The twelve pairs of cranial nerves generally recognised in
vertebrates are usually all found in mammals, though the olfactory nerves
are excessively rudimentary, if not altogether absent, in the Toothed
Whales. The spinal cord, or continuation of the central nervous axis,
lies in the canal formed by the neural arches of the vertebræ, and gives
off the compound double-rooted nerves of the trunk and the extremities,
corresponding in number to the vertebræ, through the interspaces between
which they pass out to their destination. The cord is somewhat enlarged
at the two points where it gives off the great nerves to the anterior and
the posterior extremities, which, from their interlacements soon after
their origin, are called respectively the brachial and lumbar plexuses.
The ganglionic or sympathetic portion of the nervous system is well
developed, and presents few modifications.
_Sense of Touch._—The sense of touch is situated in the skin generally,
but is most acute in certain regions more or less specialised for the
purpose by the presence of tactile papillæ, such as portions of the face,
especially the lips and end of the snout, and the extremities of the
limbs when these are used for other purposes than mere progression, and
the under surface of the end of the tail in some Monkeys. The “vibrissæ”
or long stiff bristles situated on the face of many mammals are rendered
extremely sensitive to touch by the abundant supply of branches from
the fifth nerve to their basal papillæ. In Bats the extended wing
membranes, and probably also the large ears and the folds and prominences
of skin about the face of some species, are so sensitive as to receive
impressions even from the different degrees of resistance of the air, and
so enable the animals to avoid coming in contact with obstacles to their
nocturnal flight.
_Taste and Smell._—The organs of the other special senses are confined
to the head. Taste is situated in the papillæ scattered on the dorsal
surface of the tongue. The organ of smell is present in all mammals
except the Toothed Whales. It consists of a ramification of the olfactory
nerves over a plicated, moist, mucous membrane, supported by folded
plates of bone, placed on each side of the septum nasi in the roof, or
often in a partially distinct upper chamber, of the nasal passage, so
arranged that, of the air passing into the lungs in inspiration, some
comes in contact with it, causing the perception of any odorous particles
with which it may be charged. Many mammals possess intense powers of
smelling certain odours which others are quite unable to appreciate, and
the influence which this sense exercises over the well-being of many
species is very great, especially in indicating the proximity of others
of the same kind, and giving warning of the approach of enemies. The
development and modification of the sense of smell is probably associated
with that of the odorous secretion of the cutaneous glands.
_Sight._—The organ of sight is quite rudimentary, and even concealed
beneath the integument, in some burrowing Rodents and Insectivores,
and is most imperfectly developed in the _Platanista_, or Freshwater
Dolphin of the rivers of India. In all other mammals the eyeball has
the structure characteristic of the organ in the higher Vertebrata,
consisting of parts through which the rays of light are admitted,
regulated, and concentrated upon the sensitive expansion of the
optic nerve lining the posterior part of the ball. A portion of the
fibrovascular and highly pigmented layer, the choroid, which is
interposed between the retina and the outer sclerotic coat, is in many
mammals modified into a brilliantly-coloured light-reflecting surface,
the _tapetum lucidum_. There is never a pecten or marsupium like that
of the Sauropsida, nor is the sclerotic ever supported by a ring of
flattened ossicles, as is so frequently the case in the lower vertebrated
classes. The eyeball is moved in various directions by a series of
muscles—the four straight, two oblique, and, except in the higher
Primates, a posterior retractor muscle called choanoid. The superior
oblique muscle passes through a tendinous pulley fastened to the roof
of the orbit, which is a feature not found beyond the limits of the
mammalian class. The eye is protected by the lids, generally distinctly
separated into an upper and a lower movable flap, which, when closed,
meet over the front of the eye in a more or less nearly horizontal line:
but sometimes, as in the Sirenia, the lids are not distinct, and the
aperture is circular, closing to a point. In almost all mammals below the
Primates, except the Cetacea, a “nictitating membrane” or third eyelid is
placed at the inner corner of the eyeball, and works horizontally across
the front of the ball within the true lids. Its action is instantaneous,
being apparently for the purpose of cleaning the front of the transparent
cornea;—a function unnecessary in animals whose eyes are habitually
bathed in water, and which in Man and his nearest allies is performed
by winking the true eyelids. Except in Cetacea the surface of the eye
is kept moist by the secretion of the lachrymal gland, placed under the
upper lid at its outer side, and the lids are lubricated by the Harderian
and Meibornian glands, the former being situated at the inner side of the
orbit, and especially related to the nictitating membrane, the latter in
the lining membrane of the lids.
_Hearing._—The organ of hearing is inclosed in a bony capsule (periotic)
situated in the side of the head, intercalated between the posterior
(occipital) and the penultimate (parietal) segment of the skull. It
has, in common with other vertebrates, three semicircular canals and
a vestibule, but the cochlea is more fully developed than in the
Sauropsida, and, except in the Monotremes, spirally convoluted. The
tympanic cavity is often dilated below, forming a smooth rounded
prominence on the base of the skull, the auditory bulla (Fig. 8). The
three principal ossicles, the “malleus,” “incus,” and “stapes,” are
always present, but variable in characters. In the Sirenia, Cetacea, and
Seals they are massive in form, being in the first-named order of larger
size than in any other mammals. In the Cetacea the malleus is ankylosed
to the tympanic; but in other mammals it is connected only with the
membrana tympani. The stapes in the lower orders—Edentates, Marsupials,
and Monotremes—has a great tendency to assume the columnar form of the
corresponding bone in Sauropsida, its two rami entirely or partially
coalescing.[16] The tympanic membrane (drum of the ear) forms the outer
wall of the cavity. In the fœtal state it is level with the external
surface of the skull, and remains so permanently in a few mammals as the
American Monkeys; but commonly, by the growth of the squamosal bone, it
becomes deeply buried at the bottom of a bony tube (_meatus auditorus
externus_), which is continued to the surface of the skin in a fibrous
or fibro-cartilaginous form. In Whales, owing to the thickness of the
subcutaneous adipose tissue, this meatus is of great length, and is also
extremely narrow. In most aquatic and burrowing animals it opens upon
the surface by a simple aperture, but in the large majority of the class
there is a projecting fold of skin, strengthened by fibro-cartilages,
called the pinna, auricle, or “external ear,” of very variable size and
shape, generally movably articulated on the skull, and provided with
muscles to vary its position; this pinna helping to collect and direct
the vibrations of sound into the meatus.
VII. REPRODUCTIVE ORGANS.
_Testes._—In the male the testes retain nearly their primitive or
internal position throughout life in the Monotremata, Sirenia, Cetacea,
most Edentata, Hyracoidea, Proboscidea, and Seals, but, in other groups
they either periodically (as in Rodentia, Insectivora, and Chiroptera)
or permanently pass out of the abdominal cavity through the inguinal
canal, forming a projection beneath the skin of the perineum, or becoming
suspended in a distinct pouch of integument called the scrotum. All the
Marsupials have a pedunculated scrotum, the position of which differs
from that of other mammals, being in front of, instead of behind, the
preputial orifice. As regards the presence, absence, or comparative size
and number of the accessory generative glands—prostate, vesicular, and
Cowper’s glands, as they are called—there is much variation in different
groups of mammals.
_Penis._—The penis is almost always completely developed, consisting of
two corpora cavernosa attached to the ischial bones, and of a median
corpus spongiosum enclosing the urethra, and forming the glans at
the distal portion of the organ. In Marsupials, Monotremes, and the
Sloths and Anteaters, the corpora cavernosa are not attached directly
to the ischia, and in the last-named the penis is otherwise of a very
rudimentary character, the corpus spongiosum not being present. In many
Marsupials the glans penis is bifurcated. In most Primates, Carnivora,
Rodentia, Insectivora, and Chiroptera, but in no other orders, an _os
penis_ is present.
_Ovaries and Oviduct._—In the female, the ovaries permanently retain
their original abdominal position, or only descend a short distance
into the pelvis. They are of comparatively smaller size than in other
vertebrates, have a definite flattened oval form, and are enclosed in a
more or less firm “tunica albiginea.” The oviduct has a trumpet-like, and
usually fimbriated abdominal aperture, and is more or less differentiated
into three portions:—(1) a contracted upper part, called in Man and
the higher mammals the “Fallopian tube”; (2) an expanded part with
muscular walls, in which the ovum undergoes the changes by which it is
developed into the fœtus, called the “uterus”; (3) a canal, the “vagina,”
separated from the last by a valvular aperture, and terminating in the
urino-genital canal, or common urinal and genital passage, which in
higher mammals is so short as scarcely to be distinct from the vagina.
The complete distinction of the oviducts of the two sides throughout
their whole length, found in all lower vertebrates, only occurs in this
class in Monotremes; a prevailing mammalian characteristic being their
more or less perfect coalescence in the middle line to form a single
median canal. In the Marsupials this union only includes the lower part
of the vagina; but in most Placentals it extends to the whole vagina
and a certain portion of the uterus, which cavity is then described as
“bicornuate.” In the higher mammals, as in Man, and also in some of
the Edentates, the whole of the uterus is single, the contracted upper
portion of the oviducts or Fallopian tubes, as they are then called,
entering its upper lateral angles by small apertures. In certain lower
forms the urino-genital canal opens with the termination of the rectum
into a common cloaca, as in other vertebrates; but it is characteristic
of the majority of the class that the two orifices are more or less
distinct externally.
_Mammary Glands._—Mammary glands secreting the milk by which the young
are nourished during the first portion of their existence after birth,
are present in both sexes in all mammals, though usually only functional
in the female. In the Monotremes alone their orifices are mere scattered
pores in the skin, but in all other forms they are situated upon the
end of conical elevations, called mammillæ, or teats, which, taken into
the mouth of the young animal, facilitate the process of sucking. These
are always placed in pairs upon some part of the ventral surface of the
body, but vary greatly in number and position in different groups. In the
Cetacea, where the prolonged action of sucking would be incompatible with
their subaqueous life, the ducts of the glands are dilated into large
reservoirs from which the contents are injected into the mouth of the
young animal by the action of a compressor muscle.
_Secondary Sexual Characters._—Secondary sexual characters, or
modifications of structure peculiar to one sex, but not directly related
to the reproductive function, are very general in mammals. They almost
always consist of the acquisition or perfection of some character by
the male as it attains maturity, which is not found in the female or
the young in either sex. In a large number of cases these clearly
relate to the combats in which the males of many species engage for
the possession of the females during the breeding season; others are
apparently ornamental, and of many it is still difficult to apprehend
the meaning. Many suggestions on this subject will, however, be found in
the chapters devoted to it in Darwin’s work on _The Descent of Man and
Selection in Relation to Sex_, where most of the best-known instances are
collected. Superiority of size and strength in the male of many species
is a well-marked secondary sexual character related to the purpose
indicated above, being probably perpetuated by the survivors or victors
in combats transmitting to their descendants those qualities which gave
them advantages over others of their kind. To the same category belong
the great development of the canine teeth of the males of many species
which do not use these organs in procuring their food, as the Apes,
Swine, Musk and some other Deer, the tusk of the male Narwhal, the
antlers of Deer, which are present in most cases only in the males, and
the usual superiority in size and strength of the horns of the _Bovidæ_.
Other secondary sexual characters, the use of which is not so obvious, or
which may only relate to ornament, are the presence of masses or tufts
of long hair on different parts of the body, as the mane of the male
Lion and Bison, the beards of some Ruminants and Bats (as _Taphozous
melanopogon_), Monkeys, and of Man, and all the variations of coloration
in the sexes, in which, as a general rule, the adult male is darker and
more vividly coloured than the female. Here may also be mentioned the
presence or the greater development of odoriferous glands in the male,
as in the Musk Deer, and the remarkable perforated spur with its glands
and duct, so like the poison-tooth of the venomous serpents, found in the
males of both _Ornithorhynchus_ and _Echidna_, the use of which is at
present unknown.
_Placenta._—The development of the mammalian ovum, and the changes which
the various tissues and organs of the body undergo in the process of
growth, are too intricate subjects to be explained without entering into
details incompatible with the limits of this work, especially as they
scarcely differ, excepting in their later stages, from those of other
vertebrates, upon which, owing to the greater facilities these present
for examination and study, the subject has been more fully worked out.
There are, however, some points which require notice, as peculiar to the
mammalian class, and as affording at least some hints upon the difficult
subject of the affinities and classification of the members of the group.
The nourishment of the fœtus during intra-uterine life takes place
through the medium of certain structures, partly belonging to the fœtus
itself and partly belonging to the inner parietes of the uterus of the
parent. These in their complete form constitute the complex organ called
the “placenta,” serving as the medium of communication between the mother
and fœtus, and in which the physiological processes that are concerned
in the nutrition of the latter take place; but as we shall see, though
a placenta, in the usual acceptation of the term, is peculiar to the
mammalian class, it is not in all of its members that one is developed.
The structures to which we shall have especially to refer are the outer
tunic of the ovum, to which, however formed, the term “chorion” is
commonly applied, and two sac-like organs connected with the body-cavity
of the embryo, both formed from the splanchnic mesoblast, lined by a
layer of the hypoblast. These are the “umbilical vesicle” or “yolk-sac”
and the “allantois.”
The umbilical vesicle is a thin membrane enclosing the yolk, which by
the doubling in of the ventral walls of the embryo becomes gradually
formed into a distinct sac external to the body, with a pedicle (the
omphalo-enteric duct) by which for a time a communication is maintained
between its cavity and the intestinal canal. In the walls of this sac
blood-vessels (omphalo-meseraic or vitelline) are developed in connection
with the vascular system of the embryo, through which, either by their
contact with the outer surface of the walls of the ovum, or by the
absorption through them of the contents of the yolk-sac, the nutrition
of the embryo in the lower vertebrates chiefly takes place. In mammals
the umbilical vesicle plays a comparatively subordinate part in the
nourishment of the fœtus, its function being generally superseded by the
allantois.
The last-named sac commences at a very early period as a diverticulum
from the hinder end of the alimentary tract of the embryo. Its proximal
portion afterwards becomes the urinary bladder, the contracted part
between this and the cavity of the allantois proper constituting the
urachus, which passes out of the body of the fœtus at the umbilicus
together with the vitelline duct. The mesoblastic tissue of the walls of
the allantois soon becomes vascular; its arteries are supplied with fœtal
blood by the two hypogastric branches of the iliacs, or main divisions of
the abdominal aorta, and the blood is returned by venous trunks uniting
to form the single umbilical vein which runs to the under surface of the
liver, where, part of it joining the portal vein and part entering the
vena cava directly, it is brought to the heart. These are the vessels
which, with their surrounding membranes, constitute the umbilical
cord—the medium of communication between the fœtus and the placenta, when
that organ is fully developed.
The egg membranes of the Monotremes present many points of agreement
with those of the ovum of the Marsupials,[17] and differ from those of
the Placental types. Thus Monotremes and Marsupials agree in having
a vitelline membrane, which appears between the young ovum and the
follicular epithelium, persisting in the one case until the time of
hatching, and in the other till a late uterine stage. There are also
several other common features fully described in Mr. Caldwell’s memoir,
but which cannot be detailed in this work.
In the Marsupialia the observations made many years ago by Sir R. Owen
upon the development of the Kangaroo have been confirmed by those of Dr.
H. C. Chapman,[18] while Dr. Selenka,[19] and Professor H. F. Osborn[20]
have contributed important evidence as to the structure and relations
of the fœtal membranes of the Opossums and others. It thus appears that
up to the period of the very premature birth of these animals the outer
covering of the ovum, or false chorion, is free from persistent villi,
and not adherent to the epithelium of the uterine walls; for, although
fitting into the folds of the latter, it is perfectly and readily
separable in its entire extent from them. The umbilical vesicle or
yolk-sac is large, vascular, and adherent to a considerable portion of
the false chorion or subzonal membrane, while the allantois is relatively
small, and although the usual blood-vessels can be traced into it, it
does not appear to contract any connection with the false chorion, and,
therefore, much less with the walls of the uterus, of such a nature as
to constitute a placenta. In some forms, however, such as the Opossums,
the umbilical vesicle or yolk-sac develops temporary villi, which unite
with the subzonal membrane, or false chorion, to form a disc-like area
closely attached to the cells covering the utricular glands of the
uterine epithelium, and thus forming a so-called _yolk-sac placenta_.
The function of this organ is considered to be the transmission of
the secretions of the utricular glands to the embryo by means of the
umbilical vesicle; the function of the allantois being either respiratory
or the absorption of the fluid secreted in the uterine cavity by the
utricular glands.
While in the uterus the nourishment of the fœtus seems, therefore, to be
derived from the umbilical vesicle, as in reptiles and birds, rather
than from the uterine walls by means of the allantoic vessels, as in
the higher mammals. The latter vessels, in fact, play even a much less
important part in the development of these animals, not only than in
the placental mammals, but even than in the Sauropsida, for they can
scarcely have the respiratory function assigned to them in that group:
pulmonary respiration and the lacteal secretion of the mother very early
superseding all other methods of providing the due supply, both of oxygen
and of food required for the development and growth of the young animal.
In this sense the Marsupials may be looked upon as the most typically
“mammalian” of the whole class. In no other group do the milk-secreting
glands play such an important part in providing for the continuity of the
race.
In the third primary division of the Mammalia, the so-called Placentalia,
the umbilical vesicle generally does not quite unite with the chorion,
and disappears as development proceeds, so that no trace of it can be
seen in the membranes of an advanced embryo; but it may persist until the
end of the intra-uterine life as a distinct sac in the umbilical cord, or
lying between the allantois and amnion. The disappearance or persistence
of the umbilical vesicle does not, according to our present knowledge,
appear to be correlated with a higher or lower general grade of
development, as might be presupposed. It is stated to have been found in
Man even up to the end of intra-uterine life, and also in the Carnivora,
while in the Ungulata and Cetacea it disappears at an earlier age. In
many, if not all, of the Rodentia, Insectivora, and Chiroptera, it plays
a more important part, becoming adherent to a considerable part of the
inner surface of the chorion, to which it conveys blood-vessels, although
villi do not appear to be developed from the surface of this part, as
they are on the portion of the chorion supplied by the allantoic vessels.
These orders thus present to a certain extent a transitional condition
from the Marsupials, although essentially different, in possessing the
structures next to be described.
The special characteristic of the whole of the placental mammals
constituting the majority of the class, is that the allantois and its
vessels become intimately blended with a smaller or greater part of the
parietes of the ovum, forming a structure on the outer surface of which
villi are developed, and which, penetrating into corresponding cavities
of the “decidua,” or soft, vascular, hypertrophied lining membrane of
the uterus, constitutes the placenta. This organ may be regarded, as Sir
William Turner says, both in its function and in the relative arrangement
of its constituent textures, as a specially modified secreting gland, the
ducts of which are represented by the extremities of the blood-vessels
of the fœtal system. The passage of material from the maternal to the
fœtal-system of vessels is not a simple percolation or diffusion through
their walls, but is occasioned by the action of a layer of cells derived
from the maternal or uterine structures, and interposed between the
blood-vessels of the maternal part of the placenta and those of the villi
covering the chorion, in which the embryonic vessels ramify.
The numerous modifications in the details of the structure of this
organ relate to augmenting the absorbing capacity of the vessels of the
chorion, and are brought about either by increasing the complexity of the
fœtal villi and maternal crypts over a limited area, or by increasing the
area of the part of the chorion covered by the placental villi, or by
various combinations of the two methods.
The first class of variations has given rise to a distinction into
two principal kinds of placenta: (1) simple or non-deciduate, and
(2) deciduate. In the former the fœtal villi are received into
corresponding depressions of the maternal surface, from which at the
period of parturition they are simply withdrawn. In the second, or more
complex form, the relation is more intimate, a layer of greater or
less thickness of the lining membrane of the uterus, called “decidua,”
becoming so intimately blended with the chorion as to form part of the
placenta proper, or that structure which is cast off as a solid body
at parturition. In other words, in the one case the line of separation
between the placenta and uterus at birth takes place at the junction of
the fœtal and maternal structures, in the other through the latter, so
that a portion of them, often of considerable thickness, and containing
highly organised structures, is cast off with the former. It was once
thought that the distinction between these two forms of placentation is
so important as to constitute a sufficiently valid basis for a primary
division of the placental mammals into two groups. It has, however, been
shown that the distinction is one rather of degree than of kind, as
intermediate conditions may exist, and it is probable that in different
primary groups the simpler, non-deciduate form may have become developed
independently into one or other of the more complex kinds.
Apart from its intimate structure, the placenta may be met with of very
varied general form. It may consist of villi scattered more or less
regularly over the greater part of the surface of the chorion, the two
extremities or poles being usually more or less bare. This form is called
the “diffused placenta.” It is probably a primitive condition, from which
most of the others are derived, although its existence must presuppose
the absence of the umbilical vesicle as a constituent of the chorionic
wall. It is found at present in the Manis among Edentates, the Cetacea,
the Perissodactyle Ungulates, and the Camels, Pigs, and Chevrotains
among the Artiodactyles. Such placentæ are always non-deciduate. Recent
observations by Sir W. Turner on the placentation of the Dugong show that
the Sirenia present the peculiarity of having a zonary placenta, which
is either entirely or in great part non-deciduate, and is, therefore,
transitional between the diffused and the true zonary type.
In the true Ruminants or Pecora, among the Artiodactyle Ungulates,
the villi are aggregated in masses called cotyledons, with bare
spaces between. Such a placentation is called “polycotyledonary.” In
another modification the villi are collected in a more or less broad
band encircling the chorion, leaving a very large portion of the two
poles bare, constituting the “zonary placenta,” characteristic of the
Carnivora, and also occurring in the Elephant, Hyrax, and Orycteropus.
The fact of the form of the placenta of these three last-named animals
agreeing together, and with that of the Carnivora, does not, however,
necessitate the ascription of zoological affinities, as the same ultimate
form may have been attained by different processes of development.
In another form one pole only of the chorion is non-vascular, the
placenta assuming a dome or bell shape, as in the Lemurs and the
Sloths. The transition from this, by the gradual restriction of the
vascular area, is easy to the oval or discoidal form of placenta of
the Anteaters, Armadillos, and higher Primates. The discoidal placenta
of the Rodents, Insectivores, and Chiroptera, though showing so much
superficial resemblance to that of the last-named order as to have led
to the inclusion of all these forms in one primary group, is now known
to be developed in another manner, not by the concentration of villi
from a diffused to a limited area, but by retaining the area to which
it was originally restricted in consequence of the large surface of the
chorion occupied, as before mentioned, by the umbilical vesicle. To
compensate for the smallness of area, the complex or deciduate structure
has been developed. Among some Rodents there is evidence to show that the
discoidal placenta has been derived from a zonary one, of which distinct
vestiges have been detected in the Mouse. We may conclude that, although
the characters and arrangement of the fœtal structures may not have that
extreme importance which has been attributed to them by some zoologists,
they will form, especially when more completely understood, valuable aids
in the study of the natural affinities and evolution of the Mammalia.[21]
CHAPTER III
ORIGIN AND CLASSIFICATION OF THE MAMMALIA
_Origin._—Although, as stated in the first chapter, the mammalian
class, as at present known either by existing or extinct forms, is
completely isolated from all other groups of the animal kingdom, yet it
is impossible to refrain from speculating as to its origin and nearest
affinities. In arranging the classes of vertebrates in a linear series
it is customary to place them in the following order—Pisces, Amphibia,
Reptilia, Aves, Mammalia,—an order which probably indicates the relative
degree of elevation to which the most highly developed members of each
class has attained. Such an arrangement appears to express the true
relationship of the first four classes to one another, but it is quite
clear that the Mammalia have no sort of affinity with the Aves. Writing
in 1879, Professor Huxley[22] came to the conclusion that, in looking
among vertebrates for the progenitors of the Mammalia, we must pass
over all known forms of birds and reptiles, and go straight down to the
Amphibia. In addition to the characters derived from the conformation of
the pelvis upon which the argument was primarily based, the following
reasons were given for this conclusion: “The Amphibia are the only
air-breathing Vertebrata which, like mammals, have a dicondylian skull.
It is only in them that the articular element of the mandibular arch
remains cartilaginous, while the quadrate ossification is small, and the
squamosal extends down over it to the osseous elements of the mandible,
thus affording an easy transition to the mammalian condition of those
parts. The pectoral arch [girdle] of the Monotremes is as much amphibian
as it is sauropsidian; the carpus and the tarsus of all Sauropsida,
except the Chelonia, are modified away from the Urodele type, while those
of the mammal are directly reducible to it. Finally, the fact that in
all Sauropsida it is a right aortic arch which is the main conduit of
arterial blood leaving the heart, while in mammals it is a left aortic
arch which performs this office, is a great stumbling-block in the way
of the derivation of the Mammalia from any of the Sauropsida. But, if
we suppose the earliest forms of both the Mammalia and the Sauropsida
to have had a common Amphibian origin, there is no difficulty in the
supposition that, from the first, it was a left aortic arch in the one
series, and the corresponding right aortic arch in the other, which
became the predominant feeder of the arterial system.” Subsequently
Professor E. D. Cope[23] in a suggestive paper called attention to the
remarkable resemblances to the Monotremes presented by the skeleton of
that group of early secondary reptiles which he then designated the
Theromorpha, but which may be included in the Anomodontia of Sir R. Owen,
and came to the conclusion that in that group we have the true ancestors
of the Mammalia. This conclusion was, however, disputed by Dr. Baur,[24]
who considered that the Anomodontia were too specialised to have been
the actual progenitors of the Mammalia, and that they should rather be
regarded as a divergent branch of the stem which had given origin to the
Mammalia. Since that date observations made on the structure of the South
African Anomodonts have shown such an intimate connection between that
group and the Labyrinthodont Amphibians, that there can be no hesitation
in regarding the one as the direct descendant of the other; and we may
probably regard the Mammalia as having originated from the same ancestral
stock at the time the Amphibian type was passing into the Reptilian. From
this point of view, some of the mammalian features found in the more
specialised Anomodonts may probably be regarded as having been acquired
during a parallel line of development.
Both the Anomodontia and the Mammalia differ from the Amphibians in the
loss of the splint-like parasphenoid which underlies the basisphenoid
axis of the skull, and by the ossification of that axis; but while the
former have become monocondylic by the participation of the basioccipital
in the support of the cranium, the latter retain the Amphibian dicondylic
plan. The skull of the Anomodonts presents mammalian resemblances not
found in any other Reptiles, this being especially noticeable in the
region of the squamosal; and it is only in this group and mammals that
the temporal or zygomatic arch is a squamoso-maxillary one (see p.
37). The resemblance between the pectoral and pelvic girdles of the
Anomodonts and those of the Monotreme Mammals is noticed under the head
of the latter, where reference is also made to the similarity in the
structure of the humerus in the two groups. The pes of the Amphibia and
Anomodontia agree in having a distinct intermedium, tibiale, fibulare,
and centrale, whereas in other Reptiles these bones are not generally
distinct; in Mammals the intermedium, fibulare, and centrale are
distinct, and according to Cope’s interpretation there may be a distinct
tibiale.
_Classification._—In the present condition of the world, mammals
have become so broken up into distinct groups by the extinction of
intermediate forms, that a systematic classification is perfectly
practicable. Most of the associations of species, which we call “orders,”
and even the “suborders” and “families,” are natural groups. In
isolating, defining, and naming them, we are really dealing with facts
of nature of a totally different order from the artificial and fanciful
divisions formed in the infancy of zoological science.
When, however, we pass to the extinct world, all is changed. In many
cases the boundaries of our groups become enlarged until they touch those
of others. New forms are discovered which cannot be placed within any of
the existing divisions. As the horizon of our vision is thus expanded,
the principles upon which a scheme of classification is constructed must
be altogether changed. Our present divisions and terminology are no
longer sufficient for the purpose; and some other method will have to be
invented to show the complex relationships existing between different
animal forms when viewed as a whole. The present time, pre-eminently
distinguished by the rapidly changing and advancing knowledge of extinct
forms, is scarcely one in which this can be done with any satisfactory
result; so that all attempts to form a classification embracing even the
already known extinct species must be only of a provisional and temporary
nature.
In systematic descriptions in books, in lists, and catalogues, and in
arranging collections, the objects dealt with must be placed in a single
linear series. But by no means whatever can such a series be made to
coincide with natural affinities. The artificial character of such an
arrangement, the constant violation of all true relationships, are the
more painfully evident the greater the knowledge of the real structure
and affinities. But the necessity is obvious; and all that can be done is
to make such an arrangement as little as possible discordant with facts.
The following table contains a list of the orders, suborders, and
families of existing mammals as recognised by the authors, and placed
in the order in which they will be treated of in this work. The more
important of the groups containing only extinct forms are added in a
different type, being interpolated, as near as may be, among those that
appear to be their existing relatives.
A few explanatory remarks upon the mutual relations of some of the
principal groups mentioned in the table may be useful here, but the
subject will be more fully developed in treating separately of each
division.
One of the most certain and fundamental points in the classification
of the Mammalia is, that all the animals now composing the class can
be grouped primarily into three natural divisions, which, presenting
very marked differential characters, and having no existing, or yet
certainly demonstrated extinct, intermediate, or transitional forms,
may be considered as subclasses of equal value, taxonomically speaking,
though very different in the numbers and importance of the animals at
present composing them. These three groups are often called by the names
originally proposed for them by Blainville—(1) _Ornithodelphia_, (2)
_Didelphia_, (3) _Monodelphia_—the first being equivalent to the order
_Monotremata_, the second to the _Marsupialia_, and the third including
all the remaining members of the class. Although actual palæontological
proof is wanting, there is much reason to believe that each of these, as
now existing, are survivors of distinct branches to which the earliest
forms of mammals have successively given rise, and for which hypothetical
branches Professor Huxley has proposed the names of _Prototheria_,
_Metatheria_, and _Eutheria_, names which, being far less open to
objection than those of Blainville, are here used as equivalents of the
latter.
The only known existing PROTOTHERIA, although agreeing in many important
characters, evidently represent two very divergent stocks, perhaps as
far removed as are the members of some of the accepted orders of the
Eutheria. It would, however, be merely encumbering zoological science
with new names to give them any other than the ordinarily known family
designations of _Ornithorhynchidæ_ and _Echidnidæ_.
Similarly with regard to the METATHERIA, although the great diversity
in external form, in anatomical characters, and in mode of life of the
various animals of this section might lead to their division into groups
equivalent to the orders of the Eutheria, we do not think it advisable to
depart from the usual custom of treating them all as forming one order,
called Marsupialia, the limits of which are equivalent to those of the
subclass. The characters of the six families which compose the group are
extremely well marked and easily defined; and since they form a regular
gradation between two extreme types, they can be satisfactorily arranged
in a serial order. A marked distinction in the dentition enables us to
divide them into primary groups or suborders.
The remaining mammals are included in the EUTHERIA, PLACENTALIA, or
MONODELPHIA. Their affinities with one another are so complex that
it is impossible to arrange them serially with any regard to natural
affinities. Indeed each order is now so isolated that it is almost
impossible to say what its affinities are; and none of the hitherto
proposed associations of the orders into larger groups stand the test
of critical investigation. All serial arrangements of the orders are
therefore perfectly arbitrary; and although it would be of very great
convenience for reference in books and museums if some general sequence,
such as that here proposed, were generally adopted, such a result can
scarcely be expected, since equally good reasons might be given for
almost any other combination of the various elements of which the series
is composed. In fact, we have already seen reason to depart in some
respects from that used in the “Encyclopædia.”
The Edentata, Sirenia, and Cetacea stand apart from all the rest in the
fact that their dentition does not conform to the general heterodont,
diphyodont type to which that of all other Eutheria can be reduced, and
which is such a close bond of union between them. In all three orders,
however, some indications may be traced of relationship, however distant,
with the general type.
With regard to the Edentata, reasons will be given for believing
that both the Sloths and Anteaters are nearly related, and that the
Armadillos, though much modified, belong to the same stock, but that the
Pangolins and the Aard-varks represent very isolated forms.
There is no difficulty about the limits of the order Sirenia, comprising
aquatic, vegetable-eating animals, with complete absence of hind limbs,
and low cerebral organisation, represented in our present state of
knowledge only by two existing genera, _Halicore_ and _Manatus_, and a
few extinct forms, which, though approaching a more generalised mammalian
type, show no special characters allying them to any of the other orders.
The few facts as yet collected relating to the former history of the
Sirenia leave us as much in the dark as to the origin and affinities of
this peculiar group of animals as we were when we only knew the living
members. They lend no countenance to their association with the Cetacea;
and, on the other hand, their supposed affinity with the Ungulata
receives no very material support from them.
Another equally well-marked and equally isolated, though far more
numerously represented and diversified order, is that of the Cetacea,
placed simply for convenience next to the Sirenia; with which, except in
their fish-like adaptation to aquatic life, they have little in common.
The old association of these orders in one group can only be maintained
either in ignorance of their structure or in an avowedly artificial
system. Among the existing members of the order, there are two very
distinct types, the toothed Whales or Odontoceti, and the Baleen Whales
or Mystacoceti, which present as many marked distinguishing structural
characters as are found between many other divisions of the Mammalia
usually reckoned as orders. Since the extinct Zeuglodonts, so far as
their characters are known, do not fall into either of these groups, but
are in some respects annectant forms, we have placed them provisionally,
at least, in a third group by themselves, named Archæoceti. There is
nothing known at present to connect the Cetacea with any other order of
Mammals; but it is quite as likely that they are offsets of a primitive
Ungulate as of a Carnivorous type, or perhaps of a still more generalised
mammalian stock.
The remaining Eutherian mammals are clearly united by the characters
of their teeth, being all heterodont and diphyodont, with their dental
system reducible to a common formula.
Although older views of the relationship of Ungulate mammals expressed
by the terms _Pachydermata_, _Ruminantia_, and so forth, still
linger in some corners of zoological literature, no single point in
zoological classification can be considered so firmly established as
the distinction between the Perissodactyle and Artiodactyle Ungulates;
both being in the existing fauna of the world perfectly natural and
distinctly circumscribed groups. The breaking-up of the latter into
four equivalent sections, the Pecora, Tylopoda, Tragulina, and Suina,
is equally in accordance with all known facts. Less certain, however,
is the association of the Proboscidea and the Hyracoidea with the true
Ungulates. By many zoologists they are each, although containing so very
few existing species, made into distinct orders; and much is to be said
in favour of this view. The discovery, however, of a vast number of
extinct species of Ungulates which cannot be brought under the definition
of either Perissodactyla or Artiodactyla, and yet are evidently allied
to both, and to a certain extent bridge over the interval between them
and the isolated groups just mentioned, make it necessary either to
introduce a number of new and ill-defined ordinal divisions, or so to
widen the scope of the original order as to embrace them all, considering
the Elephants and the Hyraces as representing suborders equivalent to
the great Perissodactyle and Artiodactyle groups. It is the latter
alternative that we have adopted.
The Rodentia, although generally presenting a low grade of development,
are a very specialised and distinct group. The position here assigned to
them would accord with apparent relationships with the Ungulates, through
the Elephant on the one hand and the extinct _Typotherium_ on the other.
In the present state of the fauna of the earth, the Carnivora form a
very distinct order, though naturally subdivided into two groups, the
members of the one being more typical, while those of the other (the
_Pinnipedia_) are aberrant, having the whole of their organisation
specially modified for living habitually in the water.
The Insectivora comprise various lowly organised and generalised forms,
exhibiting considerable divergence of character, and apparently connected
through transitional extinct species with the Carnivora. As no other
order can claim the family _Galeopithecidæ_, it is placed here, but
rather for convenience than for any other consideration, since it has but
little if any relationship with any of the other members. Its isolated
position is indicated by assigning it a distinct subordinal rank.
The Chiroptera have always been placed near the Insectivora; but they
are really a highly specialised group, as much isolated from all other
mammals by the modification of their anterior limbs in adaptation to
aerial locomotion, as the Cetacea and the Sirenia, by the absence of hind
limbs, are specially adapted for an aquatic life.
Lastly, the Primates, which in any natural system must be placed at the
head of the series, are divisible into two very distinct groups—one
containing the various forms of Lemurs (Lemuroidea), and the other the
Monkeys and Man (Anthropoidea). Whether the Lemuroidea should form part
of the Primates (according to the traditional view), or a distinct order
altogether removed from it, is as yet an undetermined question, for both
sides of which there is much to be said. There can, however, be no doubt
that the Anthropoidea form a perfectly natural group, presenting a series
of tolerably regular gradations from the Marmosets (_Hapale_) to Man.
Certain breaks in the series, however, enable us to divide it into five
distinct families:—_Hapalidæ_ or Marmosets: _Cebidæ_ or American Monkeys,
with three premolar teeth on each side of each jaw; _Cercopithecidæ_,
containing the majority of Old-world Monkeys; _Simiidæ_, consisting of
the genera _Hylobates_, _Simia_, _Gorilla_, and _Anthropopithecus_, the
true Man-like Apes; and, lastly, _Hominidæ_, containing the genus _Homo_
alone.
Subclass I. PROTOTHERIA.
Order i. MONOTREMATA—Monotremes.
Fam. 1. _Ornithorhynchidæ_—Duck-bill.
2. _Echidnidæ_—Spiny Anteater.
Group. =MULTITUBERCULATA.=[25]
Fam. 1. =Plagiaulacidæ=—Plagiaulax.
2. =Polymastodontidæ=—Polymastodon.
3. =Tritylodontidæ=—Tritylodon.
Subclass II. METATHERIA.
Order ii. MARSUPIALIA—Marsupials.
Suborder 1. POLYPROTODONTIA—Polyprotodonts.
Fam. 1. =Dromatheriidæ=—Dromatherium.
2. =Amphitheriidæ=—Amphitherium, etc.
3. =Spalacotheriidæ=—Spalacotherium.
4. =Tritylodontidæ=—Tritylodon.
5. _Didelphyidæ_—Opossums.
6. _Dasyuridæ_—Thylacine and Dasyures.
7. _Peramelidæ_—Bandicoots.
Suborder 2. DIPROTODONTIA—Diprotodonts.
Fam. 8. _Phascolomyidæ_—Wombats.
9. _Phalangeridæ_—Phalangers.
10. =Diprotodontidæ=—Diprotodon.
11. =Nototheriidæ=—Notothere.
12. _Macropodidæ_—Kangaroos.
Subclass III. EUTHERIA.
Order iii. EDENTATA—Edentates.
Fam. 1. _Bradypodidæ_—Sloths.
2. =Megatheriidæ=—Ground Sloths.
3. _Myrmecophagidæ_—Anteaters.
4. _Dasypodidæ_—Armadillos.
5. =Glyptodontidæ=—Glyptodonts.
6. _Manidæ_—Pangolins.
7. _Orycteropodidæ_—Aard-varks.
Order iv. SIRENIA—Sirenians.
Fam. 1. _Manatidæ_—Manatees.
2. =Rhytinidæ=—Rhytina.
3. _Halicoridæ_—Dugongs.
4. =Halitheriidæ=—Halithere.
Order v. CETACEA—Cetaceans.
Suborder 1. MYSTACOCETI—Baleen Whales.
Fam. 1. _Balænidæ_—Greenland Whale, etc.
Suborder 2. =ARCHÆOCETI.=
Fam. 2. =Zeuglodontidæ=—Zeuglodonts.
Suborder 3. ODONTOCETI—Toothed Whales.
Fam. 3. _Physeteridæ_—Sperm Whale.
4. _Platanistidæ_—Freshwater Dolphins.
5. _Delphinidæ_—Dolphins, Porpoises, etc.
Order vi. UNGULATA—Hoofed Mammals.
Suborder 1. ARTIODACTYLA—Artiodactyles.
Section A. SUINA—Pig-like Artiodactyles.
Fam 1. _Hippopotamidæ_—Hippopotamus.
2. _Suidæ_—Pigs and Peccaries.
Annectant types.
{ 3. =Chœropotamidæ=—Chœropotamus.
{ 4. =Anthracotheriidæ=—Anthracothere.
{ 5. =Merycopotamidæ=—Merycopotamus.
{ 6. =Cotylopidæ=—Oreodonts.
{ 7. =Anoplotheriidæ=—Anoplothere.
{ 8. =Dichodontidæ=—Dichodon.
Section B. TRAGULINA—Chevrotains.
9. _Tragulidæ_—Chevrotains.
Section C. TYLOPODA—Camels.
10. _Camelidæ_—Camels and Llamas.
11. =Poebrotheriidæ=—Poëbrotherium.
Section D. PECORA—True Ruminants.
12. _Cervidæ_—Deer.
13. _Giraffidæ_—Giraffe.
14. _Antilocapridæ_—Prong-buck.
15. _Bovidæ_—Sheep, Cattle, etc.
Suborder 2. PERISSODACTYLA—Perissodactyles.
Fam. 16. _Tapiridæ_—Tapirs.
17. =Lophiodontidæ=—Lophiodonts.
18. =Palæotheriidæ=—Palæotheres.
19. _Equidæ_—Horses.
20. _Rhinocerotidæ_—Rhinoceroses.
21. =Lambdotheriidæ=—Palæosyops.
22. =Chalicotheriidæ=—Chalicothere.
23. =Titanotheriidæ=—Titanothere.
24. =Macraucheniidæ=—Macrauchenia.
Suborder 3. =TOXODONTIA=—Toxodonts.
Fam. 25. =Toxodontidæ=—Toxodon.
26. =Typotheriidæ=—Typothere.
Suborder 4. =CONDYLARTHRA.=
Fam. 27. =Periptychidæ=—Periptychus.
28. =Phenacodontidæ=—Phenacodus.
29. =Meniscotheriidæ=—Meniscothere.
Suborder 5. HYRACOIDEA—Hyraces.
Fam. 30. _Hyracidæ_—Hyrax.
Suborder 6. =AMBLYPODA.=
Fam. 31. =Pantolambdidæ=—Pantolambda.
32. =Coryphodontidæ=—Coryphodon.
33. =Uintatheriidæ=—Uintathere.
Suborder 7. PROBOSCIDEA—Proboscideans.
Fam. 34. =Dinotheriidæ=—Dinothere.
35. _Elephantidæ_—Elephants.
Group. =TILLODONTIA=—Tillodonts.
Fam. =Anchippodontidæ=—Anchippodus.
=Calamodontidæ=—Calamodon.
Order vii. RODENTIA—Rodents.
Suborder 1. SIMPLICIDENTATA.
Fam. 1. _Anomaluridæ_—Anomalurus.
2. _Sciuridæ_—Squirrels and Marmots.
3. _Haplodontidæ_—Haplodon.
4. =Ischyromyidæ=—Ischyromys.
5. _Castoridæ_—Beavers.
6. _Myoxidæ_—Dormice.
7. _Lophiomyidæ_—Lophiomys.
8. _Muridæ_—Rats, Mice, and Voles.
9. _Spalacidæ_—Mole-rats.
10. _Geomyidæ_—Pouched Rats.
11. _Dipodidæ_—Jerboas.
12. =Theridomyidæ=—Theridomys.
13. _Octodontidæ_—Spiny Mice.
14. =Castoroididæ=—Castoroides.
15. _Hystricidæ_—Porcupines.
16. _Chinchillidæ_—Chinchillas.
17. _Dinomyidæ_—Dinomys.
18. _Caviidæ_—Cavies.
19. _Dasyproctidæ_—Agouties.
Suborder 2. DUPLICIDENTATA.
Fam. 20. _Lagomyidæ_—Picas.
21. _Leporidæ_—Hares and Rabbits.
Order viii. CARNIVORA—Carnivores.
Suborder 1. CARNIVORA VERA—Fissipedes.
Fam. 1. _Felidæ_—Cats.
2. _Hyænidæ_—Hyænas.
3. _Proteleidæ_—Earth-wolf.
4. _Viverridæ_—Civets and Ichneumons.
5. _Canidæ_—Wolves and Foxes.
6. _Ursidæ_—Bears.
7. _Mustelidæ_—Weasels and Otters.
8. _Procyonidæ_—Raccoons and Cat-bear.
Suborder 2. PINNIPEDIA—Pinnipedes.
Fam. 9. _Otariidæ_—Eared Seals.
10. _Trichechidæ_—Walrus.
11. _Phocidæ_—Seals.
Suborder 3. =CREODONTA=—Creodonts.
Fam. 12. =Hyænodontidæ=—Hyænodon.
13. =Proviverridæ=—Proviverra.
14. =Arctocyonidæ=—Arctocyon.
15. =Mesonychidæ=—Mesonyx.
Order ix. INSECTIVORA—Insectivores.
Suborder 1. INSECTIVORA VERA.
Fam. 1. _Tupaiidæ_—Tupaias.
2. _Macroscelididæ_—Elephant-Shrews.
3. _Erinaceidæ_—Hedgehogs.
4. _Soricidæ_—Shrews.
5. _Talpidæ_—Moles.
6. _Potamogalidæ_—Potamogale.
7. _Solenodontidæ_—Solenodon.
8. _Centetidæ_—Centetes.
9. _Chrysochloridæ_—Golden Moles.
Suborder 2. DERMOPTERA.
Fam. 10. _Galeopithecidæ_—Galeopithecus.
Order x. CHIROPTERA—Bats.
Suborder 1. MEGACHIROPTERA—Frugivorous Bats.
Fam. 1. _Pteropodidæ_—Flying Foxes.
Suborder 2. MICROCHIROPTERA—Insectivorous Bats.
Fam. 2. _Vespertilionidæ_—Common Bats.
3. _Nycteridæ_—Nycteris.
4. _Rhinolophidæ_—Leaf-nosed Bats.
5. _Emballonuridæ_—Emballonura.
6. _Phyllostomatidæ_—Vampyres.
Order xi. PRIMATES.
Suborder 1. LEMUROIDEA—Lemuroids.
Fam. 1. =Hyopsodontidæ=—Hyopsodus.
2. _Chiromyidæ_—Aye-Aye.
3. _Tarsiidæ_—Tarsier.
4. _Lemuridæ_—Lemurs.
Suborder 2. ANTHROPOIDEA—Anthropoids.
Fam. 5. _Hapalidæ_—Marmosets.
6. _Cebidæ_—American Monkeys.
7. _Cercopithecidæ_—Old World Monkeys.
8. _Simiidæ_—Gibbons and Man-like Apes.
9. _Hominidæ_—Man.
The distinctive character of these subclasses and orders, with an account
of their subdivisions and the principal forms contained in each, will be
given in subsequent chapters.
CHAPTER IV
GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION
I. GEOGRAPHICAL DISTRIBUTION.[26]
In considering the present distribution of mammals over the globe, we
may, in the first place, direct our attention to terrestrial or land
types, reserving the consideration of aerial types, like the Bats, and
aquatic forms, as exemplified by the Cetaceans, Sirenians, and Seals, to
separate sections.
Among terrestrial forms each species has a certain definite area of
distribution in space, which may be of very wide extent, or may be
confined to a restricted region. This distributional area is, however,
always connected, or continuous; that is to say, that although we may
have a single species inhabiting two continents, like the Lion in Asia
and Africa, or dwelling both on a continent and adjacent continental
islands, like the Javan Rhinoceros of India, Java, and Borneo, yet we
shall always find that such areas, if not still connected, show evident
signs of having been so connected in comparatively late geological
epochs; and we never find instances of the same species inhabiting
totally disconnected areas, such as India and South America. As examples
of mammals with a wide distribution we may mention the Lion and the
Leopard, which are now found throughout Africa, and also occur in India,
as well as in the intervening areas of Arabia and Persia. In the case of
the former species, palæontology further teaches us that its distribution
in the last geological epoch was even more extensive, since we have good
evidence to show that it formerly ranged over the greater part of Europe,
including the British Isles. The Jackal affords another well-known
instance of a species common to India and Africa. The American Puma,
again, may be cited as an example of a mammal having a very wide range
in latitude, since it is found from Patagonia in the south to Canada in
the north. As instances of wide range in the opposite direction we have
only to mention the Reindeer and the Elk or Moose, found in the northern
regions of both the Old and New Worlds, which are only separated from one
another by the narrow channel of Behring Strait.
Of mammals with extremely restricted distributional areas, we may mention
many of the Insectivora, such as the Desman of the Pyrenees, and some of
the Madagascar types of this order, the Lemurs from the same island, some
of the species of Marmots, the remarkable bear-like _Æluropus_ of Eastern
Tibet, one species of Zebra, and other Ungulates from Africa.
The distribution of a genus (except of course when the genus is
represented only by a single form) is very generally more extensive
than that of a species; and this may be markedly the case when there
are only some two or three species in a genus. In genera, moreover, we
meet with what is known as discontinuous distribution, that is, where
the distributional area of one or more species is totally separated from
that of others. The best instance of this occurs in the case of the
Tapirs, where we find one species inhabiting the Malayan Peninsula, and
no others anywhere in the world, with the exception of South America.
The explanation of such an apparently anomalous feature in distribution
is to be found in the past history of the globe, which shows us that
Tapirs once existed in China, Europe, and North America, and, therefore,
indicates that the existing isolated species are the sole survivors of a
group once spread over a large portion of the earth’s surface. In regard
to generic distribution it must, however, be mentioned that this depends
to a great extent on the limits which we are disposed to assign to genera
themselves.
As the distributional area of a genus generally exceeds that of a
species, so that of a family, or group of genera, is larger than that of
a single genus; and similarly the distribution of an order, or assemblage
of families, usually occupies a larger area than that of a single family.
Thus, for instance, the genus _Thylacinus_, represented only by the
so-called Tasmanian Wolf or Thylacine, is now entirely restricted to
Tasmania; but the family _Dasyuridæ_, to which that genus belongs, ranges
all over Australia, while the order Marsupialia, which includes the
_Dasyuridæ_, is found both in Australia and America, and in past epochs
was probably spread over the entire globe.
A remarkable feature in connection with the distribution of the
terrestrial Mammalia is the circumstance that, with the exception of
certain species introduced by human agency, and small forms which can
easily have been transported on floating timber or other similar means,
they are totally absent from what are known as oceanic islands—that is
islands arising from great depths in the ocean, mainly composed of coral
or volcanic rocks, and showing no signs of having ever been connected
with the existing continents, or the larger and so-called continental
islands. The obvious explanation of this feature is, that from their
total isolation these islands have never been able to receive a mammalian
fauna from the great continental areas on which mammalian life was
probably first developed.
As an intermediate step between these islands which are practically void
of mammalian life and the continents which teem with such a variety of
forms, are certain larger islands and portions of continents containing
a mammalian fauna more or less markedly distinct from that of the
whole of the other regions of the globe. The best instance of this is
Australia, which, with the exception of one dog—the Dingo—and certain
_Muridæ_ and Bats, has no mammals except Monotremes and Marsupials. The
latter are, moreover, perfectly distinct from those of America, which,
if we exclude the islands in the neighbourhood of Australia, is the
only other region which now possesses any Marsupials at all. Here also
we have a ready and full explanation which accords with all the facts;
since it is evident that Australia has been isolated from the Asiatic
continent from some very remote geological epoch, at which period it is
probable that Monotremes and Marsupials were the dominant if not the sole
representatives of the Mammalia then existing. Consequently Australia has
never been able to receive an influx of the Eutherian orders, which have
probably swept away all the Marsupials except the small American Opossums
from the rest of the globe. Again, the large island of Madagascar, which
has a fauna of an African type, but still very markedly different from
that of the mainland, may be considered to have been connected with the
latter at a time when the Eutheria had become the dominant forms, but has
been separated for a sufficiently long period to have enabled a large
number of its species and genera to have become distinct from those of
the adjacent continent. Similarly, there is evidence to show that South
America was probably cut off for a considerable period from the northern
half of the American continent, in consequence of which its lowly
organised fauna of Edentates were enabled to attain such a remarkable
development in the later geological periods.
In contrast to the mammalian fauna of islands of the preceding type is,
or rather was, that of the British Islands, which in the early historic
and prehistoric periods was identical with that of the Continent. This
leads to the inference that at a comparatively late epoch there was a
direct land communication between Britain and the Continent, which is
shown by geological evidence to have actually been the case.
The above instances are sufficient to show what an important influence
the date of separation of islands from the adjacent continents has
had upon their existing mammalian fauna, and how largely the present
distribution of mammalian life is bound up with the past history of our
globe. We must, however, not omit to mention another very important
agency of past times which has likewise had great influence on the
present distribution of the various faunas of the northern hemisphere.
This is the so-called glacial epoch, which took place immediately before
the establishment of the present condition of things, and appears to have
been the cause of the extinction of many of the larger mammalian types
which formerly inhabited Europe, and whose retreat to the warmer regions
of the south was apparently cut off by the Mediterranean.
_Zoological Regions._—Zoologists are now generally agreed in dividing
the land surfaces of the globe into a number of zoological regions or
provinces, characterised by a more or less distinctly marked general
_facies_ of their fauna as a whole. Some of these regions are much more
distinctly defined than the others; and in the majority of cases there is
a kind of neutral ground or No-man’s-land at the junction between any two
of these regions. It must also be remembered that in the Old World proper
as we go back in time we find a gradual assimilation in the mammalian
faunas of the different regions, indicating that originally there was one
large fauna of a generally similar type occupying the greater portion of
this area. Thus we find that Hippopotami, Giraffes, Kudus, Elands, and
other types of Antelopes now restricted to Africa, formerly extended to
Europe and India, while there is also evidence to show that the group
of large anthropoid Apes, now found only in Africa and the Bornean
region, were likewise spread over a large part of the south-western half
of the Old World. Moreover, while at the present day there is a marked
connection between the mammals of the northern regions of both the Old
and New Worlds, in the Tertiary period it appears that the fauna of the
whole of North America was much more nearly allied to that of the central
regions of the Old World than is now the case. Thus in the Tertiary rocks
of America we meet with remains of what we are accustomed to regard as
such essentially Old World genera as Horses and Rhinoceroses. On the
other hand there are no traces in America of the existence at any period
of Apes, Giraffes, Hippopotami, or Hyænas, while that continent has
yielded evidence of groups of Ungulates totally unrepresented in the
eastern hemisphere.
The chief zoological regions of the globe, proposed by Mr. Sclater in
1857, and now recognised by the majority of authorities, are six in
number, and are named as follows. Firstly, the Palæarctic region,
embracing the whole of Europe, Persia, Northern Arabia, and all of Asia
northward of the line of the Himalaya proper, Japan, that part of Africa
lying northward of the Sahara Desert, and the oceanic islands of the
North Atlantic. Secondly, the Ethiopian region, which comprises all
Africa lying to the south of the Sahara, the southern part of Arabia,
Madagascar, and the Mascarene Islands. Thirdly, the Oriental or Indian
region, which is taken to include India south of the Himalaya, and to the
north-west as far as Beluchistan, the Malay peninsula, southern China,
Sumatra, Java, Borneo, and the Philippines. Fourthly, the Australasian
region, which is usually defined as being bounded to the north-west by
the deep sea channel lying between Borneo and Celebes known as Wallace’s
line, and is taken to include Celebes, Lumbok, New Guinea, Australia,
Tasmania, New Zealand, and the host of oceanic islands in the South
Pacific. Several writers, however, prefer to regard Celebes and some
of the adjacent islands as representing a transitional Austro-Malayan
region. Fifthly, the Nearctic region, comprising Greenland and North
America as far south as the north of Mexico. And sixthly, the Neotropical
region, which embraces the remaining portion of the American continent
and the West Indies.
Various minor modifications of this scheme have been proposed. Thus some
writers are disposed to raise India to the rank of a distinct primary
region, while others propose the same for New Zealand. The Palæarctic and
Nearctic regions have a large number of common types, more especially
among the mammals, and Dr. A. Heilprin[27] has expressed his opinion that
they should be regarded as a single primary region under the name of the
Holarctic. The same writer would also separate the South Pacific Islands
as constituting a Polynesian region.
Minor divisions or sub-regions have also been marked out, but it will
be unnecessary to indicate their limits in the present work. We may,
however, mention the Mediterranean sub-region of the Palæarctic, which
includes the peninsular portion of southern Europe, North Africa, Asia
Minor, Persia, Afghanistan, Beluchistan, and Northern Arabia, as a good
instance of the transition from one region to another, since its fauna
has a mingling of Palæarctic, Ethiopian, and Oriental types, the former
being, however, the predominant ones.
Of the chief mammalian types characteristic of these various regions only
a brief sketch can be given in this work.
_Palæarctic Region._—The Palæarctic region is of enormous extent,
and includes countries varying greatly in their flora, climate, and
elevation. Thus it embraces the Arctic plains of Siberia, the warm
regions of Italy, Southern France, and Northern Africa, the forest-clad
slopes of the outer Himalaya, and the lofty arid plains of Turkestan
and Tibet, scorched by a burning sun in summer and chilled by a still
more terrible cold in winter. Its extreme limits in the west are marked
by the Canaries and Azores, and in the east by distant Japan; and yet
throughout this vast expanse we find a great uniformity of life, as
exemplified by the large number of British genera which occur also in
Japan. The mammals which are on the whole the most characteristic of this
region are the Sheep and Goats, forming a section of the great family
of _Bovidæ_; nearly all the species of which are Palæarctic, although
we meet with one Goat (_Capra_) in the Nilgherries of Southern India,
and a Sheep (_Ovis_) in the Nearctic region. The Musk Ox (_Ovibos_)
is characteristic of the Palæarctic and Nearctic regions. At least
one species of Camel is characteristic of this region, and it is not
improbable that the second may also have originated in it. There are
a few characteristic types of Antelopes, such as the Alpine Chamois
(_Rupicapra_), the Saiga of Tartary, and the Chiru (_Pantholops_) of
Tibet, each of which is represented by only a single species: and we
miss the host of Antelopes so characteristic of the Ethiopian region.
Deer (_Cervus_) are abundant, although by no means confined to this
region; and the Musk Deer (_Moschus_), the sole representative of the
subfamily _Moschinæ_, is exclusively Palæarctic. Monkeys, as a rule,
are absent, although we meet with one species of _Macacus_ in Northern
Africa and at Gibraltar, and some other types on the southern border of
Tibet. The Moles (_Talpa_) are mainly Palæarctic, although one species
enters Northern India, while the Desmans (_Myogale_) of the Pyrenees
and Southern Russia are unknown beyond the limits of this region. The
Water-shrew (_Nectogale_) is likewise a peculiar eastern Palæarctic
type. Among the Rodents, the Picas or Tailless Hares (_Lagomys_) and
the Dormice (_Myoxus_) are essentially Palæarctic forms, only one
species of each being found beyond the limits of the region, and the one
extra-Palæarctic species of _Lagomys_ occurring in the cognate Nearctic
region. The Mice and Rats are represented by the typical genus _Mus_ and
other types, and Hares (_Lepus_) and one species of Squirrel (_Sciurus_)
are common. The Carnivora include two species of Bears (_Ursus_), Wolves
and Foxes (_Canis_), a Lynx and a few species of Cats (_Felis_), as well
as numerous weasels (_Mustela_), and some other types.
_Ethiopian Region._—The Ethiopian region is of great interest to the
student of mammals, since it is inhabited by a number of forms remarkable
for their large size. A considerable portion of the area consists of
desert, especially in the north; but there is also a wide extent of
grassy plains (veltd), as well as vast tracts of equatorial forests of
great density. Perhaps the most striking feature in the Ethiopian fauna
is the number of Ungulates, both of the Artiodactyle and Perissodactyle
sections. In the former section we have the Giraffes (_Giraffa_)
represented by one species, which is the type of a family, and is
unknown elsewhere. Equally characteristic are the Hippopotami, which
likewise form the type of a family, while the Pigs are represented by
the Wart-hogs (_Phacochœrus_) and the River-hogs, forming an aberrant
group of the genus _Sus_. The Oxen (_Bos_) are represented by Buffaloes,
but there are no species of true Oxen or Bison. The Antelopes attain
an extraordinary development, the number of species being estimated at
from eighty to ninety, which are referred to a large number of genera,
although several of these are more or less ill-defined. Most of these
genera are peculiar to this region, but the Gazelles (_Gazella_) are also
found in the desert regions of other parts of the Old World, and _Oryx_
ranges into Arabia and Persia. In contrast to this abundance of Antelopes
is the total absence of the Deer family, or _Cervidæ_, which are so
characteristic of the Palæarctic and Oriental regions. The Chevrotains
or _Tragulidæ_ are, however, represented by _Dorcatherium_.[28] In the
Perissodactyle section we may notice the presence of two species of
_Rhinoceros_, both furnished with two horns, and distinguished from
those of the Oriental region by the absence of incisor and canine teeth.
The Horse family (_Equidæ_) is also represented by several species, and
includes the peculiar group of Zebras, characterised by their beautifully
striped skins. Of other Ungulates the Elephants, which, like the
Rhinoceroses, are now peculiar to the Ethiopian and Oriental regions,
have one species, which is widely different from its Indian congener.
The Hyraces are mainly characteristic of this region, although one
species occurs in Syria and Palestine. The Carnivora include some forms
like the Lion, Leopard, and Jackal, common to the Oriental region, but
likewise include certain peculiar types like the Earth-wolf (_Proteles_),
which may be regarded as the type of a distinct family, and two species
Hyænas, which are referred by some authorities to a distinct genus
(_Crocuta_). There is also the Hunting dog (_Lycaon_), and the peculiar
group of Foxes known as the Fennecs, together with _Otocyon_. Bears,
Wolves, and true Foxes are absent; but Civets, etc., are abundant,
although not characteristic of the region. The Primates yield several
very characteristic types, such as the Gorilla and the Chimpanzee
(_Anthropopithecus_) among the _Simiidæ_, which, with the exception of
the Orangs of Borneo, are the only existing large man-like Apes, and the
group of Dog-faced Baboons (_Cynocephalus_) in the _Cercopithecidæ_.
The genus _Colobus_ is also a group of the latter family, absolutely
characteristic of the region. Lemurs, again, occur on the continent of
Africa, but the great development of this group is in the adjacent island
of Madagascar, where several peculiar genera occur, and where the larger
Carnivora and Ungulata are absent. These peculiarities of the fauna of
Madagascar apparently point, as previously mentioned, to its separation
from the mainland before the latter was overrun by the larger types, and
at a time when its chief mammals were Lemurs and Insectivores. There
are two genera of Edentates, the Pangolins (_Manis_), and the Aard-vark
(_Orycteropus_), the latter being peculiar.
Although the foregoing groups of mammals are now so characteristic of
the Ethiopian region, it cannot be too strongly insisted that their
restriction to this region is, so to speak, merely a feature of the
present day, and that at a late geological epoch nearly all the peculiar
genera were represented in India, and many of them also in Europe.
_Oriental Region._—The third or Oriental region is likewise of very
considerable extent, and is the only one, in addition to the Ethiopian,
which is the home of huge Ungulates, like Elephants and Rhinoceroses,
and the large man-like Apes. A large proportion of this extensive area
is occupied by tropical and subtropical forests and swamps; these being
especially abundant in Burma, Southern China, Siam, and the southern
ridges of the Himalaya, collectively constituting the Indo-Chinese
sub-region, and also in the Indo-Malayan sub-region of the Malay
peninsula and adjacent islands. In the third or Indian sub-region,
comprising peninsular India, with the exception of the Carnatic, there
are large tracts of open country, including some of the hottest regions
in the world, parts of which form plains more or less covered with
vegetation during the cooler and rainy seasons, while others are barren
rocky table-lands, as in the Deccan, or arid deserts like those of parts
of the Punjab and Sind. Finally, in the fourth or Cingalese sub-region,
represented by the Carnatic and the island of Ceylon, we find vast areas
of luxuriant forest and jungle. In the north-western desert area of
the Indian sub-region the fauna includes a mixture of Palæarctic and
Ethiopian forms, with those characteristic of the Oriental region.
Among the chief features of the mammalian fauna of this region we may
notice the absence of Hippopotami and Giraffes, the greatly diminished
number of Antelopes, as compared with those of Africa, and the abundance
of Deer and true Pigs. The Antelopes comprise the two peculiar genera
_Boselaphus_ (Nilghai) and the typical _Antilope_ (Black-buck), each
of which is represented by only a single species, while the Deer
belong to the so-called Rusine group, which is markedly different
from that to which the Palæarctic Red Deer belongs. True Chevrotains
(_Tragulus_) are peculiar to this region. The Oxen include the true
Buffalo, differing in many respects from the African species of the
same group, and also certain species of true Oxen, such as the Gaour
and Banting, belonging to the Bibovine group, which is confined to this
region. In the Perissodactyla Horses (_Equus_) are represented only
by a single species in the desert area of the Indian sub-region, while
the two species of _Rhinoceros_ differ from those of Africa in being
furnished with canines and incisors. The Malayan Tapir is the only Old
World species of its genus. The Indian Elephant differs, moreover, so
markedly from its African ally that some writers regard the two as types
of distinct genera. The Carnivora include the Lion, Leopard, Jackal,
and Hunting-Leopard, which are common to Africa; but the Tiger is very
characteristic of this region, although extending northwards into the
Palæarctic. Civets are abundant, comprising some peculiar genera, of
which it will suffice to mention the well known _Paradoxurus_. Wolves
closely allied to the Palæarctic species occur in Northern India, and
there are also Foxes related to the typical species. The Dog-like animals
which hunt in packs, and are separated by some writers from _Canis_ under
the name of _Cyon_, occur in the present and the Palæarctic region.
The striped Hyæna is the Indian representative of its genus. Ratels
are common to this and the Ethiopian region, and constitute the genus
_Mellivora_. The most striking feature in the Carnivorous fauna of this
region, as distinguished from the Ethiopian, is, however, the presence
of Bears, some of which belong to the typical genus _Ursus_, while one
species is usually generically separated under the name of _Melursus_.
Among the Rodents we may especially notice the abundance of the _Muridæ_
and _Sciuridæ_. In the former family we have numbers of true Mice
(_Mus_), and also the peculiar genus _Nesocia_ (Bandicoot-Rat), while in
the latter both the true Squirrels (_Sciurus_) and the Flying-Squirrels
(_Pteromys_) attain great development. The genus (_Pteromys_) is, indeed,
mainly characteristic of this region, although in Kashmir and Japan it
enters the Palæarctic. The Bats are very numerous, being represented
by all the families, with the exception of the _Phyllostomatidæ_, or
Vampyres, of South America. Among the Insectivora the genera _Tupaia_ and
_Galeopithecus_ (Flying Lemur) are peculiar to this region, although not
found in India. Finally, in the Primates we have the genera _Macacus_
and _Semnopithecus_ very abundantly represented, although both also
enter the Palæarctic region; but the Anthropoid types are confined to
the south-eastern half of the region, and include the Orangs (_Simia_)
of Borneo, and the smaller long-armed Gibbons (_Hylobates_), which are
abundant in the Malay peninsula, both genera not being found beyond this
region. The Lemurs are much less abundant than in the Ethiopian region,
but they include the peculiar Tarsier of Sumatra, Borneo, and Celebes
(Austro-Malayan region), which differs so markedly in dentition and
structure of the feet from all other forms that it has been made the type
of a separate family. The Edentates, so poorly represented in the Old
World, include only Pangolins (_Manis_), which, as we have already seen,
also occur in the Ethiopian region.
_Australasian Region._—With the fourth or Australasian region we come
to a mammalian fauna so peculiar that we have no difficulty whatever
in defining it from all the other regions of the globe, although it
should be observed that in the Austro-Malayan islands we have a partial
mingling of the Australasian and Malayan faunas. If we exclude Celebes
from this region we find that, with the exception of a Pig in New Guinea,
of the Dingo in Australia, of numerous Mice and Rats (_Muridæ_), and
Bats, there are no Eutherian mammals throughout the area. The mammals
of this region are restricted to the Australian mainland, the island of
Tasmania, New Guinea, and the Aru islands, the whole area of New Zealand
having been totally devoid of mammalian life until introduced by man.
The whole of the Monotremata, constituting the subclass Prototheria, and
all the Marsupials, exclusive of the few outlying forms ranging into the
transitional Austro-Malayan area, and with the exception of the American
family of the Opossums (_Didelphyidæ_), are absolutely confined to this
region.
_Celebes._—The mammals of Celebes—the typical representative of the
Austro-Malayan transitional region or sub-region—include the peculiar Ape
known as _Cynopithecus_, _Tarsius_ (also Oriental), the Anoa, and the
single species of _Babirusa_. Several other types of placental mammals
are found in this transitional area, while the Marsupials are represented
by _Phalanger_ and _Petaurus_.
_Nearctic Region._—The two remaining regions we have to consider are
comprised in the New World. The first of these is the Nearctic, which,
as already mentioned, has a fauna showing such a strongly marked
relationship to that of the Palæarctic region, that it has been proposed
to unite the two regions. Among types common to these two regions we may
mention closely allied species of true Deer (_Cervus_) as exemplified
by the Red Deer and the Wapiti; the allied Bisons of the two regions;
the Reindeer and Elk common to both; as well as nearly related, and in
some cases identical, species of Cats, Lynxes, Bears, Wolves, Foxes,
Beavers, Squirrels, Marmots, and Hares. The Glutton or Wolverene, and
the Musk Ox is also common to the Arctic portions of the two regions.
The Ungulates are very poorly represented, but we have, in addition to
the forms already mentioned, one species of the Palæarctic genus _Ovis_,
namely the Bighorn, and the Prong-buck (_Antilocapra_), which is quite
peculiar. There are, however, no Perissodactyla. The Raccoons and Coatis
(_Procyonidæ_) constitute a family represented out of the New World
only by the aberrant Cat-Bear (_Ælurus_) of Nipal. The characteristic
American feline known as the Puma extends over this region; but there
are no Edentates, and the Marsupials are represented only by a single
species of Opossum. Rodents are extremely numerous, and comprise several
characteristic types, which alone would tell us what part of the globe we
were visiting. The most distinctive are the Pouched Rats (_Geomyidæ_),
and the Beaver-like rodents known as the _Haplodontidæ_. True Rats
and Mice (_Mus_), which are represented throughout the Old World, are
totally wanting in the New, where they are replaced by the Vesper-mice,
which may be included in the European genus _Cricetus_, although often
separated as _Hesperomys_. This feature alone would seem to justify the
distinction of the Nearctic from the Palæarctic region. The Musquash
(_Fiber_) is a genus of Nearctic rodents unknown in the Old World. Among
other characteristic genera we may mention, in the Carnivora, the Skunk
(_Mephitis_) and the American Badger (_Taxidea_). Primates are absent
from the entire region.
_Neotropical Region._—The last of the six main regions is the
Neotropical, including Mexico, South America, and the West Indies.
A very large extent of this area is occupied by forests, which are
described as being denser and more luxuriant than those of any other
part of the globe. Alternating with these forest areas are the vast
grassy plains known in different regions as llanos, savannas, and
pampas. The back-bone of the region is formed by the great chain of
the Andes. Next to the Australasian, this region is perhaps better
characterised by its mammalian fauna than any of the others. Commencing
with the Ungulates, we find a total absence of Antelopes, Sheep, and
Oxen, and also of all Perissodactyles except Tapirs. Deer are, however,
represented, although by peculiar forms (_Cariacus_) unknown beyond
the New World. The Peccaries (_Dicotyles_), which are often made the
type of a distinct family, take the place of the Old World Pigs,
while the Llamas and Alpacas (_Auchenia_) are the substitutes for the
Palæarctic Camels. The Carnivora include several Cats (_Felis_), among
which the Puma and the Jaguar are the most noticeable; and there are
also Raccoons, Coatis, Foxes, and one species of Bear. Insectivora are
totally wanting; but the Bats are characterised by the presence of
the Vampyres (_Phyllostomatidæ_), which are almost restricted to this
region. The Rodents likewise include three families unknown elsewhere,
namely the Chinchillas and Viscacha (_Chinchillidæ_), the Agouties
(_Dasyproctidæ_), and the Cavies (_Caviidæ_); while a large number of the
_Octodontidæ_ are Neotropical, all the other forms being Ethiopian. In
the Primates, again, we have all the forms quite peculiar to this region,
and constituting two families, viz. the _Cebidæ_ or Prehensile-tailed
Monkeys, and the _Hapalidæ_, or Marmosets, both of which differ decidedly
in their dentition, as well as in other features, from the Old World
Monkeys. Lemuroids are unknown. Perhaps, however, the mammals which may
be considered as most characteristic of the Nearctic region are the
numerous Edentates, which form three families, mostly confined to it.
These comprise the _Bradypodidæ_ or Sloths, which solely inhabit the
forest region; the _Myrmecophagidæ_ or Anteaters; and the _Dasypodidæ_
or Armadillos, of which one species has crept northward as far as Texas.
Almost equally characteristic are the numerous Opossums, the majority of
which belong to the genus _Didelphys_. Finally, it should be observed
that the West Indies are distinguished from the rest of the region by the
absence of Primates, Carnivora, and Edentates.
_Aquatic Mammals._—Many mammals grouped for the present purpose as
terrestrial pass a great portion of their lives in brooks, lakes, or
rivers, and, being dependent upon such waters for obtaining their
subsistence, are necessarily confined to their vicinity; but the truly
aquatic mammals, or those living constantly in the water, and unable to
move their quarters from place to place by land, are the orders Cetacea
and Sirenia, with which may also be grouped the Seals, forming the
Pinniped division of the order Carnivora.
For the marine Cetacea, animals mostly of large size and endowed with
powers of rapid locomotion, there are obviously no barriers to universal
distribution over the surface of the earth covered by sea, except such as
are interposed by uncongenial temperature or absence of suitable food.
Nevertheless it was thought some years ago that the fact of a Whale or
a Dolphin occurring in a sea distant from that in which it had usually
been found was sufficient justification for considering it as a distinct
species and imposing a new name upon it. There are now, however, so many
cases known in which Cetaceans from the northern and southern seas, from
the Atlantic and Pacific Oceans, present absolutely no distinguishing
external or anatomical characters upon which specific determination
can be based that the opposite view is gaining ground; and, since some
species are undoubtedly very widely distributed, being in fact almost
cosmopolitan, there seems little reason why many others should not be
included in the same category. The evidence is satisfactory enough in
those instances in which the intermediate regions are inhabited by the
same forms;—the cases of “continuous areas” of distribution. In those in
which the areas of distribution are apparently discontinuous, there may
be more room for doubt; but it must not be forgotten that the negative
evidence is here of much less value than in the case of land animals,
since the existence of Cetaceans in any particular part of the ocean may
be easily overlooked. The great Sperm Whale (_Physeter macrocephalus_)
is known to be almost cosmopolitan, inhabiting or passing through all
the tropical and temperate seas, although not found near either pole.
At least three of the well-known species of Rorqual (_Balænoptera_) of
the British coasts are represented in the North Pacific, on the South
American shores, and near New Zealand, by species so closely allied that
it is difficult to point out any valid distinctive characters, though
it may perhaps be desirable to wait for a more exhaustive examination
of a large series of individuals before absolutely pronouncing them to
be specifically identical. There is nothing yet known by which we can
separate the “Humpback Whales” (_Megaptera_) of Greenland, the Cape of
Good Hope, and Japan. The same may be said of the common Dolphin of
the European seas (_Delphinus delphis_) and the so-called _D. bairdi_
of the North Pacific and _D. forsteri_ of the Australian seas. The
Pilot Whale (_Globicephalus melas_) and the _Pseudorca_ of the North
Atlantic and of New Zealand are also, so far as present knowledge
enables us to judge, respectively alike. Many other similar cases might
be given. Captain Maury collected much valuable evidence about the
distribution of the larger Cetacea, and, finding Right Whales (_Balæna_)
common in both northern and southern temperate seas, and absent in the
intermediate region, laid down the axiom that “the torrid zone is to
the Right Whale as a sea of fire, through which he cannot pass.” Hence
all cetologists have assumed that the Right Whale of the North Atlantic
(_B. biscayensis_), that of the South Seas (_B. australis_), and that
of the North Pacific (_B. japonica_), are necessarily distinct species.
The anatomical structure and external appearance of all are, however, so
far as yet known, marvellously alike, and, unless some distinguishing
characters can be pointed out, it seems scarcely justifiable to separate
them from geographical position alone; as, though the tropical seas
may be usually avoided by them, it does not seem impossible, or even
improbable, that some individuals of animals of such size and rapid
powers of swimming may have at some time traversed so small a space of
ocean as that which divides the present habitual localities of these
supposed distinct species. If identity or diversity of structural
characters is not to be allowed as a test of species in these cases, as
it is usually admitted to be in others, the study of their geographical
distribution becomes an impossibility.
Although many species are thus apparently of such wide distribution,
others are certainly restricted; thus the Arctic Right Whale (_Balæna
mysticetus_) has been conclusively shown to be limited in its range to
the region of the northern circumpolar ice, and no corresponding species
has been met with in the southern hemisphere. In this case, not only
temperature, but also the peculiarity of its mode of feeding, may be
the cause. The Narwhal and the Beluga have a very similar distribution,
though the latter occasionally ranges farther south. The common
Hyperoödon is restricted to the North Atlantic, never entering, so far as
is yet known, the tropical seas. Other species are exclusively tropical
or austral in their range. One of the true Whalebone Whales (_Neobalæna
marginata_) has only been met with hitherto in the seas round Australia
and New Zealand; and a large Ziphioid (_Berardius arnouxi_) only near the
last-named islands.
The Cetacea are not limited to the ocean, or even to salt water, some
entering large rivers for considerable distances, and others being
exclusively fluviatile. One species of _Platanista_ is extensively
distributed throughout nearly the whole of the river systems of the
Ganges, Brahmaputra, and Indus, ascending as high as there is water
enough to swim in, but apparently never passing out to sea. The
individuals inhabiting the Indus and the Ganges must therefore have been
for long ages isolated without developing any definite distinguishing
anatomical characters; for those by which the supposed _P. indi_ was
formerly separated from _P. gangetica_ have been shown by Anderson to be
of no constant value. _Orcella fluminalis_ appears to be limited to the
Irawaddy river, and at least two distinct species of Dolphin belonging
to different genera are found in the waters of the upper Amazon. A
_Neomeris_ has been found in the great Chinese river, the Yang-tsi-Kiang,
nearly a thousand miles from the sea. It is remarkable, however, that
none of the great lakes or inland seas of the world are, according to our
present knowledge, inhabited by Cetaceans. A regular seasonal migration
has been observed in many of the oceanic Cetacea, especially those
inhabiting the North Atlantic, but further observations upon this subject
are still much needed.
The great difference in the manner of life of the Sirenia, as compared
with that of the Cetacea, causes a corresponding difference in their
geographical distribution. Slow in their movements, and feeding
exclusively upon vegetable substances, water-grasses, or fuci, the
Sirenia are confined to rivers, estuaries, or coasts where these grow,
and are not denizens of the open sea, although of course there is a
possibility of accidental transport by the assistance of oceanic currents
across considerable distances. Of the three genera existing within
historic times, one (_Manatus_) is exclusively confined to the shores
of the tropical Atlantic and the rivers entering into it, individuals
scarcely specifically distinguishable being found both on the American
and the African side of the ocean. The Dugong (_Halicore_) is distributed
in different colonies, at present isolated, throughout the Indian Ocean
from Arabia to North Australia. The _Rhytina_ or Northern Sea-Cow was,
for some time before its extinction, limited to a single island in the
extreme north of the Pacific Ocean.
The Pinnipeds, although capable of traversing long reaches of ocean, are
less truly aquatic than the last two groups, always resorting to the land
or to extensive ice-floes for the purpose of breeding. The geographical
range of the various species is generally more or less restricted,
usually according to climate, as they are mostly inhabitants either of
the Arctic or Antarctic seas and adjacent temperate regions, very few
being found within the tropics. For this reason the northern and the
southern species are for the most part quite distinct. In fact, the only
known exception is the case of a colony of the Sea-Elephant (_Macrorhinus
leoninus_), the general range of which is in the southern hemisphere,
inhabiting the coast of California. Even in this case a different
specific name has been given to the northern form; but the characters
by which it is distinguished are not of great importance, and probably,
except for the abnormal geographical distribution, would never have been
noticed. The most remarkable circumstance connected with the distribution
of the Pinnipeds is the presence of members of the suborder in the three
isolated great lakes or inland seas of Central Asia—the Caspian, Aral,
and Baikal; these forms, notwithstanding their long isolation, having
varied but slightly from species now inhabiting the Polar Seas.
II. GEOLOGICAL DISTRIBUTION.
_Geological Sequence._—In order to understand the geological
distribution, or in other words the distribution in time of mammals, it
is necessary to be acquainted with the chief divisions, or time-periods,
of the strata constituting the crust of the globe. These are shown in the
following table, which commences with the uppermost or most recent beds
and ends with the lowest and oldest.
I. CAINOZOIC OR TERTIARY—
1. Pleistocene—River alluvia, etc.
2. Pliocene—Suffolk Crag.
3. Miocene—Hempstead Beds of Hampshire.
4. Eocene—Paris Gypsum and London Clay.
II. MESOZOIC OR SECONDARY—
1. Cretaceous—Chalk, Greensands, etc.
2. Jurassic—Oolites and Lias.
3. Triassic—Red Marls, Dolomites, etc.
III. PALÆOZOIC OR PRIMARY—
1. Permian—Beds overlying the Coal.
2. Carboniferous—Coal-measures, etc.
3. Devonian—Old Red Sandstone.
4. Silurian—Wenlock Limestone, etc.
5. Cambrian—Llanberis Slate, etc.
6. Archæan—Gneiss and other schists.
The names in the first column indicate the primary divisions or
life-periods, while those in the second column are the great systems,
each of which is again divided into minor groups, the popular names of
a few of these minor groups being given in the third column. There are
at present no means of arriving at any satisfactory conclusion as to the
absolute length of time indicated by either the primary or secondary
divisions; but there is little doubt that the whole of the Tertiary
period is only equal to a fraction of the Mesozoic as regards its
duration, while it is probable that the duration of the Mesozoic epoch
was largely exceeded by that of the Palæozoic.
_Mesozoic Mammals._—The earliest date at which mammals are at present
known is in the upper part of the Triassic period, which forms the base
of the great Mesozoic epoch; and from this date they are represented more
or less abundantly in various horizons of the Jurassic and Cretaceous.
The very rapid advances in our knowledge of these forms which have been
made in the last few years, especially in consequence of the explorations
of rich fossiliferous beds in North America, have not only completely
changed the present aspect of the science, but give such promise for
the future, that any sketch which we may now attempt of this branch of
the subject can only be regarded as representing a transient phase of
knowledge. It will be well, however, to gather together in this place the
leading facts now ascertained with regard to the most ancient forms, as,
owing to the uncertainty of their relationship with any of the existing
orders, they will be most conveniently treated of separately, while the
ascertained facts relating to the geological history of the forms more
nearly allied to those now living will be more appropriately described
under the account of the different groups into which the class may now be
divided.
The remains of mammals which existed anterior to the Tertiary period
hitherto discovered nearly all belong to creatures of very small size,
many of the largest scarcely exceeding the common Polecat or Squirrel.
Some are known only by a few isolated teeth, others by nearly complete
sets of these organs, and the majority by more or less nearly perfect
specimens of the rami of the lower jaw. It is a very curious circumstance
that this part of the skeleton alone has been preserved in such a large
number of instances. Only very rarely has a nearly complete cranium been
found; and there is no satisfactory evidence of the structure of the
vertebral column of any single individual, and only one known case of a
complete limb.[29] The species already described from European strata
are numerous, although the number of genera and species has lately
been reduced. Of these by far the greater number have been found at a
single spot near Swanage in Dorsetshire, in a bed of calcareous mud only
forty feet long, ten feet wide, and averaging five inches in depth. The
marvellous results obtained by the exploration by Mr. S. H. Beckles of
this small fragment of the earth’s surface show by what accidents, as
it were, our knowledge of the past history of life has been gained,
and what may still remain in store where little thought of at present.
A bed, apparently equally rich, has been discovered in the Jurassic of
Wyoming, North America, the contents of which have been made known by
Professor Marsh, while another fertile source of these remains occurs in
the Laramie beds of the Upper Cretaceous of the United States.[30]
The whole of the Mesozoic mammals at present known may be divided into
two great groups, the one characterised by a type of dentition more or
less clearly resembling that found among the existing Polyprotodont
Marsupials, while the other presents an altogether peculiar modification,
recalling in some respects that of the Diprotodont Marsupials, although
differing so decidedly as to show that the owners of this form of
dentition cannot be included in that group.
[Illustration: FIG. 24.—Frontal and oral aspects of the cranium of
_Tritylodon longævus_; from the Karoo system of Basuto-land, South
Africa. ⅔ natural size. (After Owen.)]
_Multituberculata._—The name Multituberculata has been proposed for
the group exhibiting the type of dentition last mentioned, and is
generally adopted, although the term Allotheria has been also suggested.
The essential characteristic of the dentition of this group is the
presence of a single scalpriform incisor on each side of the lower
jaw (Fig. 25) and of one larger incisor, and in some instances of one
or two smaller ones in each premaxilla (Fig. 24). These incisors are
separated by an interval or diastema from the first of the premolars.
The true molars, and in some instances the premolars (Fig. 24), are
characterised by having longitudinal rows of tubercles separated by
one or more grooves; there being either two or three of these rows in
the upper molars of those forms in which these teeth are known, while
there are, at least usually, only two in those of the lower jaw. In
other cases the premolars are of a secant type, with a highly convex
cutting-edge, and usually either serrated or obliquely grooved (Figs.
25, 26). From a certain resemblance between these secant premolars and
those of some of the smaller _Macropodidæ_ it was at one time considered
that we had in these mammals representatives of Diprotodont Marsupials.
The great difference in the structure of the molar teeth of these forms,
coupled with the circumstance that when the number of upper incisors is
reduced below three it is the second in place of the first which becomes
enlarged and opposed to the incisor of the lower jaw, seems to prevent
the acceptation of this view. Moreover, in their peculiar structure
the molars seem, on the whole, to make a nearer approximation to the
teeth of _Ornithorhynchus_ than to any other known mammal; and it has
accordingly been suggested that the Multituberculata may really represent
an order of Prototheria. Some support is afforded to this suggestion by
certain fragmentary bones from the Cretaceous of the United States, which
are regarded by Marsh as parts of a coracoid and interclavicle. The
peculiar character of the whole dentition of these forms indicates that
if they are really Prototherians they cannot be regarded as primitive and
ancestral types.
[Illustration: FIG. 25.—The right ramus of the mandible of _Plagiaulax
beklesi_; from the Purbeck of Swanage. Twice natural size. _i_, Incisor;
_m_, molar; _b_, coronoid process; _c_, condyle. (After Owen.)]
It would be beyond the scope of the present work to describe in detail,
or even to mention the names of all the members of this group, and it
will therefore suffice to refer to a few of the principal types. Of the
forms with tubercular premolars the best known is the genus _Tritylodon_
(Fig. 24), which occurs typically in beds of Lower Mesozoic in South
Africa, but is also known from the Trias of Stuttgart. In the Stonesfield
Slate, near Oxford, which belongs to the lower part of the Jurassic
system, and is separated from the Trias by the intervening Lias, a
fragmentary jaw with three teeth (Fig. 27) appears to indicate an allied
type, the teeth having three longitudinal ridges separated by grooves.
In the Purbeck beds of Dorsetshire, forming the top of the Jurassic
system, we find another member of this group, which has been described as
_Bolodon_, closely allied to which is _Allodon_ of the Upper Jurassic of
the United States.
[Illustration: FIG. 26.—The imperfect right ramus of the mandible
of _Plagiaulax minor_; from Swanage. Four times natural size. _p_,
Premolars; _m_, molars. (After Lyall.)]
The first discovery of the remains of Mesozoic mammals was made in the
Keuper or Upper Trias of the Rhætian Alps in Bavaria. In 1847 Professor
Pleininger of Stuttgart, while sifting some sand from the Keuper of
Diegerloch and Steinenbronn, found, among an immense mass of teeth,
scales, and unrecognisable fragments of skeletons of fish and saurians,
two minute teeth, each with well-defined, enamelled, tuberculated crowns
and distinct roots, plainly showing their mammalian character. These were
considered by their discoverer to indicate a predaceous and carnivorous
animal of very small size, to which he gave the name of _Microlestes
antiquus_. Subsequently Mr. C. Moore discovered in a bone bed of Rhætic
(topmost Trias) age, filling a fissure in the Mountain Limestone at
Holwell, near Frome in Somersetshire, various isolated teeth with their
crowns much worn, but apparently including both upper and lower molars
and a canine, which are assigned by Sir R. Owen to Pleininger’s genus
_Microlestes_, and described specifically as _M. moorei_. Under the name
of _Hypsiprymnopsis rhæticus_, Professor Boyd Dawkins described a single
tooth with two roots discovered in the Rhætic Marlstone at Watchet in
Somersetshire. Sir R. Owen referred the latter tooth to _Microlestes_,
and if its describer is right in regarding it as a much worn premolar of
the type of those of _Plagiaulax_ (Fig. 25) there would be evidence that
_Microlestes_ was closely allied to the latter, from the molars of which
those of _Microlestes_ are scarcely distinguishable.
[Illustration: FIG. 27.—_Stereognathus oölithicus_. Fragment of jaw with
three teeth (_a_, _b_, _c_), in matrix; from the Stonesfield Slate.
Natural size. (After Owen.)]
_Plagiaulax_, of the Dorsetshire Purbeck (Figs. 24, 25), is at once
distinguished from _Tritylodon_ by its secant premolars, which, as
already mentioned, recall those of some of the _Macropodidæ_, although
readily distinguished by the convexity of the cutting edge and their
oblique grooving. This remarkable and highly specialised type has
been the occasion of one of the most interesting discussions on the
inferences which may be drawn as to the affinities and habits of an
otherwise unknown animal from the structure of a small portion of
its organisation which occurs in the annals of natural history—a
discussion carried on with great ability, ingenuity, and wealth of
illustration on both sides. Dr. Falconer maintained that it was more
nearly allied to the Rat-Kangaroo (_Potorous_ or _Hypsiprymnus_) than
to any other existing form, and that, as it is known that these animals
feed upon grass and roots, “it may be inferred of _Plagiaulax_ that
the species were herbivorous or frugivorous. I can see nothing in the
character of their teeth,” he adds, “to indicate that they were either
insectivorous or omnivorous.” Sir R. Owen, on the other hand, from the
same materials came to the conclusion that “the physiological deductions
from the above-described characteristics of the lower jaw and teeth of
_Plagiaulax_ are that it was a carnivorous Marsupial. It probably found
its prey in the contemporary small insectivorous mammals and Lizards,
supposing no herbivorous form like _Stereognathus_ to have co-existed
during the Upper Oolitic period.”
It is impossible here to give at any length the arguments by which these
opposing views are respectively supported, but it may be indicated that
the first-mentioned is strongly countenanced by the consideration of the
following facts: (1) all existing Marsupials may be divided, so far as
their dentition is concerned, into two groups—(_a_) those which have a
pair of large more or less procumbent incisors close to the symphysis of
the lower jaw, and rudimentary or no canines (diprotodont dentition), and
(_b_) those which have numerous small incisors and large pointed canines
(polyprotodont dentition); (2) the vast majority of the former group are
purely vegetable feeders, and almost all of the latter are carnivorous or
insectivorous; and (3) _Plagiaulax_, so far as its structure is known,
shows an analogy with the former group; and, as we have no sure basis for
inferences as to the habits of an unknown animal, but the knowledge of
the habits of such as are known, we have no grounds for supposing that
its habits differed from those forms having an analogous type of dental
structure.[31]
Allied types, such as _Ctenacodon_, are also met with in the Upper
Jurassic of North America; and the _Plagiaulacidæ_ also persisted
into the lower part of the Eocene division of the Tertiary period;
_Neoplagiaulax_ being a Tertiary form common to Europe and the United
States, while _Liotomus_ and _Ptilodus_ are at present known only from
the latter country.
The present group is also represented in the upper Cretaceous of the
United States by _Selenacodon_ (_Meniscoëssus_ in part), _Cimoliomys_,
etc. _Polymastodon_, of the Lowest or Puerco Eocene of New Mexico is the
largest known form, and is characterised by the presence of only one
premolar and the elongated molars. The angle of the mandible is inflected
after the Marsupial fashion.
_Polyprotodont Types._—The second type of mammalian dentition found in
the Mesozoic period resembles that occurring among recent Polyprotodont
Marsupials—that is to say there are at least three lower incisors, the
canines are well developed, and the premolars and molars are cuspidate,
the number of the latter reaching in some cases to seven or eight. There
has been much discussion as to the taxonomic position of these forms, and
while the majority of writers admit the Marsupial affinities of at least
a moiety, it has been contended that others indicate distinct ordinal
groups more or less closely allied to the Insectivora. At present,
however, there is no decisive evidence to support such a view. Important
proof of the Marsupial affinity of one of these forms is afforded by
the replacement of the teeth, which appears to be of the same nature as
in the existing Marsupials, that is to say, the last premolar alone is
preceded by a milk-tooth.
The most generalised forms appear to be _Dromatherium_ and
_Microconodon_, from Lower Mesozoic beds in the United States, of which
enlarged views of the teeth are given in Fig. 4 (1, 2), p. 31. Professor
Osborn points out the extremely simple character of these teeth, and it
is quite possible that these forms may prove to be _Prototheria_. There
are three premolars and seven molars in the lower jaw of _Dromatherium_.
[Illustration: FIG. 28.—Reversed view of the left ramus of the mandible
of _Triconodon mordax_; from the Purbeck of Swanage. Natural size. (After
Owen.)]
A common form in the Purbeck of Dorsetshire is _Triconodon_
(_Triacanthodon_), in which the formula of the lower teeth is _i_ 3,
_c_ 1, _p_ 4, _m_ 3-4. A lower jaw is shown in Fig. 28, and an enlarged
view of a molar tooth in Fig. 4 (5). The molar teeth consist of three
flattened cones placed in the same antero-posterior line, those of
the upper and lower jaw being alike. _Priacodon_, of the Jurassic of
the United States, is probably inseparable from _Triconodon_. In the
genus _Phascolotherium_ (Fig. 29) of the Lower Jurassic Stonesfield
Slate, the lower teeth may be classified as _i_ 4, _c_ 1, _p_ 3, _m_
4, the premolars and molars being much alike. The molars approximate
to the type of those of _Triconodon_, but the anterior and posterior
cones are relatively smaller. Like that of the last-named genus, the
mandible of _Phascolotherium_ is remarkable for the extremely low
position of its articular condyle. In _Amphilestes_ (Fig. 30) of the
Stonesfield Slate the molars appear to be of the same general type as
those of _Phascolotherium_, but are more numerous, although their exact
number cannot be determined. A somewhat different type of lower molar
is displayed by the genus _Amblotherium_, of the Dorsetshire Purbeck,
to which _Amphitherium_ of the Stonesfield Slate was probably allied.
This type of tooth is shown in Fig. 4 (8, 9, 12) p. 31, and, as there
stated, represents that modification of the tritubercular type known
as the tubercular sectorial. The three primitive tritubercular cusps
form what is known as the blade of the tooth, behind which there is
the talon or hypocone. A similar form of molar occurs in the existing
Opossums and Bandicoots. The number of lower teeth in _Amblotherium_ is
_i_ 4, _c_ 1, _p_ 4, _m_ 7-8. Numerous allied types, such as _Achyrodon_
and _Dryolestes_ occur in the Upper Jurassic of Europe or the United
States, while from only one side of the jaw being exposed in each case
so-called genera like _Stylodon_ and _Stylacodon_ have been formed upon
specimens showing the opposite side to that which is exposed in the
types of _Amblotherium_ and _Amphitherium_. The only parallel among
existing forms to the excessive number of molar teeth found in these
Mesozoic genera occurs in the Marsupial genus _Myrmecobius_, of which a
description is given in a succeeding chapter. Jaws more or less closely
resembling those described under the names mentioned above are also found
in the uppermost Cretaceous of the United States. A feature common to
these Mesozoic mammals and _Myrmecobius_ and some other existing forms
is the presence of a narrow channel on the inner side of the mandibular
ramus known as the mylohyoid groove (Fig. 29).
[Illustration: FIG. 29.—Inner view of the right ramus of the mandible
of _Phascolotherium bucklandi_; from the Stonesfield Slate. The outline
shows the natural size. _i_, Incisors (one missing); _c_, canine; _p_,
premolars; _m_, molars. The mylohyoid groove is seen near the lower
border. (After Owen.)]
[Illustration: FIG. 30.—Reversed inner view of the left ramus of the
mandible of _Amphilestes broderipi_; from the Stonesfield Slate. Twice
natural size. The restoration of the anterior teeth is conjectural, and
the condyle is placed too high. (After Owen.)]
The last type of molar dentition occurring among the Mesozoic
Mammalia is that found in the lower jaws (Fig. 31), upon which the
genus _Spalacotherium_ was established, the upper jaws, described as
_Peralestes_, being apparently referable to the same animal. Upper
and lower teeth of this form are represented in Fig. 4 (6, 7), p. 31,
where they are described as typical examples of the tritubercular type
of molars, the upper teeth having one inner and two outer cusps, and
the reverse condition obtaining in the lower ones. This type of molar
presents a marked resemblance to that found in the existing Insectivorous
genus _Chrysochloris_; the number of lower teeth in _Spalacotherium_ is,
however, _i_ 3, _c_ 1, _p_ + _m_ 10, by which it is widely distinguished
from all the Insectivora. _Menacodon_, of the Upper Jurassic of the
United States, appears to be allied to _Spalacotherium_.
[Illustration: FIG. 31.—Part of the left ramus of the mandible, viewed
from the outer side, of _Spalacotherium tricuspidens_; from the Purbeck
of Swanage. Twice natural size. (After Owen.)]
_Tertiary Mammals._—The more important types of Tertiary mammals will,
as already mentioned, be noticed under the heads of the groups to which
they are severally allied; but a few general remarks on this subject may
be advantageously recorded in this chapter. In the first place, it may
be observed that the comparatively scanty evidence of mammalian life
hitherto yielded by the Cretaceous, coupled with the number and variety
of forms approximating to the existing groups found even in the lowest
Tertiary, indicates a great imperfection of the geological record. At
present, indeed, we have no decisive evidence of the existence of any
members of the Eutherian subclass previously to the Tertiary; but it can
hardly be doubted that in some part of the world they had made their
appearance before that epoch. The Eutherian mammals of the lowest Eocene,
both in Europe and the United States, are of an extremely generalised
type; and although many of them approximate to existing groups, they show
such a combination of characters, now restricted to individual groups, as
to indicate that several of the various orders into which the subclass
is now divided were at that period very intimately connected. A marked
feature of these early Eutherians is the prevalency of trituberculism
in the dentition, not less noteworthy being the frequent occurrence of
pentadactylism in the feet, while many of the individual bones were
devoid of the grooves and ridges found in those of later types. By the
time that we reach the upper division of the Eocene period, such as the
horizon of the well-known gypsum of the Paris basin, nearly all the chief
groups of mammals had become clearly differentiated from one another,
although their representatives were usually more generalised than their
existing allies. From this date to the later geological periods there is
a gradual approximation to the types of mammalian life existing at the
present day.
In addition to the features of trituberculism and pentadactylism so
characteristic of the oldest known Eutherians, we may notice some other
points in connection with the earlier types. Thus the older Tertiary
mammals, as we have already stated, had relatively smaller and simpler
brains than the later types, so that a gradual evolution in this respect
may be traced from the Eocene to the Pleistocene. Again, there is a
great tendency among the Eocene forms to a retention of the typical
Eutherian dental formula noticed on page 25, and also to the absence of
an interval, or diastema, in the dental series. Concomitantly with this
feature we may notice the short crowns and simpler structure of the molar
teeth of the earlier Ungulates as compared with those of to-day, of which
details will be given in a later chapter. Another instance of the more
generalised characters of the earlier mammals is afforded by the absence
or slight development of horns, antlers, and tusks among the Ungulata.
Thus the earlier Rhinoceroses were hornless, and the Deer either without
antlers or with antlers of a very simple kind, while the male Swine were
not furnished with the formidable tusks of the existing Wild Boars.
Finally, all, or nearly all of the mammals, from the lowest Eocene of
Rheims present the peculiarity of having a vertical perforation in the
astragalus.
The intimate connection existing during the Middle Tertiary between many
families of mammals now widely distinguished from one another may be more
conveniently noted when we come to the consideration of the families in
question.
CHAPTER V
THE SUBCLASS PROTOTHERIA OR ORNITHODELPHIA
_General Characters._—The characters of the Prototheria can at present
only be deduced from the two existing families, since hitherto no extinct
animals which can be referred with certainty to other divisions of this
remarkable and well-characterised group have been discovered. These two
isolated forms, in many respects widely dissimilar, yet having numerous
common characters which unite them together and distinguish them from the
rest of the Mammalia, are the _Ornithorhynchidæ_ and the _Echidnidæ_,
both restricted in their geographical range to the Australian region
of the globe. Taken altogether they represent the lowest type of
evolution of the mammalian class, and most of the characters in which
they differ from the other two subclasses tend to connect them with the
inferior vertebrates, the Sauropsida and Amphibia; for, though the name
Ornithodelphia owes its origin to the resemblance of the structure of the
female reproductive organs to those of birds, there is nothing especially
bird-like about them.
Their principal distinctive characters are these. The brain has a very
large anterior commissure, and a very small corpus callosum, agreeing
exactly in this respect with the Marsupials. The cerebral hemispheres,
in _Echidna_ at least, are well developed and convoluted on the surface.
The auditory ossicles present a low grade of development, the malleus
being very large, the incus small, and the stapes columelliform. The
coracoid bone is complete, and articulates with the sternum, and there
is a pre-coracoid (epi-coracoid) in advance of the coracoid, while there
is also a large “interclavicle” or episternum in front of the sternum,
and connecting it with the clavicles. There are also “epipubic” bones.
The oviducts (not differentiated into uterine and Fallopian portions) are
completely distinct, and open, as in oviparous vertebrates, separately
into a cloacal chamber, and there is no distinct vagina. The testes
of the male are abdominal in position throughout life, and the vasa
deferentia open into the cloaca, not into a distinct urethral passage.
The penis, attached to the ventral wall of the cloaca, is perforated by
a canal in the greater part of its length, and not merely grooved, as in
reptiles and those birds which have such an organ. The canal is open at
the base and brought only temporarily in contact with the termination of
the vasa deferentia, so as to form a seminal urethra when required; but
it never transmits the urinary secretion. This condition is a distinct
advance on that of the Sauropsida in the direction of the more complex
development of these parts in most of the other Mammalia. The ureters
do not open into the bladder, but behind it into the dorsal wall of the
genito-urinary passage. The mammary glands have no distinct nipple,
but pour out their secretion through numerous apertures situated in a
cup-shaped depression of the abdominal skin, forming a mammary marsupium,
especially developed in the females during lactation. It should be
mentioned that, according to the observations of Professor Gegenbaur, the
mammary glands of the Monotremes are the simplest found in the entire
class. The region of the glands is, indeed, distinguished from the rest
of the abdomen merely by its thicker layers of muscles. The glands
themselves are closely connected with the hair-follicles, and belong to
the sudoriparous type, whereas the glands of all other mammals are of
sebaceous origin.
The young are produced from eggs laid by the female parent, which are
meroblastic, like those of birds; that is to say only a portion of
the yolk segments and forms the embryo, the remainder serving for the
nourishment of the latter.
The above are the principal distinguishing characters of the group, and
apply not only to the subclass, but of course equally to the one order
Monotremata, in which the two existing genera are included. In addition
to these more important characters, the following minor features may also
be mentioned.
The scapula differs from that of all other mammals in that the ridge
corresponding to the spine of other forms is situated on the anterior
border instead of in the middle of the outer or dorsal surface. The
humerus is much expanded at its two extremities, and has a very prominent
deltoid crest, and a well-marked entepicondylar foramen.
The dorso-thoracic vertebræ are nineteen in number, and have no terminal
epiphyses to their bodies. The transverse processes of the cervical
vertebræ are of autogenous formation, and remain suturally connected with
the remainder of the vertebra until the animal is full-grown. Though in
this respect they present an approximation to the Sauropsida (Reptiles
and Birds), they differ from these classes, inasmuch as there is not a
gradual transition from these autogenous transverse processes of the neck
(or cervical ribs, as they may be considered) into the thoracic ribs, for
in the seventh vertebra the costal element is much smaller than in the
others, indicative of a very marked separation of neck from thorax, not
seen in the existing Sauropsida. The upper ends of the ribs are attached
to the sides of the bodies of the dorsal vertebræ only, and not to the
transverse processes. The sternal ribs are well ossified, and there are
distinct partly ossified intermediate ribs. The cerebral cavity, unlike
that of the lower Marsupials or the Reptiles, is large and hemispherical,
flattened below and arched above, and about as broad as long. The
cribriform plate of the ethmoid is nearly horizontal. The cranial walls
are very thin, and smoothly rounded externally, and the sutures become
completely obliterated in adult skulls, as in Birds. The broad occipital
region slopes upwards and forwards, and the face is produced into a long
and depressed rostrum. The bony palate is prolonged backwards, so that
the posterior nares are nearly on a level with the glenoid fossæ. The
mandible is without distinct ascending ramus; the coronoid process and
angle are rudimentary, and the two halves are loosely connected at the
symphysis. The fibula has a broad, flattened process, projecting upwards
from its upper extremity above the articulation, like an olecranon. In
the male there is an additional, flat, curved ossicle on the hinder and
tibial side of the plantar aspect of the tarsus, articulating chiefly
to the tibia, which supports in the adult a sharp-pointed perforated
horny spur, with which is connected the duct of a gland situated
beneath the skin of the back of the thigh, the function of which is
not yet clearly understood. (A rudimentary spur is found in the young
female _Ornithorhynchus_, but this disappears when the animal becomes
adult.) The stomach is subglobular and simple; the alimentary canal
has no ileo-cæcal valve, or marked distinction between large and small
intestine, but has a small, slender vermiform cæcum with glandular walls.
The liver is divided into the usual number of lobes characteristic of the
Mammalia, and is provided with a gall-bladder.
In the presence of three distinct bones developed from cartilage in the
shoulder-girdle (viz. scapula, coracoid, and pre- or epi-coracoid) the
Monotremes agree with the Anomodont reptiles (see p. 83), and with no
other representatives of that class. The pre-coracoid of the Anomodonts
is, however, distinguished by extending upwards to articulate with the
acromial process of the scapula. The Monotreme humerus is, moreover,
strikingly like the corresponding bone of many of the Anomodonts and of
some of the allied Labyrinthodont Amphibians.
_Family_ ORNITHORHYNCHIDÆ.
_Ornithorhynchus._[32]—Cerebral hemispheres smooth. Premaxillæ and
mandible expanded anteriorly and supporting a horny beak something
like that of a duck, bordered by a naked and very sensitive membranous
expansion. The place of teeth in the adult is supplied functionally by
horny structures, elongated, narrow, and sharp-edged, along the anterior
part of the sides of the mouth, and broad, flat-topped or molariform
behind. Functional molar teeth present in the young and adolescent
condition. Legs short, fitted for swimming; feet webbed, each with five
well-developed toes armed with large claws, beyond which in the fore feet
the interdigital membrane is extended. Vertebræ: C 7, D 17, L 2, S 2,
Ca 21. Acetabulum not perforated. Tongue not extensile. Mucous membrane
of small intestine covered with delicate, close-set transverse folds or
ridges. Tail rather short, broad, and depressed. Eyes very small. Fur
close and soft.
The Duck-billed Platypus (_Platypus anatinus_) was the name assigned to
one of the most remarkable of known animals by Shaw, who had the good
fortune to introduce it to the notice of the scientific world in the
_Naturalist’s Miscellany_ (vol. x., 1799). In the following year it was
independently described by Blumenbach (_Voigts Magazin_, ii. p. 205)
under the name of _Ornithorhynchus paradoxus_. Shaw’s generic name,
although having priority to that of Blumenbach, could not be retained, as
it had been used at a still earlier time (1793) by Herbst for a genus of
Coleoptera. _Ornithorhynchus_ is therefore now universally adopted as the
scientific designation, although Duck-billed Platypus or Duck-bill may be
conveniently retained as a vernacular appellation. By the colonists it is
called “Water-Mole,” but it need scarcely be said, its affinities with
the true moles are of the slightest and most superficial description.
Until the last few years the early stages of the development of the young
were not fully known. It had, indeed, been repeatedly affirmed, in some
cases by persons who have had actual opportunities of observation, that
the Platypus lays eggs; but these statements were generally received
with scepticism and even denial. This much-vexed question was, however,
settled by the researches of Mr. W. H. Caldwell in 1884, who found that
these animals, although undoubtedly mammals throughout the greater part
of their structure, are oviparous, laying eggs, which in the manner of
their development bear a close resemblance to the development of those
of the Reptilia. Two eggs are produced at a time, each measuring about
three-fourths of an inch in its long, and half an inch in its short,
axis, and enclosed in a strong, flexible, white shell.
The Platypus is pretty generally distributed in situations suitable to
its aquatic habits throughout the island of Tasmania and the southern and
eastern portions of Australia. Slight variations in the colouring and
size of different individuals have given rise to the idea that more than
one species may exist; but all naturalists who have had the opportunity
of investigating this question by the aid of a good series of specimens
have come to the conclusion that there is but one, and no traces of any
extinct allied forms have yet been discovered.
[Illustration: FIG. 32.—Platypus or Duck-bill (_Ornithorhynchus
anatinus_). From Gould’s _Mammals of Australia_.]
The length of the animal when full grown is from eighteen to twenty
inches from the extremity of the beak to the end of the tail, the male
being slightly larger than the female. The fur is short, dense, and
rather soft to the touch, and composed of an extremely fine and close
under-fur, and of longer hairs projecting beyond this, each of which is
very slender at the base, and expanded, flattened, and glossy towards
the free end. The general colour is deep brown, but paler on the under
parts. The tail is short, broad, and depressed, and covered with coarse
hairs, which in old animals generally become worn off from the under
surface. The eyes are small and brown. There is no projecting pinna or
ear-conch. The mouth, as is well known, bears a striking resemblance
to the bill of a Duck. It is covered with a naked skin, a strong fold
of which projects outwards around its base. The nostrils are situated
near the extremity of the upper surface. There are no true teeth in the
adult, but their purposes are served by horny prominences, or cornules,
two on either side of each jaw—those in the front, narrow, longitudinal,
sharp-edged ridges, and those behind broad, flattened, and molariform.
The upper surface of the lateral edges of the mandible has also a
number of parallel fine transverse ridges, like those on the bill of a
Duck. Until 1888 it was thought that true teeth were totally wanting
throughout the life of this animal; but in the spring of that year Mr. E.
B. Poulton[33] announced the discovery in an embryo of teeth which were
regarded as quite functionless. In the following year, however, Mr. O.
Thomas[34] was fortunate enough to find some young skulls with functional
teeth _in situ_, and was thus enabled to give a detailed account of their
structure and of their relations to the cornules. From those specimens
it appears that the teeth are functional for a considerable part of the
life of the animal, cutting the gum in the usual manner, and, after being
worn down by friction with food and sand, are shed from the mouth in the
same manner as are the milk-teeth of other mammals. The cornules are
developed from the epithelium of the mouth under and around the teeth,
and the hollows found in the middle of them are the vestiges of the
alveoli from which the teeth have been shed. One of the skulls showed on
either side, both above and below, two completely calcified teeth; but in
another example there were three teeth on either side of the lower jaw.
According to Mr. Thomas’s account, “the teeth themselves are broad, flat,
and low-crowned. The upper ones have each two high, conical, internal
cusps, from which minute ridges run downwards and outwards to the outer
borders of the crowns, where the edge is peculiarly crenulate rather than
cuspidate, in the ordinary sense of the word. On the whole, the anterior
and posterior upper teeth are essentially similar to one another, except
that the former are narrower, and their outer edges are less markedly
crenulated. In the lower jaw there is a greater difference between the
two. The anterior is triangular in outline, its longest side is placed
antero-externally, and its anterior and postero-external angles have each
a high pointed cusp, ridged on its internal aspect, while the posterior
and internal borders are indistinctly crenulated. The posterior tooth is
broadly quadrangular in outline, with a projecting antero-internal angle.
As in the corresponding tooth above, there are two cusps on one side, and
a series of crenulations on the other, but they are of course reversed,
the cusps being external and the crenulations internal. The cusps are
high, and connected with transverse ridges running across towards the
internal border.”
In trying to find any teeth like those of the Duck-bill among other known
mammals Mr. Thomas considers, as was first suggested by Professor Cope,
that those of the Mesozoic Multituberculata (p. 109) make the nearest
approximation. He adds, however, that “it must be insisted that the
resemblance between the Multituberculate and the Ornithorhynchus teeth
is of the most general character, and that the two are certainly widely
separated generically, even if we do admit that they appear to possess
a relationship nearer to each other than to any other known groups of
mammals.”
Reverting to the description of the Duck-bill, we find that in the
cheeks are tolerably capacious pouches, which appear to be used as
receptacles for food. The limbs are strong and very short, each with
five well-developed toes provided with strong claws. In the fore feet
the web not only fills the interspaces between the toes, but extends
considerably beyond the ends of the long, broad, and somewhat flattened
nails, giving great expanse to the foot when used for swimming, though
capable of being folded back on the palm when the animal is burrowing
or walking on the land. On the hind foot the nails are long, curved,
and pointed, and the web extends only to their base. On the heel of the
male is a strong, curved, sharply pointed, movable horny spur, directed
upwards and backwards, attached by its expanded base to the accessory
bone of the tarsus. This spur, which attains the length of nearly an
inch, is traversed by a minute canal, terminating in a fine longitudinal
slit near the point, and connected at its base with the duct of a large
gland situated at the back part of the thigh. The whole apparatus is so
exactly similar in structure to the poison-gland and tooth of a venomous
snake as to suggest a similar function, but evidence that the Platypus
ever employs its spur as an offensive weapon has, at all events until
lately, been wanting. A case is, however, related by Mr. Spicer in the
_Proceedings of the Royal Society of Tasmania for 1876_ (p. 162), of a
captured Platypus inflicting a severe wound by a powerful lateral and
inward movement of the hind legs, which wound was followed by symptoms of
active local poisoning. It is not improbable that both the inclination
to use the weapon and the activity of the secretion of the gland may
be limited to the breeding season, and that their purpose may be, like
that of the antlers of deer and many similar organs, for combat among
the males. In the young female the spur is present in a rudimentary
condition, but it disappears in the adult of that sex.
The Platypus is aquatic in its habits, passing most of its time in the
water or close to the margin of lakes and streams, swimming and diving
with the greatest ease, and forming for the purpose of sleeping and
breeding deep burrows in the banks, which generally have two orifices—one
just above the water level, concealed among long grasses and leaves,
and the other below the surface. The passage at first runs obliquely
upwards in the bank, sometimes to a distance of as much as fifty feet,
and expands at its termination into a cavity, the floor of which is lined
with dried grass and leaves, and in which the eggs are laid and the young
brought up. The food consists of aquatic insects, small crustaceans, and
worms, which are caught under water, the sand and small stones at the
bottom being turned over with the bill. The creatures appear at first to
deposit what they have thus collected in their cheek pouches, and when
these are filled they rise to the surface and quietly triturate their
meal with the horny plates before swallowing it. Swimming is effected
chiefly by the action of the broad forepaws, the hind feet and tail
taking little share in locomotion in the water. When asleep they roll
themselves into a ball, as shown in the figure. In their native haunts
they are extremely timid and wary, and very difficult to approach, being
rarely seen out of their burrows in the daytime. Mr. A. B. Crowther, who
has supplemented the often quoted observations of Dr. Bennett upon the
habits of these animals in confinement, says, “They soon become very
tame in captivity; in a few days the young ones appeared to recognise a
call, swimming rapidly to the hand paddling the water; and it is curious
to see their attempts to procure a worm enclosed in the hand, which they
greedily take when offered to them. I have noticed that they appear to be
able to smell whether or not a worm is contained in the closed hand to
which they swim; for they desisted from their efforts if an empty fist
was offered.” When irritated they utter a soft low growl, resembling that
of a puppy.
_Family_ ECHIDNIDÆ.
Cerebral hemispheres larger and well convoluted. Facial portion of skull
produced into a long, tapering, tubular rostrum, at the end of which
the anterior nares are situated. Rami of mandible slender, styliform.
Opening of mouth small, and placed below the extremity of the rostrum.
No teeth or laterally placed horny plates, though the palate and tongue
are furnished with spines. Tongue very long, vermiform, slender, and
protractile. Lining membrane of small intestine villous, but without
transverse folds. Feet not webbed, but with long strong claws fitted
for scratching and burrowing. The hinder feet with the ends of the toes
turned outwards and backwards in the ordinary position of the animal when
on the ground. Tail very short. Acetabulum with a large perforation,
as in Birds. Calcaneal spur and gland of the male much smaller than in
_Ornithorhynchus_. Fur intermixed with strong, sharp-pointed spines.
Terrestrial and fossorial in habits, feeding exclusively on ants, and
recalling in the structure of the mouth and various other parts, relating
to their peculiar mode of life the true Anteaters of the order Edentata.
The Echidnas or Spiny Anteaters constitute a family which appears in some
respects to be less specialised than the _Ornithorhynchidæ_. According
to Mr. O. Thomas, all the living forms may be included in two species,
which, with some hesitation, are referred to two genera—_Echidna_ and
_Proechidna_ (_Acanthoglossus_).
_Echidna._[35]—In _Echidna_ there are five toes, all of which are
provided with claws, those of the fore foot being broad, slightly curved,
and directed forwards, while the posterior ones are slender, more curved,
and inclined outwardly. The beak is about as long as the rest of the
head, and either nearly straight, or slightly curved upwards, while the
palate is comparatively wide, and but slightly vaulted. The number of the
vertebræ is C 7, D 16, L 3, S 3, Ca 12. The one existing representative
of the genus (_E. aculeata_) occurs in New Guinea, Tasmania, and
Australia.
So much variation is displayed by this animal, that it has been divided
into several species, but the latest researches tend to show that these
variations cannot be regarded as indicating more than races, of which
there are three well-marked types.
The first race, or variety, has been termed the Port Moresby Echidna,
and is only known from that Papuan locality. It is distinguished from
the typical form by its smaller size, by the shorter spines on the back,
which admit of the fur being seen, and by the more spinous covering
of the head, belly, and limbs, as well as by the lighter skull and
relatively larger beak.
The typical variety is confined to the Australian mainland, and is of
medium size. The spines of the back are very long and stout, often
reaching a length of two inches, and almost completely concealing the
hair. The colour of these spines varies from yellow at the roots to black
at the tips, but some may be altogether yellow. The hair of the back is
black or dark brown in colour, but it may be occasionally absent, or
in the region of the loins may exceed the spines in length. The limbs
and under surface of the body are covered with dark brown hair, thinly
interspersed with short spines; and the hair of the face is of the same
general hue as that of the body. The skull has a slender rostrum and a
flat and narrow brain-case.
In the third or Tasmanian race, which is confined to Tasmania, the
average size is somewhat larger than in the typical form. The most
characteristic feature is, however, the shortness of the spines of the
back, which in the greater part of that region are almost or quite
concealed by the hairs. The hairs of the back are dark brown, those of
the under surface and sides of the head being generally rather paler.
There is often a white spot on the chest. Very frequently there is a
difference in the proportionate lengths of the hinder claws from those of
the typical race. In the skull the beak is comparatively short and stout,
and the brain-case large and wide.
Echidnas are usually found in rocky districts, and more especially
in the mountains. In a wild state they live mainly on ants. Specimens
have been brought to this country and kept in the Zoological Society’s
Gardens; and in captivity they will readily eat eggs, and bread-and-milk.
They are able, however, to endure long fasts, an individual having been
known to go without food for upwards of a month.
These animals seem to be mainly of nocturnal habits, and if brought out
during the daytime appear to be sluggish and stupid, crouching to the
ground with the head between the legs, and thus presenting a mass of
spines to an enemy. They burrow rapidly in soft ground, sinking directly
downwards, and not going head forwards. A specimen placed on a large
chest of earth containing plants reached the bottom in less than two
minutes; and it is said that the muzzle assists in the work of burrowing.
[Illustration: FIG. 33.—The Three-toed Echidna (_Proechidna bruijnii_).
From Gervais.]
_Proechidna._[36]—The one known representative of the genus _Proechidna_
(Fig. 33) attains dimensions about equal to those of the largest race
of _Echidna aculeata_. The skull is less depressed than in the latter,
with the anterior portion of the palate very concave, and the deflected
beak nearly twice the length of the remainder of the skull. As a rule,
there are only three claws to each foot; but the first and fifth digits
are represented by several phalanges, and one instance is known where
there are five complete claws on the anterior and four on the posterior
feet. There are two more vertebræ in the dorsal and lumbar region than in
_Echidna_.
The head and body are covered with a thick coat of hair, among which
there are a number of short spines in the region of the back, which are
much less numerous than in the typical race of the last species. The
colour of the fur is generally dark brown or black, but the head may be
almost white; and the spines are usually entirely white, although in
certain cases they may be brown at the root.
This species is known only from New Guinea, the recorded specimens being
from the north-western regions of that country. It inhabits rocky ground,
and dwells chiefly in the mountains, the specimens which were first
described having been obtained at an elevation of about 3500 feet above
the sea level. The Papuans capture it by digging trenches in the ground
to a depth of about a yard, by which means they generally come upon its
runs.
_Fossil Species._—Remains of a species of Echidna of very much larger
size than the existing forms have been obtained from the cave-deposits of
New South Wales, which appear to be of Pleistocene age. This species was
named _Echidna oweni_ by the late Mr. Krefft, but was subsequently called
_E. ramsayi_ by Sir R. Owen. In referring this species to the genus
_Echidna_, that term must be regarded as including _Proechidna_.
CHAPTER VI
THE SUBCLASS METATHERIA OR DIDELPHIA
_General Characters._—The Metatheria or Didelphia are represented at
present by numerous species, presenting great diversities of general
appearance, structure, and habits, although all united by many essential
anatomical and physiological characters, which, taken altogether, give
them an intermediate position between the Prototheria and the Eutheria.
Although the striking differences in external form, in many anatomical
characters, and in mode of life of various animals of this section
might lead to their division into groups equivalent to the orders of
the Eutheria, it is more convenient on the whole to adhere to the usual
custom of treating them all as forming one order called MARSUPIALIA,[37]
the limits of which are therefore equivalent to that of the subclass. The
more essentially distinctive characters are as follows.
In the structure of the brain and the presence of epipubic bones they
agree with the Prototheria, while in the structure of the ear-bones and
the shoulder-girdle and the presence of teats on the mammary glands they
resemble the Eutheria, the reproductive organs belonging to neither
one nor the other type, but having a special character representing an
intermediate grade of development. The ureters open into the base of
the bladder. The oviducts are differentiated into uterine and Fallopian
portions, and open into a long and distinct vagina, quite separate from
the cystic urethra. The penis is large, but its crura are not directly
attached to the ischia. The spongy body has a large bifurcated bulb.
The young are born in an exceedingly rudimentary condition, and are
never nourished by means of an allantoic placenta, but are transferred
to the nipple of the mother, to which they remain firmly attached for
a considerable time, nourished by the milk injected into the mouth by
compression of the muscle covering the mammary gland. They are therefore
the most typically mammalian of the whole class. The nipples are nearly
always concealed in a fold of the abdominal integument or “pouch”
(marsupium) which serves to support and protect the young in their early
helpless condition.
Entering more fully into the characters of the subclass, which are
also those of the order Marsupialia, it may be observed that the brain
is generally small in proportion to the size of the animal, and the
surface-folding of the cerebral hemispheres, though well marked in the
larger species, is never very complex in character, and is absent in the
medium-sized and smaller species. The arrangement of the folding of the
inner wall of the cerebrum differs essentially from that of all known
Eutheria, the hippocampal fissure being continued forward above the
corpus callosum, which is of very small size. The anterior commissure is,
on the other hand, greatly developed.
[Illustration: FIG. 34.—Teeth of upper jaw of Opossum (_Didelphys
marsupialis_), all of which are unchanged, except the last premolar, the
place of which is occupied in the young animal by a molariform tooth,
represented in the figure below the line of the other teeth.]
The teeth are always divisible, according to their position and form,
into incisors, canines, premolars, and molars; but they vary much in
number and character in the different families. Except in the genus
_Phascolomys_, the number of incisors in the upper and lower jaws is
never equal. The true molars are very generally four in number on either
side of each jaw. The chief peculiarity in the dentition lies, however,
in the mode of succession. Thus there is no vertical displacement and
succession of the teeth, except in the case of a single tooth on either
side of each jaw, which is always the hindermost of the premolar series,
and is preceded by a tooth having more or less of the characters of
a true molar (see Fig. 34); this deciduous tooth being the only one
comparable to the “milk-teeth” of the diphyodont Eutheria. In some cases
(as in _Potorous_) this tooth retains its place and function until the
animal has nearly, if not quite, attained its full stature, and is not
shed and replaced by its successor until after all the other teeth of
the permanent series, including the posterior molars, are fully in place
and use. In others, as the Thylacine, it is very rudimentary in form
and size, being shed or absorbed before any of the other teeth have
cut the gum, and therefore quite functionless. It must further be noted
that there are some Marsupials, as the Wombat, _Myrmecobius_, and the
Dasyures, in which no such milk-tooth, even in a rudimentary state, has
yet been discovered, possibly in some cases from want of materials for
observation at the right stage of development.
Epipubic or marsupial bones are present in both sexes of nearly all
species. In one genus alone, _Thylacinus_, they are not ossified. The
number of dorso-lumbar vertebræ is always nineteen, although there are
some apparent exceptions caused by the last lumbar being modified into a
sacral vertebra. The number of pairs of ribs is nearly always thirteen.
The tympanic bone remains permanently distinct. The carotid canal
perforates the basisphenoid. The lachrymal foramen is situated upon or
external to the anterior margin of the orbit, and there are generally
large vacuities in the bony palate. The angle of the mandible is (except
in _Tarsipes_) more or less inflected. The hyoid bones have always
a peculiar form, consisting of a small, more or less lozenge-shaped
basihyal, broad ceratohyals, with the remainder of the anterior arch
usually unossified, and stout, somewhat compressed thyrohyals. There
are two anterior venæ cavæ,[38] into each of which a “vena azygos”
enters. In the male the testes are always contained in a scrotum, which
is suspended by a narrow pedicle to the abdomen in front of the penis.
The vasa deferentia open into a complete and continuous urethra, which
is also the passage by which the urine escapes from the bladder, and is
perfectly distinct from the passage for the fæces, although the anus
and the termination of the urethro-sexual canal are embraced by the
same sphincter muscle. The glans is often bifurcated anteriorly. In the
female the oviducts never unite to form a common cavity or uterus, but
open separately into the vagina, which at least for part of its course
is double. The mammæ vary much in number, but are always abdominal in
position, having long teats, and in most of the species are more or
less enclosed in a fold of the integument forming a pouch or marsupium,
though in some this is entirely wanting, and the newly-born, blind,
naked, and helpless young, attached by their mouths to the teat, are
merely concealed and protected by the hairy covering of the mother’s
abdomen. In this stage of their existence they are fed by milk injected
into their stomach by the contraction of the muscles covering the
mammary gland, the respiratory organs being modified temporarily, much
as they are permanently in the Cetacea—the elongated upper part of the
larynx projecting into the posterior nares, and so maintaining a free
communication between the lungs and the external surface independently
of the mouth and gullet, thus averting the danger of suffocation while
the milk is passing down the latter passage.
[Illustration: FIG. 35.—Front view of skull of _Sarcophilus ursinus_,
showing polyprotodont and carnivorous dentition (_Quart. Journ. Geol.
Soc._ vol xxiv. p. 313).]
_Distribution._—The existing species of Marsupials are, with the
exception of one family (the _Didelphyidæ_), limited in geographical
distribution to the Australasian region,[39] forming the chief mammalian
fauna of Australia, New Guinea, and some of the adjacent islands. The
_Didelphyidæ_ are almost purely Neotropical, one or two species ranging
northwards into the Nearctic region. Fossil remains of members of this
family have also been found in Europe and America in strata of the Eocene
and early Miocene periods; and it is probable that at least many of the
polyprotodont Mesozoic mammals noticed in Chapter IV. are referable to
the Marsupialia.
[Illustration: FIG. 36.—Front view of skull of Koala (_Phascolarctus
cinereus_), showing diprotodont and herbivorous dentition (_Quart. Journ.
Geol. Soc._ vol. xxiv. p. 313).]
_Classification._—In dividing the Marsupials into minor groups, it may
be observed that one of the most obvious distinctive characters among
them is derived from the form and arrangement of the teeth. In certain
species, as the Opossums, Dasyures, and Thylacine, the incisors are
numerous, small, and subequal in size, and the canines large, as in the
typical placental Carnivores (Fig. 35). To these the term “polyprotodont”
is applied, and they are all more or less carnivorous in their habits.
In others the central incisors are very prominent, and the lateral
incisors and canines absent or subordinate in function (Fig. 36). These
are called “diprotodont,” and they are all wholly or in great part
vegetable feeders. In one group of these, the Wombats, there are but two
incisors above and the same number below; but all the others, including
the Kangaroos, Koalas, and Phalangers, have two functional incisors below
and as many as six above, three on each side, but of these the first or
central pair is the most fully developed.
Some hesitation has frequently been expressed as to whether the
Polyprotodont and Diprotodont types are entitled to constitute distinct
primary groups, owing to the presence of syndactylism among the
_Peramelidæ_ in the former, as well as in the latter; but if Mr. O.
Thomas is right in regarding this feature as acquired independently
in the two groups we may safely adopt such a division. Taking various
combinations into consideration, the existing Marsupials readily group
themselves into six very natural families, the leading characters of
which may be summarised as follows:—
_Order_ MARSUPIALIA.
_A._ POLYPROTODONTIA.—Incisors numerous, small, subequal. Canines larger
than the incisors. Molars with sharp cusps.
α. Incisors ⁵⁄₄. Hind feet with the four outer toes subequal,
distinct, and a well-developed opposable hallux. _Didelphyidæ._
β. Incisors ⁴⁄₃. Hind feet with four outer toes distinct.
Hallux small or rudimentary, rarely opposable. _Dasyuridæ._
γ. Incisors ⁴⁻⁵⁄₃. Hind feet long and narrow. Fourth toe
larger than the others. Hallux rudimentary or absent. Second
and third toes very slender, and united in a common integument
(syndactylous). _Peramelidæ._
_B._ DIPROTODONTIA.—Incisors not exceeding ³⁄₃, usually ³⁄₁ but
occasionally ¹⁄₁. Central (first) upper and lower incisors large and
cutting. Upper canines generally, and lower invariably, absent or small.
Molars with bluntly tuberculated or transversely ridged crowns.
α. Teeth with persistent pulps. Incisors ¹⁄₁, large,
scalpriform, with enamel on the outer surface only. No
canines. Hind feet with four subequal outer toes, partially
syndactylous, and with rudimentary hallux. _Phascolomyidæ._
β. Teeth rooted. Three upper incisors and a canine. Hind
limbs not disproportionately large. Feet syndactylous, broad,
with four subequal outer toes, and a large opposable hallux.
_Phalangeridæ._
γ. Teeth rooted. Three upper incisors, and frequently a canine.
Hind limbs disproportionately large, with syndactylous feet as
in _Peramelidæ_. _Macropodidæ._
_Suborder_ POLYPROTODONTIA.
The leading characters of this group are given in the foregoing schedule.
This group is the only one represented at the present day, and so far
as we know also in past epochs, beyond the confines of the Australasian
region and adjacent islands.
_Family_ DIDELPHYIDÆ.
Dentition: _i_ ⁵⁄₄, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ⁴⁄₄; total 50. Incisors very
small and pointed. Canines large. Premolars with compressed pointed
crowns. Molars with numerous sharp cusps. The last premolar preceded by
a deciduous multicuspidate milk-molar, which remains in place until the
animal is nearly adult (Fig. 34). Limbs of moderate development, each
with five complete and distinct toes, all of which are provided with
short, compressed, curved, sharp claws of nearly equal size, except the
first toe of the hind foot or hallux (Fig. 37), which is large, widely
separable from the others, to which it is opposed in climbing, and
terminates in a dilated rounded extremity, without a nail. Tail generally
long, partially naked and prehensile. Stomach simple. Cæcum of small
or moderate size. Pouch generally absent, sometimes represented by two
lateral folds of the abdominal integument, partially covering the teats,
rarely complete. Vertebræ: C 7, D 13, L 6, S 2, C 19-35.
[Illustration: FIG. 37.—Skeleton of the right hind foot of the Virginian
Opossum (_Didelphys marsupialis_).]
The _Didelphyidæ_, or true Opossums, differ from all other existing
Marsupials in their habitat, being peculiar to the American continent.
They are mostly carnivorous or insectivorous in their diet, and arboreal
in habits.
Opossums occur throughout the greater part of the American continent,
ranging from the United States to Patagonia, the greater number of
species being found in the warmer regions. In South America the opossums
take the place of the Eutherian Insectivora, and the sharp cusps on their
teeth are admirably adapted for crushing the insects on which they mainly
subsist.
_Chironectes._[40]—The family comprises two genera only, namely
_Didelphys_, containing all the species, with the exception of
the curious Yapock, which forms by itself the genus _Chironectes_
and is distinguished from all other Opossums by its webbed feet,
non-tuberculated soles, and peculiar coloration. Its ground colour is
light gray, with four or five sharply-contrasted brown bands passing
across its head and back, and thus giving it a very peculiar mottled
appearance. It is almost wholly aquatic in its habits, living on small
fish, crustaceans, and water insects. Its range extends from Guatemala to
southern Brazil.
_Didelphys._[41]—The type genus _Didelphys_ is a very large one,
containing, according to Mr. O. Thomas, twenty-three existing species.
It may be divided into five groups, or subgenera, all of which have
received distinct names. The typical group is represented only by the
common or Virginian Opossum (_D. marsupialis_), of which the numerous
varieties have received separate specific names. This species is of large
size, with a long, scaly, prehensile tail, and long bristle-like hairs
mingled with the fur. The pouch is complete. It ranges over all temperate
North America, and is also found in central and tropical South America,
where it is commonly known as the Crab-eating Opossum. This animal is
extremely common, being even found living in the towns, where it acts as
a scavenger by night, retiring for shelter by day upon the roofs of the
houses or into the sewers. The female produces in the spring from six
to sixteen young ones, which are placed in her pouch immediately after
birth, and remain there until able to take care of themselves.
The second or _Metachirine_ group includes three species found all over
the tropical parts of the New World. They are of medium size, with
short close fur, very long, scaly, and naked tails, and less developed
ridges on their skulls than in the type species. As a rule there is no
pouch adapted to carry the young, which commonly ride on their mother’s
back, holding on by winding their prehensile tails round hers. The
_Philanderine_ group is closely allied to the preceding, but is readily
distinguished by the woolly hair, and the brown streak down the middle
of the face. The Woolly Opossum (_D. lanigera_), which is represented
in the accompanying woodcut (Fig. 38) carrying its young in the fashion
mentioned above, is one of the two species of this group. In the fourth
or _Micoureine_ group the numerous species are all smaller than in the
preceding groups, and have short and close hair, and no dark streak down
the face. The best known species is the Murine Opossum (_D. murina_),
little larger than a House-Mouse, and of a bright red colour, which is
found as far north as central Mexico, and extends thence right down
to the south of Brazil. The last or _Peramyne_ group contains several
extremely shrew-like species, of very small size, with short, hairy,
and usually non-prehensile tails, not half the length of the trunk, and
with wholly unridged skulls. The most striking member of the group is
the Three-striped Opossum (_D. americana_), from Brazil, which is of a
reddish-gray colour, with three clearly-defined deep-black bands down its
back, very much as in some of the striped mice of Africa.
[Illustration: FIG. 38.—The Woolly Opossum (_Didelphys lanigera_).]
The numerous fossil species of Opossum found in the Upper Eocene and
Lower Miocene of Europe are of especial interest from a distributional
point of view, since they indicate how the Opossums of America may
have been connected with the Australian Marsupials. These forms were
originally referred to _Didelphys_, but have been subsequently described
as _Peratherium_ and _Amphiperatherium_. The characters of the molar
teeth on which these genera are based do not appear to be sufficiently
important to justify their separation from _Didelphys_. Allied forms
occur in the Tertiaries of North America, which were originally described
under the name of _Herpetotherium_, but have been subsequently referred
to _Peratherium_. Remains of many of the existing species of Opossum are
found in a fossil condition in the Pleistocene cave-deposits of Brazil.
_Family_ DASYURIDÆ
Dentition: _i_ ⁴⁄₃, _c_ ¹⁄₁, _p_ and _m_ numerous, variable. Incisors
small; canines well developed; molars with pointed cusps. Limbs equal.
Fore feet with five subequal toes terminating in claws. Hind feet with
the four outer toes well developed, and distinct from each other and
bearing claws; the first (or hallux) clawless, generally rudimentary,
sometimes entirely wanting. Stomach simple. No cæcum. Predatory
carnivorous or insectivorous animals, inhabitants of Australia, Tasmania,
and the southern parts of New Guinea and some of the adjacent islands.
The aberrant genus _Myrmecobius_, though clearly a member of this family,
is so sharply distinguished from all the others as to render a division
into two subfamilies necessary.
[Illustration: FIG. 39.—The Thylacine (_Thylacinus cynocephalus_).]
Subfamily =Dasyurinæ=.—This comprises the more typical _Dasyuridæ_, in
which the premolars and molars never exceed the normal number of seven
on either side of each jaw, and in which the tongue is not specially
extensile.
_Thylacinus._[42]—Dentition: _i_ ⁴⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ⁴⁄₄ = 46.
Incisors small, vertical, the outer one in the upper jaw larger than
the others. Summits of the lower incisors, before they are worn, with a
deep transverse groove dividing them into an anterior and a posterior
cusp. Canines long, strong, and conical. Premolars separated from one
another by intervals, with compressed crowns, increasing in size from
before backwards. True molars in general characters resembling those of
_Dasyurus_, but of more simple form, the cusps being not so distinct nor
sharply pointed. Milk-molar very small, and shed before the animal leaves
the mother’s pouch. Humerus with an entepicondylar foramen. General form
very Dog-like. Head elongated. Muzzle pointed. Ears moderate, erect,
triangular. Fur short and closely applied to the skin. Tail of moderate
length, thick at the base and tapering towards the apex, clothed with
short hair. Hallux (including the metacarpal bone) wanting. Vertebræ:
C 7, D 13, L 6, S 2, C 23. Marsupial bones represented only by small
unossified fibro-cartilages.
The only known existing species of this genus, _T. cynocephalus_ (Fig.
39), though smaller than a common Wolf, is the largest predaceous
Marsupial at present living. It is now entirely confined to the island
of Tasmania, although fragments of bones and teeth found in caves afford
evidence that a closely allied species once inhabited the Australian
mainland. The general colour of the Thylacine is grayish brown, but
it has a series of transverse black bands on the hinder part of the
back and loins, whence the name of “Tiger” frequently applied to it
by the colonists. It is also called “Wolf,” and sometimes, though
less appropriately, “Hyæna.” Owing to the havoc it commits among the
sheepfolds, it has been nearly exterminated in all the more settled parts
of Tasmania, but still finds shelter in the almost impenetrable rocky
glens of the more mountainous regions of the island. The female produces
four young at a time. The pouch opens backwardly, and there are four
mammæ. The figure of the skull exhibits the peculiar Dog-like form so
characteristic of the genus.
[Illustration: FIG. 40.—Right lateral aspect of the skull of the
Thylacine.]
_Sarcophilus._[43]—Dentition: _i_ ⁴⁄₃, _c_ ¹⁄₁, _p_ ²⁄₂, _m_ ⁴⁄₄.
Upper incisors nearly equal, and placed vertically, the first not
differentiated from the rest. Premolars rounded and closely crowded
between the canine and molars, with broad crowns; molars broad and heavy,
the last one without a distinct hind talon. Form thick and powerful;
head disproportionately large for the body; muzzle short and broad;
ears broad and rounded; tail of moderate length, and evenly hairy.
Hallux wanting; soles of feet naked, without defined pads. Humerus with
entepicondylar foramen.
This genus is now represented only by a single species (_S. ursinus_)
found in Tasmania, where, from its ferocious and destructive habits, it
is commonly known under the name of the “Devil.” A front view of the
skull is shown in Fig. 35.
The prevailing colour of this animal is black, and the size about equal
to that of an English Badger; its habits are fossorial, and it is very
destructive to sheep. On account of the similarity in the number of its
teeth this genus has been generally included in the next one, but in the
structure of the teeth it is much nearer to _Thylacinus_. An extinct
species is found in the Pleistocene deposits of the mainland of Australia.
It may be observed that the two premolars missing from the typical
series of four in this and the next genus are the second and the fourth;
the fourth milk-molar being likewise absent. In _Thylacinus_ and other
Polyprotodonts with three premolars it is the second that is missing.
_Dasyurus._[44]—Dentition: _i_ ⁴⁄₃, _c_ ¹⁄₁, _p_ ²⁄₂, _m_ ⁴⁄₄; total
42. Upper incisors nearly equal, and placed vertically; first slightly
longer, narrower, and separated from the rest. Lower incisors sloping
forwards and upwards. Canines large and sharply pointed. Premolars with
compressed and sharp-pointed crowns, and slightly developed anterior and
posterior accessory basal cusps. True molars with numerous sharp-pointed
cusps. In the upper jaw the first three with crowns having a triangular
oral surface, the fourth small, simple, narrow, and placed transversely.
In the lower jaw the molars more compressed, with longer cusps; the
fourth not notably smaller than the others. Form viverrine. Ears long and
narrow, prominent, and obtusely pointed. Hallux rudimentary, or absent;
its metatarsal bone always present. Tail long and well clothed with hair.
Humerus without an entepicondylar foramen. Vertebræ: C 7, D 13, L 6, S 2,
C 18-20.
The Dasyures are small Civet-like animals with a gray or brown pellage
profusely spotted with white; they are mostly inhabitants of the
Australian continent and Tasmania, where in the economy of nature they
take the place of the smaller predaceous Carnivora, the Cats, Civets, and
Weasels of other parts of the world. They hide themselves in the daytime
in holes among rocks or in hollow trees, but prowl about at night in
search of the small living mammals and birds which constitute their prey.
The species are not numerous, and include _D. maculatus_, about the size
of a common Cat, inhabiting Tasmania and the southern part of Australia;
_D. viverrinus_, Tasmania and Victoria; _D. geoffroyi_, nearly all
Australia; _D. hallucatus_, North Australia; _D. albopunctatus_, New
Guinea.
Remains referred to _D. viverrinus_ occur in the Australian Pleistocene
deposits.
_Phascologale._[45]—This genus comprises a considerable number of small
Marsupials, none of them exceeding a common Rat in size, differing from
the Dasyures in possessing an additional premolar—the dentition being _i_
⁴⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ⁴⁄₄; total 46,—and having the teeth generally
developed upon an insectivorous rather than a carnivorous pattern, the
upper middle incisors being larger and inclined forwards, the canines
relatively smaller, and the molars with broad crowns, armed with prickly
tubercles. The muzzle is pointed. Ears moderately rounded and nearly
naked. Feet broad and short. Fore feet with five subequal toes, having
compressed, slightly curved, pointed claws. Hind feet with the four outer
toes subequal, having claws similar to those in the fore feet; the hallux
always distinct and partially opposable, though small and nailless.
Tail long, very variable in its covering, being either bushy, crested,
or nearly naked. Pouch represented merely by a few folds of skin. Mammæ
varying from four to ten in number. The food of these animals is almost
entirely insects; some species pursuing their prey among the branches of
trees, while others are purely terrestrial. They are found throughout
Australia, and also in New Guinea and the Aru and some of the adjacent
islands.
_P. cristicaudata_, a species with a thick compressed tail ornamented
upon its apical half with a crest of black hair, differs from the others
by the very reduced size of the fourth premolar in the upper, and its
complete absence in the lower jaw, thus forming an interesting transition
in dentition towards _Dasyurus_. It constitutes the genus _Chætocercus_
of Krefft, but is included by Mr. O. Thomas in _Phascologale_, the
frequent absence of the fourth lower premolar in _P. thorbeckiana_
indicating that the total absence of this tooth in the known specimens of
this species cannot be regarded as of generic importance. All the members
of this and the two following genera can be at once distinguished from
_Dasyurus_ by the absence of white spots on the fur.
_Sminthopsis._[46]—The genus _Sminthopsis_ includes several small species
allied to _Phascologale_ but characterised by the narrowness of the hind
foot, and by the soles of the feet being either granulated or hairy,
instead of naked.
_Antechinomys._[47]—The last genus of the _Dasyurinæ_ is _Antechinomys_,
represented only by _A. laniger_ of Queensland and New South Wales. This
elegant little mouse-like creature, which has large oval ears and a long
tail with the terminal part bushy, is distinguished from _Sminthopsis_
by the absence of the hallux and the great elongation of the limbs. The
tympanic bullæ of the skull are also unusually large, with the mastoid
portion much swollen. A full account of the habits and anatomy of this
animal, which appears to be of very rare occurrence, is given in the
_Proc. Zool. Soc._ 1880, p. 454.
Subfamily =Myrmecobiinæ=.—Molars and premolars exceeding the normal
number of seven on each side. Tongue, long cylindrical, and extensile.
[Illustration: FIG. 41.—_Myrmecobius fasciatus._ From Gould.]
_Myrmecobius._[48]—Dentition: _i_ ⁴⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ⁵⁄₅ or
⁶⁄₆; total 52 or 56, being the largest number of teeth in any existing
Marsupial. The distinction between the molars and premolars is founded
not on a knowledge of the succession of the teeth, but on their form.
The teeth are all small and (except the four posterior inferior molars)
separated from each other by an interval. Head elongated, but broad
behind. Muzzle long and pointed. Ears of moderate size, ovate, and rather
pointed. Fore feet with five toes, all having strong, pointed, compressed
claws, the second, third, and fourth nearly equal, the fifth somewhat,
and the first considerably, shorter. Hind feet with no trace of hallux
externally, but the metatarsal bone present. Tail long, clothed with
long hairs. Fur rather harsh and bristly. Female without any pouch, the
young when attached to the nipples being concealed only by the long hair
of the abdomen. Vertebræ: C 7, D 13, L 6, S 3, C 23. A gland on the under
surface of the body just in advance of the sternum.
Of this singular genus but one species is known, _M. fasciatus_ (Fig.
41), found in western and southern Australia. It is about the size of
an English squirrel, to which animal its long bushy tail gives it some
resemblance; but it lives entirely on the ground, especially in sterile,
sandy districts, feeding on ants. Its prevailing colour is chestnut red,
but the hinder part of the back is elegantly marked with broad, white,
transverse bands on a dark ground.
The special interest of this form lies in its apparent relationship to
those Mesozoic mammals which possess a large number of true molars (see
p. 114); and it is suggested by Thomas that it may eventually be found
advisable to include some of the latter in the present subfamily.
_Family_ PERAMELIDÆ.
Dentition: _i_ ⁴⁻⁵⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ⁴⁄₄; total 46 or 48. Upper
incisors small, with short broad crowns. Lower incisors moderate, narrow,
proclivous. Canines well developed. Premolars compressed, pointed. Molars
with quadrate tuberculated crowns. Fourth premolar preceded by a small
molariform tooth, which remains in place until the animal is nearly full
grown. Fore feet with two or three of the middle toes of nearly equal
size, and provided with strong, sharp, slightly curved claws; the other
toes rudimentary. Hind feet long and narrow; the hallux rudimentary or
absent; the second and third toes very slender, and united in a common
integument; the fourth very large, with a stout elongated conical claw;
the fifth smaller than the fourth (see Fig. 43). The ungual phalanges of
the large toes of both feet cleft at their extremities (as in _Manis_
among the Edentata, but in no other Marsupials). Head elongated. Muzzle
long, narrow, and pointed. Stomach simple. Cæcum of moderate size.
Pouch complete, opening backwards. Alone among Marsupials they have no
clavicles.
The _Peramelidæ_ form a very distinct family, in some respects
intermediate between the sarcophagous _Dasyuridæ_ and the phytophagous
_Macropodidæ_. In dentition they resemble the former, but they agree
with the latter in the peculiar structure of the hind feet. In the
construction of the fore feet they differ from all other Marsupials.
The Bandicoots, as these Marsupials are popularly termed, are of
fossorial habits, and subsist either on an insectivorous or omnivorous
diet. It has been generally considered that their syndactylous feet
indicate direct affinity with the Diprotodonts, but owing to the
essentially Polyprotodont character of the organisation—which extends
even to their carpal and tarsal bones—Thomas dissents from this view, and
concludes that their syndactylism is an independently acquired character,
and that they are really a direct offshoot from the _Dasyuridæ_. Some
individuals are remarkable for the presence of a longitudinal groove in
the root of the canines, by which feature they approximate to some of the
Mesozoic Polyprotodont forms. They may be divided into three genera.
[Illustration: FIG. 42.—_Perameles gunni._ From Gould.]
_Perameles._[49]—Anterior and posterior extremities not differing greatly
in development. Fore feet with the three middle toes well developed,
the third slightly larger than the second, the fourth somewhat shorter,
provided with long, strong, slightly curved, pointed claws. First and
fifth toes very short and without claws. Hind feet with hallux of one or
two phalanges, forming a distinct tubercle visible externally; the second
and third toes very slender, of equal length, joined as far as the ungual
phalanges, but with distinct claws; the fifth intermediate in length
between these and the largely developed fourth toe. Ears of moderate
or small size, ovate, pointed. Tail rather short, clothed with short
adpressed hairs. Fur short and harsh. Vertebræ; C 7, D 13, L 6, S 1, C
17. Skull long and narrow, with the bulla single, and its mastoid portion
not inflated.
The animals of this genus are all small, and live entirely on the ground,
making nests composed of dried leaves, grass, and sticks in hollow
places. They are rather mixed feeders; but insects, worms, roots, and
bulbs constitute their ordinary diet. The various species are widely
distributed over Australia, Tasmania, New Guinea, and several of the
adjacent islands, as Aru, Kei, and New Ireland. The best known are—_P.
gunni_ (Fig. 42), _bougainvillei_, _nasuta_, _obesula_, and _macrura_
from Australia, and _P. doreyana_, _raffrayana_, and _longicaudata_ from
New Guinea.
Remains apparently referable to existing species are found in the
cave-deposits of New South Wales.
_Peragale._[50]—Molar teeth curved, typically with longer crowns and
shorter roots than in the last. Hinder extremities proportionally longer,
and hallux without claw. Muzzle much elongated and narrow. Fur soft
and silky. Ears very large, long, and pointed. Tail long, its apical
half clothed on the dorsal surface with long hairs which form a crest.
Vertebræ: C 7, D 13, L 6, S 2, C 23. Skull distinguished from that of
_Perameles_ by the large size and double structure of the auditory
bulla, of which the mastoid portion is inflated. There is also an abrupt
contraction of the muzzle at the third premolar.
The type species of Rabbit-Bandicoot (_P. lagotis_), as these animals
are called, is found in Western Australia, and also occurs fossil in the
cave-deposits of New South Wales. It is the largest member of the family,
being about the size of the common Rabbit, to which animal it bears
sufficient superficial resemblance to have acquired the name of “Native
Rabbit” from the colonists. It burrows in the ground, but in other
respects resembles the true Bandicoots in its habits.
The smaller _P. leucura_ has short-crowned molars, with distinct cusps,
which are almost obsolete in the type species.
[Illustration: FIG. 43.—Skeleton of right hind foot of _Chœropus
castanotis_. _c_, Calcaneum; _a_, astragalus; _cb_, cuboid; _n_,
navicular; _c³_, ectocuneiform; II and III, the conjoined second and
third digits; IV, the large and only functional digit; V, the rudimentary
fifth digit.]
_Chœropus._[51]—Dentition generally resembling that of _Perameles_, but
the canines are less developed, and in the upper jaw two-rooted. Limbs
very slender; posterior nearly twice the length of the anterior. Fore
feet with the functional toes reduced to two, the second and third, of
equal length, with closely united metacarpals and short, sharp, slightly
curved, compressed claws. First toe represented by a minute rudiment of
a metacarpal bone; the fourth by a metacarpal and two small phalanges
without a claw, and not reaching the middle of the metacarpal of the
third; fifth entirely absent. Hind foot (Fig. 43) long and narrow,
mainly composed of the strongly developed fourth toe, terminating in a
conical pointed nail, with a strong pad behind it; the hallux absent or
represented by a rudimentary metatarsal; the remaining toes completely
developed, and with claws, but exceedingly slender; the united second and
third reaching a little way beyond the metatarso-phalangeal articulation
of the fourth; the fifth somewhat shorter. Tail not quite so long as the
body, and covered with short hairs forming a slight crest. Ears large and
pointed, and folded down when the animal is at rest. Fur soft and loose.
Vertebræ: C 7, D 13, L 6, S 1, C 20. Skull short and wide, with a small
and single bulla, and a contraction of the muzzle at the third premolar.
The only known species of this genus (Fig. 44), chiefly remarkable for
the singular construction of its limbs, is an animal about the size of a
small Rat, found in the interior of the Australian continent. Its general
habits and food appear to resemble those of the other _Peramelidæ_.
It was first described as _C. ecaudatus_ by Ogilby from a mutilated
specimen, but the specific name was afterwards changed, as being
inappropriate, by Gray to _castanotis_.
_Suborder_ DIPROTODONTIA.
For the leading characters of this group, see page 132.
_Family_ PHASCOLOMYIDÆ.
Dentition: _c_ ¹⁄₁, _i_ ⁰⁄₀, _p_ ¹⁄₁, _m_ ⁴⁄₄ = 24. All the teeth with
persistent pulps. The incisors large, scalpriform, with enamel only
on the front surface, as in the Rodentia. The molars strongly curved,
forming from the base to the summit about a quarter of a circle, the
concavity being directed outwards in the upper and inwards in the
lower teeth. The first of the series, or premolar, appears to have no
milk-predecessor, and is single-lobed; the other four composed of two
lobes, each subtriangular in section. Limbs equal, stout, and short.
Fore feet with five distinct toes, each furnished with a long, strong,
and slightly curved nail, the first and fifth considerably shorter
than the other three. Hind feet with a very short nailless hallux, the
second, third, and fourth toes partially united by integument, of nearly
equal length, the fifth distinct and rather shorter; all four provided
with long and curved nails. In the skeleton of the foot, the second
and third toes are distinctly more slender than the fourth, showing a
slight tendency towards the peculiar character so marked in the next
two families. Tail rudimentary. Stomach simple, provided with a special
gland situated near the cardiac orifice. Cæcum very short, wide, and with
a peculiar vermiform appendage. Pouch present. The auditory bullæ of
the skull are imperfect, open behind, with their anterior wall formed
by a descending process of the squamosal, instead of the alisphenoid.
Masseteric fossa of mandible with a perforation and a deep pit.
[Illustration: FIG. 44.—_Chœropus castanotis._ From Gould.]
_Phascolomys._[52]—The existing Wombats (Fig. 45) comprise three
species, all of which are included in the one genus _Phascolomys_, and
all of which date from the Pleistocene.
In the typical group we find the following characters. Fur rough and
coarse. Ears short and rounded. Muffle naked. Postorbital process of the
frontal bone obsolete. Ribs fifteen pairs. Vertebræ: C 7, D 15, L 4, S
4, C 10-12. The Wombat of Tasmania and the islands of Bass’s Straits
(_P. ursinus_) and the closely similar but larger animal of the southern
portion of the mainland of Australia (_P. mitchelli_) belong to this
group.
[Illustration: FIG. 45.—Common Wombat (_Phascolomys ursinus_).]
In the second group the characters are as follows. Fur smooth and silky.
Ears large and more pointed. Muffle hairy. Frontal region of skull
broader than in the other group, with well-marked postorbital processes.
Ribs thirteen. Vertebræ: C 7, D 13, L 6, S 4, C 15-16. One species, _P.
latifrons_, the Hairy-nosed Wombat of Southern Australia.
In their general form and actions the Wombats resemble small bears,
having a somewhat similar shuffling manner of walking, but they are still
shorter in the legs, and have broader, flatter backs than bears. They
live entirely on the ground, or in burrows or holes among rocks, never
climbing trees, and feed entirely on grass, roots, and other vegetable
substances. They sleep during the day, and wander forth at night in
search of food, and are shy and gentle in their habits generally, though
they can bite strongly when provoked. The only noise the common wombat
makes is a low kind of hissing, but the Hairy-nosed Wombat is said to
emit a short quick grunt when annoyed. The prevailing colour of the
last-named species, as well as of _P. ursinus_ of Tasmania, is a brownish
gray. The large wombat of the mainland is very variable in colour, some
individuals being found of a pale yellowish brown, others dark gray, and
some quite black. The length of head and body is about three feet.
It is noteworthy that _P. mitchelli_ was first described from the
evidence of fossil remains, the living form subsequently described as _P.
platyrhinus_ being found to be indistinguishable. Other extinct species
occur in the Pleistocene of Australia.
_Phascolonus._[53]—Remains of a large extinct Wombat, which must have
nearly equalled the dimensions of a Tapir, occur in the Pleistocene of
Queensland, and have been described as _Phascolonus_. It is probable that
the expanded and flattened upper incisors from the same deposits upon
the evidence of which the presumed genus _Sceparnodon_ was founded, are
likewise referable to the same form. The characters of both the upper and
lower incisors distinguish _Phascolonus_ from _Phascolomys_.
_Family_ PHALANGERIDÆ.
Dentition extremely variable, owing to the presence of minute rudimental
teeth not constant in the same species, or even in the two sides of
the jaws of the same individual; exclusive, however, of _Tarsipes_,
the formula _i_ ³⁄₁, _c_ ¹⁄₀, _p_ ²⁻³⁄₀₋₂, _m_ ³⁻⁴⁄₃₋₄ represents
fairly the general condition of the functional teeth. First incisors
long and stout; the lower pair very large and pointed, but without the
scissor-like action found in the existing _Macropodidæ_; second and
third lower incisors minute and probably functionless. Fourth premolar
generally secant; milk-molar generally minute and deciduous at an early
period. Molars either with sharp cutting-crests or bluntly tuberculate;
fourth sometimes absent. Mandible without pit, and at most a very minute
perforation in the masseteric fossa. Limbs subequal. Fore feet with five
distinct, subequal toes, furnished with claws. Hind feet short and broad,
with five well developed toes; the hallux large, nailless and opposable;
the second and third slender, and united by a common integument as far as
the claws. Tail generally long, and frequently more or less prehensile.
Stomach simple. Cæcum present (except in _Tarsipes_), and usually large.
Pouch complete. Animals of small or moderate size and arboreal habits,
usually feeding on a vegetable or mixed diet, inhabiting Australia and
the Papuan Islands.
The homologies of the lower functionless teeth between the first
incisor and fourth premolar are very difficult to determine, but it is
probable that one represents a canine only when the largest known number
is present; this tooth, according to Mr. Thomas, being the first to
disappear.
Phalangers are small woolly-coated animals, with long, powerful, and
often prehensile tails, large claws, and, as in the American opossums,
with opposable nailless great toes. Their expression seems in the
day to be dull and sleepy, but by night they appear to decidedly
greater advantage. They live mostly upon fruit, leaves, and blossoms,
although some few feed habitually upon insects, and all relish, when
in confinement, an occasional bird or other small animal. Several of
the Phalangers possess flying membranes stretched between their fore
and hind limbs (Fig. 48), by the help of which they can make long and
sustained leaps through the air, like the Flying Squirrels, but it is
interesting to notice that the possession of these flying membranes
does not seem to be any indication of special affinity, the characters
of the skull and teeth sharply dividing the flying forms, and uniting
them with other species of the non-flying groups. Their skulls (Fig. 47)
are as a rule broad and flattened, with the posterior part swollen out
laterally, owing to the numerous air-cells situated in the substance of
the squamosal.
The Phalangers are interesting from an historical point of view, since
the Gray Cuscus (_Phalanger orientalis_) was the first of the Marsupials
of the eastern hemisphere brought to the notice of Europeans, having been
described in a work published at Leyden in 1611, from an account of a
specimen seen at Amboyna during the third expedition of Admiral Van der
Hagen.
The present family corresponds to the _Dasyuridæ_ among the
Polyprotodonts as presenting, on the whole, the most generalised types of
the suborder. The existing forms may be divided into three subfamilies.
Subfamily =Tarsipedinæ=.—Cheek-teeth almost rudimentary and variable in
number. Tongue long, slender, pointed, and very extensile. Tail long.
Cæcum absent.
[Illustration: FIG. 46.—_Tarsipes rostratus._ From Gould.]
_Tarsipes._[54]—So named from some supposed resemblance of its foot to
that of the Lemurine genus _Tarsius_; but it must be remarked that it
has none of the peculiar elongation of the calcaneum and navicular so
characteristic of that genus. Head with elongated and slender muzzle.
Mouth-opening small. The two lower incisors are long, very slender,
sharp-pointed, and horizontally placed. All the other teeth are simple,
conical, minute, and placed at considerable and irregular intervals
apart in the jaws, the number appearing to vary in different individuals
and even on different sides of the same individual. The formula, in a
specimen in the Museum of the Royal College of Surgeons, is _i_ ²⁄₁,
_c_ ¹⁄₀, _p_ and _m_ ³⁄₂ on one side, and ⁴⁄₃ on the other; total 20.
Rami of the mandible extremely slender, nearly straight, and without
coronoid process or inflected angle. Fore feet with five well-developed
toes, furnished with small, flat, scale-like nails, not reaching to the
extremity of the digits. Hind feet rather long and slender compared
with those of the _Phalangerinæ_, having a well-developed opposable
and nailless hallux; second and third digits syndactylous, with sharp
compressed curved claws; the fourth and fifth free, and with small flat
nails. Ears of moderate size and rounded. Tail longer than the body and
head, scantily clothed with short hairs, prehensile. Vertebræ: C 7, D 13,
L 5, S 3, C 24.
Of this singular genus but one species, _T. rostratus_ (Fig. 46), is
known, about the size of a common Mouse. It inhabits Western Australia,
lives in trees and bushes, uses its tail in climbing, and feeds on honey,
which it procures by inserting its long tongue into the blossoms of
_Melaleucæ_, etc. One kept in confinement by Mr. Gould was also observed
to eat flies.
Subfamily =Phalangerinæ=.—Teeth normal. One or more rudimentary teeth
between the upper canine and fourth premolar, and between the first
lower incisor and fourth premolar. Tongue of ordinary structure. No
cheek-pouches. Stomach and ascending colon simple. Cæcum long, simple.
Tail well-developed, generally prehensile.
A numerous group of animals, varying from the size of a mouse to that
of a large cat, arboreal in their habits, and abundantly distributed
throughout the Australian region. The members of this group are the
typical representatives of the family, and are commonly known to the
colonists as Opossums.
_Phalanger._[55]—The typical genus _Phalanger_ (_Cuscus_) presents the
following characters. No flying membrane; size large or medium, and
build stout and clumsy; fur thick and woolly. Ears short or medium,
hairy externally, and in some cases also internally. Toes of fore feet
subequal, their relative lengths in the order 4, 3, 5, 2, 1. Claws
long, stout, and curved. Soles of feet naked and striated, with large
ill-defined pads. Tail stout and markedly prehensile, with the proximal
half furred like the body, and the terminal portion entirely naked. Four
mammæ. Skull (Fig. 47) stout and strong, with large vacuities in the
hinder half of the palate, and the auditory bullæ thick and inflated.
Dentition usually _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ³⁄₃, _m_ ⁴⁄₄. First upper incisor
with nearly circular section, or only slightly flattened in front; canine
more or less closely approximated to third incisor (which is very small),
and situated partly in front of the suture between the premaxilla and
maxilla. Fourth premolar large, secant, and placed obliquely to line
of molars. Molars four-cusped, with the inner cusps of the upper ones
crescentoid, and imperfect transverse ridges connecting each pair of
cusps.
[Illustration: FIG. 47.—Left lateral view of skull of Gray Cuscus
(_Phalanger orientalis_). After Peters.]
The Cuscuses are curious sleepy-looking animals, inhabiting the various
islands of the East Indian Archipelago as far west as Celebes, and
being the only Marsupials found west of New Guinea. As already noted,
it was a member of this genus, the Gray Cuscus (_P. orientalis_), a
native of Amboyna, Timor, and the neighbouring islands, which was the
first Australasian Marsupial known to European naturalists. There are
altogether five species known, all of about the size of a large cat;
their habits resemble those of other Phalangers, except that they are
said to be somewhat more carnivorous.
_Trichosurus._[56]—The members of the genus _Trichosurus_ are of
relatively large size, and are distinguished from _Phalanger_ by the
following characters. Ears more or less hairy behind. Relative lengths of
toes of fore feet in the order 4, 3, 2, 5, 1. Hair on the soles of the
hind feet beneath the heel, but not elsewhere. Tail thick, not tapering,
covered with bushy hair up to the extreme tip, which is naked, but with a
naked strip on the inferior surface in the distal third or half. A gland
on the chest. Dentition usually _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ²⁄₂, _m_ ⁴⁄₄. Upper
incisors of nearly uniform length, the first much flattened in front.
Canine situated some distance behind the third upper incisor, which it
scarcely exceeds in size. Last premolar and molars very similar to those
of _Phalanger_.
The true Phalangers comprise two species, of which the best known is the
Vulpine Phalanger (_T. vulpecula_), so common in zoological gardens,
where, however, it is seldom seen, owing to its nocturnal habits. It is
of about the size and general build of a small fox, whence its name. In
the typical variety the colour is gray, with a yellowish white belly,
white ears, and a black tail. This variety is a native of the greater
part of the continent of Australia, but is replaced in Tasmania by the
closely allied Brown Phalanger (_var. fuliginosa_). Its habits are very
similar to those of the Yellow-bellied Flying-Phalanger (_Petaurus
australis_) described below, except that it is unable to take the flying
leaps of that animal. Like all the other phalangers, its flesh is freely
eaten both by the natives and the lower class of settlers.
_Pseudochirus._[57]—The genus _Pseudochirus_ agrees with the preceding
in the absence of a flying membrane, and presents the following leading
characters. Size large or medium. Fur comparatively short and woolly.
Ears medium or short, hairy behind, although seldom closely furred
over all this aspect. Claws medium. Fore toes subequal, the first two
distinctly opposable to the other three. Soles of feet naked, with large,
striated, round pads, and hair beneath the heels. Tail tapering, markedly
prehensile, with its distal third and the whole of the under surface
short-haired; tip naked underneath for a short distance. Four mammæ. No
gland on chest. Skull with larger nasals than in the preceding genera;
the posterior part of the palate in most cases fully ossified, and the
auditory bullæ generally somewhat inflated. Dentition (at most) _i_
²⁻³⁄₂, _c_ ⁰⁻¹⁄₀, _p_ ³⁄₃, _m_ ⁴⁄₄. Upper teeth nearly uniform in length,
but the first incisor distinctly longer than second. Upper premolars
variable. Molars with both inner and outer cusps distinctly crescentoid,
and recalling those of the Selenodont Artiodactyle Ungulates.
_Range._—Tasmania, Australia, and New Guinea.
There are about ten species of this genus known, of which the commonest
is Cook’s Ring-tailed Phalanger (_Pseudochirus peregrinus_), an animal
discovered by Captain Cook during his first voyage, at Endeavour river,
North Queensland.
The complex and sub-selenodont character of the molars of this and
the following genus readily distinguish them from the more typical
Phalangers, and show an approximation to the type of dentition prevailing
in _Phascolarctus_; according, however, to Mr. O. Thomas, a tendency
towards the same structure is observable in unworn molars of young
Cuscuses. The genus may be divided into three groups, of which the first,
as typified by the common _P. peregrinus_, is restricted to Australia
and Tasmania, while the third, as represented by _P. canescens_, is only
found in New Guinea. _P. albertisi_ may be taken as the type of the
second group, which is represented by that species in New Guinea, and by
_P. archeri_ in Queensland. With the exception of _P. peregrinus_, the
species have a more or less restricted range. Remains of _Pseudochirus_,
probably referable to existing species, are found in the cave-deposits of
New South Wales.
_Petauroides._[58]—With the genus _Petauroides_, containing only
the single species _P. volans_, we come to the first of the
Flying-Phalangers, characterised by the possession of a living membrane
along the flanks. The characters of this genus are as follows. Size
large. Fur very long and silky. Ears large and oval, thickly furred on
the back, but naked internally. Flying-membrane reaching from wrist to
ankle, but very narrow along the sides of the forearm and lower leg.
Fore toes subequal, their relative lengths in the order 4, 3, 5, 2, 1.
Claws long, curved, and sharp. Tail long, cylindrical, and bushy, except
near its tip, where it is naked and prehensile. Skull short and broad,
with the nasals short, and not extending nearly as far forwards as the
premaxillæ. Large vacuities in hinder part of palate. Auditory bullæ
inflated and smooth. Dentition usually _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ²⁄₂, _m_
⁴⁄₄. General characters of teeth very similar to those of _Pseudochirus_,
but the first upper incisor scarcely longer than the second.
The single species is found in Australia, from Queensland to Victoria,
and is commonly known as the Taguan Flying-Phalanger. The structure
of the skull and teeth indicates close affinity with _Pseudochirus_,
although the external form is widely different in the two genera.
This Phalanger seems, indeed, to be, so to speak, a very specialised
_Pseudochirus_, in which the teeth have become somewhat further
diminished and the flying membrane has been developed.
_Dactylopsila._[59]—The genus _Dactylopsila_ is one of the forms without
any trace of a flying membrane, its characters being as follows. Size
medium. Body striped black and white. Ears oval, nearly naked at the
ends. Fore toes of very unequal length, the fourth being enormously
elongated; fourth and fifth toes of pes also markedly elongated. Claws
long, moderately curved. Tail long, cylindrical, and evenly bushy, with
the extremity more or less naked below. Skull narrow, but with the
zygomatic arches greatly expanded; palate fully ossified. Dentition: _i_
³⁄₃, _c_ ¹⁄₀, _p_ ³⁄₂, _m_ ⁴⁄₄. Upper incisors very large, the third
being directed horizontally forwards; canine small and approximated to
the third incisor, which it resembles. The fourth premolar of moderate
size, with its longer axis placed obliquely. First lower incisor longer
than in any other genus. Molars oblong, with four cusps.
The typical _D. trivirgata_, or Striped Phalanger, inhabits the Papuan
and North Australian sub-region; a second species (_D. palpator_),
characterised by the still greater elongation of the fourth finger,
occurring in South New Guinea. These animals are said to be of
insectivorous habits, the elongated fourth finger, as in the analogous
instance of the Lemuroid genus _Chiromys_, being apparently specially
adapted for extracting insects and larvæ from their hiding places.
_Petaurus._[60]—Size medium or small. Fur very soft and silky. A broad
flying membrane extending from the outer side of the fifth digit of the
manus to the ankle. Fore toes usually increasing regularly in length from
the first to the fifth, but in some of the smaller species the fourth
is the longest. Claws strong, sharp, and much curved. Tail long, evenly
bushy to the extremity. Glands on the chest and between the ears. Skull
short and wide, with the nasals expanded posteriorly, and usually two
small palatal vacuities near the second molars. Auditory bullæ inflated,
and variable in size. Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ³⁄₃, _m_ ⁴⁄₄.
First upper incisors very large, and taller than canine. Molars with
square crowns rounded at the angles, and four cusps, except in the last,
which is triangular.
This genus, which ranges from New Ireland to South Australia, but is
not found in Tasmania, contains three species, the largest of which is
the Yellow-bellied Flying-Phalanger (_P. australis_), whose habits are
recorded by Mr. Gould as follows. “This animal is common in all the
brushes of New South Wales, particularly those which stretch along the
coast from Port Philip to Moreton Bay. In these vast forests trees of one
kind or another are perpetually flowering, and thus offer a never-failing
supply of the blossoms upon which it feeds; the flowers of the various
kinds of gums, some of which are of great magnitude, are the principal
favourites. Like the rest of the genus, it is nocturnal in its habits,
dwelling in holes and in the spouts of the larger branches during the
day, and displaying the greatest activity at night while running over
the small leafy branches, frequently even to their very extremities,
in search of insects and the honey of the newly-opened blossoms. Its
structure being ill adapted for terrestrial habits, it seldom descends
to the ground except for the purpose of passing to a tree too distant
to be reached by flight. When chased, or forced to flight it ascends to
the highest branch and performs the most enormous leaps, sweeping from
tree to tree with wonderful address; a slight elevation gives its body an
impetus which, with the expansion of its membrane, enables it to pass to
a considerable distance, always ascending a little at the extremity of
the leap; by this ascent the animal is prevented from receiving the shock
which it would otherwise sustain.”
A second species, _P. sciureus_, in some ways one of the most beautiful
of all mammals, has been chosen for the accompanying woodcut.
_Gymnobelideus._[61]—Like _Petaurus_ in every respect, but without
any trace of a flying membrane, and with the fifth digit of the manus
slightly shorter than the third. This genus is represented only by _G.
leadbeateri_ of Victoria, and according to Mr. Thomas, may be regarded
as the primitive form from which the specialised _Petaurus_ has been
developed.
[Illustration: FIG. 48.—Squirrel Flying-Phalanger (_Petaurus sciureus_).]
_Dromicia._[62]—Size small, and general appearance dormouse-like. Ears
large and thin, almost naked, and without internal or basal tufts. No
flying membrane. Digits of normal proportions, the relative lengths of
those of the manus in the order 3, 4, 2, 5, 1; fore claws rudimentary,
hind ones long and sharp. Tail mouse-like, cylindrical, furry at base,
the remainder scaly, with fine hairs, except at the tip, which is naked
and prehensile. Skull short and broad, with the hinder part of the
palate incomplete, and the auditory bullæ large, much inflated, and
transparent. Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ³⁄₃, _m_ ³⁻⁴⁄₃₋₄. First
upper incisor spatulate, and much longer than either of the others.
Canine large, placed at some distance behind the third incisor. Molars
(except the last) with evenly rounded crowns, carrying four small smooth
cusps.
This genus, which occurs in New Guinea, Western Australia, and Tasmania,
is represented by four species. It seems to be intermediate between
_Petaurus_ and _Acrobates_, and it has apparently had to yield place to
those more highly organised types in regions where they have come in
contact with one another.
_Distœchurus._[63]—Size small. Ears rather short, thinly covered with
hair, but with small tufts at the base. No flying membrane. Digits of
normal proportions, without expanded terminal pads. Claws curved and
sharp. Tail, skull, and dentition as in _Acrobates_, with the exception
that the fourth premolar is small in the upper, and absent in the lower
jaw.
The one species of Feather-tailed Phalanger (_D. pennatus_) is found in
New Guinea.
_Acrobates._[64]—Size very small. Ears moderate, thinly covered
with hair, but with small tufts round the base and on the internal
prominences. A narrow flying membrane, fringed with long hairs, running
from the elbow to the flank, and from the latter to the knee. Four
mammæ. Digits furnished with expanded and striated terminal pads, the
relative length of those of the manus being in the order 4, 3, 5, 2,
1. Claws sharp, although somewhat concealed by the terminal pads. Tail
short-haired above and below, with a broad fringe on either side. Skull
short, wide, and depressed. Posterior portion of palate very imperfectly
ossified; anterior palatal vacuities almost confined to the maxillæ.
Auditory bullæ low, rounded, and but slightly prominent. Dentition: _i_
³⁄₂, _c_ ¹⁄₀, _p_ ³⁄₃, _m_ ³⁄₃. Teeth sharp, and of an insectivorous
type. Upper canine long, and approximated to third incisor. The three
upper premolars large, functional, and taller than the molars. Molars
small and rounded, with smooth unridged cusps.
There is only one species in this genus, the beautiful little Pigmy
Flying-Phalanger (_A. pygmæus_), not so big as a Mouse, which is found
in Queensland, New South Wales, and Victoria, and feeds on the honey
it abstracts from flowers, and on insects. Its agility and powers of
leaping are exceedingly great, and it is said by Mr. Gould to make a most
charming little pet.
Subfamily =Phascolarctinæ=.—Teeth large, normal; no rudimentary premolars
before the last upper premolar, or any teeth between the first lower
incisor and fourth premolar. Tongue of ordinary structure. Distinct
cheek-pouches. Stomach with a special gland near the cardiac orifice.
Cæcum very long, and (with the upper portion of the colon) dilated and
provided with numerous longitudinal folds of mucous membrane. In many
anatomical characters, especially the possession of a special gastric
gland, this group resembles the _Phascolomyidæ_.[65]
[Illustration: FIG. 49.—Skeleton of right hind foot of Koala
(_Phascolarctus cinereus_), showing the stout opposable hallux, followed
by two slender toes, which in the living animal are enclosed as far as
the nails in a common integument.]
_Phascolarctus._[66]—Dentition: _i_ ³⁄₁, _c_ ¹⁄₀, _p_ ¹⁄₁, _m_ ⁴⁄₄; total
30. Upper incisors crowded together, cylindroidal, the first much larger
than the others, with a bevelled cutting edge (Fig. 36). Canine very
small; a considerable interval between it and the premolar, which is as
long from before backwards but not so broad as the true molars, and has
a cutting edge, with a smaller parallel inner ridge. The molars slightly
diminishing in size from the first to the fourth, with square crowns,
each bearing four pyramidal cusps, with curved ridges radiating from
them, and having a structure very similar to these of _Pseudochirus_. The
lower incisors are semiproclivous, compressed and tapering, bevelled at
the ends. Premolars and molars in continuous series, as in the upper jaw.
Milk-tooth very minute, and almost functionless. Fore feet with the two
inner toes slightly separated from and opposable to the remaining three,
all with strong, curved, and much compressed claws. Hind foot (Fig. 49)
with the hallux placed very far back, large and broad, the second and
third (united) toes considerably smaller than the other two; the fourth
the largest. No external tail. Fur dense and woolly. Ears of moderate
size, thickly clothed with long hairs. Vertebræ: C 7, D 11, L 8, S 2, C
8. Ribs eleven pairs, a rare exception to the usual number (13) in the
Marsupialia.
There is but one species, the Koala or Native Bear of the Australian
colonists (_P. cinereus_), an animal of comparatively large size and
heavy build (Fig. 50), found in the south-eastern parts of the Australian
continent. It is about two feet in length, and of an ash-gray colour, an
excellent climber, and residing generally in lofty _Eucalyptus_ trees,
on the buds and tender shoots of which it feeds, though occasionally
descending to the ground in the night.
EXTINCT PHALANGEROIDS.
Numerous imperfect remains recently described by De Vis are regarded as
indicating large extinct types of _Phalangeridæ_, but further evidence
is required before all these determinations can be definitely accepted.
Thus part of an upper jaw is provisionally referred to a large species
of _Pseudochirus_, while part of a scapula is made the type of a genus
_Archizonurus_ which appears to be allied to the former. Another
fragmentary scapula is considered to indicate a large _Phalanger_.
Finally, part of a fibula, described under the name of _Koalemus_ is
regarded as affording evidence of the former existence of a large
ancestral form allied to the Koala, and it is suggested that an upper jaw
with teeth may belong to the same or an allied type.
[Illustration: FIG. 50.—The Koala (_Phascolarctus cinereus_). From
Sclater, _Proc. Zool. Soc._ 1880, p. 355.]
_Thylacoleo._[67]—Dentition of adult: _i_ ³⁄₁, _c_ ¹⁄₀, _p_ ³⁄₃, _m_ ¹⁄₂;
total 28. First upper incisor much larger than the others; canine and
first two premolars rudimentary. In the lower jaw the two small anterior
premolars are functionless, and often deciduous; posterior premolars of
both jaws formed on the same type as those of _Potorous_, but relatively
much larger; true molars rudimentary, tubercular. One species, _T.
carnifex_. This animal presents a most anomalous condition of dentition,
the functional teeth being reduced to one pair of large cutting incisors
situated close to the median line, and one great, trenchant, compressed
premolar, on each side above and below. It was first described as a
carnivorous Marsupial, and named, in accordance with its presumed habits,
“as one of the fellest and most destructive of predatory beasts”; but, as
its affinities are certainly with the _Phalangeridæ_ and _Macropodidæ_,
and its dentition completely unlike that of any known predaceous animal,
this view has been called in question.
[Illustration: FIG. 51.—Front view of skull of _Thylacoleo carnifex_,
restored. ¹⁄₃ natural size. From _Quart. Journ. Geol. Soc._ vol. xxiv. p.
312.]
The dentition is nearer to that of the existing _Phalangeridæ_ than to
that of the _Macropodidæ_, and the genus may be provisionally regarded as
the type of a distinct subfamily of the former.
_Family_ MACROPODIDÆ.
Dentition _i_ ³⁄₁, _c_ ⁰⁻¹⁄₀, _p_ ²⁄₂, _m_ ⁴⁄₄. Incisors sharp and
cutting, those of the lower jaw frequently having a scissor-like action
against one another; upper canine, if present, small. Penultimate
premolar shed with the fourth milk-molar, which is molariform and long
persistent. Molars wide, and either transversely ridged or bluntly
tuberculate. Premolars and molars moving forwards in the skull as the age
of the animal increases, this being most marked in the larger species.
Masseteric fossa of mandible hollowed out below into a deep cavity walled
in externally by a plate of bone, and communicating with the inferior
dental canal by a large foramen. Hind limbs usually larger than the
anterior ones, and progression generally saltatorial. Fore feet with five
digits; hind feet syndactylous, the fourth digit being very large and
strongly clawed; hallux usually absent. Tail generally long and hairy,
occasionally prehensile; stomach sacculated. Pouch large and opening
forwards.
[Illustration: FIG. 52.—Skeleton of right hind foot of Kangaroo.]
The _Macropodidæ_ or Kangaroos, taken as a whole, form a very well-marked
family, easily distinguished from the other members of the suborder by
their general conformation, and by peculiarities in the structure of
their limbs, teeth, and other organs. They vary in size from that of a
sheep down to a small rabbit. The head, especially in the larger species,
is small, compared with the rest of the body, and tapers forward to the
muzzle. The shoulders and fore limbs are feebly developed, and the hind
limbs usually of disproportionate strength and magnitude, which gives
them a peculiarly awkward appearance when moving about on all fours,
as they occasionally do when feeding. Rapid progression is, however,
performed only by the powerful hind limbs, the animal covering the ground
by a series of immense bounds, during which the fore part of the body is
inclined forwards, and balanced by the long, strong, and tapering tail,
which is carried horizontally backwards. When not moving they often
assume a perfectly upright position, the tail aiding the two hind legs
to form a sort of supporting tripod, and the front limbs dangling by
the side of the chest. This position gives full scope for the senses of
sight, hearing, and smell to warn of the approach of enemies, from which
these animals save themselves by their bounding flight. The fore paws
have live distinct digits, each armed with a strong curved claw.
The hind foot (Fig. 52), as being a typical example of the syndactylous
modification, may be noticed in some detail. It is extremely long and
narrow, and (with only one exception) without any hallux or great toe.
It consists mainly of one very large and strong toe, corresponding to
the fourth of the human or other typically developed foot, ending in a
strong, curved, and pointed claw. Close to the outer side of this lies
a smaller fifth digit, and to the inner side two excessively slender
toes (the second and third), bound together almost to the extremity in
a common integument. The two little claws of these toes, projecting
together from the skin, may be of use in scratching and cleaning the fur
of the animal, but the toes themselves must have quite lost all connexion
with the functions of support or progression.
The dentition of the Kangaroos, functionally considered, consists of
sharp-edged incisors, most fully developed near the median line of the
mouth, for the purpose of cropping the various kinds of herbage on which
they feed, and ridged and tuberculated molars for crushing it, there
being no tusks or canines for offensive or defensive purposes.
The number of vertebræ is—in the cervical region 7, dorsal 13, lumbar
6, sacral 2, caudal varying according to the length of the tail, but
generally from 21 to 25. In the fore limb the clavicle and the radius and
ulna are well developed, allowing of considerable freedom of motion of
the hand. The pelvis has large epipubic or “marsupial” bones. The femur
is short, and the tibia and fibula are of great length, as is the foot,
the whole of which is applied to the ground when the animal is at rest in
the upright position.
[Illustration: FIG. 53.—The Great Gray Kangaroo (_Macropus giganteus_).]
The stomach is of large size, and very complex, its walls being puckered
up by longitudinal muscular bands into a great number of sacculi, like
those of the human colon. The alimentary canal is long, and the cæcum
well developed. All the species have a marsupium or pouch formed by a
fold of the skin of the abdomen, covering the mammary glands with their
four nipples. In this pouch the young are placed as soon as they are
born; there their growth and development proceeds; and to it they resort
temporarily for the purpose of shelter, concealment, or transport, for
some time after they are able to run and jump about the ground and feed
upon the same herbage which forms the nourishment of the parent. During
the early period of their sojourn in the pouch, the blind, naked,
helpless young creatures (which in the Great Kangaroo [Fig. 53] scarcely
exceed an inch in length) are attached by their mouths to the nipples
of the mother, and are fed by milk injected into their stomach by the
contraction of the muscle covering the mammary gland.
The Kangaroos are all vegetable feeders, browsing on grass and various
kinds of herbage, the smaller species also eating roots. They are
naturally timid, inoffensive creatures; but the larger ones when hard
pressed will turn and defend themselves, sometimes killing a dog by
grasping it in their fore paws, and inflicting terrible wounds with the
sharp claws of their powerful hind legs, sustaining themselves meanwhile
upon the tail. A few aberrant forms are arboreal. The great majority are
inhabitants of Australia and Tasmania, forming one of the most prominent
and characteristic features of the fauna of these lands, and in the
scenery of the country, as well as the economy of nature, performing the
part of the deer and antelopes of other parts of the world, which are
entirely wanting in Australia. Kangaroos were very important sources of
food-supply to the natives, and are hunted by the colonists, both for
sport and with a view to their destruction, on account of the damage they
naturally do in consuming the grass, now required for feeding cattle and
sheep. Notwithstanding this, they have in some districts increased in
numbers, owing to the suppression of their former enemies, the aborigines
and the Dingo or native dog. A few species are found in New Guinea and
the adjacent islands, which belong, in the zoological sense, to the
Australian region.
Before noticing the various generic types of the _Macropodidæ_, a few
words are necessary in respect of the tooth-change, and we may here quote
the observations of Mr. O. Thomas on this subject. “The full dentition
of the members of this family consists, in the upper jaw, first of three
incisors, then of a small canine (often, however, suppressed, as in Fig.
55), and then of six cheek-teeth, of which the second in the series is
the only one which has a milk or deciduous predecessor, and is therefore
the one to be regarded as the last premolar of the typical mammalian
dentition. The special characteristics that render the development and
succession of the teeth in the _Macropodidæ_, and especially in the genus
_Macropus_, so puzzling to systematic zoologists, are: firstly, a general
progression forwards in the jaw of the whole tooth-row, comparable to
that found elsewhere only in the Elephants and some Sirenians; and,
secondly, the fact that before the tooth-change the first tooth of the
series (_p_ 3) and the single milk-tooth (_dm_ 4) placed next to it,
both of which fall out at the change, are respectively so very similar
in shape and size to the first and second teeth of the permanent series,
viz. the permanent premolar (_p_ 4) and the first molar (_m_ 1), as
to be most naturally mistaken for, or compared with, them in specific
descriptions.... The necessary knowledge as to the stage of dentition in
which any skull may be, can often be gained only by cutting open the bone
either above and behind the first tooth of the series to see if the true
permanent _p_ 4 be still buried there (in which case, of course, that
first tooth is only _p_ 3), or behind the last visible molar to see if
there be yet another tooth behind it, showing it to be _m_ 3 and not _m_
4. The first plan is, as a rule, the better, since _p_ 4 is generally by
far the most important tooth for diagnostic purposes, and its characters
have, therefore, in any case to be taken into account.”
The _Macropodidæ_ are divided into three well-marked sections: (1)
the true Kangaroos (_Macropodinæ_); (2) a group consisting of smaller
animals, commonly called Rat Kangaroos, or (improperly) “Kangaroo Rats,”
or sometimes Potoroos; and (3) the _Hypsiprymnodontinæ_, now represented
only by a single species.
Subfamily =Hypsiprymnodontinæ=.—Size very small. Claws small, feeble,
and subequal. Hind feet with an opposable hallux. Tail naked and scaly.
The fourth premolar twisted obliquely outwards, as in _Phalanger_. Other
teeth as in the _Potoroinæ_.
This subfamily is now represented only by the genus _Hypsiprymnodon_,[68]
which is a form of great interest, as showing a structure of foot
connecting that of the Kangaroos with that of the Phalangers. The
single known species, _H. moschatus_, was described by Ramsay from
specimens discovered in north-east Australia. It was described almost
simultaneously by Owen under the name of _Pleopus nudicaudatus_. From
the resemblance in the structure of the foot and the obliquity of the
premolars to the Phalangers Mr. Thomas has some hesitation as to which
family should receive this genus, but the macropine characters of the
mandible preponderate in favour of the _Macropodidæ_.
_Triclis._[69]—A lower jaw of a much larger form from the Pleistocene
deposits of Australia apparently indicates another member of this
subfamily, having the outwardly directed and grooved premolar
characteristic of _Hypsiprymnodon_. It differs, however, from that genus,
and also from all other known _Macropodidæ_, in having a small tooth
between the incisor and fourth premolar, which apparently represents a
canine, or perhaps an anterior premolar. This form indicates, therefore,
a closer connexion between the _Phalangeridæ_ and _Macropodidæ_ than any
other.
Subfamily =Potoroinæ=.—The second section or subfamily, the _Potoroinæ_,
have the first upper incisor narrow, curved, and much exceeding the
others in length (Fig. 54). Upper canines always persistent, flattened,
blunt, and slightly curved. Premolars of both jaws always having large,
simple, compressed crowns, with a nearly straight or slightly concave
free cutting edge, both outer and inner surfaces usually marked by a
series of parallel, vertical grooves and ridges, these teeth being either
set in the same line with the molars, or slightly bent outwards. Molars
with quadrate crowns, having a blunt, conical cusp at each corner,
the fourth notably smaller than the third, sometimes rudimentary, and
appearing early. Fore feet narrow; three middle toes considerably
exceeding the first and fifth in length; their claws long, compressed,
and but slightly curved. Hind feet as in _Macropus_. Tail long and hairy,
sometimes partially prehensile, being used for carrying bundles of grass
with which these animals build their nests.
[Illustration: FIG. 54.—Skull and teeth of Rat Kangaroo (_Bettongia
lesueuiri_). _c_, Upper canine. The other letters as in Fig. 51.]
The Potoroos or Rat Kangaroos are all small animals, none of them
exceeding a common rabbit in size. They inhabit Australia and Tasmania,
are nocturnal, and feed on the leaves of various kinds of grasses and
other plants, as well as roots and bulbs, which they dig up with their
fore paws. Nine species are known, presenting a considerable range of
diversity in minor characters, and admitting of being grouped in four
principal sections, which may be allowed the rank of genera. These are:
_Potorous._[70]—Head long and slender. Auditory bullæ somewhat inflated.
Ridges on premolars few and perpendicular. Large palatine foramina.
Tarsus short. Muffle naked. Three species, viz. _P. tridactylus_, _P.
gilberti_, and _P. platyops_; the last two being confined to West
Australia.
_Bettongia._[71]—Head comparatively short and broad. Ears short and
rounded. Auditory bullæ generally much inflated. Large palatine foramina.
Tarsus long. Ridges on premolars numerous and oblique. Tail more or less
prehensile, thickly haired, and the hairs on the upper surface longer
than those on the lower, and forming a crest. Muffle naked. Four species,
viz. _B. penicillata_, _B. cuniculus_, _B. gaimardi_, _B. lesueuiri_.
_Caloprymnus._[72]—Muffle naked, as in _Bettongia_, but the edge of
the hairy part less emarginate backwards in the middle line. Ears
short, rounded, and hairy. Auditory bullæ much inflated, and of large
size. Nasals larger and wider behind than in the other genera. Very
long anterior palatine foramina. Limbs as in _Bettongia_. Tail thin,
cylindrical, evenly coated with short hair, without trace of a crest.
Skull broad and flat, with a remarkably short and conical muzzle. The
sole representative of this genus is _C. campestris_ of South Australia,
originally referred to _Bettongia_.
[Illustration: FIG. 55.—Skull and Teeth of the Red-necked Wallaby
(_Macropus ruficollis_). _i¹_, _i²_, _i³_, First, second, and third upper
incisors; _pm_, fourth or posterior premolar (the penultimate or third
having been already shed); _m¹_, _m²_, _m³_, _m⁴_, the four true molars.
The last, not fully developed, is nearly concealed by the ascending ramus
of the jaw.]
_Æpyprymnus._[73]—Head short and broad. Auditory bullæ not inflated.
No palatine foramina. Tarsus long. Muffle partially hairy. Tail
evenly hairy, not crested above. Molars oblong, less distinctly
quadritubercular, and not decreasing so much in size posteriorly as in
the other genera. Represented only by _Æ. rufescens_.
Remains of _Æ. rufescens_ occur in the Pleistocene cave-deposits of New
South Wales.
Subfamily =Macropodinæ=.—This subfamily includes the largest forms.
The cutting edges of the upper incisors are nearly level, or the first
pair but slightly longer than the others (Fig. 55). The canines are
rudimentary and often wanting. The premolars are usually not longer
(from before backwards) than the true molars and less compressed than
in the last subfamily; they are placed in precisely the same line with
the molars. The crowns of the molars always have two prominent transverse
ridges; and these teeth increase in size from before backwards, the
fourth molar appearing very late. The fore limbs are small, with subequal
toes armed with strong, moderately long, curved claws. Hind limbs very
long and strongly made. Head small, with more or less elongated muzzle.
Ears generally rather long and ovate.
Upwards of forty-four existing species of this group have been described,
and many attempts have been made to subdivide them into smaller groups or
genera for the convenience of arrangement and description, but these have
generally been based upon such trivial characters that it is preferable
to speak of many of them as sections of the genus _Macropus_, reserving
generic rank only to forms somewhat aberrant in structure. According to
this arrangement the genera will be as follows:
_Lagostrophus._[74]—Represented only by the Banded Wallaby (_L.
fasciatus_) of Western Australia, which presents the following
distinctive features. Size small. Muffle naked. Hind feet covered with
long bristly hairs, concealing the claws. Lower part of back marked
by dark cross-bands. Skull with a narrow pointed muzzle and inflated
auditory bullæ; symphysis of mandible firmly united. No canine. Upper
incisive series meeting at a sharp angle, and diverging but slightly
behind. First incisor smaller in section than either of the others and
scarcely longer, bluntly pointed; second with a flattened oral surface;
third smaller, similarly flattened, but with a groove on oral surface
forming a notch at its postero-external angle. Fourth premolar short,
with a distinct inner ledge. Molars as in _Macropus_.
_Dendrolagus._[75]—General proportions of limbs and body normal and
unlike those of other members of the family. Muffle broad and only partly
naked. Fur on nape, and sometimes on back, directed forwards. Fore limbs
nearly as large as the hind; hind feet with the syndactylous second and
third digits relatively large; claws of fourth and fifth hind digits
curved like those of the manus. Tail very long, and thickly furred. Skull
stout, with a short and wide muzzle; the posterior part of the palate
fully ossified, and the auditory bullæ not inflated. A small canine.
Fourth premolar large, but much shorter antero-posteriorly than in the
next genus; molars as in the latter.
This genus includes four species of Tree-Kangaroos, three of which occur
in New Guinea, while _D. lumholtzi_ is found in North Queensland. They
differ greatly from all the other forms in being chiefly arboreal in
their habits, climbing with facility among the branches of large trees,
and feeding on the bark, leaves, and fruit. They are confined to the
tropical forests of the regions mentioned; and it would appear that we
must regard their resemblance in the proportions of the limbs and habits
to the Phalangers as having been independently acquired.
_Dorcopsis._[76]—Hind limbs relatively less large than in _Macropus_.
Muffle large, broad, and naked. Ears small. Fur on nape directed wholly
or partially forwards. Hind claws not concealed by hair. Tail with a
nearly naked tip. Skull long and narrow, with the auditory bullæ not
inflated. A well-developed canine. First upper incisor somewhat short;
second and third nearly equal, notched externally. Fourth premolar
greatly elongated antero-posteriorly, its length generally exceeding the
united lengths of the first and second molars; a distinct inner ledge,
and vertical grooves on both sides. Molars low and rounded, with the
median longitudinal bridge between the ridges almost or quite aborted,
and the talon in front of the first transverse ridge very narrow, and not
extending to the inner side. The two series of cheek-teeth parallel, or
nearly so, instead of converging at the extremities.
Three species of this genus are known, all of which are from New Guinea;
the type being _D. muelleri_. In the characters of the dentition, the
forward inclination of the fur on the nape, and other points, this genus
is allied to _Dendrolagus_; but _Dorcopsis macleayi_ connects the other
species with _Macropus_.
_Lagorchestes._[77]—Muffle entirely or partially covered with hair.
Fourth hind digit with a long claw, not concealed by hair. Tail rather
short, evenly furred, without a spur. Skull with short muzzle and
diastema, and inflated auditory bulla. Canine present, sometimes very
small. Fourth premolar large, not constricted in the middle, with a
continuous inner ledge.
This genus includes the Hare-Kangaroos, a group of small hare-like
animals, great leapers and swift runners, which mostly affect the open
grassy ridges, particularly those of a stony character, sleeping in forms
or seats like the common hare. Their limbs are comparatively small, their
claws sharp and slender, and their muffle is clothed with velvet-like
hairs. Three species—_M. leporoides_, _M. hirsutus_, _M. conspicillatus_.
The range extends over the whole of Australia, but does not embrace
Tasmania.
_Onychogale._[78]—Muffle hairy. Fourth hind claw long, narrow,
compressed, and sharp. Tail long and tapering, covered with short
hair, and furnished at the tip with a horny spur. Skull nearly as in
_Macropus_, with the auditory bullæ more or less inflated. Canine small
or wanting. Upper incisors small, decreasing in size from first to third.
Fourth premolar small, hour-glass shaped, and without inner ledge. Molars
as in _Macropus_.
This genus contains three species, having the same distribution as
_Lagorchestes_. Mr. O. Thomas observes: “The spur-tailed Wallabies form
a natural little group, distinguished both by the shape of the incisors
and the peculiar horny excrescence at the tip of the tail. The latter
character is altogether unique among Marsupials, and is only found among
other mammals in the Lion, which occasionally has a somewhat similar
horny spur at the end of its tail. In the case of the Wallabies it is
difficult to conceive what can be the use of this spur; and observations
on the living animal are much needed with regard to this interesting
point.”
_Petrogale._[79]—Muffle naked. Fur of nape directed backwards. Claw of
fourth hind digit very short. Tail long, cylindrical, thinner than in
_Macropus_, and thickly haired and pencilled at the extremity. Skull
as in the smaller species of _Macropus_, with large posterior palatal
vacuities, and the bullæ sometimes inflated. No canine. Upper incisors
small, the third resembling that of _Macropus_. Fourth premolar large
and stout, as in some of the Wallabies, with a continuous inner ledge,
and two or three indistinct vertical ridges externally. Molars as in the
Wallabies.
This genus is represented by six species, of which _P. penicillata_
is a well-known example, ranging over the whole of the mainland of
Australia. The Rock-Wallabies, as its members may be called, are very
closely allied to some of the true Wallabies; and some hesitation may be
expressed as to the advisability of accepting their generic separation
from _Macropus_. They inhabit rocky regions, making their retreats
in caverns and crevices, leaping with surprising agility from one
narrow ledge to another, and browsing upon the scanty herbage that the
neighbourhood of such situations affords. The species are _P. xanthopus_,
_P. penicillata_, _P. lateralis_, _P. concinna_, _P. brachyotis_, _P.
inornata_.
Remains of _P. penicillata_ are found in a fossil state in the
Pleistocene cave-deposits of New South Wales.
_Macropus._[80]—Muffle generally completely naked. Ears large. Fur on
nape (with an occasional exception in two species) directed backwards.
Claw of fourth hind digit very long. Tail thick, tapering, and evenly
furred. Four mammæ. Skull (Fig. 55) long, smooth, and rounded; the nasals
expanded behind; generally large palatal vacuities; and the auditory
bullæ not inflated. Canine minute, and shed at an early period. Incisor
series forming an open curve; the first the tallest, and the third nearly
always the longest antero-posteriorly, and generally with an infolding
of enamel near its postero-external angle. Fourth upper premolar with a
secant edge, and an inner basal ledge or tubercle; corresponding lower
tooth secant; both maybe longer or shorter than first molar. Molars
(except very occasionally) with a distinct longitudinal bridge connecting
transverse ridges. Lower incisors long and scalpriform, with inner secant
edges opposable, owing to the loose articulation of the mandibular
symphysis.
This genus includes the true Kangaroos and Wallabies, the size of the
individual existing species varying from that of a Rabbit to that of a
Man. There are no less than twenty-three existing species, which may be
divided into three groups, as well as many extinct ones. The genus is
found in Australia and New Guinea, as well as in the eastern half of the
Austro-Malayan transitional region.
The first group, or true Kangaroos, comprises the largest existing forms,
which are generally of a uniform and sombre colour.
The skull is of a large and massive type, with the palate more or less
well ossified posteriorly, while the molars frequently have a median
longitudinal bridge connecting the first transverse ridge with the
anterior talon, and no antero-external bridge between the same ridge and
talon. The history of the discovery of the typical representative of this
group, as being of considerable interest, may be given at some length.
When Captain Cook, during his first memorable voyage of discovery, was
detained for the purpose of refitting his ship at Endeavour river on
the north-east coast of Australia, a strange-looking animal, entirely
unknown to them, was frequently seen by the ship’s company; and it is
recorded in the annals of the voyage that, on the 14th of July 1770,
“Mr. Gore, who went out this day with his gun, had the good fortune
to kill one of the animals which had been so much the subject of our
speculation, ... and which is called by the natives kanguroo,” a name
which, though it does not appear to be now known to any of the aboriginal
tribes of the country, has been adopted for this animal in all European
languages, with only slight modifications of spelling. With the exception
of a passing glimpse in the beginning of the same century by the Dutch
traveller Bruyn of some living examples of an allied species, this was
the first introduction to the civilised world of any member of a group
of animals now so familiar. The affinities of the species, skins of
which were brought home by Captain Cook and subsequent voyagers, were
recognised by Schreber as nearer to the American opossums (then the
only known Marsupials) than to any other mammals with which zoologists
were acquainted, and consequently it was placed by him, in his great
work on the Mammalia, then in the course of publication, in the genus
_Didelphys_, with _gigantea_ for a specific designation,—the latter
having been bestowed upon it by Zimmermann under the impression that
it was a huge species of jerboa. Soon afterwards (1791) Dr. Shaw very
properly formed a new genus for its reception, which he named _Macropus_,
in allusion to the peculiar length of its hind foot. By the name thus
formed, _Macropus giganteus_, this kind of Kangaroo has ever since been
known in zoological literature. It is the common Gray Kangaroo, called
“boomer,” “forrester,” or “old man” by the colonists, and frequents the
open grassy plains of the greater part of eastern Australia and Tasmania;
a figure being given in the woodcut on p. 160. The muffle is partly
covered with hair, and the fourth premolar very short. Several varieties
are known.
A sub-group, distinguished from the above by the naked muffle, includes
some very large and handsome species, which principally dwell in rocky
mountain ranges, as _M. rufus_, the great Red Kangaroo, _M. antilopinus_,
and _M. robustus_. The fourth premolar is of large or medium size in
these forms. Remains of _M. giganteus_ occur fossil in the Pleistocene
of Australia, where we also find the allied extinct _M. titan_, which
attains somewhat larger dimensions. _M. robustus_ also dates from the
same geological epoch, where it was accompanied by two allied types known
as _M. altus_ and _M. cooperi_.
The second group includes the larger Wallabies, which are smaller than
the true Kangaroos, with a brighter and more variegated coloration. The
palate is generally more incomplete than in the typical group; and in the
molars the anterior talon is connected with the first transverse ridge
by an external instead of a median longitudinal bridge. The members of
this group are frequenters of forests and dense impenetrable brushes and
scrubs, and hence are often called Brush Kangaroos, though a native name,
“Wallaby,” is now generally applied to them. There are several species,
of which _M. ruficollis_, _M. ualabatus_, _M. parryi_, and _M. agilis_
are the best known.
_M. ualabatus_ and _M. parryi_ are found fossil in the Pleistocene
deposits of Australia. In those beds we also meet with remains of several
very large extinct species, which appear to be allied to those Wallabies
in which the fourth premolar is large and elongated, all of them agreeing
with the Wallabies in the absence of the median bridge between the first
ridge and talon of the molars. These fossil forms comprise _M. brehus_,
in which the skull was probably about one foot in length, and _M.
rœchus_, and _M. anak_, which were of somewhat inferior dimensions. In
the last-named species the length of the fourth upper premolar is equal
to that of the first and half of the second molar.[81]
The third and last group of the genus includes the small Wallabies,
which are small and lightly-built animals, in some instances not larger
than a Rabbit. Their muffles are always naked, and in the skull the
anterior palatine foramina are small and the posterior vacuities very
large, while the posterior expansion of the nasals is very marked. The
third upper incisor is smaller than in the last group. This group extends
farther into the tropics than either of the others, being found in the
New Britain and Aru islands, as well as in New Guinea. _M. brachyurus_
is remarkable for its comparatively short and slender tail and small
ears. The earliest known species of Kangaroo, referred to before, _M.
bruni_, belongs to this section. Several examples were seen by Bruyn in
1711 living in captivity in the garden of the Dutch governor of Batavia,
and described and figured in the account of his travels (_Reizen over
Moskovie_, etc.) under the name of “Filander.” It was quite lost sight
of, and its name even transferred by S. Müller to another species
(_Dorcopsis muelleri_), until rediscovered in 1865 by Rosenberg, who
sent a series of specimens to the Leyden Museum from the islands of Aru
and Great Key, thus determining its true habitat. _M. thetidis_ is a
well-known Australian representative of this group.
_Extinct genera._—In addition to the fossil forms already mentioned which
can be referred to existing genera, there are others from the Australian
Pleistocene indicating extinct generic types of _Macropodidæ_, to which
brief reference may now be made. The first of these is _Sthenurus_,[82]
represented by a single large species (_S. atlas_), and characterised by
the presence of a complete inner lobe to the fourth upper premolar, and
of an outer one in the opposing lower tooth, so that these teeth present
a flat and oval grinding surface when worn. The median longitudinal
bridge connecting the transverse ridges of the molars is very imperfect;
and in the upper molars there is no bridge between the first ridge and
talon. In _Procoptodon_[83] the premolars resemble those of _Sthenurus_,
but the molars are elongated, and usually have their enamel thrown into
numerous vertical foldings. The most distinctive feature is, however, the
complete ankylosis of the mandibular symphysis; the mandibular rami being
deep, and the diastema in the dental series short. The lower incisors are
nearly cylindrical, and the palate has large vacuities. Three species are
known. The largest representation of the whole family is the type of the
genus _Palorchestes_[84] (_P. azael_), in which the length of the skull
is estimated at sixteen inches. It is distinguished from _Procoptodon_
by the longer mandibular symphysis and diastema, and the spatulate lower
incisors. The true molars have no distinct anterior talon, and are not
grooved, while the palate was fully ossified.
EXTINCT FAMILIES.
Here may be noticed two genera of extinct Marsupials, the remains of
which have been found in the Pleistocene deposits of Australia, which
agree with the _Macropodidæ_ and the _Phalangeridæ_ in having ³⁄₁
incisors, those of the lower jaw being very large and proclivous. As the
whole of their structure, especially that of the hind feet, is not yet
known, their precise affinities cannot be determined.
_Diprotodon._[85]—Dentition: _i_ ³⁄₁, _c_ ⁰⁄₀, _p_ ¹⁄₁, _m_ ⁴⁄₄; total
28. The first upper incisor very large and scalpriform (Fig. 56). True
molars with prominent transverse ridges, as in _Macropus_, but wanting
the longitudinal connecting bridge. Anterior and posterior limbs less
disproportionate than in the Kangaroos. Humerus elongated, and differing
from that of nearly all Marsupials in the absence of an entepicondylar
foramen. The palate is fully ossified, and there is no pit or perforation
in the masseteric fossa of the mandible. _D. australis_ is the largest
known Marsupial, being fully equal in bulk to a Rhinoceros. It may be
regarded as the type of a family—_Diprotodontidæ_—having affinity on the
one hand with the Phalangers and on the other with the Kangaroos.
[Illustration: FIG. 56.—Left lateral aspect of the skull of _Diprotodon
australis_; from the Pleistocene of Australia. ⅒ natural size. _i_,
Incisors; _p_, premolar; _m_, molars. (After Owen.)]
_Nototherium._[86]—Represented by a species of somewhat smaller size
than the type of _Diprotodon_, with a shorter skull, in which the
zygomatic arches are very wide and the nasals curiously expanded at
their extremities. The mandibular symphysis is ankylosed; and, as in
_Diprotodon_, there appears to have been no tooth-change. The humerus
probably referable to _Nototherium_ is of a short and widely expanded
type, with a large entepicondylar foramen, and coming nearer to that of
the Wombat than to that of any other existing form. The _Nototheriidæ_
may apparently be regarded as a distinct family connecting the
_Diprotodontidæ_ with the _Phascolomyidæ_ and _Phalangeridæ_.
_Bibliography of Marsupialia._—G. R. Waterhouse, _Nat. Hist. of
the Mammalia_, vol. i. “Marsupiata,” 1846; J. Gould, _Mammals
of Australia_, 1863; R. Owen, article “Marsupialia,” in
_Cyclop. of Anatomy and Physiology_, and various memoirs “On
Extinct Mammals of Australia” in _Philosophical Transactions_;
W. H. Flower, “On the Development and Succession of the Teeth
in the Marsupialia,” _Phil. Trans._ 1867; O. Thomas, “On the
Homologies and Succession of the Teeth in the Dasyuridæ,”
_Phil. Trans._ 1887; and “Catalogue of Marsupialia and
Monotremata in the British Museum,” 1888.
CHAPTER VII
THE SUBCLASS EUTHERIA AND THE ORDER EDENTATA
The whole of the remaining groups of mammals are included in a single
subclass, known by the names Eutheria, Monodelphia, or Placentalia.[87]
The one distinctive feature they have in common (from which the
last-mentioned name is derived) is the presence of an allantoic placenta
by means of which the fœtus is nourished within the uterus of the mother.
Throughout the entire subclass, as a general rule, the urino-genital
organs open quite independently of the rectum; the corpus callosum of the
brain is well developed; the mandible does not show a marked inflection
of its angle; and distinct epipubic bones are not attached to the
anterior margin of the pubic symphysis. In those cases where there is a
heterodont and diphyodont dentition the dental formula can be reduced to
some modification of the one given on p. 25, there being only one known
genus where four true molars occur, and even that not invariably. As
in the Metatheria, the coracoid is reduced to a mere appendage of the
scapula, and the acetabular cavity of the pelvis is imperforate. While
the survivors of the other subclasses have probably been for a long time
in a stationary condition, these have, as there is already good evidence
to show throughout all the Tertiary geological age, and by inference
for some time before, been multiplying in numbers and variations of
form, and attaining higher stages of development and specialisation in
various directions. They consequently exhibit far greater diversity of
external or adaptive modification than is met with in either of the other
subclasses,—some being fitted to live as exclusively in the water as
fishes, and others to emulate the aerial flight of birds.
To facilitate the study of the different component members of this large
group, it is usual to separate them into certain divisions which are
called “orders.” In the main zoologists are now of accord as to the
general number and limits of these divisions among the existing forms,
but the affinities and relationships of the orders to one another are
far from being understood, and there are very many extinct forms already
discovered which do not fit at all satisfactorily into any of the orders
as commonly defined.
Commencing with the most easily distinguished, we may first separate
a group called Edentata, composed of several very distinct forms, the
Sloths, Anteaters, and Armadillos, which under great modifications of
characters of limbs and digestive organs, as well as habits of life,
have just enough in common to make it probable that they are the very
specialised survivors of an ancient group, most of the members of
which are extinct, although the researches of palæontology have not
yet revealed them to us. The characters of their cerebral, dental, and
in many cases of their reproductive organs show an inferior grade of
organisation to that of the generality of the subclass. The next order,
about the limits of which there is no difficulty, is the Sirenia,—aquatic
vegetable-eating animals, with complete absence of hind limbs, and low
cerebral organisation,—represented in our present state of knowledge by
but two existing genera, the Dugongs and Manatees, and by a few extinct
forms, which, though approaching a more generalised mammalian type, show
no special characters allying them to any of the other orders. Another
equally well-marked and equally isolated, though far more numerously
represented and diversified order, is that of the Cetacea, composed of
the various forms of Whales, Dolphins, and Porpoises. In aquatic habits,
external fish-like form, and absence of hind limbs, they resemble the
last, though in all other characters they are as widely removed as are
any two orders among the Eutheria.
All the remaining orders are more nearly allied together, the steps by
which they have become modified from one general type being in most cases
not difficult to realise. Their dentition especially, however diversified
in detail, always responds to the formula already alluded to, and,
although the existing forms are broken up into groups in most cases easy
of definition, the discoveries already made in palæontology have in great
measure filled up the gaps between them.
Very isolated among existing Eutheria are the two species of Elephant
constituting the group called Proboscidea. These, however, are now known
to be the survivors of a large series of similar animals, Mammoths,
Mastodons, and Dinotheres, which as we pass backwards in time gradually
assume a more ordinary or generalised type; and the interval which was
lately supposed to exist between even these and the rest of the class
is partially bridged over by the discovery in American Eocene and early
Miocene formations of the gigantic Dinocerata, evidently offshoots of
the great group of hoofed animals, or Ungulata, represented in the
actual fauna by the Horses, Rhinoceroses, Tapirs, Swine, and Ruminants.
Almost as isolated as the Proboscidea among existing mammals are the
few small species constituting the family _Hyracidæ_, and in their case
palæontology affords no help at present, and therefore, pending further
discoveries, it has been thought advisable in most recent systems to
give them the honour of an order to themselves, under the name of
Hyracoidea. But the number of extinct forms already known allied to
the Ungulata, though not coming under the definition of either of the
two groups (Artiodactyla and Perissodactyla) under which all existing
species range themselves, is so great that either many new orders must
be made for their reception or the definition of the old order Ungulata
so far extended as to receive them all, in which case both Proboscidea
and Hyracoidea may be included within it. Again, the Rodentia or gnawing
animals—Rabbits, Rats, Squirrels, Porcupines, Beavers, etc.—are, if
we look only at the present state of the class, most isolated. No one
can doubt what is meant by a Rodent animal, or have any difficulty
about defining it clearly, at least by its dental characters; yet our
definitions break down before the extinct South American _Typotherium_,
half Rodent and half Ungulate, which leads by an easy transition to
the still more truly Ungulate _Toxodon_, for the reception of which a
distinct order (Toxodontia) has been proposed. It has also been suggested
that the Rodents are connected by some of the extinct Tillodontia (or
Tæniodontia) with the Edentates. The Insectivora and the Carnivora
again are at present quite distinct orders, but they merge into one
another through fossil forms, and are especially connected by the large
group of primitive Carnivora, so abundantly represented in the Eocene
deposits both of America and Europe, to which Cope has given the name
of Creodonta. The Carnivora also appear to have been closely connected
with the primitive Ungulates as represented by the extinct group called
Condylarthra. In another direction the step from the Insectivores to
the Lemurs is not great, and in past times the transition was probably
complete. The Bats or Chiroptera are allied to the Insectivora in all
characters except the extraordinary modification of their anterior
extremities into wings; but this, like the want of the hind limbs in the
Cetacea and Sirenia, makes such a clear distinction between them and all
other mammals that, in the absence of any knowledge of any completely
intermediate or transitional forms, they can be perfectly separated,
and constitute as well-defined an order as any in the class. We have,
however, an inkling of the mode in which the Insectivora were modified
into Chiroptera shown us by the so-called Flying Lemur (_Galeopithecus_).
Finally, we have the important and well-characterised group called
Primates, including all the Monkeys and Man; and the question is not yet
solved as to how and through what forms this is linked on to the other
groups. It is commonly assumed that the Lemurs are nothing more than
inferior Primates, but the interval between them in the actual fauna of
the world is very great, and our knowledge of numerous extinct types
recently discovered in America, said to be intermediate in characters,
is not yet sufficient to enable us to form a definite opinion upon the
subject.
The Edentata may be taken first as standing in some respects apart from
all the others; and the Primates must be placed at the head of the
series. The position of the others is quite arbitrary, as none of the
hitherto proposed associations of the orders into larger groups stand
the test of critical investigation, and palæontological researches have
already gone far to show that they are all modifications of a common
heterodont, diphyodont, pentadactylate form.
_Order_ EDENTATA.
The name assigned to this group (which some zoologists think ought
rather to be ranked as a subclass[88] than an order) by Cuvier is often
objected to as inappropriate—for although some of the members are
edentulous, others have very numerous teeth—and the Linnæan name Bruta
is occasionally substituted. But that term is quite as objectionable,
especially since the group to which Linnæus applied it is by no
means equivalent to the order as now understood, as the names of the
genera contained in it, viz. _Elephas_, _Trichechus_, _Bradypus_,
_Myrmecophaga_, _Manis_ and _Dasypus_, indicate. It contained, in fact,
all the animals then known which are comprised in the modern groups
of Proboscidea, Sirenia and Edentata together with the Walrus, one
of the Carnivora. If retained at all, it should rather belong to the
Proboscidea, as _Elephas_ stands first in the list of genera in the
_Systema Naturæ_. Cuvier’s order included the _Ornithorhynchus_ and
_Echidna_, the structure of which was then imperfectly known, and which
are now by common consent removed to an altogether different section
of the class; but otherwise its limits are those now adopted. The name
Edentata is so generally used, and its meaning so well understood, that
it would be undesirable to change it now; in fact similar reasons might
be assigned for ceasing to use nearly all the other current ordinal
designations, for it might be equally well objected that all Carnivora
are not flesheaters, many of the Marsupialia have not pouches, and so
forth.
If the teeth are not always absent, they invariably exhibit certain
imperfections, which are indeed almost the only common characters
binding together the various extinct and existing members of the order.
These are—that they are homodont and, with the remarkable exceptions
of _Tatusia_ and _Orycteropus_, monophyodont; they are never rooted,
but have persistent pulps; except in some fossil forms, they are always
deficient in one of the constituents which enter into the formation of
the complete mammalian tooth, the enamel; and, at least among living
forms, are never present either in the upper or lower jaw in the fore
part of the mouth, the situation occupied by the incisors of other
mammals.[89]
The peculiar nature of the dentition in the aberrant _Orycteropus_ will
be noticed under the heading of that genus. As a rule, the coracoid
process of the scapula of the Edentates is more developed than in other
Eutheria.
The degree of development of the brain varies considerably in the
different families, the hemispheres being in some cases almost or quite
smooth (Fig. 57), with a small corpus callosum, and large anterior
commissure; while in other instances the hemispheres are convoluted, and
the corpus callosum is larger.
[Illustration: FIG. 57.—Upper surface of the brain of the Broad-banded
Armadillo (_Xenurus unicinctus_). The large olfactory lobes are seen at
the anterior extremity (left of figure); the hemispheres have only three
sulci. (From Garrod, _Proc. Zool. Soc._ 1878, p. 230).]
There is so great a difference in structure and habits between some of
the existing animals assigned to this order that, beyond the negative
characters just mentioned, there seems little to connect them. The Sloths
and Anteaters, for instance, in mode of life, general conformation of
limbs, structure of digestive organs, etc., appear at first sight almost
as widely separated as any mammals. Palæontology has, however, thrown
great light upon their relations, and proved their real affinities.
Perfectly intermediate forms have been discovered in the great Ground
Sloths of America, which have the dentition and general form of the
head of the Sloths, combined with the limbs and trunk of the Anteaters.
It is, indeed, highly probable that the existing members of this order
are very much differentiated representatives of a large group, the
greater number of which are now extinct, and have become so without ever
attaining a high grade of organisation. The great diversity of structure
in the existing families, the high degree of specialisation to which many
have attained, the paucity of species and even of individuals, their
limited area of distribution, and their small size compared with known
ancestral forms, all show that this is an ancient and a waning group, the
members of which seem still to hold their own either by the remoteness
and seclusion of their dwelling-places, by their remarkable adaptation
of structure to special conditions of life, or by aid of the peculiar
defensive armature with which they are invested. Their former history
can, however, only be thus surmised, rather than read, at present; for,
though we have ample evidence of the abundance and superior magnitude of
certain forms in the most recent or Pleistocene geological age, yet we
have at present no definite evidence as to their origin, or relationship
to other orders of mammals.
The existing members of the order readily group themselves into five
distinct families, the limits of which are perfectly clear. These are
(1) _Bradypodidæ_, or Sloths; (2) _Myrmecophagidæ_, or Anteaters;
(3) _Dasypodidæ_, or Armadillos; (4) _Manidæ_, Pangolins or Scaly
Anteaters; and (5) _Orycteropodidæ_, Aard-varks or African Anteaters.
The geographical distribution of these families coincides with their
structural distinction, the first three being inhabitants of the New
and the last two of the Old World. It has been usual to arrange these
families into two large groups or suborders: (1) the Phyllophaga,
leaf-eaters, also called Tardigrada, containing the _Bradypodidæ_ alone;
and (2) the Entomophaga, insect-eaters, or Vermilingua, containing
all the other families, from which sometimes the _Orycteropodidæ_
are separated as a third suborder under the name of Effodientia, or
Tubulidentata. Such an arrangement is, however, an artificial one,
founded on superficial resemblance. The bonds which unite the _Manidæ_
to the _Myrmecophagidæ_ are mainly to be found in the structure of the
mouth, especially the extensile character of the tongue, the great
development of the submaxillary glands, and the absence of teeth.
These characters are exactly analogous to those found in the Echidna
among Monotremes, the Woodpeckers among Birds, and the Chameleon among
Reptiles,—the fact probably being that in countries where Termites and
similar insects flourish various distinct forms of vertebrates have
become modified in special relation to this abundance of nutritious
food, which could only be made available by a peculiar structure of the
alimentary organs. A close study of the more essential portions of the
anatomy of these animals[90] leads to the belief that all the American
Edentates at present known, however diversified in form and habits,
belong to a common stock. Thus the _Bradypodidæ_, _Megatheriidæ_, and
_Myrmecophagidæ_ are certainly allied, the modifications seen in the
existing families relating only to food and manner of life. The ancestral
forms may have been omnivorous, and gradually separated into the purely
vegetable and purely animal feeders; from the former are developed
the modern Sloths, from the latter the Anteaters. The Armadillos
(_Dasypodidæ_) are another modification of the same type, retaining some
generalised characters, as those of the alimentary organs, but in other
respects, as in their defensive armature, remarkably specialised. The
two Old World families _Manidæ_ and _Orycteropodidæ_ are so essentially
distinct, both from the American families and from each other, that it
may even be considered doubtful whether they are derived from the same
primary branch of mammals, or whether they may not be offsets of some
other branch, the remaining members of which have been lost to knowledge.
Further remarks on this point are recorded under the description of the
_Orycteropodidæ_.[91]
_Family_ BRADYPODIDÆ.
Externally clothed with long, coarse, crisp hair. Head short and rounded.
External ears inconspicuous. Teeth ⁵⁄₄ in each jaw, subcylindrical, of
persistent growth, consisting of a central axis of vaso-dentine, with a
thin investment of hard dentine, and a thick outer coating of cement;
without (so far as is yet known) any succession. Clavicles present. Fore
limbs greatly longer than the hind limbs. All the extremities terminating
in narrow, curved feet; the digits never exceeding three in number,
encased for nearly their whole length in a common integument, and armed
with long strong claws. Tail rudimentary. Stomach complex. No cæcum.
Uterus simple and globular. Placenta deciduate, dome-like, composed of an
aggregation of numerous discoidal lobes. Strictly arboreal in habits,
vegetable feeders, and limited geographically to the forest regions of
South and Central America.
[Illustration: FIG. 58.—Two-toed Sloth (_Cholœpus hoffmanni_).]
The Sloths, as the animals of this family are called on account of the
habitual sluggishness of their movements, are the most strictly arboreal
of all mammals, living entirely among the branches of trees, usually
hanging under them, with their backs downwards (Fig. 58), and clinging
to them with the simple hook-like organs to which the terminations of
all their limbs are reduced. When they are obliged from any cause to
descend to the ground, which they rarely, if ever, do voluntarily, their
limbs, owing to their unequal length and the peculiar conformation of the
feet—which allows the animals to rest only on the outer edge—are most
inefficient for terrestrial progression, and they crawl along a level
surface with considerable difficulty. Though generally slow and inactive,
even when in their natural haunts, Sloths can on occasions travel with
considerable rapidity along the branches; and, as they do not leap, like
most other arboreal creatures, they avail themselves of the swaying of
the boughs by the wind to pass from tree to tree. They feed entirely on
leaves and young shoots and fruits, which they gather in their mouth, the
fore limbs aiding in dragging boughs within reach, but not being used
like hands, as they are by monkeys, squirrels, etc. When sleeping they
roll themselves up in a ball, and, owing to the dry shaggy character of
their hair, are very inconspicuous among the mosses and lichens with
which the trees of their native forests abound; the concealment thus
afforded being heightened in some species by the peculiar greenish tint
of the outer covering—very uncommon in mammals. This is not due to the
colour of the hair itself, but to the presence upon its surface of an
alga, the lodgment of which is facilitated by the fluted or rough surface
of the exterior of the hair, and the growth of which is promoted by the
dampness of the atmosphere in the gloomy tropical forests, as it soon
disappears from the hair of animals kept in captivity in England. Sloths
are nocturnal, silent, inoffensive, and solitary animals, and usually
produce but one young at birth. They appear to show an almost reptilian
tenacity of life, surviving the most severe injuries and large doses of
poisons, and exhibiting longer persistence of irritability of muscular
tissue after death than other mammals.
In the _Bradypodidæ_, as well as in the _Myrmecophagidæ_, the testes
are placed close to each other, lying on the rectum between it and the
bladder; the penis is quite rudimentary, consisting of a pair of small
corpora cavernosa, not directly attached by their crura to the rami
of the ischia, and having a glans scarcely larger than that of the
clitoris of most mammals, and, as in birds and reptiles, without any
true corpus spongiosum. In the females of both families the uterus is
simple and globular; and the vagina, at least in the virgin state, is
divided into two channels by a strong median partition. The deciduate
placenta of _Cholœpus_ is composed of a number of lobes aggregated into a
dome-like mass; and it does not appear that the placenta of the Anteaters
departs in any important characters from this type. According to the
late Professor W. K. Parker, the embryos of the Sloths, Anteaters, and
Pangolins have the stapes of the middle ear in the form of a rod, thus
showing affinities with a very primitive type of mammalian organisation.
The Sloths were all included in the Linnæan genus _Bradypus_, but Illiger
very properly separated the species with but two claws on the fore feet,
under the name of _Cholœpus_, leaving _Bradypus_ for those with three.
_Bradypus._[92]—Three-toed Sloths. Teeth usually ⁵⁄₄ on each side; no
tooth projecting greatly beyond the others; the first in the upper jaw
much smaller than any of the rest; the first in the lower jaw broad and
compressed; the grinding surfaces of all much cupped. Vertebræ: C 9, D
and L 20 (of which 15 to 17 bear ribs), S 6, C 11. All the known species
present the remarkable peculiarity of possessing nine cervical vertebræ,
_i.e._ nine vertebræ in front of the one which bears the first thoracic
rib (or first rib connected with the sternum, and corresponding in its
general relations with the first rib of other mammals); but the ninth,
and sometimes the eighth, bears a pair of short movable ribs. The arms
or fore limbs are considerably longer than the hind legs. The bones of
the fore arm are complete, free, and capable of pronation and supination.
The hand is long, very narrow, habitually curved, and terminates in three
pointed curved claws, in close apposition with each other. The claws are,
in fact, incapable of being divaricated, so that the hand is reduced to
the condition of a triple hook, fit only for the function of suspension
from the boughs of trees. The foot closely resembles the hand in its
general structure and mode of use; the sole being habitually turned
inwards, so that it cannot be applied to the ground in walking. The
tongue is short and soft, and the stomach large and complex, bearing some
resemblance to that of the ruminating Ungulates. The windpipe or trachea
has the remarkable peculiarity among mammals—not unfrequent among birds
and reptiles—of being folded on itself before it reaches the lungs. The
mammæ are two, and pectoral in position.
“Ai” is the common name given in books to the Three-toed Sloths. They
were all comprised by Linnæus under the species _Bradypus tridactylus_.
More recently Dr. Gray described as many as eleven species, ranged in two
genera, _Bradypus_ and _Arctopithecus_; but the distinctions which he
assigned both to species and genera do not bear close examination. Some
are covered uniformly with a gray or grayish-brown coat; others have a
dark collar of elongated hairs around the shoulders (_B. torquatus_);
some have the hair of the face very much shorter than that of the rest
of the head and neck; and others have a remarkable-looking patch of soft
short hair on the back between the shoulders, consisting, when best
marked, of a median stripe of glossy black, bordered on each side by
bright orange, yellow, or white. There are also structural differences in
the skulls, as in the amount of inflation of the pterygoid bones, which
indicate real differences of species; but the materials in our museums
are not yet sufficient to correlate these with external characters and
geographical distribution. The habits of all are apparently alike. They
are natives of Guiana, Brazil, and Peru, and one if not two species (_B.
infuscatus_ and _B. castaneiceps_) extend north of the Isthmus of Panama
as far as Nicaragua. Of the former of these Dr. Seeman says that, though
generally silent, a specimen in captivity uttered a shrill sound like a
monkey when forcibly pulled away from the tree to which it was holding.
_Cholœpus._[93]—Teeth ⁵⁄₄; the most anterior in both jaws separated by
an interval from the others, very large, caniniform, wearing to a sharp,
bevelled edge against the opposing tooth, the upper shutting in front of
the lower when the mouth is closed (Fig. 59), unlike the true canines
of heterodont mammals. Vertebræ: C 6 or 7, D 23-24, L 3, S 7-8, C 4-6.
One species (_C. didactylus_) has the ordinary number of vertebræ in
the neck; but an otherwise closely allied form (_C. hoffmanni_) has but
six. The tail is very rudimentary. The hand generally resembles that of
_Bradypus_; but there are only two functional digits with claws—those
answering to the second and third of the typical pentadactylate manus.
The structure of the hind limb generally resembles that of _Bradypus_,
the appellation “two-toed” referring only to the anterior limb, for
in the foot the three middle toes are functionally developed and of
nearly equal size. _C. didactylus_, which has been longest known, is
commonly called by the native name of _Unau_. It inhabits the forests
of Brazil. _C. hoffmanni_ (Fig. 58) has a more northern geographical
range, extending from Ecuador through Panama to Costa Rica. Its voice,
which is seldom heard, is like the bleat of a sheep, and if the animal is
seized it snorts violently. Both species are very variable in external
coloration.
[Illustration: FIG. 59.—Skull of Two-toed Sloth (_Cholœpus didactylus_).
From _Proc. Zool. Soc._ 1871, p. 432.]
_Nothropus._[94]—The only fossil form which has been referred to this
family is indicated by a lower jaw, described by Dr. Burmeister, from the
Pleistocene of Argentina, which appears to have belonged to an animal
of about double the dimensions of _Cholœpus didactylus_. Professor Cope
states, however, that this jaw really belongs to a Glyptodont; while it
is referred by Dr. Ameghino to the next family.
_Family_ MEGATHERIIDÆ.
[Illustration: FIG. 60.—Section of upper molar teeth of _Megatherium
americanum_. × ⅓. _p_, pulp-cavity; the other letters explained in the
text. (After Owen.)]
The members of this family are all extinct. Their characters, so far as
is known from the well-preserved remains of many species found abundantly
in deposits of Pleistocene age in both North and South America, were
intermediate between those of the existing _Bradypodidæ_ and the
_Myrmecophagidæ_, combining the head and dentition of the former with
the structure of the vertebral column, limbs, and tail of the latter.
Almost all the known species are of comparatively gigantic size, the
smallest, _Nothrotherium escrivanense_, exceeding the largest existing
Anteater, and the Megatherium being larger than a Rhinoceros. The femur
has no third trochanter, and the odontoid process of the axis vertebra
has a peculiar facet on the ventral surface. The dentition is usually
⁵⁄₄ on each side, as in the Sloths, but ⁴⁄₃ in _Nothrotherium_.[95]
This genus, and in a still more marked degree _Megatherium_, differ
from all the others in the details of the structure of the teeth. They
are very deeply implanted, of prismatic form (quadrate in transverse
section), and the component tissues—hard dentine (Fig. 60, _d_), softer
vaso-dentine (_v_), and cement (_c_)—are so arranged that, as the tooth
wears, the surface always presents a pair of transverse ridges, thus
producing a triturating apparatus comparable to the “bilophodont” molar
of _Dinotherium_, _Tapirus_, _Manatus_, _Macropus_, and others, though
produced in a different manner. In all the other genera the teeth are
more or less cylindrical, though sometimes laterally compressed or even
longitudinally grooved on the sides, and on the grinding surface the
prominent ridge of hard dentine follows the external contour, and is
surrounded only by a thin layer of cement, as in the existing Sloths.
The Ground Sloths, as the members of this family may be conveniently
designated, agree with the Sloths and Anteaters, and thereby differ from
all other mammals, in that the coracoid process of the scapula and the
coracoidal border of the same unite over the coraco-scapular notch, which
is thus converted into a foramen. Large clavicles are present.
_Megatherium._[96]—The typical genus _Megatherium_, as being the longest
known representative of the family, may be noticed in some detail. A
nearly complete skeleton, found on the banks of the River Luxan, near
Buenos Ayres, and sent in 1789 to the Royal Museum at Madrid, long
remained the principal if not the only source of information with regard
to the species to which it belonged, and furnished the materials for
many descriptions, notably that of Cuvier, who determined its affinities
with the Sloths.[97] In 1832 an important collection of bones of the
Megatherium was discovered near the Rio Salado, and secured for the
Museum of the College of Surgeons of England; and these, with another
collection found at Luxan in 1837, and now in the British Museum,
supplied the materials for the complete description of the skeleton
published by Sir R. Owen in 1861. Other skeletons have subsequently been
received by several of the Continental museums, as Milan and Paris, and
also by those in South America; and consequently our knowledge of the
organisation of the Megatherium, so far as it can be deduced from the
bones and teeth, is as complete as that of any other animal, recent or
extinct.
[Illustration: FIG. 61.—Oral surface of mandible of _Megatherium
americanum_. _a_, Condyle; _b_, masseteric process; _c_, angle; _d_,
symphysis. (After Owen.)]
The remains hitherto spoken of are all referred to one species,
_Megatherium americanum_ of Blumenbach (_M. cuvieri_ of Desmarest), and
are all from the newest or Pleistocene geological formations of the
Argentine Republic and Paraguay, or the lands forming the basin of the
Rio de la Plata. Dr. Leidy has described, from similar formations in
Georgia and South Carolina, bones of a closely allied species, about
one-fourth smaller, which he has named _M. mirabile_. Three other South
American species have been described; but _M. laurillardi_, of Lund,
founded upon remains found in Brazil, has been made the type of the genus
_Ocnopus_.
[Illustration: FIG. 62.—Skeleton of _Megatherium_, from the specimen in
the Museum of the Royal College of Surgeons. × ¹⁄₂₅.]
The following description will apply especially to the best-known
South American form, _Megatherium americanum_. In size it exceeded any
existing land animal except the elephant, to which it was inferior only
in consequence of the comparative shortness of its limbs; for in length
and bulk of body it was its equal, if not superior. The full length of
a mounted skeleton (Fig. 62), from the fore part of the head to the end
of the tail, is 18 feet, of which the tail occupies 5 feet. The head,
which is small for the size of the animal, presents a general resemblance
to that of the Sloth; the anterior part of the mouth is, however, more
elongated, and the jugal bone, though branched posteriorly in the same
way as that of the Sloth, meets the zygomatic process of the squamosal,
thus completing the arch. The lower jaw has the middle part of its
horizontal ramus curiously deepened, so as to admit of implantation of
the very long-rooted teeth, the peculiar structure of which has been
already described. A skull recently discovered shows that, instead of the
wide gap between the extremity of the nasals and the premaxillæ exhibited
in Fig. 62, there was a prenasal bone, towards which a process extended
upwards and backwards from the extremity of the upper surface of the
premaxillæ.
The vertebral column consists of seven cervical, sixteen dorsal, three
lumbar, five sacral, and eighteen caudal vertebræ. The spinous processes
are much better developed than in the Sloths, and are all directed
backwards, there being no reversing of the inclination near the posterior
end of the dorsal series, as in most active-bodied mammals. In the lumbar
region, the accessory zygapophyses, rudimentary in Sloths, are fully
developed, as in the Anteaters.
The tail is large, and its basal vertebræ have strong lateral and spinous
processes and chevron bones, indicating great muscular development.
The scapula resembles that of the Sloths in the union of the acromion
with the coracoid, and in the bridging over of the suprascapular notch.
The clavicle is complete and very large, much resembling that of man
on a large scale. The fore limbs are longer than the hind limbs. The
humerus has no entepicondylar foramen. The radius and ulna are both
well developed, and have a considerable amount of freedom of movement.
The hand is singularly modified. The pollex is represented only by
a rudimentary metacarpal, but the next three digits are large, and
terminate in phalanges adapted for the support of immense claws, the
middle one being especially large. The outer or fifth digit has no claw,
and it may be considered as certain that the weight of the foot was, in
standing and walking, chiefly thrown upon this one, which was protected
by a callous pad below, as in the existing great Anteater, while the
other toes were curved inwards towards the palm, and only came in contact
with the ground by their outer surfaces. The mechanical arrangements by
which the weight of the body was thrown entirely upon the outer side of
the foot are very curious, and are fully described in Owen’s memoir. The
pelvis is remarkably wide, even more so than that of the Elephant, but it
is formed on the same principle as in the Sloths. The femur is extremely
broad and flattened; the tibia and fibula are short and strong, and
united together at each end. The hind foot, contrary to the usual rule
in the Edentata, is even more singularly modified than the hand. Thus
the ankle-joint is formed upon a peculiar plan, quite unlike that of the
Sloths, or of any other mammal, except the Megatherium’s nearest allies;
and the calcaneum projects nearly as far backwards as the fore part of
the foot does forwards. There is no trace of great toe or hallux, or of
its corresponding cuneiform bone; the second toe is rudimentary; while
the third has an enormous ungual phalanx, which, as in those of the hand,
is remarkable for the immense development of the bony sheath reflected
from its proximal end around the base of the claw. The two outer toes
have large and very peculiarly-shaped metatarsals, but only small
phalanges, and no claws. The creature probably walked upon the outer edge
of the sole, so that the great falcate claw of the third toe did not come
into contact with the ground, and so was kept in a state of sharpness
ready for use. The foot was therefore formed upon quite a different
principle from that of the Anteaters or Sloths, though somewhat like the
latter in having two of the toes aborted.
Taking all the various points of its structure together, they clearly
indicate affinities both with the existing Sloths and with the
Anteaters, the skull and teeth more resembling those of the former, and
the vertebral column and limbs the latter. It is also not difficult
to infer the food and habits of this enormous creature. That it was a
leaf-eater there can be little doubt; but the greater size and more
complex structure of its teeth might have enabled it to crush the smaller
branches as well as the leaves and succulent shoots which form the food
of the existing Sloths. It is, however, very improbable that it climbed
into the branches of the trees like its diminutive congeners, and it is
far more likely that it obtained its subsistence by tearing them down
with the great hook-like claws of its powerful prehensile fore limbs,
being easily enabled to reach them by raising itself up upon the massive
tripod formed by the two hind feet, firmly fixed to the ground by the one
huge falcate claw, and the stout, muscular tail. The whole conformation
of the hinder part of the animal is strongly suggestive of such an
action. There can also be little doubt but that all its movements were as
slow and deliberate as those of its modern representatives.
An idea at one time prevailed that the Megatherium was covered externally
with a coat of bony armour like that of the Armadillos; but this
originated in dermal plates belonging to the Glyptodon having been
accidentally associated with bones of the Megatherium. Similar plates,
on a smaller scale, have indeed been found in connection with the
skeleton of the Mylodon, but never yet with the Megatherium, which we may
therefore imagine with a covering of coarse hair like that of its nearest
living allies, the Sloths and Anteaters.
_Scelidotherium_, _Mylodon_, etc.—Of the more important remaining
genera of this family a briefer notice will suffice. _Scelidotherium_
(in which _Platyonyx_ may be included) comprises several species of
considerably smaller dimensions than the Megatherium, and is in some
respects intermediate between that genus and _Mylodon_. The teeth have
an oval cross-section, like those of the Sloths, while the skull, in
which the length of the nasals is subject to great variation in the
different species, approximates more or less closely to that of the
_Myrmecophagidæ_. The humerus generally has an entepicondylar foramen;
and the form and relations of the bones of the feet differ considerably
from those obtaining in the type genus. _S. leptocephalum_, the type of
the genus, occurs in Patagonia and Argentina but other species are found
in Brazil and Chili. The genus _Mylodon_, in its widest sense, may be
taken to include a number of comparatively large Edentates, some of which
have been described under the names of _Grypotherium_, _Lestodon_, and
_Pseudolestodon_. The teeth of the upper jaw are generally of an oval or
subtriangular section; and in the more typical forms the first and second
teeth are separated by a short interval, the former being horizontally
worn. In other species, however, like _M. (Lestodon) armatus_, there is
a considerable space between the first and second teeth, and the first
is worn obliquely. The skull is exceedingly like that of the Sloths in
general contour; and there is not the descending process at the angle of
the mandible found in _Megatherium_. The humerus has no entepicondylar
foramen. The species represented in Fig. 63 is from the Pleistocene of
South America; but the type of the genus is _M. harlani_, from beds
of corresponding age in Kentucky. The Patagonian _M. (Grypotherium)
darwini_ is a remarkable form, characterised by the presence of a
bony arch connecting the premaxillæ with the nasals, of which, as
already mentioned, there is an incomplete development in _Megatherium_.
_Megalonyx_, from the Pleistocene of Kentucky, differs from _Mylodon_ by
the long interval between the first and second teeth, and also by the
presence of an entepicondylar foramen in the humerus. _Nothrotherium_
is a smaller form, occurring in the deposits of the Brazilian caves, of
which the dental features have been already mentioned. The osteological
characters of these and other allied genera have been fully described
in the works of Cuvier, Owen, Burmeister, Leidy, Ameghino, Gervais,
Reinhardt, and others.
[Illustration: FIG. 63.—Skeleton of _Mylodon robustus_ (Pleistocene,
South America). From Owen.]
_Promegatherium._—Two genera from the infra-Pampean beds of Argentina,
described as _Promegatherium_ and _Promylodon_, are respectively
distinguished from _Megatherium_ and _Mylodon_ by the presence of bands
of enamel on the teeth, which points to the descent of the Edentates from
mammals with enamelled teeth.
The Tertiary North American forms described as _Moropus_ and
_Morotherium_,[98] and originally regarded as Edentates, would appear to
be aberrant Ungulates.
_Family_ MYRMECOPHAGIDÆ.
Externally clothed with hair. No teeth. Head elongated. Mouth tubular,
with a small terminal aperture, through which the long, vermiform tongue,
covered with the viscid secretion of the enormous submaxillary glands,
is rapidly protruded in feeding, and withdrawn again with the adhering
particles of aliment, which are then sucked into the pharynx. Clavicles
rudimentary. In the manus, the third toe is greatly developed, and has
a long falcate claw, the others are reduced or suppressed. The pes has
four or five subequal digits with claws. Posterior dorsal and lumbar
vertebræ, with additional interlocking zygapophyses. Tail long, sometimes
prehensile. Uterus simple. Placenta dome-like or discoidal. Brain fairly
convoluted, and with a large corpus callosum and anterior commissure.
The animals of this family are the “Anteaters” _par excellence_. They
feed exclusively on animal substances, mostly insects. One species is
terrestrial, the others arboreal; none burrow in the ground. They are all
inhabitants of the Neotropical region.
The reproductive organs, as noticed on p. 181, are of the same general
type as in the _Bradypodidæ_.
_Myrmecophaga._[99]—Skull greatly elongated and narrow, its upper
surface smooth and cylindriform. Anteriorly the face is produced into a
long, tubular rostrum, rounded above and flattened below, with terminal
nares, and composed of the mesethmoid ossified for more than half its
length, the vomer, the maxillæ, and the long and narrow nasal bones,
the premaxillæ being extremely short and confined to the margin of the
anterior nares. The zygomatic arch is incomplete, the styliform jugal
only articulating with the maxilla in front, and not reaching to the
very short zygomatic process of the squamosal. The lachrymal foramen is
in front of the margin of the orbit. There are no postorbital processes
to the frontals, or any other demarcation between the orbits and the
temporal fossæ. Palate extremely elongated, and produced backwards as
far as the level of the external auditory meatus by the meeting in
the middle line of the largely developed pterygoids. The glenoid fossa
a shallow oval facet, with its long diameter from before backwards.
Mandible very long and slender with an exceedingly short symphysis, no
distinct coronoid process, and a slightly elevated, elongated, flattened,
condylar articular surface. Vertebræ: C 7, D 15-16, L 3-2, S 6, C 31.
Clavicles rudimentary. In the manus the first digit is very slender, the
second also slender, with compressed phalanges of nearly equal length.
The third digit is immensely developed; though its proximal phalanx is
extremely short, its ungual phalanx is so long that the entire length of
the digit exceeds that of the second. The fourth has a long and rather
slender metacarpal, and three phalanges diminishing in size, the ungual
phalanx being very small. The fifth has the metacarpal nearly as long,
but not so stout, as the fourth, and followed by two small phalanges, the
last rudimentary and conical. Claws are developed upon all but the fifth.
In walking the toes are kept strongly flexed, and have their points
turned upwards and inwards, the weight being supported upon a callous pad
over the end of the fifth digit, and by the dorsal surfaces of the third
and fourth digits. The hind feet are short and rather broad, with five
subequal claws, the fourth the longest, the first shortest; the whole
sole is placed on the ground in walking. Body rather compressed, clothed
with long, coarse hair. Tail about as long as the body, and covered with
very long hair; not prehensile. Ears small, oval, erect. Eyes very small.
Stomach consisting of a subglobular, thin-walled, cardiac portion, and
a muscular pyloric gizzard with dense epithelial lining. No ileo-colic
valve, and a short wide ill-defined cæcum. Mammæ two, pectoral.
There is one species,[100] _M. jubata_, the Great Anteater, or Ant Bear
(Fig. 64), measuring 4 feet in length without the tail, and upwards of
2 feet in height at the shoulder. Its prevailing colour is gray, with
a broad black band, bordered with white, commencing on the chest, and
passing obliquely over the shoulder, diminishing gradually in breadth
as it approaches the loins, where it ends in a point. It is extensively
distributed in the tropical parts of South and Central America,
frequenting low swampy savannas along the banks of rivers, and the depths
of the humid forests, but is nowhere abundant. Its food consists mainly
of termites, to obtain which it opens their nests with its powerful sharp
anterior claws, and as the insects swarm to the damaged part of their
dwelling, it draws them into its mouth by means of its long, flexible,
rapidly-moving tongue covered with glutinous saliva. The Great Anteater
is quite terrestrial in its habits, being never known to climb trees,
nor does it burrow underground like the Armadillos. Though generally an
inoffensive animal, when attacked it can defend itself vigorously and
effectively with its sabre-like anterior claws. The female bears but a
single young at a birth.
The union of the pterygoids in the middle line to prolong the narial
passage is a character found elsewhere among existing mammals only in the
next genus, in one Armadillo (_Tatusia_), and in certain Cetacea. The
contrast in length between the skull of the Great Anteater and that of
the Sloth is, as Professor Parker observes, very marked indeed; the one
being relatively the longest and the other almost the shortest in the
whole class. The small size and incomplete development of the jugal bone
in the zygomatic arch affords another striking contrast to the Sloths
(Fig. 59).
[Illustration: FIG. 64.—The Great Anteater (_Myrmecophaga jubata_). (From
Sclater, _List of Animals in Zoological Society’s Gardens_, 1883, p.
190.)]
_Tamandua._[101]—This genus closely resembles the last in anatomical
structure, but the head is much less elongated, the fur is short and
bristly, the tail tapering, prehensile, with the under side throughout
and the whole of the terminal portion naked and scaly. The stomach is
similar to that of _Myrmecophaga_, but with the muscular pyloric gizzard
not quite so strongly developed. There is a distinct ileo-colic valve and
a short globular cæcum. The fore foot has a very large claw on the third
toe, moderate-sized claws on the second and fourth, a very minute one on
the first, and none on the fifth, which is entirely concealed within the
skin. The hind foot has five subequal claws. Vertebræ: C 7, D 17, L 2, S
5, C 37. There are very rudimentary clavicles.
[Illustration: FIG. 65.—Tamandua Anteater (_Tamandua tetradactyla_). From
_Proc. Zool. Soc._ 1871, pl. xliii.]
The Tamandua (Fig. 65) is much smaller than the Great Anteater, and
differs essentially from it in its habits, being mainly arboreal. It
is an inhabitant of the dense primeval forests of South and Central
America. As different individuals vary much in their coloration, it is
possible that there may be more than one species. The usual colour is
yellowish-white, with a broad black lateral band, covering nearly the
whole of the side of the body.
[Illustration: FIG. 66.—Cæca of the Two-toed Anteater (_Cycloturus
didactylus_). _i_, Ileum; _c_, colon.]
_Cycloturus._[102]—The skull is much shorter even than in _Tamandua_, and
is arched considerably in the longitudinal direction. It differs from
that of the other members of the family mainly in the long canal for
the posterior nares not being closed by bone below, as the greater part
of the palatines and the pterygoids do not meet in the middle line. The
mandible has a prominent, narrow, recurved coronoid, and a well-developed
angular process; it is strongly decurved in front. Vertebræ: C 7, D 16, L
2, S 4, C 40. Ribs remarkably broad and flat. Clavicles well developed.
Manus remarkably modified, the third digit being greatly developed at the
expense of all the others, and having a stout short metacarpal and but
two phalanges, of which the most distal is large, compressed, pointed,
and much curved, and bears a very strong hook-like claw. The second digit
has the same number of phalanges, and bears a claw, but is very much more
slender than the third. The fourth is represented only by the metacarpal
and one nailless phalanx, the first and fifth only by very rudimentary
metacarpals. The pes is also completely modified into a climbing organ.
The hallux is rudimentary, consisting of a metatarsal and one phalanx,
concealed beneath the skin; but the other four toes are subequal and
much curved, with long pointed compressed claws. The tuber calcanei is
directed towards the plantar surface, and parallel with it and extending
to about double its length is a greatly elongated sesamoid ossicle.
These together support a prominent calcarine cushion, to which the nails
are opposed in climbing. Stomach pyriform, with muscular walls, but no
distinct gizzard-like portion, as in the foregoing genera. Commencement
of the colon provided with two small cæca (Fig. 66), resembling those
of many birds, narrow at the base, and rather dilated at their terminal
blind ends, and communicating with the general cavity by very minute
apertures. Tail longer than the body, tapering, bare on the under
surface, and very prehensile. Fur soft and silky.
This genus has also but one species certainly known, the Little or
Two-toed Anteater (_C. didactylus_), an animal not larger than a Rat, of
a general yellowish-colour, and exclusively arboreal in its habits. It is
a native of the hottest parts of South and Central America.
_Family_ DASYPODIDÆ.
The greater part of the skin strongly ossified. On the back and sides
the union of numerous quadrate or polygonal scutes forms a hard shield,
usually consisting of an anterior (scapular) and posterior (pelvic)
solid portion (which overhang on each side the parts of the body they
respectively cover, forming chambers into which the limbs are withdrawn),
and a variable number of rings between, connected by soft flexible skin
so as to allow of curvature of the body. The top of the head has also a
similar shield (cephalic), and the tail is usually encased in bony rings
or plates. The outer or exposed surfaces of the limbs are protected by
irregular bony scutes, not united at their margins; but the skin of the
inner surface of the limbs and under side of the body is soft, and more
or less clothed with hair. Hairs also in many species project through
apertures between the bony scutes of the back. The ossified dermal scutes
are everywhere covered by a layer of horny epidermis. Teeth numerous,
simple, of persistent growth, and usually monophyodont, but in one
genus (_Tatusia_) a succession of teeth has been observed. Zygomatic
arch of skull complete. Cervical vertebræ with extremely short, broad,
and depressed bodies. The atlas free, but the second and third, and
often several of the others, ankylosed together both by their bodies
and arches. Lumbar vertebræ with accessory zygomatic processes, and
very large metapophyses, supporting the bony carapace. Clavicles well
developed. A third trochanter on the femur. Tibia and fibula ankylosed
at their distal extremities. Fore feet with strongly developed, curved
claws, adapted for digging and scratching—three, four, or five in
number. Hind feet plantigrade, with five toes, all provided with nails.
Tongue long, pointed, and extensile, though to a less degree than in
the Anteaters. Submaxillary glands largely developed. Stomach simple.
Uterus simple. Placenta discoidal, deciduate. The brain is generally
characterised by the large size of the olfactory lobes (Fig. 57), and the
slight development of sulci on the hemispheres; the sylvian fissure being
represented only by a very open and shallow angle. From the earliest
stage of development the stapes is stirrup-shaped, thus showing a nearer
affinity to the higher mammals than is presented by the Sloths.
The animals of this family are commonly called Armadillos, a word
of Spanish origin, having reference to their armour-like covering.
The existing species are all of small or moderate size. They are
mostly, though not universally, nocturnal in their habits, and are all
omnivorous, feeding on roots, insects, worms, reptiles, and carrion.
Armadillos are harmless and inoffensive creatures, offering no resistance
when caught, their principal means of escape from their enemies being
the extraordinary rapidity with which they can burrow in the ground, and
the tenacity with which they retain their hold in their subterranean
retreats. Notwithstanding the shortness of their limbs they can run with
great rapidity. Most of the species are esteemed good eating by the
natives of the countries in which they live. They are all inhabitants
of the open plains or the forests of the tropical and temperate
parts of South America, with the exception of one species (_Tatusia
novemcincta_), which ranges as far north as Texas. Of the existing
genera, _Chlamydophorus_ stands apart from the rest in the formation
of its external covering; but in all other respects _Tatusia_ is the
most aberrant form, exhibiting a peculiar type of structure of the fore
feet, which in all the others show modifications, though in very varying
degrees, of a single and different type.
The reproductive organs of the _Dasypodidæ_ differ from those of the
Sloths and Armadillos in the presence of a largely developed copulating
organ in the male, and of a simple vagina of corresponding length in
the female. The testes are still abdominal, although not in the same
position; and the penis still wants both the glans and bulb. The uterus
is nearly or quite as simple as in the Sloths and Anteaters; and there is
no reason to believe that the placentation is essentially different from
that obtaining in the other groups.
Subfamily =Chlamydophorinæ=.—In most anatomical characters, especially
the structure of the fore foot, this little group resembles the
_Dasypodinæ_; but it differs remarkably from all other known Armadillos,
living or extinct, in the peculiar modification of the dermal armour.
_Chlamydophorus._[103]—Teeth ⁸⁄₈₋₉, subcylindrical, somewhat compressed,
moderate in size, smaller at each end (especially in front) than at
the middle of the series. Skull broad and rounded behind, pointed in
front. Muzzle subcylindrical and depressed. A conspicuous rounded,
rough prominence on the frontal bone, just before each orbit. Tympanic
prolonged into a tubular auditory meatus, curving upwards round the base
of the zygoma. Vertebræ: C 7, D 11, L 3, S 10, C 15. Upper part of head
and trunk covered with four-sided horny plates (with very small thin
ossifications beneath), forming a shield, free, and overhanging the
sides of the trunk, and attached only along the middle line of the back.
The plates are arranged in a series of distinct transverse bands, about
twenty in number between the occiput and the posterior truncated end, and
not divided into solid thoracic and pelvic shields with movable bands
between. The hinder end of the body is abruptly truncated and covered by
a vertically-placed, strong, solid, bony shield, of an oval (transversely
extended) form, covered by thin epidermic plates. This shield is firmly
ankylosed by five bony processes to the hinder part of the pelvis.
Through a notch in the middle of its lower border the tail passes out.
The latter is rather short, cylindrical in its proximal half, and
expanded and depressed or spatulate in its terminal portion, and covered
with horny plates. The dorsal surfaces of the fore and hind feet are also
covered with horny plates. The remainder of the limbs and under surface
and sides of the body beneath the overlapping lateral parts of the dorsal
shield are clothed with rather long, very soft, silky hair. Eyes and ears
very small, and concealed by the hair. Extremities short. Feet large,
each with five well-developed claws, those on the fore feet very long,
stout, and subcompressed, the structure of the digits being essentially
the same as those of _Xenurus_ and _Priodon_. Nipples two, pectoral.
Visceral anatomy closely resembling that of _Dasypus_, the cæcum being
broad, short, and bifid.
The Pichiciago (_C. truncatus_), a small burrowing animal, about 5 inches
long, inhabits the sandy plains of the western part of the Argentine
Republic, especially the vicinity of Mendoza. Its horny covering is of
a pinkish colour, and its silky hair snow white. It is rare, and its
habits are but little known. A second species, _C. retusa_, from Bolivia,
has been described by Burmeister. It is of rather larger size, and has
the dorsal shield attached to the skin of the back as far as its edge,
instead of only along the median line.
Subfamily =Dasypodinæ=.—Fore feet usually with all five digits developed
and with nails, though the first and fifth may be suppressed. The
first and second long and slender, with the normal number and relative
length of phalanges. The others stout, with short broad metacarpals,
and the phalanges greatly reduced in length and generally in number
by coalescence. The ungual phalanx of the third very large, that of
the others gradually diminishing to the fifth. _Dasypus_, as now
restricted, has the most normal form of manus, but the modifications so
markedly developed in all the others (and culminating in _Tolypeutes_)
are foreshadowed, as it were, in it. Ears wide apart. Mammæ one pair,
pectoral.
_Dasypus._[104]—Teeth ⁹⁄₁₀ or ⁸⁄₉, of which the anterior in the upper
jaw is usually implanted in the premaxillary bone. The series of teeth
extends posteriorly some distance behind the anterior root of the
zygoma, almost level with the hinder edge of the palate. They are large,
subcylindrical, slightly compressed, diminishing in size towards each
end of the series; the anterior two in the mandible much smaller, and
more compressed than the others. Cranial portion of the skull broad and
depressed. Facial portion triangular, broad in front and much depressed.
Auditory bulla completely ossified, perforated on the inner side by the
carotid canal, and continued externally into an elongated bony meatus
auditorius, with its aperture directed upwards and backwards. (In all the
remaining genera of _Dasypodinæ_ the tympanic bone is a mere half ring,
loosely attached to the cranium.) Mandible with a high ascending ramus,
broad transversely-placed condyle, and high slender coronoid process.
Vertebræ: C 7, D 11-12, L 3, S 8, C 17-19. Head broad and flat above.
Muzzle obtusely pointed. Ears of moderate size or rather small, placed
laterally, far apart. Body broad and depressed. Carapace with six or
seven movable bands between the scapular and pelvic shields, each plate,
or scute, being marked by a regular ellipse formed of widely separated
punctures. Tail shorter than the body, tapering, covered with plates
forming distinct rings near the base. Fore feet with five toes; the first
much more slender than the others, and with a smaller ungual phalanx and
nail; the second, though the longest, also slender. The third, fourth,
and fifth gradually diminishing in length, all armed with very strong,
slightly curved, compressed claws, sloping away from an elevated rounded
inner border to a sharp, outer, and inferior edge. The hind foot rather
short, with all five toes armed with stout, compressed, slightly curved,
obtusely pointed claws—the third the longest, the second nearly equal to
it, the fourth the next, the first and fifth shorter, and nearly equal.
To this genus belongs one of the best known-species of the group, the
Six-banded Armadillo or Encoubert (_D. sexcinctus_) of Brazil and
Paraguay. A very similar species, _D. villosus_, the Hairy Armadillo,
replaces it south of the Rio Plata. There are also two very small
species—_D. vellerosus_, from the Argentine Republic and North Patagonia,
and _D. minutus_ from La Plata. The latter differs from the other three
in having no tooth implanted in the premaxillary bone. Remains apparently
referable to _D. villosus_ occur in the Pleistocene cavern-deposits of
Brazil.
_Xenurus._[105]—Teeth ⁹⁄₉ or ⁸⁄₈, of moderate size and subcylindrical.
The most posterior placed a little way behind the anterior root of the
zygoma, but far from the hinder margin of the palate. Cranium somewhat
elongated, much constricted behind the orbits, and immediately in front
of the constriction considerably dilated. Mandible slender; coronoid
process very small and sharp-pointed, sometimes obsolete. Vertebræ: C
7, D 12-13, L 3, S 10, C 18. Head broad behind. Ears rather large and
rounded, wide apart. Movable bands of carapace 12-13; the scutes being
marked by an obscurely granular sculpture. Tail considerably shorter
than the body, slender, and covered with nearly naked skin, with but a
few small, scattered, dermal bony plates, chiefly on the under surface
and near the apex. On the fore feet the first and second toes are long
and slender, with small claws and the normal number of phalanges; the
other toes have but two phalanges; the third has an immense falcate
claw; the fourth and fifth similar but smaller claws. The hind feet are
comparatively small, with five toes, bearing small, triangular, blunt
nails; the third longest, the first shortest. The best known species of
this genus, the Tatouay or Cabasson, _X. unicinctus_, is, after _Priodon
gigas_, the largest of the group. It is found, though not abundantly, in
Surinam, Brazil, and Paraguay, its remains occurring in the Pleistocene
cavern-deposits of Brazil. Others, _X. hispidus_ and _lugubris_, have
been described, but little is as yet known of them.
_Priodon._[106]—Teeth variable in number, and generally differing on
the two sides of each jaw, usually from 20 to 25 on each side above and
below, so that as many as 100 may be present altogether; but as life
advances the anterior teeth fall out, and all traces of their alveoli
disappear. The series extends as far back as the hinder edge of the
anterior root of the zygoma. The teeth are all very small; those in the
anterior half of each series being strongly compressed, with flat sides
and a straight free edge; the posterior ones are more nearly cylindrical,
with flat truncated, free surfaces. Vertebræ: C 7, D 12, L 3, S 10, C
23. Head small, elongated, conical. Ears moderate, ovate. Carapace with
12-13 movable bands. Tail nearly equal to the body in length, gradually
tapering, closely covered with quadrangular scales, arranged in a
quincunx pattern. Fore feet with five toes, formed on the same plan as
those of _Xenurus_, but with the claw of the third of still greater size,
and that of each of the others, especially the fifth, proportionately
reduced. Hind foot short and rounded, with five very short toes, with
short, broad, flat, obtuse nails. The only known species, the Great
Armadillo (_P. gigas_), is by far the largest of existing members of the
family, measuring rather more than 3 feet from the tip of the nose to the
root of the tail, the tail being about 20 inches long. It inhabits the
forests of Surinam and Brazil. The powerful falcate claws of its fore
feet enable it to dig with great facility. Its food consists chiefly
of termites and other insects, but it is said to attack and uproot
newly-made graves for the purpose of devouring the flesh of the bodies
contained in them.
_Tolypeutes._[107]—Teeth ⁹⁄₉ or ⁸⁄₉, rather large in proportion to the
size of the skull, the hinder end of the series reaching nearly to the
posterior margin of the palate. Vertebræ: C 7, D 11, L 3, S 12, C 13.
Ears placed low on the sides of the head, rather large, broadly ovate.
Carapace with its scapular and pelvic shields very free at the sides of
the body, forming large chambers into which the limbs can be readily
withdrawn. Only three movable bands; sculpture of scutes in the form
of subconcentrically arranged granules. Tail short, conical, covered
with large bony tubercles. The fore feet formed on the same type as in
the last genus, but the peculiarities carried out to a still greater
extent. The claw of the third toe is very long and falcate, the first and
fifth greatly reduced and sometimes wanting. On the hind foot the three
middle toes have broad, flat, subequal nails, forming together a kind of
tripartite hoof; the first and fifth much shorter, with more compressed
nails.
The Armadillos of this genus have the power of rolling themselves up into
a perfect ball, the shield on the top of the head and the tuberculated
dorsal surface of the tail exactly fitting into and filling up the
apertures left by the notches at either end of the carapace. This
appears to be their usual means of defence when frightened or surprised,
as they do not burrow like the other species. They run very quickly,
with a very peculiar gait, only the tips of the claws of the fore feet
touching the ground. Three species are described:—_T. tricinctus_, the
Apar; _T. conurus_, the Matico; and _T. muriei_. Remains apparently
referable to _T. conurus_ are of not uncommon occurrence in the Brazilian
cavern-deposits.
Subfamily =Tatusiinæ=.—This group contains but one genus, _Tatusia_.[108]
Teeth ⁸⁄₈ or ⁷⁄₇, very small subcylindrical. The first and second
subcompressed, the last considerably smaller than the others. They
present the remarkable peculiarity (elsewhere found among Edentates,
so far as is yet known, only in _Orycteropus_) of all being, with the
exception of the last, preceded by two-rooted milk teeth, which are not
changed until the animal has nearly attained its full size. Vertebræ:
C 7, D 9-11, L 5, S 8, C 20-27. Head narrow, with a long, narrow,
subcylindrical, obliquely-truncated snout; pterygoids meeting in the
middle line below the nasal passage. Ears rather large, ovate, and
erect, placed close together on the occiput. Carapace with seven to nine
distinct movable bands; sculpture on scutes consisting of pits arranged
in a V-shape. Body generally elongated and narrow. Tail moderate or long,
gradually tapering; its dermal scutes forming very distinct rings for
the greater part of its length. Fore feet with four visible toes, and
a concealed clawless rudiment of the fifth. Claws all long, slightly
curved, and very slender, the third and fourth subequal and alike, the
first and fourth much shorter. Hind feet with five toes, all armed with
strong, slightly curved, conical, obtusely-pointed nails. The third
longest, then the second and fourth; the first and fifth much shorter
than the others.
[Illustration: FIG. 67.—The Peba Armadillo (_Tatusia novemcincta_).]
This genus differs from all the other Armadillos in having a pair of
inguinal mammæ, in addition to the usual pectoral pair, and in producing
a large number (four to ten) of young at a birth, all the others having
usually but one or two.
The Peba Armadillo, _T. novemcincta_ (Fig. 67), is a well-known species,
having an extensive range from Texas to Paraguay. It is replaced in the
more southern regions of South America by a smaller species, with shorter
tail, the Mulita (_T. hybrida_), so called from the resemblance of its
head and ears to those of a mule. _T. kappleri_ is a large species from
Surinam.
A rare Armadillo from Peru described under the names of _Cryptophractus
pilosus_ and _Praopus hirsutus_, but which evidently belongs to
_Tatusia_, is of some interest owing to the thick coat of hair with
which it is covered. This animal appears to be closely allied to _T.
novemcincta_, from which it mainly differs by having the whole of the
carapace covered with a thick coating of light brown, fine, but rather
stiff hair, about an inch and a half in length. Similar hair is found
on the cheeks, the proximal portions of the limbs, and (although less
abundantly and shorter) on the under surface of the body. The cephalic
shield, snout, feet, and the tail, with the exception of the root, are
bare. The coating of hair on the back and sides completely conceals
the carapace, except near the margin of the scapular region; but by
separating the hairs the bands and scutes are rendered visible.[109]
In the Pleistocene cavern-deposits of Brazil have been found remains
of _T. novemcincta_, and also of _T. punctata_, which appears to be an
extinct form nearly allied to _T. kappleri_, but of somewhat larger size.
_Extinct genera._—In addition to remains referable to existing genera,
the above-mentioned deposits have also yielded evidence of the former
existence of extinct generic types of Armadillos, some of which attained
very large dimensions. Of these _Eutatus_ was a large form distinguished
from all existing genera by the circumstance that the whole of the
carapace was composed of movable bands, which were thirty-three in
number. _Dasypotherium_ was a still larger form, furnished with eight
teeth, of which the second seems to have been larger than the others;
this genus is regarded as connecting the modern Armadillos with the next
one. The gigantic _Chlamydotherium_, the scutes of which are common in
the Brazilian caves, is considered to have been as large as a Rhinoceros;
the carapace has several movable bands, but the teeth approximate in
structure to those of the next family, so that the genus tends to connect
the Armadillos with the Glyptodonts.
_Family_ GLYPTODONTIDÆ.
[Illustration: FIG. 68.—Tooth of _Glyptodon_ from the side, and from the
grinding surface. (After Owen.)]
In the Pleistocene cavern-deposits of Brazil, but still more abundantly
in the fluviatile deposits which cover the country in the neighbourhood
of Buenos Ayres, are found the remains of some of the most remarkable
forms of mammals yet discovered, the Glyptodonts, which may be regarded
as forming a separate extinct family. They differ from the existing
_Dasypodidæ_ in their large size, and in having the carapace composed of
a solid piece (formed by the union of a multitude of bony dermal scutes)
without any movable rings, and in usually having also a ventral piece or
plastron. The facial portion of the skull is very short. A long process
of the maxillary bone descends from the anterior part of the zygomatic
arch. The ascending ramus of the mandible is remarkably high. The teeth
are ⁸⁄₈ in the known species, all much alike, having two deep grooves or
flutings on each side, so as to divide them into three nearly distinct
lobes (Fig. 68). The vertebral column is almost entirely ankylosed into
a solid tube, and there is a complex joint at the base of the neck, to
allow of the head being retracted within the carapace. The limbs are
very strong, and the feet short and broad, resembling externally those
of an elephant or tortoise. This family is mainly characteristic of the
southern half of the American continent, but some species of the type
genus ranged into Texas and Mexico. Many species of the family have
been described and figured, especially by Burmeister (in the _Annales
del Museo publico de Buenos Aires_), among which the following may be
noticed. _Hoplophorus_ is characterised by the sculptured and frequently
thin scutes of the carapace, those of the periphery being flat, and
not raised into prominences. The caudal sheath has several overlapping
movable rings at the base, and ends in a long subcylindrical terminal
tube similar to the one represented with the carapace of _Glyptodon_
in Fig. 69, which in all probability really belongs to the genus under
consideration. Each foot has four complete digits, and the humerus has
an entepicondylar foramen. Most of the species are of medium size. Part
of a caudal tube from Uruguay described as _Eleutherocercus_ indicates,
however, a much larger allied form, in which the tail appears to have
had a number of stout bristles protruding from the joints between the
scutes. _Panochthus_ comprises very large Glyptodonts, distinguished by
the great thickness of the scutes of the carapace, which are ornamented
with tubercles. The termination of the caudal sheath forms a tube bearing
large radiated tubercles. _Euryurus_ is distinguished by the radiate
sculpture of the scutes of the carapace. _Dœdicurus_, of which one
species was about twelve feet in length, also has a rugose sculpture
on the carapace; but the termination of the caudal tube is expanded
into a club-like shape, flattened from above downwards, and covered
with tubercles mingled with a few large radiate discs, which, as in
_Panochthus_, probably carried horny spines in the living condition. The
typical genus _Glyptodon_ has each scute of the carapace ornamented with
a rosette-like sculpture, the peripheral scutes being raised into conical
prominences (Fig. 69). The caudal sheath, instead of being like the one
represented in the figure, was entirely composed of a series of movable
rings, ornamented with large tubercles. The manus had five digits, and
the pes four; and there was an entepicondylar foramen to the humerus. A
species of this genus, which attained very large dimensions, was made the
type of _Schistopleurum_, on the supposition that the tail of _Glyptodon_
was of the type represented in Fig. 69. The genus _Thoracophorus_,
of the Pleistocene of South America, as well as _Carioderma_, of the
Pliocene of Texas, differ from all the preceding in having the scutes of
the carapace in the form of disconnected nodules. Glyptodonts also occur
in South American beds of earlier age than the Pleistocene, some of these
forms having enamel bands on the teeth. “Why such a form as the Glyptodon
should have failed to keep his ground is,” as the late Professor W. K.
Parker remarks, “a great mystery; nature seems to have built him, as Rome
was built, for eternity.”
[Illustration: FIG. 69.—_Glyptodon clavipes_ (Pleistocene, South
America). From Owen. The tail is incorrectly restored, and it is probable
that the figured portion belongs to _Hoplophorus_. The left lower corner
shows an upper and a lower view of the skull, and the right a section of
the caudal sheath.]
_Family_ MANIDÆ.
Covered externally (except the under surface of the body and inside
of the limbs) with large imbricated horny scales, and scattered
hairs growing in the intervals. No teeth. Tongue long, vermiform,
and protractile. No accessory articular processes to the lumbar
vertebræ, but the anterior zygapophyses largely developed and deeply
concave, completely embracing the semicylindrical surfaces of the
posterior zygapophyses. Limbs short, with five complete digits on each
foot. Scaphoid and lunar bones of carpus united. Uterus bicornuate.
Placenta diffused and non-deciduate. All the existing forms belong to
the Ethiopian and Oriental regions of the Old World. The absence of
additional articular processes to the lumbar vertebræ is a character in
which this and the following family differ from all the preceding forms.
_Manis._[110]—Skull somewhat of the form of an elongated cone, with the
small end turned forwards; very smooth and free from crests and ridges.
No distinction between the orbits and temporal fossæ. The zygomatic arch
usually incomplete, owing to the absence of the jugal bone. No distinct
lachrymal bone. Palate long and narrow. The pterygoids extend backwards
as far as the tympanics, but do not meet in the middle line below.
Tympanic ankylosed to the surrounding bones, and more or less bullate,
but not produced into a tubular auditory meatus. Rami of mandible very
slender and straight, without any angle or coronoid process. From near
the anterior extremity of the upper edge a sharp, conical, tooth-like
process projects upwards and outwards. No clavicles. No third trochanter
to the femur. Ungual phalanges bifid at their terminations. Caudal
vertebræ with very long, strong transverse processes and numerous
chevron bones. Tongue long, vermiform, flattened towards the tip; its
retractor or sterno-glossal muscles arising from the hinder extremity
of the immensely prolonged ensiform cartilage of the sternum. Stomach
with thick lining membrane and muscular walls, and a special gland near
the middle of the great curvature, consisting of a mass of complex
secreting follicles, the ducts of which terminate in a common orifice.
No cæcum. A gall-bladder. Head small, depressed, narrow, pointed in
front, with a very small mouth-opening. Eyes and pinna of ear very small.
Body elongated, narrow. Tail more or less elongated, convex above,
flat underneath. The whole of the upper surface of the head, the upper
surface and sides of the body, the whole of the tail, and the outer sides
of the extremities covered with large, overlapping, horny scales, but
usually with a few stiff hairs growing between and projecting beyond
them. The sides and under surface of the head, the under surface of the
body, and the inner sides of the limbs without scales, but with a rather
scanty covering of hair. Limbs short. In walking the dorsal surface and
outer sides of the phalanges of the two outer digits of the front feet
alone rest on the ground, the points of the nails turning upwards and
inwards. The third toe the longest, with a powerful compressed curved
claw; the second and fourth with similar but smaller claws, that of the
pollex often almost rudimentary. Hind feet plantigrade, with the hallux
very short, and the four other toes subequal, with moderate, curved,
subcompressed nails.
The reproductive organs of _Manis_ are of a totally different type from
those of the families already noticed. The testes lie in the inguinal
canal; and the penis is external and well developed. The uterus is
truly bicornuate, the vagina not divided, and the placenta diffused and
non-deciduate. All the organs and fœtal membranes are, indeed, formed
very much on the plan of those of the Ungulates, without any trace of the
special peculiarities obtaining in the typical American Edentates.
The animals of this genus, which includes all the existing forms, are
called Pangolins or Scaly Anteaters, and are all of small or moderate
size, terrestrial and burrowing, and feed mainly on termites. Several
of them can climb trees. Their length varies from 1 to 5 feet. They can
roll themselves up in a ball when in danger. Their peculiar elongated
form, short limbs, long, gradually-tapering tail, and scaly covering give
them on a superficial inspection more the appearance of reptiles than of
mammals. The species are not numerous, and may be divided into two groups
distinguished by a few not very important external characters; these
groups also coinciding with the present geographical distribution of the
genus. These two groups, according to Mr. O. Thomas, may be distinguished
as follows.
The Asiatic pangolins are characterised by having the central series of
body-scales continued quite to the extreme end of the tail, by having
many isolated hairs growing up between the scales of the back, and by
their small external ears. They all have a small naked spot beneath
the tip of the tail, which is said to be of service as an organ of
touch. There are three species, viz. _Manis javanica_, ranging from
Burma, through Malacca and Java, to Borneo; _M. aurita_, found in China,
Formosa, and Nipal; and the common Indian Pangolin, _M. pentadactyla_,
distributed over the whole of India and Ceylon. The African species have
the central series of scales suddenly interrupted and breaking into
two at a point about 2 or 3 inches from the tip of the tail; they have
no hair between the scales, and no external ear-conch. The following
are the four species belonging to this group:—the Long-tailed Pangolin
(_M. macrura_), which has a tail nearly twice as long as its body, and
containing as many as forty-nine caudal vertebræ, being the largest
number known among mammals; the White-bellied Pangolin (_M. tricuspis_),
Fig. 70, closely allied to the last, but with longer and tricuspid
scales, and white belly hairs. These two, like the Indian species, have
a naked spot beneath the tail tip, a character probably correlated with
the power of climbing, and they are, moreover, peculiar in having the
outer sides of their fore legs clothed with hair, all the other species
being scaly there as elsewhere. Lastly, the Short-tailed and the Giant
Pangolins (_M. temmincki_ and _gigantea_), both of which have their
tails covered entirely with scales, and evidently never take to arboreal
habits. All the four species of the second group are found in the West
African region, one only, _M. temmincki_, extending also into south and
eastern equatorial Africa.
[Illustration: FIG. 70.—The White-bellied Pangolin (_Manis tricuspis_).]
According to Professor W. K. Parker,[111] who remarks upon the peculiarly
aberrant nature of the group, the horny scales of the Pangolins really
consist of cemented hairs. This writer states that “in the early embryo
lozenge-shaped tracts of skin are seen all over its body, with lines of
thinner cuticle between. Under the microscope, sections of these thicker
tracts show that they are composed of fine hairs, cemented together by a
copious growth of epidermic cells; here and there larger hairs are seen,
but these fail to reach the surface, turning again towards the inside,
like nails driven into wood that is too hard for their points.”
The same author also observes[112] that there are occasional instances of
the presence of eight cervical vertebræ in the Pangolins—a feature which
has been considered to indicate some former genetic connection between
this family and the Sloths.
The following account of the habits of _Manis tricuspis_ is given by Mr.
L. Fraser in his _Zoologia Typica_:—
“During my short residence at Fernando Po I succeeded in procuring two
living specimens of this animal. The individuals, judging from the bones,
were evidently not adult; the largest measured 30 inches in length,
of which the head and body were 12 inches and the tail 18 inches. I
kept them alive for about a week at Fernando Po, and allowed them the
range of a room, where they fed upon a small black ant, which is very
abundant and troublesome in the houses and elsewhere. Even when first
procured they displayed little or no fear, but continued to climb about
the room without noticing my occasional entrance. They would climb up
the somewhat roughly hewn square posts which supported the building
with great facility, and upon reaching the ceiling would return head
foremost; sometimes they would roll themselves up into a ball and throw
themselves down, and apparently without experiencing any inconvenience
from the fall, which was in a measure broken upon reaching the ground by
the semi-yielding scales, which were thrown into an erect position by the
curve of the body of the animal. In climbing, the tail, with its strongly
pointed scales beneath, was used to assist the feet; and the grasp of
the hind feet, assisted by the tail, was so powerful that the animal
would throw the body back (when on the post) into a horizontal position,
and sway itself to and fro, apparently taking pleasure in this kind of
exercise. It always slept with the body rolled up; and when in this
position in a corner of the building, owing to the position and strength
of the scales, and the power of the limbs combined, I found it impossible
to remove the animal against its will, the points of the scales being
inserted into every little notch and hollow of the surrounding objects.
The eyes are very dark hazel, and very prominent. The colonial name for
this species of _Manis_ is ‘Attadillo,’ and it is called by the Boobies,
the natives of the island, ‘Gahlah.’ The flesh is said to be exceedingly
good eating, and is in great request among the natives.”
The Indian species is said to live in pairs, and to give birth to one or
two young at a time in the spring. Their burrow reaches a depth of some
twelve feet, and terminates in a large chamber, which may be as much as
six feet in diameter. A faint hiss appears to be the only sound emitted
by these animals.
Remains of a large species of _Manis_, which are indistinguishable from
the corresponding bones of the existing West African _M. gigantea_,
are found fossil in cave-deposits in the Karnul district of Madras.
This is one among several instances of the close connection between the
Pleistocene and Pliocene mammalian fauna of India with the existing
African fauna.
_Palæomanis._[113]—The lower Pliocene deposits of the Isle of Samos, in
the Turkish Archipelago, have yielded remains of a Pangolin fully three
times the dimensions of _M. gigantea_, upon the evidence of which the
genus _Palæomanis_ has been established.
_Family_ ORYCTEROPODIDÆ
External surface scantily covered with bristle-like hairs. Teeth
numerous, apparently heterodont, diphyodont, and of peculiar and complex
structure, being traversed by a number of parallel vertical pulp-canals.
Lumbar vertebræ with no accessory zygapophyses. Femur with a third
trochanter. Fore feet without pollex, but all the other digits well
developed, with strong moderate-sized nails, suited to digging, the
plantar surfaces of which rest on the ground in walking. Hind feet with
five subequal toes. Mouth elongated and tubular. Tongue subvermiform.
Uterus bicornuate. Placenta broadly zonular. Feeding on animal
substances. Terrestrial and fossorial in habits. Now mainly limited to
the Ethiopian region.
_Orycteropus._[114]—The total number of permanent teeth appears to be
from eight to ten in each side of the upper, and eight in the lower jaw;
but they are never all in place at one time, as the small interior teeth
are shed before the series is completed behind. In the adult they number
usually five on each side above and below, of which the first two are
simple and compressed, the next two larger and longitudinally grooved at
the sides, the most posterior simple and cylindrical. The last three in
either jaw having no milk-predecessors, may be regarded as true molars.
The structure of all these teeth is quite peculiar among mammals, though
resembling that of some fishes. Their summits are rounded before they are
worn; their bases do not taper to a root, but are evenly truncated and
continually growing. Each tooth is made up of an aggregation of parallel
dental systems, having a slender pulp-cavity in the centre, from which
the dentinal tubes radiate outwards, and being closely packed together
each system assumes a polygonal outline as seen in transverse section.
The small anterior teeth have milk-predecessors which are fully noticed
below. Skull moderately elongated. The facial portion subcylindrical
and slightly tapering. The zygoma complete and slender. The palate ends
posteriorly in the thickened transverse border of the palatines, and is
not continued back by the pterygoids. The tympanic is annular, and not
ankylosed to the surrounding bones. The mandible is slender anteriorly,
but rises high posteriorly, with a slender recurved coronoid, and an
ascending pointed process on the hinder edge below the condyle, which
is small, oval, and looks as much forwards as upwards. Vertebræ: C 7,
D 13, L 8, S 6, C 27. The large number of lumbar vertebræ is peculiar
among Edentates. Tongue less vermiform than in _Myrmecophaga_, being
thick and fleshy at the base, and gradually tapering to the apex. The
salivary apparatus is developed much in the same manner as in that genus,
but the duct of the submaxillary gland has no reservoir. The stomach
consists of a large subglobular cardiac portion, with a very thick, soft,
and corrugated lining membrane, and a smaller muscular, pyloric part,
with a comparatively thin and smooth lining. There is a very distinct
ileo-cæcal valve, and a considerable-sized cæcum; also a gall-bladder.
Head elongated, with a tubular snout, terminal nostrils, and small
mouth-opening. Ears large, pointed, erect. Tail nearly as long as the
body, cylindrical, very thick at the base, tapering to the extremity.
The reproductive organs and placentation of _Orycteropus_ are formed upon
a principle unknown in the more typical Edentates, or, in combination,
in any other mammals. Thus the testes, in the one described example,
were inguinal, but appeared to descend, at all events temporarily, into
a scrotum; but the penis is scarcely larger than that of the Great
Anteater. The uterus is still more fully bicornuate than in _Manis_,
with its two lateral chambers opening separately into the vagina, as in
certain Rodents. The placenta is broadly zonary, but it is not known
whether it is deciduate or not. It might readily be derived from the
diffused placenta of _Manis_ by the abortion of the fœtal villi at the
two poles of the ovum.
The _Orycteropodidæ_ have long been regarded as widely different from
other Edentates, their presumed affinity with the _Manidæ_ being more or
less problematical; but the discovery recently made by Mr. O. Thomas[115]
that they have a milk-dentition still further emphasises their aberrant
nature. According to this observer, it appears that there are normally
no less than seven milk-teeth in the upper jaw, the hindmost of which is
far larger than the others, having a rudimentary crown, and a distinct
anterior and posterior root. The other milk-teeth are styliform, the
four anterior ones being very minute, and separated from one another
by equal intervals; the foremost of all is situated immediately behind
the premaxillo-maxillary suture. In the mandible only four milk-teeth
have hitherto been detected, of which the hindmost has the comparatively
complex form found in the corresponding upper tooth. None of these
milk-teeth appear, however, to cut the gum, so that the whole set is
entirely functionless. Under the microscope these milk-teeth show signs
of possessing a commencement of the remarkable histological structure
found in the permanent teeth.
Mr. Thomas remarks that since “the three large posterior teeth of
_Orycteropus_, already distinguished by their more molariform shape, do
not have milk-predecessors, while all the small teeth anterior to them
do, and in addition the last milk-tooth is markedly different from those
in front of it, we ought apparently no longer to look upon this animal as
an homodont, but instead to consider it as an originally heterodont form
in which the incisors and canines have been suppressed to allow free play
to the mobile vermiform tongue.
“But important as a knowledge of the presence of a milk-dentition in
_Orycteropus_ is, it does not at present render any easier the difficult
questions as to the phylogeny and systematic position of that animal.
Although called an Edentate, it has always been recognised as possessing
many characters exceedingly different from those of the typical American
members of the order. It has in fact been placed with them rather on
account of the inconvenience of forming a special order for its reception
than because of its real relationship to them. Now, as they are either
altogether toothless, or else homodont and monophyodont (apart from the
remarkable exception of _Tatusia_), it seems more than ever incorrect
to unite with them the solitary member of the Tubulidentata, toothed,
heterodont, and diphyodont, and differing from them in addition by
its placentation, the anatomy of its reproductive organs, the minute
structure of its teeth, and the general characters of its skeleton.
“But if _Orycteropus_ is not genetically a near relation of the
Edentates, we are wholly in the dark as to what other mammals it is
allied to, and I think it would be premature to hazard a guess on the
subject. Whether even it has any special connection with _Manis_ is
a point about which there is the greatest doubt, and unfortunately
we are as yet absolutely without any palæontological knowledge of
the extinct allies of either. _Macrotherium_ even, usually supposed
from the structure of its phalangeal bones, to be related to _Manis_,
has lately proved to have the teeth and vertebræ of a perissodactyle
Ungulate, and one could not dare to suggest that ancestors of _Manis_,
or _Orycteropus_ were to be sought in that direction. Lastly, as the
numerous fossil American Edentates do not show the slightest tendency
to an approximation towards the Old World forms, we are furnished with
an additional reason for insisting on the radical distinctness of the
latter, whose phylogeny must therefore for the present remain one of the
many unsolved zoological problems.”
The Aard-Varks (Earth-Pigs) as these creatures are commonly termed,
from the name bestowed on them by the Dutch Boers of the Cape, are of
nocturnal habits, sleeping during the day in their burrows, which are
usually found in the neighbourhood of the tall hills or mounds made by
termites. Indeed, wherever these hills are abundant it is stated there
is a good chance of finding an Aard-Vark, the food of these animals
consisting almost exclusively of termites and ants.
Two existing species are recognised, namely the Cape Aard-Vark (_O.
afra_) from South Africa, and another (_O. æthiopicus_) from the
north-eastern parts of Africa, ranging into Egypt. An extinct species
has been described from the Lower Pliocene of the Isle of Samos, in the
Turkish Archipelago, differing from the existing forms by the larger
proportionate size of the lateral metatarsals.
_Bibliography of Edentata._—No general work on the order has
been published since that of Rapp (_Anat. Untersuchungen über
die Edentaten_, 2d ed. 1852). Among numerous memoirs on special
groups the following may be cited:—_Myrmecophagidæ_:—R. Owen,
“Anatomy of Great Anteater,” _Trans. Zool. Soc._ vol. iv.; G.
Pouchet, _Mém. sur le Grand Fourmilier_, 1874; W. A. Forbes,
“Anat. of Great Anteater,” _Proc. Zool. Soc._ 1882, p. 287.
_Megatheriidæ_:—R. Owen, _Extinct Gigantic Sloth (Mylodon
Robustus)_, 1842; Id., “On the Megatherium,” _Phil. Trans._
1851-56; J. Leidy, “Extinct Sloth-tribe of North America,”
_Smithsonian Contrib. to Knowledge_, vii. 1855; H. Burmeister,
_Description de la République Argentine_, t. iii. Mammifères,
1879,—which contains full references to various memoirs by
Owen, Gervais, Reinhardt, and others. _Glyptodontidæ_:—Owen,
_Catalogue of Fossil Mammals, Mus. Roy. Coll. Surgeons_, 1845;
T. H. Huxley, “Osteol. of Glyptodon,” _Phil. Trans._ 1865; H.
Burmeister, _Annales del Museo Publico de Buenos Aires_, and
_Descript. de la République Argentine_, 1879; H. Gervais and F.
Ameghino, _Les Mammifères Fossiles de l’Amérique Méridionale_,
Paris, 1880,—which also contains a list of all the S. American
Edentates described at that date. _Dasypodidæ_:—J. Murie,
“Anatomy of _Tolypeutes_,” _Trans. Linn. Soc._ vol. xxx. 1874;
A. H. Garrod, _Proc. Zool. Soc._ 1878. For Placentation of
Edentates see W. Turner, _Trans. Roy. Soc. Edin._ xxvii. (1873)
p. 72, and _Journ. Anat. and Physiol._ vols. viii. and x.; A.
Milne-Edwards, _Ann. Sciences Nat._ [6] viii. p. 1; and for
brain, P. Gervais, “Formes cérébrales des Edentés,” _Nouv.
Arch. du Muséum_, tom. v.; W. Turner, _Jour. Anatomy_, i. 313
(1867). For the dentition of _Orycteropus_ see O. Thomas, “A
Milk Dentition in _Orycteropus_,” _Proc. Roy. Soc._ vol. xlvii.
p. 246 (1890). Fuller observations on the mutual relations of
the various families are given by W. H. Flower, “On the Mutual
Affinities of the Animals composing the Order Edentata,” _Proc.
Zool. Soc._ 1882, p. 358.
CHAPTER VIII
THE ORDERS SIRENIA AND CETACEA
_Order_ SIRENIA.
The purely aquatic habits and fish-like form of the animals of this
order caused them to be formerly confounded with the Cetacea, but a more
intimate knowledge of their structure has shown that they really belong
to a widely different type of the mammalian class.
The head is rounded and not disproportionate in size as compared with
the trunk, from which it is scarcely separated by any externally visible
constriction or neck. Nostrils valvular, separate, and placed above
the fore part of the obtuse truncated muzzle. Eyes very small, with
imperfectly formed eyelids, capable, however, of contraction, and with
a well-developed nictitating membrane. Ear without any pinna. Mouth
of small or moderate size, with tumid lips beset with stiff bristles.
General form of the body depressed, fusiform. No dorsal fin. Tail
flattened and horizontally expanded. Fore limbs paddle-shaped, the digits
being enveloped in a common cutaneous covering, on which rudiments of
nails are sometimes present. No trace of hind limbs in existing forms.
External surface covered with a tough, finely wrinkled, or very rugose
skin, naked, or with fine hairs sparsely scattered over it.
The skeleton is remarkable for the massiveness and density of most of
the bones of which it is composed, especially the skull and ribs, which
must add to the specific gravity of these slow-moving animals, and
aid in keeping them to the bottom of the shallow waters in which they
dwell, while feeding on aquatic vegetables. The skull presents many
peculiarities, among which may be indicated the large size and backward
position of the anterior narial aperture, a further modification of that
met with in the Tapirs among Ungulates, and presenting some approach to
that so characteristic of the Cetacea. The nasal bones are generally
absent in the recent forms, or are only found in a most rudimentary
condition, attached to the edge of the frontals, far away from the
middle line; but in some at least of the extinct species these bones,
though small in size, are normal in situation and relations. In very few
other respects does the skull present any resemblance to that of the
Cetacea. In the spinal column of existing forms none of the vertebræ are
united together to form a sacrum, and the flat ends of the bodies do
not ossify separately, so as to form disc-like epiphyses in the young
state, as in nearly all other mammals; traces of epiphyses have, however,
been recently detected in _Manatus_, and they were fully developed in
_Halitherium_ and other fossil forms. The anterior caudal vertebræ have
well-developed chevron bones. In one genus (_Manatus_) there are only six
cervical vertebræ. There are no clavicles. The humerus has a small but
distinct trochlear articulation at the elbow-joint. The two bones of the
forearm are about equally developed, and generally ankylosed together
at both extremities. The carpus is short and broad, and the digits five
in number, with moderately elongated and flattened phalanges, which are
never increased in number beyond the limit usual in the Mammalia. The
pelvis is extremely rudimentary, consisting of a pair of bones suspended
at some distance from the vertebral column. In no existing species is
there any trace of a hind limb, but in the extinct _Halitherium_ an
acetabular depression and rudimentary femur have been discovered.
Two kinds of teeth, incisors and molars, separated by a wide interval,
are generally present. The former may be developed into tusks in
the upper jaw, or may be quite rudimentary. The molars vary much in
character. In one genus (_Rhytina_) no teeth of any kind are present, at
least in the adult. Some fossil forms show a more decidedly heterodont
dentition, while _Halitherium_ has milk-teeth, of which no traces have
been observed in the recent genera. In all recent types the anterior part
of the palate, and a corresponding surface on the prolonged symphysis
of the lower jaw, are covered with rough horny plates of peculiar
structure, which doubtless assist in mastication. The tongue is small
and fixed in position, with a surface resembling that of the plates just
spoken of. The salivary glands are largely developed. The stomach is
compound, being divided by a valvular constriction into two principal
cavities, the first of which is provided with a singular glandular pouch
near the cardiac end, and the second usually with a pair of elongated,
conical, cæcal sacs or diverticula. The intestinal canal is long, and
has very muscular walls. There is a cæcum, either simple, conical, and
with extremely thick walls, as in _Halicore_, or bifid, as in _Manatus_.
The heart is broad and flat, with its apex deeply cleft between the
ventricles. The principal arteries form very extensive and complex retia
mirabilia. The lungs are remarkably long and narrow, as, owing to the
very oblique position of the diaphragm, the thoracic cavity extends far
back over the abdomen. The epiglottis and arytenoid cartilages of the
larynx do not form a tubular prolongation as in the Cetacea, so that the
epiglottis is not intranarial. The brain is of comparatively small size,
and the convolutions on the surface of the cerebrum are few and shallow.
The kidneys are simple. The testes abdominal. The uterus is bicornuate.
The placenta (in the Dugong) is non-deciduate and zonary. The umbilical
vesicle disappears early. The mammæ are two, and pectoral, or rather
postaxillary in position.
The Sirenia pass their whole life in the water, being denizens of
shallow bays, estuaries, lagoons, and large rivers, but, unlike the
Cetacea, are not met with in the high seas, far away from the shore.
Their food consists entirely of aquatic plants, either marine algæ or
freshwater grasses, upon which they browse beneath the surface, as the
terrestrial herbivorous mammals do upon the green pastures on shore.
They are generally gregarious, slow and inactive in their movements,
mild, inoffensive, and apparently unintelligent in disposition.
Though occasionally found stranded by the tide or waves, there is no
satisfactory evidence that they voluntarily leave the water to bask or
feed on the shore. The habit of the Dugong of raising its round head
out of the water, and carrying its young under the fore fin, seems to
have given rise, among the imaginative early voyagers in the Indian
Ocean, to the legendary beings, half human and half fish, in allusion
to which the name Sirenia was bestowed by Illiger on the order, though
certainly the face of a Dugong, when closely inspected, does not bear the
slightest resemblance to that of the mermaid of romance. The species now
existing are very few, and there is reason to believe that the time is
not far distant when they will all become extinct. One species, _Rhytina
stelleri_, of the North Pacific, was totally exterminated through the
agency of man during the last century; and the others, being valuable for
their flesh as food, for their hides, and especially for the oil obtained
from the thick layer of fat which lies immediately beneath their skin,
rapidly diminish in numbers as civilised populations occupy the regions
forming their natural habitat. The surviving species are confined to the
tropical regions of the shores of both sides of the Atlantic and the
great rivers which empty themselves into that ocean, and to the coasts of
the Indian Ocean from the Red Sea to North Australia. In the Miocene and
early Pliocene epoch Sirenians abounded in the seas of Europe, and their
remains have been found in deposits of corresponding periods in North
America. Evidence has also been discovered of the existence of an animal
of this group in the seas at the bottom of which the Eocene nummulitic
limestone mountain ranges of Egypt were deposited.
The existing genera present such well-marked distinguishing characters
that it is on the whole convenient to place them in separate families,
although, as in so many similar cases, our knowledge of the extinct
forms, imperfect as it is, goes far to bridge over the distinction
between them.
_Family_ MANATIDÆ.
The characters of this and the two following families may be conveniently
included under the heading of the single genus by which they are
respectively represented.
_Manatus._[116]—Incisors ²⁄₂, rudimentary, concealed beneath the horny
oral plates, and disappearing before maturity. Molars ¹¹⁄₁₁, but rarely
more than ⁶⁄₆ present at one time, the anterior teeth falling before the
posterior come into use; similar in characters from beginning to end of
the series; with square, enamelled crowns, the grinding surface raised
into tuberculated transverse ridges. The upper teeth with two ridges
and three roots, the lower teeth with an additional (posterior) ridge,
or talon, and two roots. The cervical vertebræ present the remarkable
anomaly of being reduced to six in number, the usual vertebral formula
being C 6, D 17, L 2, and C 23-25. Rostrum of the skull, formed by
the union of the premaxillæ in front of the anterior narial aperture,
shorter than the length of the aperture and scarcely deflected from
the basicranial axis; premaxillæ and mandibular symphysis not markedly
deflected (Fig. 72). Tail entire, rounded, or shovel-shaped. Rudimentary
nails on the fore limbs. Cæcum bifid. Habitat the shores of, and the
great rivers which empty themselves into, the Atlantic within the
tropics. These animals are rather fluviatile than marine, ascending large
rivers almost to their sources.
The Manatee may be selected for a somewhat full description, as being one
of the best known representatives of this very remarkable order.
The name _Manati_ was apparently first applied to this animal by the
early Spanish colonists of the West Indies, in allusion to the hand-like
use which it frequently makes of its fore limbs; by English writers from
the time of Dampier (who gives a good account of its habits) downwards
it has been generally spelt “Manatee.” It was placed by Linnæus in his
heterogeneous genus _Trichechus_, but Storr’s name _Manatus_ is now
generally accepted for it by zoologists. The question of the specific
distinction of the African and American Manatees will be treated of
further on, but it will be chiefly to the latter and better known form
that the following description applies.
[Illustration: FIG. 71.—American Manatee (_Manatus americanus_), from
life. _Proc. Zool. Soc._ 1881, p. 457.]
The size of the Manatee has been much exaggerated, but there is no
trustworthy evidence of its attaining a greater length than 8 feet. Its
general external form may be seen in Fig. 71, taken from a living example
in the Brighton Aquarium. The body is somewhat fish-like, but depressed
and ending posteriorly in a broad, flat, shovel-like, horizontal tail,
with rounded edges. The head is of moderate size, oblong, with a blunt,
truncated muzzle, and divided from the body by a very slight constriction
or neck. The fore limbs are flattened oval paddles, placed rather low
on the sides of the body, and showing externally no signs of division
into fingers, but with a tolerably free motion at the shoulder, elbow,
and wrist joints, and with three diminutive flat nails near their
extremities. No traces of hind limbs are discernible either externally
or internally; and there is no dorsal fin. The mouth is very peculiar,
the tumid upper lip being cleft in the middle line into two lobes, each
of which is separately movable, as will be described in speaking of its
manner of feeding. The nostrils are two semilunar valve-like slits, at
the apex of the muzzle. The eyes are very minute, placed at the sides
of the head, and with a nearly circular aperture with wrinkled margins.
The external ear is a minute orifice situated behind the eye, without
any trace of pinna. The skin generally is of a dark grayish colour, not
smooth and glistening, like that of the Cetacea, but finely wrinkled. At
a little distance it appears naked, but a close inspection, at all events
in young animals, shows a scanty covering of very delicate hairs, and
both upper and under lips are well supplied with short stiff bristles.
[Illustration: FIG. 72.—Skull of African Manatee (_Manatus
senegalensis_). ⅕ natural size. From Mus. Roy. Coll. Surgeons.]
The general form of the skull is seen in Fig. 72. The cerebral cavity
is rather small as compared with the size of the animal, and of oblong
form; its roof is formed of the parietal bones as in ordinary mammals.
The squamosal has an extremely large and massive zygomatic process, which
joins the largely developed jugal bone in front. The orbit is small,
but prominent and nearly surrounded by bone. The anterior nares taken
together form a lozenge-shaped aperture, which looks upwards and extends
backwards considerably behind the orbits. Their sides are formed by the
ascending processes of the premaxillæ below, and by the supraorbital
processes of the frontals above, no traces of nasals being found in most
skulls, though these bones are occasionally present in a most rudimentary
condition, attached to the edges of the frontals, far away from the
middle line, in a position quite unique among the Mammalia. In front of
the narial aperture the face is prolonged into a narrow rostrum, formed
by the premaxillæ, supported below and at the sides by the maxillæ.
The under surface of this is very rugose, and in life covered by a
horny plate. The rami of the mandible are firmly united together at
the symphysis, which is compressed laterally, slightly deflected, and
has a rugose upper surface; to this another horny plate is attached,
which, with that of the upper jaw, functionally supplies the place of
teeth in the anterior part of the mouth. In the young state there are
rudimentary teeth concealed beneath these horny plates, which never
penetrate through them, and must therefore be quite functionless, and
altogether disappear before the animal is full-grown. There is besides
on each side of the hinder part of both upper and lower jaws, a parallel
row of molar teeth, similar in characters from the beginning to the end
of the series, with square enamelled crowns raised into tuberculated
transverse ridges; something like those of the Tapir and Kangaroo. The
upper teeth have two ridges and three roots; the lower teeth have an
additional posterior small ridge or talon, and but two roots. These teeth
succeed each other from before backwards, as in the Proboscidea, those
at the front of the mouth being worn out and shed before those at the
back are fully developed. There are altogether about eleven on either
side of each jaw, but rarely more than six are present at one time. The
brain is remarkably simple in structure, its hemispheres exhibiting none
of the richness of convolution so characteristic of the Cetacea. The
mammary glands of the female are situated just behind and to the inner
side of the origin of the pectoral limb. The red corpuscles of the blood
are among the largest of those of any members of the class, averaging in
diameter, according to Gulliver, ¹⁄₂₄₀₀ of an inch.
Manatees pass the whole of their life in the water, inhabiting bays,
lagoons, estuaries, and large rivers; but the open sea, so congenial
to the Cetacea, is quite unsuited to their peculiar mode of life. As a
general rule they prefer shallow water, in which, when not feeding, they
lie near the bottom, supporting themselves on the extremity of the tail,
or slowly moving about by the assistance of the fore limbs, the tips of
which are just allowed to touch the ground, and only raising the top of
the head above the surface for the purpose of breathing at intervals of
two or three minutes. In deeper water they often float, with the body
much arched, the rounded back close to the surface, and the head, limbs,
and tail hanging downwards. The air in the lungs obviously assists them
to maintain this position, acting in the same manner as that in the
air-sac of fishes. Their food consists exclusively of aquatic plants,
on which they browse beneath the water. They are extremely slow and
inactive in their movements, and perfectly harmless and inoffensive.
Frequent attempts have been made to keep specimens alive in captivity,
and sometimes with considerable success, one having lived in the Brighton
Aquarium for upwards of sixteen months. It was fed chiefly on lettuce
and endive, but would also eat leaves of the dandelion, sow-thistle,
cabbage, turnip, and carrot. From this and other captive specimens some
interesting observations upon the mode of life of the animal have been
made. One of these is the free use it makes of its fore limbs. From the
shoulder-joint, they can be moved in all directions, and the elbow and
wrist permit of free extension and flexion. In feeding these creatures
push the food towards their mouths by means of one of the hands, or both
used simultaneously, and any one who has seen these members thus employed
can readily believe the stories of their carrying their young about
under their arms. Still more interesting and quite unique among mammals
is the action of the peculiar lateral pads formed by the divided upper
lip, thus described by the late Professor Garrod: “These pads have the
power of transversely approaching towards and receding from one another
simultaneously (see Fig. 73, A and B). When the animal is on the point of
seizing (say) a leaf of lettuce, the pads are diverged transversely in
such a way as to make a median gap of considerable breadth. Directly the
leaf is within grasp the lip-pads are approximated, the leaf is firmly
seized between their contiguous bristly surfaces, and then drawn inwards
by a backward movement of the lower margin of the lip as a whole.” The
animal is thus enabled by the unaided means of the upper lip to introduce
food placed before it without the assistance of the comparatively
insignificant lower lip, the action greatly recalling to the observer
that of the mouth of the silkworm and other caterpillars, in which the
mandibles diverge and converge laterally during mastication. When out
of water the Manatee is an extremely helpless animal; and, although
statements are frequently met with in books of its voluntarily leaving
the water for the purpose of basking or feeding on shore, all trustworthy
observations of those acquainted with it, either in a state of nature or
in captivity, indicate that it has not the power of doing so. None of the
specimens in confinement have been observed to emit any sound.
[Illustration: FIG. 73.—Front view of head of American Manatee, showing
the eyes, nostrils, and mouth. A, With the lobes of the upper lip
divaricated; B, with the lip contracted. From Murie, _Trans. Zool. Soc._
vol. xi.]
Manatees, though much less numerous than formerly, are still occasionally
found in creeks, lagoons, and estuaries in some of the West India
Islands, and at various spots on the Atlantic coast of America from
Florida as far south as about 20° S. lat., and in the great rivers of
Brazil, almost as high as their sources. They are also met with in
similar situations on the opposite African coast, from about 16° N. to
10° S. lat., and as far into the interior as Lake Tchad. Their range may
even extend, if native reports obtained by Schweinfurth are correctly
interpreted, to the river Keebaly, 27° E. long.
A considerable number of specific names have been applied to the existing
Manatees, but according to the researches of Dr. Hartlaub[117] they
may be reduced to three species, distinguished from one another, among
other features, by the characters of the skull, and more especially the
relations of the nasals to the adjacent bones. Of these the American
Manatee may be known as _M. americanus_, although it has been described
under the names of _M. latirostris_, and _M. australis_. The African
Manatee (_M. senegalensis_) differs from the American species in the
following cranial characters: the anterior part of the rostrum is
shorter, shallower, and altogether smaller; the orbit is smaller; the
zygomatic process is more deep and massive; the jugal bone is deeper
from above downwards; the upper margin of the anterior nares is narrower
and with a smooth and rounded, instead of a thin and serrated, edge; the
upper surface of the frontal is flat, instead of concave; the foramen
magnum and occipital condyles are narrower from side to side, and the
symphysis of the mandible is smaller and shallower.
Finally, _M. inunguis_ is a fluviatile species confined to the Amazon and
Orinoco, which has been but recently fully brought under the notice of
zoologists.
_Family_ HALICORIDÆ.
_Halicore._[118]—In the upper jaw a pair of large, nearly straight,
tusk-like incisors, directed downwards and forwards, partially coated
with enamel. In the male they have persistent pulps, and bevelled cutting
edges, which project a short distance from the mouth, but in the female,
though they remain through life in the alveolar cavity, they are not
exserted, and, the pulp-cavity being filled with osteodentine, they soon
cease to grow (as in the female Narwhal). In the young there is also a
second small deciduous incisor on each side above. At this age there are
also beneath the horny plate which covers the anterior portion of the
mandible four pairs of slender conical teeth lodged in wide alveolar
depressions; these become absorbed before the animal reaches maturity.
The molars are usually ⁵⁄₅, sometimes ⁶⁄₆, altogether, but not all in
place at once, as the first falls before the last rises above the gum;
they are more or less nearly cylindrical in section (except the last,
which is compressed and grooved laterally), without distinction into
crown and root, increasing in size from before backwards, with persistent
pulps and no enamel. The summits of the crowns are tuberculated before
wearing, afterwards flattened or slightly concave. Skull with rostrum
formed by the union of the premaxillæ in front of the narial aperture,
longer than the aperture itself, bending downwards at a right angle with
the basicranial axis, and enclosing the sockets of the large incisor
tusks. Anterior part of the lower jaw bent down in a corresponding
manner. Vertebræ: C 7, D 18-19, L and C 30. Tail broadly notched in the
middle line, and with two pointed lateral lobes. No nails on the fore
limbs. Cæcum single.
The Dugongs are more distinctly marine in their habits than the Manatees,
feeding chiefly on sea-water algæ. They inhabit the shallow bays and
creeks of the Red Sea, east coast of Africa, Ceylon, islands of the Bay
of Bengal and the Indo-Malayan Archipelago (including the Philippines),
and the north coast of Australia, ranging from Barrow Reefs on the west
to Moreton Bay on the east. Although the distinctive characters are not
very obvious, they have been divided into three species, according to the
localities which they respectively inhabit:—_H. tabernaculi_ from the Red
Sea, _H. dugong_ from the Indian seas, and _H. australis_ from Australia.
The last-named has lately been the object of a regular “fishery,” chiefly
on account of its oil, which is peculiarly clear, limpid, and free from
disagreeable smell, and is said to have the same medicinal properties as
cod-liver oil. Although often stated in books to attain the length of 20
feet when adult, there does not appear to be any evidence from actual
specimens in museums that Dugongs ever reach half that size, 8 feet being
the common length of adult animals.
The placentation of this genus has been recently described by Sir W.
Turner, who first indicated its zonary form.
_Family_ RHYTINIDÆ.
_Rhytina._[119]—No teeth, their place being supplied functionally by the
dense, strongly-ridged, horny oral plates. Premaxillary rostrum about as
long as the anterior narial aperture, and moderately deflected. Vertebræ:
C 7, D 19, L and C 34-37. Head very small in proportion to the body. Tail
with two lateral pointed lobes. Pectoral limbs small and truncated. Skin
naked and covered with a very thick, hard, rugged, bark-like epidermis.
Stomach without cæcal appendages to the pyloric cavity. Cæcum simple.
Only one species of this genus is known, _R. stelleri_, the Northern
Sea-cow, by far the largest animal of the order, attaining the length of
20 to 25 feet. It was formerly an inhabitant of the shores of two small
islands in the North Pacific, Behring and the adjacent Copper Island,
on the former of which it was discovered by the ill-fated navigator
whose name the island bears, when, with his accomplished companion, the
German naturalist Steller, he was wrecked upon it in 1741. Twenty-seven
years afterwards (1768), as is commonly supposed, the last of the race
was killed,[120] and its very existence would have been unknown to
science but for the interesting account of its anatomy and habits left by
Steller, and the few more or less imperfect skeletons which have recently
rewarded the researches carried on in the frozen soil of the islands
around which it dwelt. There is no evidence at present of its having
inhabited any other coasts than those of the islands just named, although
it can hardly be supposed that its range was always so restricted. When
first discovered it was extremely numerous in the shallow bays round
Behring Island, finding abundant nutriment in the large laminariæ growing
in the sea. Its extirpation is entirely due to the Russian hunters and
traders who followed upon the track of the explorers, and, upon Steller’s
suggestion, lived upon the flesh of the great Sea-cows. Its restricted
distribution, large size, inactive habits, fearlessness of man, and even
its affectionate disposition towards its own kind when wounded or in
distress, all contributed to accelerate its final extinction.
According to Steller’s account, the Rhytina had a skin of a dark brown
colour, sometimes spotted or streaked with white. The fore limb was
covered with short brush-like hairs.
_Extinct_ SIRENIANS.
_Halitherium._[121]—The Miocene and early Pliocene seas of Europe
abounded in Sirenians, to which the generic name of _Halitherium_ was
given by Kaup, but which have also received other names. They had large
tusk-like incisors in the upper jaw, as in the existing Dugongs, though
not so greatly developed. Their molar teeth were ⁵⁄₅ or ⁶⁄₆, anteriorly
simple and single-rooted, posteriorly those above with three and those
below with two roots, and with enamelled and tuberculated or ridged
crowns, in all which respects they more resemble those of the Manatee
than of the Dugong. The anterior molars were deciduous; and there is
evidence of the presence of milk-teeth. Germs of inferior incisors were
also present. Some species at least had nasal bones, short, broad, but
normal in position, whereas in all the existing genera these bones
are quite rudimentary. Another and still more important evidence of
conformity to the general mammalian type is the better development of
the pelvic bone, and the presence of a small styliform femur articulated
to the acetabulum, although no traces of any other part of the limb
have been discovered. These ancient Sirenians, which may be regarded
as representing a distinct family—_Halitheriidæ_—were thus, in dental,
cranial, and other osteological characters, less specialised than are
either of the existing species, and if the intermediate links could be
discovered might well be looked upon as the ancestral forms from which
the latter have been derived, but at present the transitional conditions
have not been detected. So far as is yet known, when changes in the
physical conditions of the European seas rendered them unfitted to be the
habitation of Sirenians, the _Halitherium_ type still prevailed. If the
existing Dugongs and Manatees are descended from it, their evolution must
have taken place during the Pliocene and Pleistocene epochs, the one in
seas to the east, the other to the west of the African continent, which
has long formed a barrier to their intercommunication. _Halitherium_
remains have been found in many parts of Germany, especially near
Darmstadt, also in France, Italy, Belgium, Malta, etc. Until a few years
ago none were known from England, probably owing to the absence of beds
of an age corresponding to those in which they are found on the European
continent; but a skull and several teeth have been detected among the
rolled debris of which the Red Crag of Suffolk is partially composed. The
species are not yet satisfactorily characterised. Some of them appear
to have attained a larger size than the existing Manatee or Dugong. One
of these, from the Pliocene of Italy and France, having but ⁵⁄₅ molar
teeth, has been separated generically under the name of _Felsinotherium_
by Capellini, by whom it has been fully described; but the difference in
the number of the teeth does not afford sufficient grounds for separation
from _Halitherium_. _Miosiren_ of the Belgian Miocene, differs in that
the last upper molar is the smallest, in place of the largest of the
whole series of teeth.
[Illustration: FIG. 74.—The penultimate and last right lower molars of
_Halitherium fossile_; from the Miocene of the Continent. (After De
Blainville.)]
_Other forms._—Remains from the Pliocene of France described as
_Prohalicore_ are regarded as indicating a Sirenian closely allied to
_Halicore_; while a molar from the Tertiary of California has been made
the type of _Desmotylus_, which is likewise referred to the _Halicoridæ_.
_Dioplotherium_, from the Phosphorites of South Carolina, has been
considered to connect _Halicore_ with _Halitherium_, but even its ordinal
position is uncertain.
A portion of a skull found in the Pliocene of Belgium has been described
as _Crassitherium_ by Van Beneden; and some compressed teeth, somewhat
similar to but larger than those of the Dugong, discovered in the Miocene
of the department of Lot-et-Garonne, France, gave origin to the genus
_Rytiodus_ of E. Lartet. Of this genus, which may be identical with
_Trachytherium_ of the French Miocene, better preserved remains have
subsequently been described by Delfortrie. These show that the rostrum
is more elongated than in _Halitherium_, but the skull is otherwise very
similar, as are the molar teeth. The incisors are very large, exserted,
strongly compressed, almost sabre-like, rounded on the upper or anterior
surface, sharp below, concave on the external and convex on the inner
side, and transversely striated.
_Pachyacanthus_ from the Miocene of the Vienna basin is also, according
to Van Beneden, another form of Sirenian, of which, however, the skull
is not known. In various Miocene marine formations of the United States
of America other remains of Sirenians have been found, but mostly in
such a fragmentary condition that they afford at present little evidence
of the early history of the group in that country. A more satisfactory
discovery is that of a nearly complete skull and some bones from a
Tertiary limestone formation in Jamaica. It is of smaller size than
the Manatee, and, so far as the teeth are concerned, of a still more
generalised character than _Halitherium_, the dentition being apparently
_i_ ³⁄₃, _c_ ¹⁄₁, _p_ + _m_ (?⁸⁄?₈) = 48. The incisors are small, not
developed into tusks; the canines (wanting in all existing Sirenians)
are rather larger than the incisors, judging by the sockets; and the
molars are bilophodont, and covered with enamel. It has been described
by Sir R. Owen under the name of _Prorastomus sirenoides_. Some writers
regard this genus as the type of a distinct family—the _Prorastomatidæ_.
Unfortunately we have no knowledge of the geological antiquity of
the formation in which it was embedded. Lastly must be mentioned the
_Eotherium egyptiacum_, Owen, founded on the cast of a brain, with
a small quantity of surrounding bone, discovered in the nummulitic
limestone of Eocene age in the Mokattam Hills, near Cairo. The brain is
narrower than in _Manatus_, and resembles that of _Halitherium_. This is
of interest as the most ancient known evidence of any Sirenian whose age
has been geologically determined. Teeth from the same deposits referred
to _Manatus_ not improbably belong really to _Eotherium_.
The few facts as yet collected relating to the former history of the
Sirenia leave us as much in the dark as to the origin and affinities of
this peculiar group of animals as we were when we only knew the living
members. They lend no countenance to their association with the Cetacea,
and on the other hand their supposed affinity with the Ungulata, so much
favoured by modern zoologists, receives no very material support from
them.
_Bibliography of Sirenia._—J. F. Brandt, _Symbolæ
Sirenologicæ_, St. Petersburg, 3 fasciculi, 1846-61-68—an
exhaustive account of the anatomy, affinities, and literature
of the group, with copious illustrations of the osteology of
_Rhytina_. _Anatomy of Dugong_:—Everard Home, _Phil. Trans._
1820, p. 315; Owen, _Proc. Zool. Soc._ 1838, p. 29. _Placenta
of do._:—W. Turner, _Trans. Roy. Soc. Edin._ vol. xxxv.
(1889). _Manatee_:—W. Vrolik, _Bijdragen tot de Dierkunde_,
1851; J. Murie, “On the Form and Structure of the Manatee,”
_Trans. Zool. Soc. Lond._ vol. viii. p. 127, 1872, and “Further
Observations on the Manatee,” _Ibid._ vol. xi. p. 19, 1880;
A. H. Garrod, “Notes on the Manatee recently living in the
Zoological Society’s Gardens,” _Ibid._ vol. x. p. 137, 1875;
H. C. Chapman, “Observations on the Structure of the Manatee,”
_Proc. Acad. Nat. Sciences of Philadelphia_, 1875, p. 452; A.
Crane, “Notes on the Habits of the Manatees in Captivity in
the Brighton Aquarium,” _Proc. Zool. Soc. Lond._ 1881, p. 456.
_Extinct Sirenia_:—Gervais, _Journal de Zoologie_, tom. i. p.
332, 1872. R. Lydekker, _Catalogue of Fossil Mammalia in the
British Museum_, pt. v.
_Order_ CETACEA.
This is perhaps the most distinctly circumscribed and natural of all the
larger groups into which the class is divided.
The external form is fish-like, the body being fusiform, passing
anteriorly into the head without any distinct constriction or neck, and
posteriorly tapering off gradually towards the extremity of the tail,
which is provided with a pair of lateral, pointed expansions of skin
supported by dense fibrous tissue, called “flukes,” forming together a
horizontally-placed triangular propelling organ, notched in the middle
line behind.
The head is generally large, in some species attaining to even more
than one-third of the entire length of the animal, and the aperture of
the mouth is always wide, and bounded by stiff immobile lips. The fore
limbs are reduced to the condition of flattened ovoid paddles, encased
in a continuous integument, showing no external sign of division into
arm, fore arm, and manus, or of separate digits, and without any trace
of nails. There are no traces of hind limbs visible externally. The
general surface of the skin is smooth and glistening, and devoid of
hair, although in many species there are a few fine bristles in the
neighbourhood of the mouth, which may either persist through life, or
be present only in the young state. Immediately beneath the skin, and
intimately connected with it, is a thick layer of fat, held together
by a dense mesh of areolar tissue, constituting the “blubber,” which
serves the purpose of the hairy covering of other mammals in retaining
the heat of the body. In nearly all species a compressed median dorsal
tegumentary fin is present. The eye is small, and is not provided with a
nictitating membrane or true lachrymal apparatus. The external auditory
meatus is a very minute aperture in the skin situated at a short distance
behind the eye, and there is no vestige of a pinna. The nostrils open
either separately or by a single crescentic valvular aperture, not at the
extremity of the snout, but near the vertex of the head.
The bones generally are spongy in texture, the cavities being filled with
oil. In the vertebral column the cervical region is remarkably short and
immobile, and the vertebræ, originally always seven in number, are in
many species more or less fused together into a solid mass. The odontoid
process of the axis, when that bone is free, is usually very obtuse, or
even obsolete. None of the vertebræ are united together to form a sacrum.
The lumbar and caudal vertebræ are numerous and large, and, as their
arches are not connected by any articular processes (zygapophyses), they
are capable of a very free motion in all directions. The epiphyses at
the ends of the vertebral bodies are very distinct flattened disks, not
uniting until after the animal has attained its full dimensions.[122]
There are largely developed chevron bones, the presence of which
indicates the distinction between the caudal and lumbar vertebræ.
The skull (Fig. 75) is modified in a very peculiar manner. The brain-case
is short, broad, and high, in fact almost spherical. The supraoccipital
bone rises upwards and forwards from the foramen magnum, to meet the
frontals at the vertex, thus completely excluding the parietals from the
upper region of the cranium. The frontals are expanded laterally to form
the roof of the orbits. The anterior narial aperture opens upwards, and
has in front of it a more or less horizontally prolonged rostrum, formed
of the maxillæ, premaxillæ, vomer, and mesethmoid cartilage, extending
forwards to form the upper jaw or roof of the mouth.
There are no clavicles. The humerus is freely movable on the scapula
at the shoulder-joint, but beyond this the articulations of the limb
are imperfect, the flattened ends of the bones coming in contact with
each other, with fibrous tissue interposed, allowing of scarcely any
motion. The radius and ulna are distinct, about equally developed,
and much flattened, as are also all the bones of the manus. There are
four, or more commonly five digits, and the number of the phalanges
of the second and third digits always exceeds the normal number in
mammals, sometimes very considerably (hyperphalangism); they present the
exceptional character of having epiphyses at both ends.[123] The pelvis
is represented by a pair of small styliform bones placed longitudinally,
suspended below and at some distance from the vertebral column at the
commencement of the caudal region. These appear to represent the ischia,
as the crura of the corpora cavernosa are attached to them. In some
species, to the outer surface of these are fixed other small bones or
cartilages, the rudiments of the hind limb.
[Illustration: FIG. 75.—A section of the skull of a young Dolphin
(_Globicephalus melas_) × ⅕. _PMx_, Premaxilla; _Mx_, maxilla; _ME_,
ossified portion of the mesethmoid; _an_, anterior nares; _Na_, nasal;
_IP_, interparietal; _Fr_, frontal; _Pa_, parietal; _SO_, supraoccipital;
_ExO_, exoccipital; _BO_, basioccipital; _Sq_, squamosal; _Per_,
periotic; _AS_, alisphenoid; _PS_, presphenoid; _Pt_, pterygoid; _pn_,
posterior nares; _Pl_, palatine; _Vo_, vomer; _s_, symphysis of mandible;
_id_, inferior dental canal; _cp_, coronoid process of mandible; _cd_,
condyle; a, angle; sh, stylohyal; _bh_, basihyal; _th_, thyrohyal. (From
Flower’s _Osteology of Mammalia_.)]
Teeth are generally present, but exceedingly variable in number. In
the existing species they are of simple, uniform character, all having
conical or compressed crowns and single roots, and are never preceded
by milk-teeth. They are therefore homodont and monophyodont. In one
group, the Mystacocetes, the teeth are absent (except, in the fœtal
condition), and the palate is provided with numerous transversely placed
horny laminæ or “baleen.” The salivary glands are rudimentary or absent.
The stomach is multilocular, its structure being fully noticed under
the genus _Phocæna_. The intestinal canal is simple, and only in some
species provided with a small cæcum. The liver is very little fissured,
and there is no gall-bladder. The vascular system is greatly complicated
by arterial and venous plexuses, or _retia mirabilia_. The larynx is of
peculiar shape, the arytenoid cartilages and the epiglottis being much
elongated, and together forming a tubular prolongation, which projects
into the posterior nares, and when embraced by the soft palate produces a
continuous passage between the nostrils and the trachea, as in Ungulates,
but in a more perfect manner. The brain is large relatively to the size
of the animal, very round in form, and with its surface divided by sulci
into very numerous and complex convolutions. The kidneys are deeply
lobulated. The testes are abdominal. There are no vesiculæ seminales,
nor os penis. The uterus is bicornuate, and the placenta non-deciduate
and diffuse. The mammæ are two in number, and the nipples placed in
depressions on each side of the vulva. The principal ducts of the gland
are dilated during lactation into large reservoirs, into which the milk
collects, and from which it is injected by the action of a compressor
muscle into the mouth of the young animal, by which means the process of
sucking under water is greatly facilitated and expedited.
The animals of the order Cetacea abound in all known seas, and some
species are inhabitants of the larger rivers of South America and Asia.
Their organisation necessitates passing their life entirely in the
water, as on land they are absolutely helpless. They have, however, to
rise very frequently to the surface for the purpose of respiration; and,
in relation to the constant upward and downward movement in the water
thus necessitated, their principal instrument of motion, the tail, is
expanded horizontally, quite unlike that of a fish, whose movements
are mainly in straight-forward or lateral directions. The position of
the respiratory orifice or nostril on the highest part of the head is
very important for this mode of life, since it is the only part of the
body of which the exposure above the surface is absolutely necessary.
Of the numerous erroneous ideas connected with natural history, few are
so wide spread and still so firmly believed, notwithstanding repeated
expositions of its falsity, as that the Cetacea spout out through their
blowholes water taken in at the mouth. The fact is, the “spouting,” or
more properly “blowing,” of the Whale is nothing more than the ordinary
act of expiration, which, taking place at longer intervals than in land
animals, is performed with a greater amount of emphasis. The moment the
animal rises to the surface it forcibly expels from its lungs the air
taken in at the last inspiration, which of course is highly charged with
watery vapour in consequence of the natural respiratory changes. This,
rapidly condensing in the cold atmosphere in which the phenomenon is
generally observed, forms a column of steam or spray, which has been
erroneously taken for water. It also often happens, especially when the
surface of the ocean is agitated into waves, that the animal commences
its expiratory puff before the orifice has quite cleared the top of
the water, some of which may thus be driven upwards with the blast,
tending to complete the illusion. In hunting Whales the harpoon often
pierces the lungs or air passages of the unfortunate victim, and then
fountains of blood may be forced high in the air through the blowholes,
as commonly depicted in scenes of Arctic adventure; but this is nothing
more (allowance being made for the Whale’s peculiar mode of breathing)
than what always follows severe wounds of the respiratory organs of other
mammals.
All the Cetacea are predaceous, subsisting on living animal food of
some kind. One genus alone (_Orca_) eats other warm-blooded animals, as
Seals, and even members of its own order, both large and small. Some feed
on fish, others on small floating crustaceans, pteropods, and medusæ,
while the principal staple of the food of many is constituted by the
various species of cephalopods, _Loligo_ and other _Teuthidæ_, which must
abound in certain seas in vast numbers, as they form almost the entire
support of some of the largest members of the order. In size the Cetacea
vary much, some of the smaller Dolphins scarcely exceeding 4 feet in
length, while others are the most colossal of all animals. It is true
that most statements of their bulk found in general and even zoological
literature are greatly exaggerated, but even when reduced to their actual
dimensions (which will be stated under the respective genera) some of
the existing Whales exceed in size any animal living either at present
or in former times of which we have any certain evidence. With some
exceptions, the Cetacea generally are timid inoffensive animals, active
in their movements, and very affectionate in their disposition towards
one another, especially the mother towards the young, of which there is
usually but one, or at most two at a time. They are generally gregarious,
swimming in herds or “schools” (so termed by the whalers) sometimes
amounting to many thousands in number; though some species have hitherto
only been met with either singly or in pairs.
Although by their mode of life so far removed from close observation
that it is impossible to become as familiar with them in their natural
condition as with many other animals, Whales are in many respects the
most interesting and wonderful of all creatures; and there is much in
their structure and habits well worthy of study, much that is difficult
to understand, and much that leads to great generalisations and throws
light upon far-reaching philosophical speculations. One of the first
lessons which a study of these animals affords is that, in the endeavour
to discover what a creature really is, from what others it is descended,
and to what it is related, the general outward appearance affords little
clue, and we must go deep below the surface to find out the essential
characteristics of its nature. There was once, and may be still in many
places, a common idea that a Whale is a fish. To realise the fallacy of
this notion we have only to consider what a fish really is, what under
all the diversities of form, size, and colour known among fishes there is
common to them all, and we see that in everything which characterises a
true fish and separates it from other classes, as reptiles, birds, and
mammals, the Whale resembles the last-named and differs from the fish.
It is as essentially a mammal as a Cow or a Horse, and simply resembles
a fish externally because it is adapted to inhabit the same element;
but it is no more on that account a fish than is a bat, because adapted
to pass a great part of its existence on the wing in the air, nearly
related to a bird. The whole structure of a whale is a most instructive
instance of a type of organisation which is common to and characteristic
of the class Mammalia, but specially modified or adapted to a peculiar
mode of life. We see in every part the result of two great principles
acting and reacting upon each other—on the one hand, adherence to type,
or rather to fundamental inherited structural conditions, and, on the
other, adaptation to the peculiar circumstances under which it lives, and
to which in all probability it has become gradually more and more fitted.
The external fish-like form is perfectly suited for swimming through
the water; the tail, however, is not placed vertically as in fishes,
but horizontally, a position which accords better with the constant
necessity for rising to the surface for the purpose of breathing. The
hairy covering characteristic of all mammals, which if present might
interfere with rapidity of movement through the water, is reduced to the
merest rudiments—a few short bristles about the chin or upper lip—which
are often only present in very young animals; and the function of keeping
the body warm is supplied by the “blubber.” The forelimbs, though
functionally reduced to mere paddles, with no power of motion except at
the shoulder-joint, have beneath their smooth and continuous external
covering all the bones, joints, and even most of the muscles, nerves, and
arteries of the human arm and hand; and the rudiments of hind legs found
buried deep in the interior of the animal apparently subserve no useful
purpose, but point an instructive lesson to those who are able to read it.
As before said, the Cetacea form a perfectly well-defined group, sharply
separated from all other mammals, and with no outlying or doubtful
forms at present known. Among the existing members of the order, there
are two very distinct types, the Toothed Whales or Odontoceti and the
Baleen Whales or Mystacoceti, which present as many marked distinguishing
structural characters as are found between many other divisions of the
Mammalia which are reckoned as orders. The extinct _Zeuglodon_, so far
as its characters are known, does not fall into either of these groups,
but is in some respects an annectant form, and therefore must be placed,
provisionally at least, in a third group by itself.
The Mystacocetes appear at first sight to be the most specialised and
aberrant of the existing Cetacea, as indicated by the absence of teeth,
the presence of baleen, and the form and size of the mouth; but, as we
see in other groups, dental characters, and all such as relate to the
prehension of food generally, are essentially adaptive and consequently
plastic or prone to variation, and hence cannot well be relied upon
as tests of affinity. In another character, also adaptive, the laxity
of the connection of the ribs with the vertebral column and with the
sternum, and the reduction of that bone in size, allowing great freedom
of expansion of the thoracic cavity for prolonged immersion beneath
the water, the Mystacocetes have passed beyond the Odontocetes in
specialisation. On the other hand, the greater symmetry of the skull, the
more anterior position of the external nostrils and their double external
orifice, the form of the nasal bones, the presence of a distinctly
developed olfactory organ, the mode of attachment of the periotic bone to
the cranium, the presence of a cæcum and the regular arrangement of the
alimentary canal, the more normal characters of the manus and the better
development of the muscles attached to it, and the presence, in many
species at least, of parts representing not only the bones but also the
ligaments and muscles of a hind limb,[124] all show less deviation from
the ordinary mammalian type than is presented by the Odontocetes. Taking
all these characters into consideration, it does not appear reasonable to
suppose that either type has been derived from the other, at all events
in the form in which we see it now, but rather that they are parallel
groups, both modified in different fashions from common ancestors.
Among the Mystacocetes, in the especially distinguishing characters of
the division, the Rorquals are less specialised than the Right Whales,
which in the greater size of the head, the length and compression of the
rostrum, the development of the baleen, and shortness of the cervical
region, are exaggerated forms of the type, and yet they retain more fully
some primitive characters, as the better development of the hind limb,
the pentadactylous manus, and the absence of a dorsal fin. Both types
are found distinct in a fossil state at least as far back as the early
Pliocene age, but generally represented by smaller species than those
now existing. Some of the Pliocene Rorquals (_Cetotherium_) were, in
the elongated flattened form of the nasal bones, the greater distance
between the occipital and frontal bone at the top of the head, and the
greater length of the cervical vertebræ, more generalised than those
now existing. In the shape of the mandible also, Van Beneden, to whose
researches we are much indebted for a knowledge of these forms, discerns
some approximation to the Odontocetes.
Among the last-named group there are several distinct types, of which
that represented by _Platanista_, although in some respects singularly
modified, has been considered to present on the whole approximations
towards the more normal and general type of mammalian structure. It is
therefore interesting to find an apparently allied form well represented
among the earliest fossil remains of Cetaceans in Europe. Almost all the
other members of the suborder range themselves under the two principal
heads of Ziphioids (or Physeteroids) and Delphinoids. The former is an
ancient and once abounding type, of which the Sperm Whale (_Physeter_)
is a highly specialised form. Among the latter, _Globicephalus_ is a
modified form as regards the structure of its anterior extremity, and
_Monodon_ as regards its dentition, while _Delphinus_, with the various
allied genera, may be regarded as the dominating type of Cetaceans at
the present day, abundant in slightly differentiated species and also in
individuals. They are in this respect to the rest of the order much as
the hollow-horned Ruminants are to the other Ungulates.
The earliest Cetaceans of whose organisation we have anything like
complete evidence are the Zeuglodonts of the Eocene period,[125]
which approach in the structure of the skull and teeth to a much more
generalised mammalian type than either of the existing suborders. The
smallness of the cerebral cavity compared with the jaws and the rest
of the skull they share with the primitive forms of many other types.
The forward position of the narial aperture and the length and flatness
of the nasal bones, which distinguish them from all existing forms, we
must also suppose to be a character at one time common to all Cetaceans,
though now retained (but to a less degree) only by the Mystacocetes.
Even _Squalodon_, which in its heterodont dentition so much resembles
_Zeuglodon_ as to have been placed by some zoologists in the same genus,
entirely differs from it, and conforms with the ordinary Dolphins in its
essential cranial characters.
The origin of the Cetacea is at present involved in much obscurity.
They present no signs of closer affinity to any of the lower classes of
vertebrates than do many other members of their own class. Indeed in all
that essentially distinguishes a mammal from the oviparous vertebrates,
whether in the osseous, nervous, reproductive, or any other system,
they are as truly mammalian as any other group. Any supposed marks
of inferiority, as absence of limb structure, of hairy covering, of
lachrymal apparatus, etc., are obviously modifications (or degradations,
as they may be termed) in adaptation to their special mode of life. The
characters of the teeth of _Zeuglodon_ and other extinct forms, and
also of the fœtal Mystacocetes, clearly indicate that they have been
derived from mammals in which the heterodont type of dentition was fully
established. The steps by which a land mammal may have been modified
into a purely aquatic one are indicated by the stages which still
survive among the Carnivora in the _Otariidæ_ and in the true Seals. A
further change in the same direction would produce an animal somewhat
resembling a Dolphin; and it has been thought that this may have been
the route by which the Cetacean form has been developed. There are,
however, great difficulties in the way of this view. Thus if the hind
limbs had ever been developed into the very efficient aquatic propelling
organs they present in the Seals, it is not easy to imagine how they
could have become completely atrophied and their function transferred to
the tail. So that from this point of view it is more likely that Whales
were derived from animals with long tails, which were used in swimming,
eventually with such effect that the hind limbs became no longer
necessary. The powerful tail, with its lateral cutaneous flanges, of an
American species of Otter (_Lutra brasiliensis_) may give an idea of this
member in the primitive Cetaceans. But the structure of the Cetacea is,
in so many essential characters, so unlike that of the Carnivora that
the probabilities are against these orders being nearly related. Even in
the skull of the Zeuglodon, which has been cited as presenting a great
resemblance to that of a Seal, quite as many likenesses may be traced to
one of the primitive Pig-like Ungulates (except in the purely adaptive
character of the form of the teeth), while the elongated larynx,[126]
complex stomach, simple liver, reproductive organs both male and female,
and fœtal membranes of the existing Cetacea are far more like those
of that group than of the Carnivora. Indeed it appears probable that
the old popular idea which affixed the name of “Sea-Hog”[127] to the
Porpoise contains a larger element of truth than the speculations of many
accomplished zoologists of modern times. The fact that _Platanista_,
which, as mentioned above, appears to retain more of the primitive
characteristics of the group than any other existing form, and also the
somewhat related _Inia_ from South America, are both at the present day
exclusively fluviatile, may point to the freshwater origin of the whole
group, in which case their otherwise rather inexplicable absence from the
seas of the Cretaceous period would be accounted for.
On the other hand, it should be observed that the teeth of the
Zeuglodonts approximate more to a carnivorous than to an ungulate type.
It is scarcely necessary to allude to the hypothesis started by some
Continental writers to the effect that the Whales are the most primitive
type of mammals with which we are acquainted, and that they are the
descendants of the Mesozoic reptilian order Ichthyopterygia, from which
their hyperphalangism is a direct inheritance. The Ichthyopterygia have
been shown, on very strong evidence, to have been derived from land
reptiles, and to have gradually acquired their hyperphalangism as an
adaptive character suitable to their peculiar mode of life, and there can
be but little doubt that a similar adaptation has taken place in the case
of the Whales.
_Suborder_ MYSTACOCETI, _the_ BALÆNOIDEA, _Whalebone, or True
Whales_.[128]
_Family_ BALÆNIDÆ.
Teeth never functionally developed, but always disappearing before the
close of intra-uterine life. Palate provided with plates of baleen
or “whalebone.” Skull symmetrical. Nasal bones forming a roof to the
anterior nasal passages, which are directed upwards and forwards.
Maxilla produced in front of, but not over, the orbital process of the
frontal. Lachrymal bones small and distinct from the jugal. Tympanic
bone involuted (Fig. 76), and ankylosed with the periotic, which is
attached to the base of the cranium by two strong diverging processes.
Olfactory organ distinctly developed. Rami of mandible arched outwards,
their anterior ends meeting at an angle, and connected by fibrous tissue
without any true symphysis. All the ribs at their upper extremities
articulating only with the transverse processes of the vertebræ; their
capitular processes, when present, not articulating directly with
the bodies of the vertebræ. Sternum composed of a single piece, and
articulating only with a single pair of ribs. No ossified sternal ribs.
External openings of nostrils distinct from each other, longitudinal. A
short conical cæcum.
These animals have, when in the fœtal state, numerous minute calcified
teeth lying in the dental groove of both upper and lower jaws. They are
best developed about the middle of fœtal life, after which period they
are absorbed, and no trace of them remains at the time of birth.[129] The
baleen or whalebone does not make its appearance until after birth. It
consists of a series of flattened horny plates, between three and four
hundred in number, on each side of the palate, with a bare interval along
the middle line. These plates are placed transversely to the long axis of
the palate, with very short intervals between them. Each plate or blade
is somewhat triangular in form, with the base attached to the palate
and the apex hanging downwards. The outer edge of the blade is hard and
smooth; but the inner edge and apex fray out into long bristly fibres,
so that the roof of the Whale’s mouth looks as if covered with hair, as
described by Aristotle. At the inner edge of each principal blade are
two or three much smaller or subsidiary blades. The principal blades are
longest near the middle of the series, and gradually diminish towards the
front and back of the mouth. The horny plates grow from a dense fibrous
and highly vascular matrix, covering the palatal surface of the maxillæ,
and sending out lamellar processes, one of which penetrates the base of
each blade. Moreover, the free edge of these processes is covered with
very long vascular thread-like papillæ, one of which forms the central
axis of each of the hair-like epidermic fibres of which the blade is
mainly composed. A transverse section of fresh whalebone shows that it is
made up of numbers of these soft vascular papillæ, circular in outline,
each surrounded by concentrically arranged epidermic cells, and the whole
bound together by other epidermic cells, that constitute the smooth
cortical (so-called “enamel”) surface of the blade, which, disintegrating
at the free edge, allows the individual fibres to become loose and
assume the hair-like appearance before spoken of. These fibres differ
from hairs in not being formed in depressed follicles in the enderon,
but rather resemble the fibres composing the horn of the Rhinoceros.
The whalebone in fact consists of nothing more than modified papillæ of
the buccal mucous membrane, with an excessive and cornified epithelial
development. The blades are supported and bound together for a certain
distance from their base by a mass of less hardened epithelium, secreted
by the surface of the palatal membrane or matrix of the whalebone in
the intervals of the lamellar processes. This is the “intermediate
substance” of Hunter, the “gum” of the whalers. Baleen varies much in
colour in different species. In some it is almost jet black, in others
slate-colour, horn-colour, yellow, or even creamy-white. In some the
blades are variegated with longitudinal strips of different hues. Baleen
differs also greatly in other respects, being short, thick, coarse, and
stiff in some, and greatly elongated and highly elastic in those species
in which it has attained its fullest development. Its function is to
strain the water from the small marine molluscs, crustaceans, or fish
upon which the Whales subsist. In feeding the immense mouth is filled
with water containing shoals of these small creatures, and then, on the
Whale closing the jaws and raising the tongue, so as to diminish the
cavity of the mouth, the water streams out through the narrow intervals
between the hairy fringe of the whalebone blades, and escapes through the
lips, leaving the living prey to be swallowed.[130]
Our knowledge of the different structural modifications attained by
members of this important group of mammals, though largely increased
of late years, is still imperfect. Formerly they were all divided into
Right Whales (_Balæna_) and Rorquals or Fin-Whales (_Balænoptera_), the
latter distinguished by their smaller heads, elongated and slender form,
free cervical vertebræ, tetradactylous manus, and the presence of very
conspicuous longitudinal furrows or folds in the skin of the throat
and chest, and of a small adipose dorsal fin. Recent discoveries have,
however, brought to light several forms holding a somewhat intermediate
position, and presenting combinations of characters not found in either
of the longer known sections. According to our present knowledge the
group is naturally divided into five very distinct genera, of which the
leading characters are given below.
_Balæna._[131]—Skin of throat smooth, not furrowed. No dorsal fin.
Cervical vertebræ united into a single mass. Pectoral limb short, broad,
and pentadactylous. Head very large. Baleen very long and narrow, highly
elastic, and black. Scapula high, with a distinct coracoid and acromion
process. Tympanic (Fig. 78) deep and angular, its inflation comparatively
slight, and the involuted portion not fig-shaped, and frequently without
a well-marked depression at the anterior extremity of the superior border
of the inner surface for the Eustachian canal.
[Illustration: FIG. 76.—Greenland or Arctic Right Whale (_Balæna
mysticetus_).]
The Greenland, or more properly Arctic, Right Whale (_Balæna mysticetus_)
attains, when full grown, a length of from 45 to 50 feet. Its usual
vertebral formula is C 7, D 12, L 14, C 22. The external form is shown
in Fig. 76 from a careful drawing by Mr. Robert Gray. In this species
all the peculiarities which distinguish the head and mouth of the Whales
from those of other mammals have attained their greatest development.
The head is of enormous size, exceeding one-third of the whole length
of the creature. The cavity of the mouth is actually larger than that
of the body, thorax and abdomen together. The upper jaw is very narrow,
but greatly arched from before backwards, to increase the height of the
cavity and allow for the great length of the baleen blades; the rami of
the mandible are widely separated posteriorly, and have a still further
outward sweep before they meet at the symphysis in front, giving the
floor of the mouth the shape of an immense spoon. The baleen blades
attain the number of 380 or more on each side, those in the middle of
the series having a length of 10 or sometimes 12 feet. They are black in
colour, fine and highly elastic in texture, and fray out at the inner
edge and ends into long, delicate, soft, almost silky, but very tough,
hairs. The remarkable development of the mouth and the structures in
connection with it, which distinguishes the Right Whale among all its
allies, is entirely in relation to the nature of its food. It is by this
apparatus that the animal is enabled to avail itself of the minute but
highly nutritious crustaceans and pteropods which swarm in immense shoals
in the seas it frequents. The large mouth enables it to take in at one
time a sufficient quantity of water filled with these small organisms,
and the length and delicate structure of the baleen provide an efficient
strainer or hair-sieve by which the water can be drained off. If the
baleen were rigid, and only as long as is the aperture between the upper
and lower jaws when the month is shut, a space would be left beneath it
when the jaws were separated, through which the water and the minute
particles of food would escape together. But instead of this the long,
slender, brush-like, elastic ends of the whalebone blades fold back when
the mouth is closed, the front ones passing below the hinder ones in a
channel lying between the tongue and the lower jaw. When the month is
opened, their elasticity causes them to straighten out like a bow unbent,
so that at whatever distance the jaws are separated the strainer remains
in perfect action, filling the whole of the interval. The mechanical
perfection of the arrangement is completed by the great development of
the lower lip, which rises stiffly above the jaw-bone and prevents the
long, slender, flexible ends of the baleen from being carried outwards by
the rush of water from the mouth, when its cavity is being diminished by
the closure of the jaws and raising of the tongue.
If, as appears highly probable, the “bowhead” of the Okhotsk Sea and
Behring Strait belongs to this species, its range is circumpolar. Though
found in the seas on both sides of Greenland, and passing freely from
one to the other, it is never seen so far south as Cape Farewell; but on
the Labrador coast, where a cold stream sets down from the north, its
range is somewhat farther. In the Behring Sea, according to Scammon, “it
is seldom seen south of the fifty-fifth parallel, which is about the
farthest southern extent of the winter ice, while on the Sea of Okhotsk
its southern limit is about the latitude of 54°.” As has been abundantly
shown by Eschricht and Reinhardt in the case of the Greenland seas,
“everything tends to prove,” Scammon says, “that the _Balæna mysticetus_
is truly an ‘ice whale,’ for among the scattered floes, or about the
borders of the ice-fields or barriers, is its home and feeding-ground.
It is true that these animals are pursued in the open water during
the summer months; but in no instance have we learned of their being
captured south of where winter ice-fields are occasionally met with.” The
occurrence of this species, therefore, on the British or any European
coast is exceedingly unlikely, as when alive and in health the southern
limit of its range in the North Sea has been ascertained to be from the
east coast of Greenland at 64° N. lat. along the north of Iceland towards
Spitsbergen, and a glance at a physical chart will show that there are
no currents setting southwards which could bear a disabled animal or a
floating carcase to British shores. To this _à priori_ improbability may
be added the fact that no authentic instance has been recorded of the
capture or stranding of this species upon any European coast; for the
cases in which it has been reported as seen in British waters may be
explained by the supposition of one of the other species of the genus
being mistaken for it. Still, as two other essentially Arctic Cetaceans,
the Narwhal and the Beluga, have in a few undoubted instances found
their way to British shores, it would be rash absolutely to deny the
possibility of the Greenland Right Whale doing the same.
[Illustration: FIG. 77.—Southern Right Whale (_Balæna australis_).]
The southern Right Whale (_B. australis_, Fig. 77) resembles the last
in the absence of dorsal fin and of longitudinal furrows in the skin of
the throat and chest, but differs in that it possesses a smaller head
in proportion to its body, shorter baleen, a different shaped contour
of the upper margin of the lower lip, and a greater number (fifteen) of
ribs and dorsal vertebræ. This form inhabits the temperate seas of both
northern and southern hemispheres, and is divided into several so-called
species, according to their geographical distribution:—_B. biscayensis_
of the North Atlantic, _B. japonica_ of the North Pacific, _B. australis_
of the South Atlantic, and _B. antipodarum_ and _B. novæ-zealandiæ_ of
the South Pacific. The differential characters by which they have been
separated, external as well as anatomical, are, however, slight and
subject to individual variation; and the number of specimens available
for comparison in museums is not yet sufficient to afford the necessary
data to determine whether these characters can be regarded as specific
or not. The most interesting of these is the Atlantic Right Whale, which
was formerly abundant in the North Atlantic, but is now so scarce as to
appear verging on extinction. This was the Whale the pursuit of which
gave occupation to a numerous population on the shores of the Basque
provinces of France and Spain in the Middle Ages. From the tenth to
the sixteenth centuries Bayonne, Biarritz, St. Jean de Luz, and San
Sebastian, as well as numerous other towns on the north coast of Spain,
were the centres of an active Whale “fishery,” which supplied Europe
with oil and whalebone. In later times these Whales were pursued as
far as the coast of Newfoundland. They were, however, already getting
scarce when the voyages undertaken towards the close of the sixteenth
century for the discovery of the north-eastern route to China and the
East Indies opened out the seas around Spitzbergen; then for the first
time the existence of the Greenland Whale became known, and henceforth
the energies of the European whale-fishers were concentrated upon that
animal. It is a singular fact that the existence of the Atlantic Right
Whale was quite overlooked by naturalists till lately, all accounts
referring to it being attributed to the Greenland Whale, supposed once to
have had a wider distribution than now, and to have been driven by the
persecution of man to its present circumpolar haunts. To the two Danish
cetologists Eschricht and Reinhardt is due the credit of having proved
its existence as a distinct species, from a careful collation of numerous
historical notices of its structure, distribution, and habits; and
their restoration of the animal, founded upon these documents, has been
abundantly confirmed by the capture of various specimens in recent times,
showing that it still lingers in some of the localities where it formerly
was so abundant. The only known instances of its occurrence on the coasts
of Europe in modern times are in the harbour of San Sebastian in January
1854, in the Gulf of Taranto, in the Mediterranean, in February 1877, and
on the Spanish coast between Guetaria and Zarauz (Guipuzcoa) in February
1878. The skeletons of these three whales are preserved in the museums
of Copenhagen, Naples, and San Sebastian respectively. On the coast of
the United States several Whales of this species have been taken within
the last few years. In the North Pacific a very similar if not identical
species is regularly hunted by the Japanese, who tow the carcases
ashore for the purposes of flensing and extracting the whalebone. In
the tropical seas, however, according to Captain Maury’s whale charts,
Right Whales are never or rarely seen; but the southern temperate ocean,
especially the neighbourhood of the Cape of Good Hope, Kerguelen’s
Island, Australia, and New Zealand, is inhabited by “Black Whales,” once
abundant, but now nearly exterminated through the wanton destruction of
the females as they visit the bays and inlets round the coast, their
constant habit in the breeding time. The range of these Whales southward
has not been accurately determined; but no species corresponding with the
Arctic Right Whale has as yet been met with in the Antarctic icy seas.
[Illustration: FIG. 78.—The right tympanic bone of an immature individual
of the Greenland Whale (_Balæna mysticetus_), from the inner (_A_) and
outer (_B_) aspects. ¹⁄₃ natural size. (From the _Proc. Zool. Soc._)]
Remains of Right Whales are of not uncommon occurrence in the Pliocene
Crag deposits of England and Belgium. The tympanics of _B. affinis_
from these deposits appear to indicate a species closely allied to
_B. mysticetus_, in which this bone is long and angulated anteriorly
(Fig. 78); while the tympanics from the same deposits described as _B.
primigenia_ are shorter and more rounded at the antero-inferior angle,
thus resembling those of _B. australis_. A smaller species, having an
estimated length of about 20 feet, has been described as _Balænula
balænopsis_, the generic distinction being made on account of the free
condition of the atlas and seventh cervical vertebræ; but it seems
scarcely advisable to regard such a feature as indicating more than a
less specialised species. _Balæna (Balænotus) insignis_ is a whale of
somewhat larger dimensions, in which the atlas is generally, and the
seventh cervical vertebra always, free, while in young individuals the
axis vertebra may likewise be separate.
_Neobalæna._[132]—Head about one-fourth the total length. Skin of the
throat not plicated. A small falcate dorsal fin. Vertebræ, C 7, D 17, L
3, C 16 = 43. The cervical vertebræ are united. The manus small, narrow,
and tetradactylous, wanting the pollex. The ribs remarkably expanded and
flattened. The scapula very low and broad, with completely developed
acromion and coracoid processes. Tympanic approximating to that of
_Balæna_, but with certain very characteristic peculiarities of shape.
Baleen very long, slender, elastic, and white. A single species, at
present very rare, _N. marginata_, from the Australian and New Zealand
seas is the smallest of the Whalebone Whales, being not more than 20 feet
in length.
_Rhachianectes._[133]—This combines the small head, elongated form, and
narrow pectoral fin of _Balænoptera_ with the smooth skin of the throat
and absence of the dorsal fin of _Balæna_. The baleen is the shortest and
coarsest of any of the group. Its osteology is imperfectly known. One
species, _R. glaucus_, the Gray Whale of the North Pacific.
_Megaptera._[134]—Head of moderate size. Baleen plates short and broad.
Vertebræ, C 7, D 14, L 11, C 21 = 53. Cervical vertebræ free. Scapula
with acromion and coracoid process absent or rudimentary. Skin of throat
plicated. Dorsal fin low. Pectoral limb tetradactylous, very long and
narrow, attaining about one-fourth of the length of the entire animal,
the metacarpus and phalanges being greatly developed, and the latter very
numerous. Tympanic still more inflated than in _Balænoptera_, with the
involuted portion more distinctly pyriform, the Eustachian part of the
aperture well defined, and two well-marked longitudinal ridges on the
lower surface of adult specimens.
The Whale commonly called “Humpback” (_Megaptera boops_) by whalers,
perhaps on account of the low hump-like form of the dorsal fin, is very
distinctly characterised from all others of the group, especially by the
immense length of the pectoral fins or flippers, which are indented or
scalloped along their margins, and are, except at their base, of a white
colour, nearly all the rest of the body being black. The baleen plates
are of a deep black colour. Though common in the North Atlantic between
Norway and Greenland, this Whale does not frequently appear on the coasts
of the British Isles. One came ashore at Newcastle in 1839; another, a
young one, was taken in the estuary of the Dee in 1863, and its skeleton
is preserved in the Liverpool museum; and a nearly full-grown animal
was captured in the mouth of the Tay in the winter of 1883-84.[135]
The usual length of the adult ranges from 45 to 50 feet, the female
being larger than the male. Whales of the genus _Megaptera_ are found
in the South Atlantic and in both the North and the South Pacific. They
resemble those of British seas so closely that it is doubtful whether the
differences which have been observed, and upon which several species have
been founded, may not be individual peculiarities; but zoologists have
not yet had the opportunity of examining and comparing such a series of
specimens of different ages and sexes from different localities as would
be necessary to determine these points satisfactorily.
[Illustration: FIG. 79.—Humpbacked Whale (_Megaptera boops_).]
Tympanic bones of _Megaptera_ occur in the English and Belgian Crags,
although somewhat less commonly than those of _Balæna_ and _Balænoptera_;
they have been described under the names of _Megapteropsis_ and
_Burtinopsis_.
[Illustration: FIG. 80.—The Common Rorqual (_Balænoptera musculus_).]
_Balænoptera._[136]—Head small and flat, and pointed in front. Body long
and slender. Skin of throat plicated. A small falcate dorsal fin. Baleen
short and coarse. Cervical vertebræ free. Scapula low and broad, with a
large acromion and coracoid process. Pectoral limb tetradactylous, small,
narrow, and pointed. Tympanic (Fig. 81) long, much inflated, and rounded,
with the involuted portion thickened and pyriform, and the notch for the
Eustachian canal sharply defined; inner surface flattened, without the
vertical groove found in _Megaptera_.
[Illustration: FIG. 81.—The right tympanic of _Balænoptera musculus_ from
the inner (A) and outer (B) aspects. ½ natural size. (From the _Proc.
Zool. Soc._)]
The Rorquals, Fin-Whales, Fin-backs, Finners, or Razor-backs, as they
are variously called, have the plicated skin of the throat like that
of _Megaptera_, the furrows being more numerous and close set; but the
pectoral fin is comparatively small, the dorsal fin distinct and falcate,
and the tail very much compressed before it expands into the “flukes.”
The Rorquals are perhaps the most abundant and widely distributed of
all the whales, being found in some of their modifications in all seas,
except the extreme Arctic, and probably Antarctic regions. Owing to the
small quantity and inferior quality of their whalebone, the comparatively
limited amount of blubber, and their great activity and the difficulty of
capturing them by the old methods, these Whales were not until recently
an object of pursuit by whale-fishers; but, since the introduction of
steam-vessels, and especially of explosive harpoons fired from guns in
the place of those hurled by the human hand, a regular fishery has been
established on the coast of Finmark. There are four distinct species
of this genus in British seas. (1) _Balænoptera sibbaldi_, the “Blue
Whale,” the largest of all known animals, attains a length of 80 or even
sometimes 85 feet. Its colour is dark bluish gray, with small whitish
spots on the breast; the baleen is black; the flippers are larger
proportionally than in other Rorquals, measuring one-seventh of the
total length of the body; and the dorsal fin is small and placed very
far back. This Whale has usually 64 vertebræ, of which 16 bear ribs.
Like the others of the genus, this species seems to pass the winter in
the open seas, and approaches the coast of Norway at the end of April
or beginning of May. At this time its sole food is a small crustacean
(_Euphausia inermis_) which swarms in the fjords. Several specimens have
been taken on the British coasts, two fine skeletons from the Firth
of Forth being preserved in the Edinburgh museums. (2) _Balænoptera
musculus_, the Common Rorqual, has a length of 65 to 70 feet, is of a
grayish slate colour above and white underneath, and the baleen is slate
colour variegated with yellow or brown. It has usually 62 vertebræ, of
which 15 bear ribs. This is the commonest of all the large Whales on
the British coasts, scarcely a winter passing without the body of one
being somewhere washed ashore, usually after stormy weather, and more
frequently on the south coast, as this species has a more southern range
than the last, and frequently enters the Mediterranean. It feeds largely
on fish, and is frequently seen feasting among shoals of herring. (3)
_Balænoptera borealis_, often called Rudolphi’s Whale from its first
describer, is a smaller species, scarcely attaining a length of 50 feet.
It is bluish-black above, with oblong, light-coloured spots, whilst
the under parts are more or less white; the whole of the tail and both
sides of the flippers are black; the baleen is black, and the bristly
ends fine, curling, and white; the flippers are very small, measuring
one-eleventh of the total length of the body. There are 56 vertebræ,
with 14 pairs of ribs. This species, according to Collett, feeds chiefly
on minute crustaceans, mainly _Calanus finmarchicus_ and _Euphausia
inermis_, and not on fish. Until lately it was considered the rarest of
the Whales of European seas, and was only known to science from a few
individuals stranded on the coasts of northern Europe at long intervals,
the skeletons of which have been preserved in museums. The most southern
point at which it has been met with hitherto is Biarritz in France. Since
the establishment of the whaling station near the North Cape it has been
shown to be a regular summer visitor, and in 1885, 771 individuals were
captured on the coast of Finmark. (4) _Balænoptera rostrata_, the lesser
Fin-Whale or Rorqual, is the smallest species found in the northern seas,
rarely exceeding 30 feet in length. Its colour is grayish-black above,
whilst the under side is white, including the whole of the lower side of
the tail; the inner side of the flippers is white; and there is a broad
white band across the outer side, which is a very characteristic mark of
the species; the baleen is yellowish-white. The dorsal fin in this and
the last species is comparatively high, and placed far forwards on the
body. This Whale has usually 48 vertebræ, 11 of which bear ribs. It is
common in summer in the fjords of Norway, and is often seen around the
British Isles. It has been taken, though rarely, in the Mediterranean;
and ranges as far north as Davis’s Straits.
Rorquals are met with in almost all seas throughout the world, but
further and more accurate observations are required before their
specific characters and geographical distribution can be made out. Nearly
all the individuals hitherto examined with any care, whether from the
North Pacific, the Australian seas, or the Indian Ocean, come very near
in structure to one or the other of the Atlantic forms described above,
so much so that some zoologists have been induced to believe that there
are but four species, each of which has a wide, almost cosmopolitan
range, while others have described and named almost every individual
specimen captured as belonging to a different species.[137]
Tympanics, vertebræ, and other bones of Rorquals are among the commonest
cetacean remains found in the Pliocene Crags of England and Belgium.
Several species, varying in dimensions, are known from these deposits,
_B. definita (sibbaldina)_ being apparently nearly related to the
existing _B. sibbaldi_. A caudal vertebra from the Upper Eocene of
Hampshire has been referred to _Balænoptera_, but does not afford
sufficient evidence to prove the existence of the genus at that date.
_Extinct Genera._—The extinct genus _Cetotherium_ of the European
Pliocene may be taken to include a number of fossil Whalebone Whales
allied to the Balænopterine group, several of which have been
described under other names, such as _Plesiocetus_, _Heterocetus_, and
_Amphicetus_. They are readily characterised by the form of the tympanic
bone, which is much narrower in front than behind, the roughened inferior
surface being in the shape of an isosceles triangle, and the notch for
the Eustachian canal being smaller, and descending nearer to the inferior
border of the inner wall than in _Balænoptera_. The skull is longer than
the latter, with a greater interval between the occiput and the frontal,
and with longer and more flattened nasals. The relative thickness of
the cervical vertebræ is also greater. In the typical forms (_e.g._ _C.
brialmonti_ and _C. dubium_) the mandibular condyle is simple; but in _C.
(Heterocetus) brevifrons_ it is furnished with a projecting posterior
talon, as in the Sperm Whale.
_Herpetocetus_ is known by a comparatively small species from the
Belgian and English Crags, characterised by the extreme inflation of the
egg-shaped tympanic bone, which approximates to that of _Megaptera_, but
has the greater part of the cavity filled by bone. There is a talon to
the condyle of the mandible.
_Palæocetus_, as already mentioned (p. 232), is founded upon the
ankylosed cervical vertebræ of a small Whale originally considered as
having been derived from the Kimeridge Clay, but which doubtless came
from the Suffolk Crag; if it belongs to the _Balænidæ_ it indicates a
Right Whale.
_Suborder_ ARCHÆOCETI.
_Family_ ZEUGLODONTIDÆ.
This group is formed to include certain extinct Cetacean-like animals at
present only known by more or less fragmentary portions of their skeleton
and teeth, and whose position and affinities are, therefore, still
subject to doubt.[138]
In the anterior part of both jaws the teeth are simple, conical, or
slightly compressed, and sharp pointed. The first three in the upper jaw
are distinctly implanted in the premaxillary bone, and so may be reckoned
as incisors. The tooth which succeeds, or the canine, is also simple and
conical, but it does not exceed the others in size. This is followed by
five teeth having two distinct roots and compressed pointed crowns, with
denticulated cutting-edges. The dentition is therefore _i_ ³⁄₃, _c_ ¹⁄₁,
_p_ and _m_ ⁵⁄₅ = 36, resembling that of some Seals.[139] General form
of the skull elongated and much depressed. Brain-cavity very small, and
the skull between it and the orbits elongated and narrow. Temporal fossæ
very large. A strong sagittal crest. Rostrum long and narrow, differing
from that of other Cetaceans in the large extent to which the premaxillæ
form the sides of the anterior extremity. Nasal bones elongated, flat,
and narrow, the opening of the anterior nares being over the middle of
the elongated compressed rostrum. All the cervical vertebræ free. The
characters of the dorsal vertebræ and mode of articulation of the ribs
appear to have resembled those of _Platanista_ rather than _Balæna_,
_Physeter_, or _Delphinus_. Lumbar vertebræ with elongated bodies, low
neural spines, and the transverse processes placed low down on the
bodies. Characters of the limbs not known with certainty.[140]
All the known fossil remains belonging to the animals of this group may
be referred, provisionally at least, to the genus _Zeuglodon_, so named
because the first section of a molar tooth examined was taken from the
base of the crown, where it was beginning to divide into the two roots,
and looked like two single teeth “linked or yoked together.” This name
was substituted by Owen for the earlier one _Basilosaurus_ of Harlan,
with the consent of that author, on the mammalian nature of the animal
being demonstrated.[141] The latter name is, however, still generally
retained by American zoologists. The remains have hitherto been found
chiefly in the Eocene formations of the States of Alabama, Louisiana,
Mississippi, and Arkansas, and have been assigned to several species.
A portion of a skull is recorded from the Barton Clay (Eocene) of
Hampshire, England.
_Suborder_ ODONTOCETI, _the_ DELPHINOIDEA, _or Toothed Whales_.
Calcified teeth always present after birth; generally numerous, but
sometimes a very limited number (in a few cases none) are functionally
developed. No baleen. Upper surface of the skull more or less
asymmetrical. Nasal bones in the form of nodules or flattened plates,
applied closely to the frontals, and not forming any part of the roof to
the narial passage, which is directed upwards and backwards. Olfactory
organ rudimentary or absent. Hinder end of the maxilla expanded and
covering the greater part of the orbital plate of the frontal bone.
Lachrymal bone either inseparable from the jugal, or, when distinct,
very large, and forming part of the roof of the orbit. Tympanic bone
not ankylosed with the periotic, which is usually only attached to the
rest of the skull by ligament. Rami of mandible nearly straight, much
expanded in height posteriorly, with a wide funnel-shaped aperture to
the dental canal, and coming in contact in front by a flat surface of
variable length, but always constituting a true symphysis. Several of the
anterior ribs with well-developed capitular processes, articulating with
the bodies of the vertebræ. Sternum almost always composed of several
pieces, placed one behind the other, with which several pairs of ribs
are always connected by the intervention of well-developed cartilaginous
or ossified sternal ribs. External respiratory aperture single, the two
nostrils uniting before they reach the surface, usually in the form of a
transverse subcrescentic valvular aperture, situated on the top of the
head. Manus always pentadactylous, though the first and fifth digits are
usually very little developed. No cæcum, except in _Platanista_.
_Family_ PHYSETERIDÆ.
No functional teeth in the upper jaw. Mandibular teeth various, often
much reduced in number. Bones of the cranium raised so as to form an
elevated prominence or crest behind the nares. Pterygoid bones thick,
produced backwards, meeting in the middle line, and not involuted to form
the outer wall of the post-palatine air-sinuses, but simply hollowed
on their outer side. Anterior facet of periotic bone (Fig. 87) for
articulation with the tympanic quite smooth; and the posterior tympanic
surface of the former broad, with a median longitudinal ridge. Transverse
processes of the arches of the dorsal vertebræ, to which the tubercles
of the ribs are attached, ceasing abruptly near the end of the series,
and replaced by processes on the body at a much lower level, and not on a
line or serially homologous with them, but serially homologous anteriorly
with the heads of the ribs, and posteriorly with the transverse
processes of the lumbar vertebræ. (In some genera, as _Physeter_, the
two processes, upper and lower on each side, are both present and well
developed in the same vertebra in the region of transition. In others,
as _Ziphius_ and _Berardius_, they are not both developed on any single
vertebra.) Costal cartilages not ossified.
Subfamily =Physeterinæ=.—Numerous teeth in the mandible, which are not
set in distinct bony alveoli, but in a long groove imperfectly divided by
partial septa, and held in place by the strong, fibrous gum surrounding
them. No distinct lachrymal bone. Cranium strikingly asymmetrical in
the region of the narial apertures, in consequence of the left opening
greatly exceeding the right in size.
[Illustration: FIG. 82.—Skull of Sperm Whale (_Physeter macrocephalus_).]
_Physeter._[142]—Upper teeth apparently of uncertain number, rudimentary,
and functionless, being embedded in the gum. Lower jaw with from 20 to
25 teeth on each side, stout, conical, recurved, and pointed at the
apex until they are worn, without enamel. Upper surface of the cranium
concave; its posterior and lateral edges raised into a very high and
greatly compressed semicircular crest or wall. Zygomatic processes of
jugal bones thick and massive. Rostrum greatly elongated, broad at the
base, and gradually tapering to the apex. Upper edge of the mesethmoid
forming a roughened irregular projection between the narial apertures,
inclining to the left side. Mandible exceedingly long and narrow, the
symphysis being more than half the length of the ramus. Vertebræ: C 7,
D 11, L 8, C 24; total 50. Atlas free; all the other cervical vertebræ
united by their bodies and spines into a single mass. Eleventh pair of
ribs rudimentary. Head about one-third the length of the body; very
massive, high and truncated, and rather compressed in front; owing its
huge size and remarkable form mainly to the accumulation of an oily
substance secreted by the lining membranes of great cells surrounding the
narial passage and filling the large hollow on the upper surface of the
cranium and overlying the rostrum. The single blowhole is longitudinal,
slightly sigmoid, and placed at the upper and anterior extremity of the
head to the left side of the middle line. The opening of the mouth is on
the under side of the head, considerably behind the end of the snout.
Pectoral fin short, broad, and obliquely truncated. Dorsal fin a mere low
protuberance.
[Illustration: FIG. 83.—The Sperm Whale (_Physeter macrocephalus_).]
The only representative of this genus is the Cachalot or Sperm Whale (_P.
macrocephalus_, Fig. 83), one of the most colossal of animals, quite
equalling, if not exceeding, the Greenland Whale in bulk. The length of
the full-grown male is from 55 to 60 feet, but the female is stated not
to reach more than half that size. The general colour of the surface
is black above and gray below, the colours gradually shading into each
other. The Sperm Whale is one of the most widely distributed of animals,
being met with usually in herds or “schools” in almost all tropical and
subtropical seas, but not occurring, except accidentally, in the Polar
regions. Not unfrequently specimens appear on the coasts of the British
Isles, but only as solitary stragglers, or as dead carcases, floated
northwards by the Gulf Stream. It is remarkable that every one of these
of which we have an accurate record has been an old male. The food of
this Whale consists mainly of various species of cephalopods (squid and
cuttle-fish), but fish of considerable size are also eaten. The substance
called “ambergris,” formerly used in medicine and now in perfumery, is a
concretion formed in the intestine of this Whale, and is found floating
on the surface of the seas it inhabits. Its genuineness is proved by the
presence of the horny beaks of the cephalopods on which the Whale feeds.
The oil contained in the great cavity above the skull, when refined,
yields “spermaceti,” and the thick covering of blubber which everywhere
envelops the body produces the valuable “sperm-oil” of commerce; hence
this animal has long been the subject of a regular chase, by which its
numbers have been greatly diminished.
_Cogia._[143]—Teeth of the upper jaw absent, or reduced to a rudimentary
pair in front; in the lower jaw 9 to 12 on each side, rather long,
slender, pointed, and curved, with a coating of enamel. Upper surface
of the cranium concave, with thick, raised posterior and lateral
margins, massive and rounded at their anterior terminations above the
orbits. Upper edge of the mesethmoid forming a prominent sinuous ridge,
constituting a kind of longitudinal septum to the base of the great
supra-cranial cavity. Rostrum not longer than the cranial portion of the
skull, broad at the base, and rapidly tapering to the apex. Zygomatic
process of the jugal styliform. Mandible with the symphysis less than
half the length of the entire ramus. Vertebræ: C 7, D 13 or 14, L and C
30; total 50 or 51. All the cervical vertebræ united by their bodies and
arches. External characters not well known, but, judging by the somewhat
conflicting accounts of those that have had an opportunity of observing
them, the head is about one-sixth of the length of the body, and obtusely
pointed in front; the mouth small, and placed far below the apex of the
snout; the spiracle crescentic, and placed obliquely on the top of the
head anteriorly to the eyes, and to the left of the middle line; the
pectoral fins are obtusely falcate; and there is a triangular dorsal fin.
The history of this genus is a good illustration of the difficulties
in which the study of the Cetacea has been involved by the superficial
manner in which it has been investigated. The first known example, a
skull from the Cape of Good Hope in the Paris Museum, was described by De
Blainville under the name of _Physeter breviceps_. This was afterwards
with good reason generically separated by Gray. Until within a very
few years ago only five other individuals had been met with, each of
which had been described under a different specific name (viz. _grayi_,
_macleayi_, _simus_, _floweri_, and _potsii_), and which are arranged
by Gray in two distinct genera. The most careful examination of the
description given of these specimens, or of the now numerous osteological
remains available, fails to detect any differences beyond those which
may be attributed to age or sex, and hence, according to our present
knowledge, these six supposed species must all be included under one
name, _C. breviceps_. This animal appears to attain the length of 10 feet
when adult, and has been met with at various distant localities in the
Southern Ocean, and also off the coast of Madras and in the North Pacific.
_Extinct Physeteroids._—Teeth of Physeteroids are of very common
occurrence in the Belgian and English Crags, and evidently indicate the
former existence of Whales more or less closely allied to the Sperm
Whale, but often distinguished by the presence of an enamel-cap on
the crowns of the teeth. The generic determination of these teeth is,
however, exceedingly difficult, owing to the water-worn condition in
which they are frequently found, and also on account of the impossibility
of knowing whether small and large teeth may not be referable to
different parts of the jaws of the same species or to individuals of
different ages. Moreover, in the cases of isolated teeth it is impossible
to know how many were contained in the jaws, and therefore to distinguish
Physeteroid from Ziphioid teeth. _Physeterula_ is a small form about
one-third the dimensions of the Sperm Whale, and distinguished by the
length of the mandibular symphysis being only about one-third that of the
entire ramus; it is identified by Professor Cope with _Cogia_. _Eucetus_
(_Dinoziphius_) is founded on teeth which are regarded as closely
resembling those of _Physeter_, but distinguished by their subcylindrical
form and the small size of the aperture of the pulp-cavity. It does not
appear, however, to be certain that these teeth are not worn specimens
of those described as _Scaldicetus_. _Physetodon_, from the Pliocene of
Australia, is founded upon the evidence of similar teeth. The teeth from
the Belgian Crag described as _Scaldicetus_ are somewhat smaller than
those of the Sperm Whale, and are readily characterised by their cap
of grooved enamel. Other teeth with enamel-caps have been described as
_Physodon_ and _Hoplocetus_. The genus _Balænodon_ is founded upon a very
imperfect large tooth from the English Crag, which is not sufficiently
well preserved to admit of exact comparison with the other types.
Subfamily =Ziphiinæ=.—Teeth of the mandible (at least in existing forms)
quite rudimentary and concealed in the gum, except one, or very rarely
two, pairs which may be largely developed, especially in the male sex.
A distinct lachrymal bone. Externally the mouth is produced into a
slender rostrum or beak, from above which the rounded eminence formed by
a cushion of fat resting on the cranium in front of the blowhole rises
somewhat abruptly. Spiracle or blowhole single, crescentic, median, as
in the _Delphinidæ_. Pectoral fin small, ovate, the five digits all
moderately well developed. A small obtusely falcate dorsal fin situated
considerably behind the middle of the back. Longitudinal grooves on
each side of the skin of the throat, diverging posteriorly, and nearly
meeting in front. In external characters and habits the animals of this
group closely resemble each other. They appear to be almost exclusively
feeders on various species of cephalopods, and occur either singly, in
pairs, or in small herds. By their dental and osteological characters
they are easily separated into four distinct genera.
_Hyperoödon._[144]—A small conical pointed tooth at the apex of each
ramus of the mandible, concealed by the gum during life. Skull with the
upper ends of the premaxillæ rising suddenly behind the nares to the
vertex and expanded laterally, their outer edges curving backwards and
their anterior surfaces arching forwards and overhanging the nares; the
right larger than the left. Nasal bones lying in the hollow between the
upper extremities of the premaxillæ, strongly concave in the middle line
and in front; their outer edges, especially on the right side, expanded
over the front of the inner border of the maxilla. Very high longitudinal
crests on the maxillæ at the base of the rostrum, extending backwards
almost to the nares, approaching each other in the middle line above;
sometimes so massive that their inner edges come almost in contact.
Anteorbital notch distinct. Mesethmoid but slightly ossified. Vertebræ:
C 7, D 9, L 10, C 19; total 45. All the cervical vertebræ united. Upper
surface of the head in front of the blowhole hole very prominent and
rounded, rising abruptly from above the small, distinct snout.
[Illustration: FIG. 84.—_Hyperoödon rostratus._ From a female specimen
taken off the coast of Scotland, 1882.]
The genus is known typically by _H. rostratus_ (Fig. 84), but an
imperfect skull has been made the type of _H. planifrons_—a species
differing considerably in cranial characters from the typical one. The
females and young males of the first-named species have the contour of
the head of the same general form as in Fig. 84; the premaxillary crests
of the cranium being widely separated from one another, and terminating
in comparatively sharp edges. In the males, however, as age advances the
summits of these crests become gradually expanded and flattened, till
they are almost or quite in contact in the middle line. This development
of the maxillary crests produces a corresponding elevation and flattening
of the front of the head, so that in very old males this aspect presents
a flattened disc-like surface rising abruptly from the beak (which thus
becomes almost buried) and situated in a plane nearly at right angles to
the line of the back.[145] So different, indeed, is the appearance of the
skull of an old male from that of a female individual that it was long
considered that they belonged to different species—the male form having
been described as _H. latifrons_. The length of an adult male reaches 30
feet, while that of the female does not exceed 24 feet.
The Hyperoödon, sometimes called “Bottlenose,” a name also vaguely given
to several species of Dolphin, is a regular inhabitant of the North
Atlantic, passing the summer in the Spitzbergen seas and going farther
south in winter. It resembles the Sperm Whale in possessing a large
store of oil in the upper part of the head, which yields spermaceti when
refined; on this account, and also for the sake of the blubber, which
supplies an oil almost indistinguishable from sperm-oil, this Whale has
been the object of a regular chase in recent years.
The following account of its habits is taken from a paper by Captain D.
Gray, published in the _Zoological Society’s Proceedings_ for 1882:—
“These Whales are occasionally met with immediately after leaving the
Shetland Isles in March, and north across the ocean until the ice is
reached, near the margin of which they are found in the greatest numbers;
but they are seldom seen amongst it. Although it is not in their nature
to keep in amongst the ice, they like to frequent the open bays for the
shelter it gives them from the sea. Sometimes a point of ice overlaps
them; it is then only that they are seen going out again towards the
ocean. They are also to be met with from the entrance of Hudson’s Straits
and up Davis’s Straits, as far as 70° N. lat., and down the east side
round Cape Farewell, all round Iceland, north along the Greenland ice
to 77° N. lat.; also along the west coast of Spitzbergen, and east to
Cherry Island in lat. 72° N. and long. 19° E. Beyond these limits I
have never seen them; but doubtless they are to be found as far as the
Straits of Belle Isle on the west, and east to Nova Zembla. From the
fact that they are not seen in summer farther south than a day’s sail
from the ice, it would appear that they migrate south in the autumn, and
north again in the spring. They are gregarious in their habits, going
in herds of from four to ten. It is rare to see more than the latter
number together, although many different herds are frequently in sight
at the same time. The adult males very often go by themselves; but young
bulls, cows, and calves, with an old male as a leader, are sometimes seen
together. They are very unsuspicious, coming close alongside the ship,
round about underneath the boats, until their curiosity is satisfied....
They vary in colour from black in the young to light brown in the
older animals. The very old turn almost yellow, the beak and front of
the head being quite white, with a white band round their necks; all
of them are grayish-white on the belly. They can leap many feet out
of the water, even having time while in the air to turn round their
heads and look about them, taking the water head first, and not falling
helplessly into it sideways like the larger whales. The full-grown
whale is 30 feet long by 20 feet in circumference, and yields two tons
of oil besides two hundredweight of spermaceti.... Their ordinary food
consists of a bluish-white cuttle-fish, six inches long by three inches
in circumference, and pointed towards the tail.... They evidently have a
great depth to go to find them, judging from the length of time that they
remain away, and from the long heavy blasts they make on coming to the
surface again.”
Periotic bones of _Hyperoödon_ are found in the Red Crag of Suffolk,
presenting no character by which they can be specifically distinguished
from those of the common existing species.
_Ziphius._[146]—A single conical tooth of moderate size on each side of
the mandible close to the anterior extremity, and directed forwards and
upwards. Skull with the premaxillæ immediately in front of, and at the
sides of the nares expanded, hollowed, and with elevated lateral margins,
the posterior ends rising to the vertex and curving forwards, the right
being considerably more developed than the left; the conjoint nasals
forming a strongly pronounced symmetrical eminence at the top of the
cranium, projecting forwards over the nares, flat above, most prominent
and rounded in the middle line in front, and separated by a notch on
each side from the premaxillæ. Anteorbital notch not distinct. Rostrum
(seen from above) triangular, gradually tapering from the base to the
apex; upper and outer edges of maxillæ at base of rostrum raised into low
roughened tuberosities. Mesethmoid cartilage densely ossified in adult
age, and coalescing with the surrounding bones of the rostrum. Vertebræ:
C 7, D 10, L 10, C 22; total 49. The three anterior cervical vertebræ
united, the rest free.
The type of this genus is _Z. cavirostris_ of Cuvier, founded upon an
imperfect skull picked up in 1804 on the Mediterranean coast of France,
and described and figured in the _Ossemens Fossiles_ under the impression
that it was that of an extinct species. Many other individuals have,
however, been subsequently met with in various parts of the world, from
the Shetland Islands to New Zealand, all referable to the same genus,
if not to the same species; although, as is usual in such cases, they
have mostly been described under different names, the so-called genera
_Petrorhynchus_ and _Epiodon_ being probably referable to the type
species.
It is quite probable that some of the Physeteroid teeth from the Crag
deposits mentioned on p. 251 may be referable to _Ziphius_.
[Illustration: FIG. 85.—_Mesoplodon bidens._ From Reinhardt.]
_Mesoplodon._[147]—A much compressed and pointed tooth in each ramus of
the mandible, variously situated, but generally at some distance behind
the apex (Fig. 86); its point directed upwards, and often somewhat
backwards, occasionally developed to a great size. Skull with the region
around the nares as in _Hyperoödon_, except that the nasals are narrow
and more sunk between the upper ends of the premaxillæ; like those of
_Hyperoödon_, they are concave in the middle line in front and above.
No maxillary tuberosities. Anteorbital notch not very distinct. Rostrum
long, narrow, and solid throughout. Mesethmoid in adult age ossified in
its entire length, coalescing with the surrounding bones, and showing as
a narrow band on the upper surface of the rostrum. Vertebræ: C 7, D 10,
L 10 or 11, C 19 or 20; total 46 to 48. Two or three anterior cervicals
united, the rest usually free.
[Illustration: FIG. 86.—Left lateral view of skull of _Mesoplodon
densirostris_.]
Though varying in form, the mandibular teeth of the different members
of this genus agree in their essential structure, having a small and
pointed enamel-covered crown, composed of true dentine, which, instead
of surmounting a root of the ordinary character, is raised upon a solid
mass of osteodentine. The continuous growth of this greatly alters the
form and general appearance of the organ as age advances, as seen most
strikingly in the case of _M. layardi_, where the long, narrow, flat,
strap-like teeth, curving inwards at their extremities, actually meet
over the rostrum, and must greatly interfere with the movements of the
jaw. In one species (_M. grayi_) a row of minute, conical, pointed
teeth, like those of ordinary Dolphins, 17 to 19 in number, are present
even in the adults, on each side of the middle part of the upper jaw, but
embedded by their roots only in the gum, and not in bony alveoli. This
fact, with the frequent presence of rudimentary teeth in other species of
this and the last genus in both upper and lower jaws, suggests the idea
that the Ziphioids are derived from ancestral forms which had teeth of
normal character in both jaws; the dentition of the living forms having
become greatly specialised. The existing species of this genus are widely
distributed in both northern and southern hemispheres, but most frequent
in the latter. The best established are _M. bidens_, _M. europæus_, _M.
densirostris_, _M. layardi_, _M. grayi_, and _M. hectori_; but there is
still much to be learned with regard to their distinctive characters and
geographical distribution. They were abundant in the Pliocene age, as
attested by the frequency with which the most imperishable and easily
recognised portion of their structure, the long, cylindrical rostrum
of the skull, of more than ivory denseness, is found among the rolled
and water-worn fragments of animal remains which compose the well-known
“bone-bed” at the base of the Red Crag of Suffolk Several species have
been founded upon the evidence of these rostra. Periotic bones of this
genus (Fig. 87) are of less common occurrence in the Crag; the figure
is given to illustrate the characteristic features of this bone in the
present family.
[Illustration: FIG. 87.—The left periotic bone of _Mesoplodon_; from the
Red Crag of Suffolk. The smooth concave surface in the right upper corner
of the figure forms the anterior articulation with the tympanic. (From
the _Cat. Foss. Mamm. Brit. Mus._ pt. v. p. 70.)]
_Berardius._[148]—Two moderate-sized, compressed, pointed teeth on
each side of the symphysis of the mandible, with their apices directed
forwards, the anterior being the larger of the two and close to the apex.
Upper ends of the premaxillæ nearly symmetrical, moderately elevated,
very slightly expanded, and not curved forward over the nares. Nasals
broad, massive, and rounded, of nearly equal size, forming the vertex
of the skull, flattened in front, most prominent in the middle line.
Anteorbital notch distinct. Rostrum long and narrow. Mesethmoid only
partially ossified. Small rugous eminences on the outer edge of the upper
surface of the maxillæ at base of rostrum. Vertebræ: C 7, D 10, L 12, C
19; total 48. The three anterior cervicals ankylosed, the rest free and
well developed.
The only known species, _B. arnuxi_, attains the length of 30 feet, and
has hitherto only been met with in the seas around New Zealand.
_Choneziphius._[149]—The rostral portions of crania from the Antwerp and
Suffolk Crags, on the evidence of which this genus has been established,
agree with those of _Mesoplodon_ in having the premaxillæ in contact with
the intervening bones throughout the length of their inner surfaces, and
also in showing only a very small portion of the vomer on the inferior
surface; they differ, however, in that the mesethmoid cartilage remains
unossified, whereby a fistular vacuity remains. In some species the
soldering of the inner surfaces of the premaxillæ is incomplete. The
interorbital region of the skull is flat; and there are two pits in the
nasal region, of which the right is the larger.
_Family_ SQUALODONTIDÆ.
Numerous extinct forms, chiefly known by teeth and fragments of crania,
may be provisionally placed here, until more of their osteological
characters shall be brought to light. They differ from all existing
Cetaceans in having the teeth distinctly differentiated into groups,
as in the Archæoceti, the posterior molars being two-rooted. The
cranium has, however, none of the distinguishing characteristics of the
Zeuglodonts, but essentially resembles that of the Odontoceti, especially
in the position of the anterior nares and form of the nasal bones.
_Squalodon._[150]—All the forms may be included in this genus, the
so-called _Rhizoprion_ not being distinct. Dentition: _i_ ³⁄₃, _c_ ¹⁄₁,
simple teeth of the molar series (premolars?) ⁴⁄₄, two-rooted molars
⁷⁄₇ = ¹⁵⁄₁₅; total 60. The double-rooted molars differ from those of
_Zeuglodon_ in having the denticulations of the crown confined to the
posterior border, or at all events much less developed on the front
edge. Very little is known of the structure of these animals beyond the
skull and teeth, fragments of which have been found widely distributed
throughout the marine Miocene and early Pliocene formations of Europe,
especially in the Vienna basin, many parts of France, and the Antwerp and
Suffolk Crags. They have also been found in formations of corresponding
age in North America and South Australia. A few isolated teeth have been
met with in the cave-deposits of Italy, which, if contemporaneous with
the beds in which they occur, indicate the survival of the genus into the
Pleistocene period.
_Family_ PLATANISTIDÆ.
Under this heading may be placed three very singular genera, which,
though differing considerably from each other, have several points in
common, and do not altogether come under the definition either of the
_Physeteridæ_ or the _Delphinidæ_, especially in the important character
of the mode of articulation of the ribs with the dorsal vertebræ, the
tubercular and capitular articulations, distinct at the commencement of
the series, gradually blending together, as they do in most ordinary
mammals. The cervical vertebræ are all free. The lachrymal bone is not
distinct from the jugal. The jaws are long and narrow, with numerous
teeth in both. The symphysis of the mandible exceeds half the length
of the whole ramus. Externally the head is divided from the body by a
slightly constricted neck. Pectoral limbs broad and truncated. Dorsal fin
small or obsolete. Fluviatile or estuarine in habits. There are three
distinct genera, which might almost be made the types of families, but it
is probably more convenient to keep them together, only regarding them as
representing three subfamilies.
_Platanista._[151]—Teeth about ³⁰⁄₃₀ on each side, set near together,
rather large, cylindrical, and sharp-pointed in the young; in old animals
acquiring a large laterally compressed base, which in the posterior part
of the series becomes irregularly divided into roots. As the conical
enamel-covered crown wears away, the teeth of the young and old animals
have a totally different appearance. The rostrum and dentigerous portion
of the mandible are so narrow that the teeth of the two sides are almost
in contact. Maxillæ supporting very large, incurved, compressed bony
crests, which overarch the nares and base of the rostrum, and almost meet
in the middle line above. Orbits very small and eyes rudimentary, without
crystalline lens. External respiratory aperture longitudinal, linear.
Vertebræ: C 7, D 10, L 9, C 26; total: 52. A small cæcum. No pelvic
bones. Dorsal fin represented by a low ridge.
[Illustration: FIG. 88.—_Platanista gangetica._ (From Anderson.)]
One species, _P. gangetica_, entirely fluviatile, being extensively
distributed throughout nearly the whole of the river systems, not only of
the Ganges, but of the Brahmaputra and Indus, ascending as high as there
is water enough to swim in, but never passing out to sea. It is quite
blind, and feeds on small fish and crustaceans, groping for them with
its long snout in the muddy water at the bottom of the rivers. It attains
the length of 8 feet.[152]
_Inia._[153]—Teeth variable, from 26 to 33 on either side of each jaw;
those at the posterior part with a distinct tubercle at the inner side
of the base of the crown. Vertebræ: C 7, D 13, L 3, C 18; total 41.
Transverse processes of lumbar vertebræ very broad. Sternum short and
broad, and consisting of a single segment only. Dorsal fin a mere ridge.
The long cylindrical rostrum externally furnished with scattered, stout,
and crisp hairs. One species only is known, _I. geoffroyensis_, about 7
feet in length, inhabiting the upper Amazon and its tributary streams.
_Pontoporia._[154]—Teeth 50 to 60 on either side of each jaw, with a
cingulum at the base of the crown. Jaws very long and slender. Vertebræ:
C 7, D 10, L 5, C 19; total 41. Transverse processes of the lumbar
vertebræ extremely broad. Sternum elongated, composed of two segments,
with four sternal ribs attached. Dorsal fin rather small, triangular,
pointed. External respiratory aperture transverse, crescentic. This genus
connects the last two forms with the true _Delphinidæ_. The only species,
_P. blainvillei_, is one of the smallest members of the whole order, not
exceeding 5 feet in length. It has only been met with at the mouth of the
Rio de la Plata, near Buenos Ayres, and there is at present no evidence
that it ascends into the fresh waters of the river.
[Illustration: FIG. 89.—_Pontoporia blainvillei._ (From Burmeister.)]
_Fossil forms._—Remains of a Cetacean from the Pleistocene of South
America were referred by Bravard to _Pontoporia_, but they have been
regarded by other writers as indicating a distinct genus, for which
the names _Palæopontoporia_ and _Pontistes_ have been proposed. The
Upper Tertiary European genera _Champsodelphis_ and _Schizodelphis_
are generally referred to the present family. The former has wide
transverse processes to the lumbar vertebræ, as in _Inia_, while the
teeth also resemble those of that genus. In _Schizodelphis_ the form
of the rostrum presents a great resemblance to that of the Delphinoid
genus _Steno_, but the symphysis of the mandible is relatively longer. A
number of fossil Cetaceans from the Miocene of the United States, such
as _Priscodelphinus_, _Lophocetus_, _Ixacanthus_, _Rhabdosteus_, etc.,
are referred by Professor E. D. Cope to this family. _Agabelus_, from the
same deposits, is an apparently allied, but toothless type.
_Family_ DELPHINIDÆ.
Teeth usually numerous in both jaws. Pterygoid bones short, thin, each
involuted to form with a process of the palate bone the outer wall of
the post-palatine air-sinus. Symphysis of mandible short, or moderate,
never exceeding one-third of the length of the ramus. Lachrymal bone not
distinct from the jugal. The anterior facet on the periotic (Fig. 96)
for articulation with the tympanic deeply grooved; and the posterior
tympanic surface of the same bone comparatively narrow, with its ridge
for articulation with the free border of the tympanic ill-defined, and
situated close to one edge. Transverse processes of the dorsal vertebræ
gradually transferred from the arches to the bodies of the vertebræ
without any sudden break, and becoming posteriorly continuous serially
with the transverse processes of the lumbar vertebræ. Anterior ribs
attached to the transverse process by the tubercle, and to the body of
the vertebra by the head; the latter attachment lost in the posterior
ribs. Sternal ribs firmly ossified. External respiratory aperture
transverse, crescentic, with the horns of the crescent pointing forwards.
A very large group, closely united in essential characters but
presenting great modifications in details. The different types are
mostly so connected by intermediate or osculant forms that there are
great difficulties in grouping them into natural subfamilies. Even the
formation of well-defined genera is by no means satisfactory in all
cases. They may, however, be divided, perhaps artificially, into two
groups.
_Group A._—Head rounded, without distinct rostrum or beak. Rostrum of
skull about as long as cranial portion.
_Monodon._[155]—Besides some irregular rudimentary teeth, the entire
dentition is reduced to a single pair of teeth which lie horizontally in
the maxilla, and in the female remain permanently concealed within the
alveolus so that this sex is practically toothless, while in the male
(see Fig. 90) the right tooth usually remains similarly concealed and
abortive, and the left is immensely developed, attaining a length equal
to more than half that of the entire animal, projecting horizontally from
the head in the form of a cylindrical, or slightly tapering, pointed
tusk, without enamel, and with the surface marked by spiral grooves
and ridges, running in a sinistral direction. (When, as occasionally
happens, both tusks are developed, the spiral grooves have the same
direction in each.) Pterygoids very small, not meeting in the middle
line, but approximating posteriorly. Vertebræ: C 7, D 11, L 6, C 26;
total 50. Cervical region comparatively long, and all the vertebræ
distinct, or with irregular unions towards the middle of the series, the
atlas and axis being usually free. Manus small, short, and broad; second
and third digits nearly equal, fourth slightly shorter. No dorsal fin.
This genus is now represented only by the well-known Narwhal (_M.
monoceros_), in which the horn-like tusk of the male often grows to a
length of 7 or 8 feet. In very young animals several small additional
teeth, irregular in number and position, are present, but these usually
disappear soon after birth.
The head is rather short and rounded; the fore limbs or paddles are small
and broad compared with those of most Dolphins; and (as in the Beluga)
the median dorsal fin, found in nearly all other members of the group, is
wanting or replaced by a low ridge. The general colour of the surface is
dark gray above and white below, but variously marbled and spotted with
different shades of gray. In the general contour of the body the Narwhal
resembles the White Whale or Beluga.
[Illustration: FIG. 90.—Upper surface of the skull of male Narwhal
(_Monodon monoceros_), with the whole of both teeth exposed by removal of
the upper wall of their alveolar cavities.]
The Narwhal is essentially an Arctic animal, frequenting the icy
circumpolar seas, and but rarely seen south of 65° N. lat. Three
instances have, however, been recorded of its occurrence on the
British coasts, one in the Firth of Forth in 1648, one near Boston in
Lincolnshire in 1800, while a third, which entangled itself among the
rocks in the Sound of Weesdale, Shetland, in September 1808, is described
by Fleming in the _Memoirs of the Wernerian Society_, vol. i. Like most
other Cetaceans, it is gregarious in its habits, being usually met with
in “schools” or herds of fifteen or twenty individuals. Its food appears
to be various species of cephalopods, small fishes, and crustaceans.
The purpose served in the animal’s economy by the wonderfully developed
asymmetrical tusk—or “horn,” as it is commonly but erroneously called—is
not known. As it is present only in the male sex, no function essential
to the well-being of the individual, such as the procuring of sustenance,
can be assigned to it, but it must be looked upon as belonging to the
same category of organs as the antlers of deer, and perhaps may be
applied to similar purposes. Very little is, however, known of the habits
of Narwhals. Scoresby describes them as “extremely playful, frequently
elevating their horns and crossing them with each other as in fencing.”
They have never been known to charge and pierce the bottom of ships with
their weapons, as the sword-fish often does. The name “Sea Unicorn,”
sometimes applied to the Narwhal, refers to the resemblance of its tusk
to the horn represented as projecting from the forehead of the fabled
unicorn. The ivory of which the tusk is composed is of very good quality,
but, owing to the central cavity, which extends the greater part of its
length, is only fitted for the manufacture of objects of small size.
The entire tusks are sometimes used for decorative purposes, and are of
considerable, though very fluctuating, commercial value.
_Delphinapterus._[156]—This genus is closely allied to the last in
external form, as well as anatomical structure, differing mainly in
the very distinct character of the dentition. Teeth from ⁸⁄₈ to ¹⁰⁄₁₀,
occupying the anterior three-fourths of the rostrum and corresponding
portion of the mandible, rather small, conical, and pointed when unworn,
but usually becoming obliquely truncated, separated by intervals
considerably wider than the diameter of the tooth, and implanted
obliquely, the crowns inclining forwards, especially in the upper jaw.
Skull rather narrow and elongated, depressed. Premaxillæ convex in front
of the nares. Rostrum about equal in length to the cranial portion of the
skull, triangular, broad at the base, and gradually contracting towards
the apex, where it is somewhat curved downwards. Vertebræ: C 7, D 11,
L 9, C 23; total 50. Cervical vertebræ free. Manus broad, short, and
rounded, all the digits being tolerably well developed, except the first.
No dorsal fin, but a low ridge in its place.
[Illustration: FIG. 91.—Beluga or White Whale (_Delphinapterus leucas_).
From a specimen taken in the river St. Lawrence, and exhibited in London,
1877.]
One existing species, _D. leucas_ (Fig. 91), the Beluga or White Whale,
so called from its pure white colour, about 12 feet long, abundant in
the Arctic seas, and extending as far south on the American coast as the
river St. Lawrence, which it ascends for a considerable distance. On rare
occasions it has been seen on the coast of Scotland.
Remains of a Cetacean from the Lower Pliocene of Tuscany have been
referred by Brandt to this genus under the name _D. brocchii_.
In all the remaining genera of _Delphinidæ_ the cervical region of the
vertebral column is very short, and the first two, and usually more, of
the vertebræ are firmly united.
_Phocæna._[157]—Teeth ²⁵⁄₂₅, small, occupying nearly the whole length
of the rostrum, with compressed, spade-shaped crowns, separated from
the root by a constricted neck (Fig. 92). Rostrum rather shorter than
the cranium proper, broad at the base and tapering towards the apex.
Premaxillæ raised into tuberosities in front of the nares. The frontal
bones forming a somewhat square, elevated protuberance in the middle line
of the skull behind the nares, rising altogether above the flattened
nasals. Pterygoids very small, and widely separated in the middle line.
Symphysis of mandible very short. Vertebræ: C 7, D 13, L 14, C 31; total
65 (subject to slight individual variations). First to sixth cervical
vertebræ, and sometimes the seventh also, coalesced. Manus of moderate
size, oval, slightly falcate; second and third digits nearly equal in
length; fourth and fifth well developed, but shorter. Dorsal fin near the
middle of the back, triangular; its height considerably less than the
length of the base; its anterior edge frequently furnished with one or
more rows of conical horny tubercles.
[Illustration: FIG. 92.—Teeth of Porpoise. Twice natural size.]
The common Porpoise (Fig. 93), _P. communis_, is the best known of
British Cetaceans. The word Porpoise (sometimes spelled Porpus and
Porpesse) is apparently derived from the French _porc_ and _poisson_, or
the Italian _porco_ and _pesce_, and thus corresponds with some of the
English vernacular appellations, “hog-fish,” “sea-hog,” “herring-hog,”
and the German _Meerschwein_, whence the usual modern French name of the
animal, _marsouin_. “Porpoise” is commonly used by sailors to designate
all the smaller Cetaceans, especially those numerous species which
naturalists call “Dolphins”; but in scientific language it is restricted
to the genus _Phocæna_ of Cuvier, of which the Porpoise of the British
seas, _Phocæna communis_, Cuvier (_Delphinus phocæna_, Linnæus), is the
type.
The Common Porpoise, when full grown, attains a length of 5 feet or a
little more. The dimensions of an adult female specimen from the English
Channel were as follows:—length in straight line from nose to median
notch between the flukes of the tail, 62½ inches; from the nose to the
anterior edge of the dorsal fin, 29 inches; height of dorsal fin, 4½
inches; length of base of dorsal fin, 8 inches; length of pectoral fin,
9¼ inches; breadth of pectoral fin, 3½ inches; breadth of tail flukes,
13 inches. The under jaw projects about half an inch beyond the upper
one. The aperture of the mouth is tolerably wide, and is bounded by
stiff immobile lips, and curves slightly upwards at the hinder end. The
eye is small, and the external ear represented by a minute aperture in
the skin, scarcely larger than would be made by the puncture of a pin,
situated about 2 inches behind the eye. The pectoral fins are of moderate
size, and slightly falcate. The upper parts are dark gray, or nearly
black, according to the light in which they are viewed, and the state
of moisture or otherwise of the skin; the under parts are pure white.
The line of demarcation between these colours is not distinct (washes or
splashes of gray encroaching upon the white on the sides), and varies
somewhat in different individuals. Usually it passes from the throat
(the anterior part of which, with the whole of the under jaw, is dark)
above the origin of the pectoral fin, along the middle of the flank, and
descends again to the middle line before reaching the tail. Both sides of
the pectoral and caudal fins are black.
[Illustration: FIG. 93.—The Common Porpoise (_Phocæna communis_).]
The Porpoise is sociable and gregarious in its habits, being usually
seen in small herds, and frequenting coasts, bays, and estuaries rather
than the open ocean. It is the commonest Cetacean in the seas around the
British Isles, and not unfrequently ascends the river Thames, having been
seen as high up as Richmond; it has also been observed in the Seine at
Neuilly, near Paris. It frequents the Scandinavian coasts, entering the
Baltic in the summer; and is found as far north as Baffin’s Bay, and as
far west as the coasts of the United States. Southward its range is more
limited than that of the Common Dolphin, as, though very common on the
Atlantic coasts of France, it rarely enters the Mediterranean.
It feeds on fish, such as mackerel, pilchards, and herrings, of which
it devours large quantities, and, following the shoals, is often caught
by fishermen in the nets along with its prey. In former times it was a
common and esteemed article of food in England and in France, but is
now rarely if ever eaten, being commercially valuable when caught only
for the oil obtained from its blubber. Its skin is sometimes used for
leather and boot-thongs, but the so-called “porpoise hides” are generally
obtained from the Beluga.
A closely similar if not identical species from the American coast of the
North Pacific has been described under the name of _Phocæna vomerina_,
and another from the mouth of the Rio de la Plata as _P. spinipennis_.
[Illustration: FIG. 94.—Diagrammatic section of the stomach of the
Porpoise. _a_, Œsophagus; _b_, left, or cardiac, compartment; _c_, middle
compartment; _d_ and _e_, the two divisions of the right, or pyloric,
compartment; _f_, pylorus; _g_, duodenum, dilated at its commencement;
_h_, biliary duct.]
The stomach of the Porpoise (Fig. 94) may be taken as a typical
example of this organ in the Cetacea. The first and by far the largest
compartment (_b_) may be regarded as a kind of crop, or dilatation of
the large œsophagus (_a_). It is lined by a thick white epithelium,
which ceases abruptly at the entrance into the next cavity. It
corresponds to the cardiac compartment of the stomach in the Ungulates
and certain Rodents; but, although its walls do not appear to contain
peptic glands, its contents undergo partial digestion—probably caused
by the regurgitation into it of the secretions of the second, or true
digestive compartment (_c_). This, which is much smaller than the first,
has very thick walls, the mucous membrane being filled with numerous
tubular glands. The surface of this membrane is smooth and soft, being
thrown into numerous folds, which in this genus are arranged in a very
peculiar and characteristic manner, so as to form a series of prominent
longitudinal ridges, each of which sends off short lateral ridges at
right angles to itself, which interdigitate with those proceeding from
the next longitudinal ridge. The remainder of the stomach (_d_ to _f_)
may be compared to the pyloric antrum of the stomach of ordinary mammals.
It is elongated, cylindrical, and intestiniform, with a smooth lining
membrane, sharply bent upon itself, and terminating in a very small
circular pyloric aperture (_f_). In the Porpoise the commencement of
this cavity is constricted off from the remainder, so as to form a small
globular sac. In most Dolphins (as _Tursiops_, _Globicephalus_, and
_Grampus_) there are two such small sacs of very similar size and form,
communicating by circular pylorus-like apertures; and in _Hyperoödon_ the
whole compartment is divided by a series of constrictions into as many as
seven separate cavities, which have been regarded as distinct stomachs.
Immediately beyond the pylorus the duodenum has a globular dilatation, as
in the camels and some other Ungulates, into the lower end of which the
biliary duct (_h_) enters.
An allied species, differing mainly in the absence of dorsal fin, and
in the teeth (with the same form of crown) being fewer in number and of
larger size, called _Delphinus phacænoides_ by Cuvier, _D. melas_ by
Schlegel, forms the type of Gray’s genus _Neomeris_.[158] It is rather
smaller than the Common Porpoise, and almost entirely black in colour.
Common off the coast of Bombay, it has been met with in other parts of
the Indian Ocean, and near Japan. The British Museum recently received
a specimen taken in the Chinese river Yang-tse-kiang nearly a thousand
miles from the sea, which only differs from others from India in wanting
a patch of small horny tubercles on the back. As such tubercles are
present or absent in otherwise similar individuals of _P. communis_,
it is doubtful whether they can be regarded as constituting a specific
character.
_Cephalorhynchus._[159]—Rostrum as long and sometimes slightly longer
than the cranial portion of the skull. Pterygoids widely separated from
one another. Teeth small (less than 3 mm. in diameter), ²⁵⁄₂₅ to ³⁰⁄₃₀.
Vertebræ: C 7, D 13, L 15, C 30; total 65. Dorsal fin low, obtusely
triangular or rounded. Pectoral fins rather small, narrow, and ovate.
Typified by _C. heavisidei_, from the southern seas. _C. eutropia_ is
a very distinct form from the same seas, known only by the skull, and
referred provisionally to this genus.
_Orcella._[160]—Teeth ¹²⁄₁₂ to ¹⁴⁄₁₄, small, conical, pointed, rather
closely set, and occupying nearly the whole length of the rostrum. Skull
subglobular, high. Rostrum nearly equal in length to the cranial portion
of the skull, tapering. Pterygoids widely separated from one another.
Manus of moderate size, not elongated, but somewhat pointed. All the
bones of the digits broader than long, except the proximal phalanges of
the index and third fingers. Dorsal fin rather small, placed behind the
middle of the body. Two species, both of small size—_O. brevirostris_,
from the Bay of Bengal, and _O. fluminalis_, from the Irawadi river, from
300 to 900 miles from the sea. Our present knowledge of the anatomy,
geographical distribution, and habits of these interesting Cetaceans is
almost entirely due to the researches of Dr. J. Anderson.[161]
_Orca._[162]—Teeth about ¹²⁄₁₂, occupying nearly the whole length of the
rostrum, very large and stout, with conical recurved crowns, and large
roots, expanded laterally and flattened, or rather hollowed, on the
anterior and posterior surfaces. Rostrum about equal in length to the
cranial part of the skull, broad and flattened above, rounded in front;
premaxillæ broad and rather concave in front of the nares, contracted
at the middle of the rostrum, and expanding again towards the apex.
Pterygoids of normal form, but not quite meeting in the middle line.
Vertebræ: C 7, D 11-12, L 10, C 23; total 51 or 52. Bodies of the first
and second and sometimes the third cervical vertebræ united; the rest
free. Pectoral fin very large, ovate, nearly as broad as long. All the
phalanges and metacarpals broader than long. General form of body robust.
Dorsal fin near the middle of the back, very high and pointed. Anterior
part of the head broad and depressed.
The animals composing this genus are met with in almost all seas from
Greenland to Tasmania, but the number of species is still uncertain,
and possibly they may be all reduced to one. They are readily known,
when swimming in the water, by the high, erect, falcate dorsal fin,
whence their common German name of _Schwertfisch_ (Sword-fish). By
English sailors they are generally known as “Grampuses” or “Killers.”
They are distinguished from all their allies by their great strength and
ferocity, being the only Cetaceans which habitually prey on warm-blooded
animals, for, though fish form part of their food, they also attack
and devour Seals, and various species of their own order, not only the
smaller Porpoises and Dolphins, but even full-sized Whales, which last
they combine in packs to hunt down and destroy, as Wolves do the larger
Ruminants.
[Illustration: FIG. 95.—The Killer Whale, or Grampus (_Orca gladiator_).
From Hunter.]
_Orca citoniensis_, of the Italian Pliocene, was of smaller size than
the existing Killer. Teeth and periotic bones from the Suffolk Crag not
improbably belong to the same species.
_Pseudorca._[163]—Teeth about ¹⁰⁄₁₀. Cranial and dental characters
generally like those of _Orca_, except that the roots of the teeth are
cylindrical. Vertebræ: C 7, D 10, L 9, C 24; total 50. First to sixth
or seventh cervical vertebræ united. Bodies of the lumbar vertebræ
distinguished from those of the preceding genera by being more elongated,
the length being to the width as 3 to 2. Pectoral fin of moderate size,
narrow, and pointed. Dorsal fin situated near the middle of the back,
of moderate size, falcate. Head in front of the blowhole high, and
compressed anteriorly, the snout truncated.
This genus was first known by the discovery of a skull in a subfossil
state in a fen in Lincolnshire, named by Sir R. Owen _Phocæna
crassidens_. Animals of apparently the same species were afterwards
met with in small herds on the Danish coast, and fully described by
Reinhardt. Others subsequently received from Tasmania were supposed
at first to indicate a different species, but comparison of a larger
series of specimens from these extremely distant localities fails to
establish any characteristic difference, and indicates an immense range
of distribution for a species apparently so rare. The length of this
Cetacean is about 14 feet, and its colour entirely black.
_Globicephalus._[164]—Teeth ⁸⁻¹²⁄₈₋₁₂, confined to the anterior half
of the rostrum and corresponding part of the mandible, small, conical,
curved, sharp-pointed when unworn, sometimes deciduous in old age. Skull
broad and depressed. Rostrum and cranial portion about equal in length.
Upper surface of rostrum broad and flat. Premaxillæ strongly concave
in front of the nares, as wide at the middle of the rostrum as at the
base, or wider, and very nearly or completely concealing the maxillæ in
the anterior half of this region. Pterygoids of normal form, meeting,
or very nearly so, in the middle line. Vertebræ: C 7, D 11, L 12-14,
C 28-29; total 58 or 59. Bodies of the anterior five or six cervical
vertebræ united. Length of the bodies of the lumbar and anterior caudal
vertebræ about equal to their width. Pectoral limb very long and narrow,
the second digit the longest, and having as many as 12 or 13 phalanges,
the third shorter (with 9 phalanges), the first, fourth, and fifth very
short. Fore part of the head very round, in consequence of the great
development of a cushion of fat, placed on the rostrum of the skull in
front of the blowhole. Dorsal fin low and triangular, the length of its
base considerably exceeding its vertical height.
The type of this well-marked genus is _G. melas_, the Pilot Whale, Ca’ing
Whale, or Grindhval of the Faroe islanders, which attains the length of
20 feet, and is of nearly uniform black colour, except the middle of the
under surface, which is lighter. These animals are extremely gregarious,
and, unlike the Killers, are mild and inoffensive in disposition, feeding
principally on cephalopods. Their eminently sociable character constantly
leads to their destruction, since when attacked they instinctively rush
together and blindly follow the leaders of the herd. When they are seen
in the neighbourhood of land, the fishermen endeavour to get to seaward
of them in their boats, and with shouting and firing of guns to drive
them into a bay or fjord, pursuing them until they run themselves on
shore in their alarm. In this way many hundreds at a time are frequently
driven ashore and killed, when a herd enters one of the bays or fjords of
the Faroe Islands or north of Scotland. Animals of this well-marked genus
are found in nearly all seas, and their specific distinctions are not yet
made out. Specimens from the Australian coasts, where they are generally
called “Black-fish,” are quite indistinguishable, either by external or
osteological characters, from those of the North Atlantic.
[Illustration: FIG. 96.—The left periotic bone of _Globicephalus
uncidens_; from the Suffolk Crag. Natural size. The grooved surface on
the right is the anterior facet for articulation with the tympanic; the
posterior tympanic articulation being on the opposite side of the figure.
(From the _Cat. Foss. Mamm. Brit. Mus._ pt. v.)]
Teeth, periotic (Fig. 96) and tympanic bones from the Suffolk Crag,
described as _G. uncidens_, indicate a form apparently closely allied to
the existing species. The periotic is figured in order to illustrate the
distinctive characters of that bone in the _Delphinidæ_.
_Grampus._[165]—Teeth none in the upper jaw; in the mandible few (3 to
7 on each side), and confined to the region of the symphysis. Vertebræ:
C 7, D 12, L 19, C 30; total 68. General external characters much as in
_Globicephalus_, but the fore part of the head less rounded, and the
pectoral fin less elongated.
But one species, _G. griseus_, is certainly known, about 13 feet long,
and remarkable for its great variability of colour. It has been found,
though rarely, in the North Atlantic and Mediterranean. A skull from the
Cape of Good Hope, which differs slightly from that of the above, has
been described under the name of _G. richardsoni_.
_Feresia._[166]—This genus, known at present only by two skulls, may be
provisionally placed here. These appear to indicate a form connecting
_Globicephalus_, _Grampus_, and _Lagenorhynchus_. From the latter they
differ chiefly in the smaller number (about ¹²⁄₁₂) and much larger size
(6-7 mm. in diameter at base of crown) of the teeth.
_Lagenorhynchus._[167]—Rostrum scarcely exceeding the length of the
cranium, broad at the base and gradually tapering towards the apex,
depressed. Pterygoids normal, meeting in the middle line. Teeth small
(not exceeding 4 mm. in diameter), ²³⁄₂₃ to ³³⁄₃₃. Vertebræ very
numerous, 80 to 90. Spines and transverse processes of the lumbar
vertebræ very long and slender; centra short. Externally, head with a
short but not very distinct beak. Two species, _L. albirostris_ and _L.
acutus_, are occasionally captured on the British coasts. Other species
occur elsewhere.
_Group B._—Head with distinctly elongated rostrum, or beak, generally
marked off from the prenarial adipose elevation by a V-shaped groove.
Rostrum of skull considerably longer than the cranial portion. Atlas and
axis firmly united; all the other cervical vertebræ free.
If we add to it the above-mentioned genus, _Lagenorhynchus_, this group
will include all the true Dolphins, Bottle-noses, or, as they are more
commonly called by seafaring people, “Porpoises,” which are found in
considerable abundance in all seas, some species being habitually
inhabitants of large rivers, as the Amazon. They are all among the
smaller members of the order, none exceeding 10 feet in length. Their
food is chiefly fish, for the capture of which their long narrow
beaks, armed with numerous sharp-pointed teeth, are well adapted, but
some appear also to devour crustaceans and molluscs. They are mostly
gregarious, and the agility and grace of their movements in the water
are constant themes of admiration to the spectators of the scene when a
“school of Porpoises” is observed playing round the bows of a vessel at
sea.
_Delphinus._[168]—Teeth very numerous in both jaws, ⁴⁰⁄₄₀ to ⁶⁰⁄₆₀,
occupying nearly the whole length of the rostrum, small, close-set,
conical, pointed, slightly curved. Rostrum elongated, usually about
double the length of the cranial portion of the skull. Pterygoids of
normal form, meeting in the middle line throughout their length. Palate
with deep lateral grooves. Vertebræ 73 to 75. Pectoral fin of moderate
size, narrow, pointed, somewhat falcate. Second and third digits well
developed; the rest rudimental.
The type of the genus is the Common Dolphin of the Mediterranean (_D.
delphis_, Fig. 97), also found in the Atlantic, and of which a closely
allied if not identical form is met with in the Australian seas (_D.
forsteri_) and in the North Pacific (_D. bairdi_). Other species are _D.
janira_, _D. major_, etc.
[Illustration: FIG. 97.—The Common Dolphin (_Delphinus delphis_). From
Reinhardt.]
_Tursiops._[169]—Rostrum tapering moderately from base to apex; palate
not grooved; symphysis of mandible short; other cranial characters as in
_Delphinus_. Teeth ²¹⁄₂₁ to ²⁵⁄₂₅, stout (6 to 7 mm. in antero-posterior
diameter). Vertebræ: C 7, D 13, L 17, C 27; total 64. Limbs as in
_Delphinus_. Represented by the widely distributed _T. tursio_; _T.
catalania_ being a second form. Fossil remains of this genus from the
Italian Pliocene have been recently described.
_Prodelphinus._[170]—Rostrum somewhat variable; mandibular symphysis
short (less than one-fifth the length of the ramus); other cranial
characters as in the preceding genus. Teeth ³⁰⁄₃₀ to ⁵⁰⁄₅₀, small, not
exceeding 3 mm. in diameter. Vertebræ 73 to 78. Limbs as in _Delphinus_.
Four leading types of this genus are recognised (all of which have
numerous synonyms) viz. _P. obscurus_, _P. euphrosyne_, _P. doris_, and
_P. longirostris_.
Péron’s Dolphin (_Delphinus leucorhamphus_, Péron, or _Leucorhamphus
peroni_, Lilljeborg) resembles some forms of _Prodelphinus_ in its
cranial characters; but having no dorsal fin, it has been separated
generically by some writers. It is not improbable that _Delphinus
borealis_, Peale, from the North Pacific, in which there is likewise no
dorsal fin, may be an allied form.
_Steno._[171]—Rostrum long, narrow, and compressed, very distinct from
the cranium; mandibular symphysis as long as, or longer than one-fourth
the length of the ramus; other cranial characters as in the preceding
genus. Teeth ²¹⁄₂₁ to ²⁵⁄₂₅, of comparatively large size (5-6 mm. in
diameter); surface of their crowns finely grooved. Vertebræ: C 7, D 12, L
15, C 32; total 66. Represented by _S. rostratus_, from which the forms
which have received other names are probably not specifically separable.
_Sotalia._[172]—Pterygoids narrow, not meeting in the middle line, and
in their inner borders diverging posteriorly, instead of being parallel
as in the preceding genera; other cranial characters much as in _Steno_.
Teeth tolerably large (4-5 mm. in diameter), ³⁰⁄₃₀ to ³⁵⁄₃₅, with smooth
enamelled surface. Vertebræ: C 7, D 12, L 10-14, C 22; total 51-55.
Pectoral fin broad at base, the breadth being caused by the considerable
development and position of the two outer digits. Six species are
provisionally recognised as distinct, including the Chinese White Dolphin
(_S. sinensis_) and _S. pallidus_ from the river Amazon.
_Bibliography of Cetacea._—D. F. Eschricht, _Untersuchungen
über die Nordischen Wallthiere_, 1849, contains a copious
bibliography of the group up to the date of publication.
Since that time numerous monographs on special families and
genera have been published, and a large illustrated general
work, _Ostéographie des Cétacés_, by P. J. Van Beneden and P.
Gervais, 1869-80. Besides those already referred to in the
footnotes, the following may be mentioned; viz. J. F. Brandt,
“Untersuchungen über die Fossilen und Subfossilen Cetaceen
Europa’s,” in _Mém. de l’Acad. Imp. de St. Pétersbourg_, 7ⁱᵉᵐᵉ
sér. vol. xx. 1873; C. M. Scammon, _Marine Mammals of the N. W.
Coast of North America_, 1874; W. H. Flower, “On the characters
and Divisions of the Families of the _Delphinidæ_,” _Proc.
Zool. Soc._ 1883, p. 466, and _List of the Specimens of Cetacea
in the British Museum_, 1885; F. W. True, “Review of the Family
Delphinidæ,” _Bull. U.S. Nat. Museum_, No. 36, 1889; P. J. Van
Beneden, _Histoire Naturelle des Cétacés des Mers d’Europe_,
1889.
For fossil forms, in addition to the works of Van Beneden,
Gervais, and Brandt, already cited, the reader may refer to
various memoirs published by the former writer in the _Bull.
Ac. R. Belgique_ and _Ann. Mus. R. Hist. Nat. Belg._ See also
R. Lydekker, “The Cetacea of the Suffolk Crag,” _Quart. Journ.
Geol. Soc._ vol. xlii. p. 7 (1887), and _Catalogue of the
Fossil Mammalia in the British Museum_, pt. v. (1887).
CHAPTER IX
THE ORDER UNGULATA
Under this term may be included provisionally a large and rather
heterogeneous group of mammals, the existing members of which form
the Pecora and Belluæ of Linnæus, the Ruminantia and Pachydermata of
Cuvier. A few years ago it was found convenient to restrict the order
to a well-marked and distinctly circumscribed group, comprising the two
sections known as Perissodactyla and Artiodactyla, and to leave out
such isolated forms as the Elephant and Hyrax; but the discovery of a
vast number of extinct species, which could not be brought under the
definition of either perissodactyle or artiodactyle Ungulates, and yet
are evidently allied to both, and to a certain extent bridge over the
interval between these and the isolated groups just mentioned, makes it
necessary either to introduce a number of new and ill-defined ordinal
divisions, or to widen the scope of the original order so as to embrace
them all.
The existing forms are all animals eminently adapted for a terrestrial
life, and in the main for a vegetable diet. Though a few are more or
less omnivorous, and may under some circumstances kill living creatures
smaller and weaker than themselves for food, none are distinctly
and habitually predaceous. Their teeth are markedly heterodont and
diphyodont,—the milk set being well developed and not completely changed
until the animal attains its full stature. The molars have broad crowns
with tuberculated or ridged surfaces. There are no clavicles.[173] Their
toes are provided with blunt, broad nails, or in the majority of cases
with hoofs, more or less enclosing the ungual phalanges. The scaphoid
and lunar bones of the carpus are always distinct. The humerus has no
entepicondylar foramen. The number of digits varies from five to one; and
the radius and ulna may be united together.
The more generalised of the fossil forms do not conform in all
respects to the above-mentioned characters; clavicles being present in
_Typotherium_, and perhaps in some of the Condylarthra, while in the
latter group the humerus may have an entepicondylar foramen, and thus
approximate to the corresponding bone of the Carnivora. Wide as is the
gap between existing Carnivores and Ungulates, there are indeed more or
less strongly marked evidences of affinity between the earlier members of
the two orders, as will be again noticed under the head of the suborder
Condylarthra. A departure from the normal type of foot-structure is
exhibited by the extinct _Macrotherium_, provisionally included in the
Perissodactyla, where the digits terminated in long and curved claws.
As a general rule, the cheek-teeth have distinct roots, and in those of
the existing suborders a gradual increase in the height of the crowns
of these teeth may be noticed in passing from the more generalised
to the more specialised types. Those teeth in which the crowns are
low, and their whole structure visible from the grinding surface, are
termed _brachydont_ (Fig. 122); while those with higher crowns, in
which the bases of the infoldings of enamel are invisible from the
grinding surface, are known as _hypsodont_ (Fig. 123). Again, when the
tubercles on the crowns of the molars are more or less cone-like in form
the tooth is said to be _bunodont_; but when they are expanded in an
antero-posterior direction and curved into a crescent shape the tooth is
described as _selenodont_.
[Illustration: FIG. 98.—Right fore foot of Indian Elephant. × ⅛. U, ulna;
R, radius; _c_, cuneiform; _l_, lunar; _sc_, scaphoid; _u_, unciform;
_m_, magnum; _td_, trapezoid; _tm_, trapezium; I to V, first to fifth
digit.]
The whole order may be divided into the Ungulata Vera, containing the
suborders Perissodactyla and Artiodactyla, and a somewhat heterogeneous
assemblage of animals which may be called Subungulata or Ungulata
Polydactyla. Cope has pointed out a character in the structure of the
carpus by which the latter are differentiated from the former. Thus in
all the Subungulata the bones of the proximal and distal row retain the
primitive or more typical relation to each other (see Fig. 98); the os
magnum of the second row articulating mainly with the lunar of the
first, or with the cuneiform, but not with the scaphoid. But in the group
to which the vast majority of modern Ungulates belong the second or
distal row has been shifted altogether towards the inner side of the limb
(see Fig. 99), so that the magnum is brought considerably into relation
with the scaphoid, and is entirely removed from the cuneiform, as in the
great majority of existing mammals.
It will be on the whole more convenient to commence our survey of the
members of this suborder with the more specialised group of the Ungulata
Vera, in which the Artiodactyla will be taken first.
UNGULATA VERA.[174]
In the typical Ungulata the feet are never plantigrade, and the
functional toes do not exceed four—the inner digit being suppressed,
at all events in all forms which have existed since the Upper Eocene
period.[175] The os magnum of the carpus articulates freely with the
scaphoid. The allantois is largely developed, and the placenta, so far
as is known, is non-deciduate; the chorionic villi being either evenly
diffused or collected in groups or cotyledons (in Pecora). The testes
descend into a scrotum. There is never an os penis. The uterus is
bicornuate. The mammæ are usually few and inguinal, or may be numerous
and abdominal (as in Suina), but are never solely pectoral. The cerebral
hemispheres in existing Ungulates are well convoluted.
The group is now, and has been throughout almost the whole of the
Tertiary period, composed of two perfectly distinct sections, differing
from each other, not only in the obvious characters of the structure
of the limbs, but in so many other parts of their organisation that
they must be considered as of the rank at least of suborders. The
characters of these divisions, first indicated by Cuvier, were thoroughly
established by Owen, by whom the names whereby they are now generally
known were proposed.
_Suborder_ ARTIODACTYLA.
This is a well-defined group, traceable from the Eocene period, though
then apparently by no means so numerous as the Perissodactyles. Some of
its types, as that represented in the existing Swine, have retained to
the present time much of the primitive character of the group; but others
have been gradually becoming more specialised and perfected in structure,
and its latest modification, the Cavicorn Ruminants or _Bovidæ_
(Antelopes, Sheep, and Oxen), are now the dominating members of the great
Ungulate order, widespread in geographical range, rich in generic and
specific variation, and numerous in individuals—forming in all these
respects a great contrast to such decadent types as those represented by
the Tapirs and Rhinoceroses.
[Illustration: FIG. 99.—Bones of right fore foot of existing
Artiodactyles. A, Pig (_Sus scrofa_), × ⅓; B, Red Deer (_Cervus
elaphus_), × ⅐; C, Camel (_Camelus bactrianus_), × ⅛. _U_, Ulna; _R_,
radius; _c_, cuneiform; _l_, lunar; _s_, scaphoid; _u_, unciform; _m_,
magnum; _td_, trapezoid; _tm_, trapezium. From Flower’s _Osteology of
Mammalia_.]
The principal anatomical characters by which the Artiodactyles are
distinguished from the Perissodactyles are as follows. The premolar and
molar teeth usually not alike, the former being single and the latter
two-lobed. The last lower molar of both first and second dentition
almost invariably three-lobed; and the first tooth of the upper cheek
series always without a milk-predecessor. Nasal bones not expanded
posteriorly. No alisphenoid canal. Dorsal and lumbar vertebræ together
always nineteen, though the former may vary from twelve to fifteen. Femur
without third trochanter. Third and fourth digits of both feet almost
equally developed, and their ungual phalanges flattened on their inner or
contiguous surfaces, so that each is not symmetrical in itself, but when
the two are placed together they form a figure symmetrically disposed to
a line drawn between them. Or, in other words, the axis or median line
of the whole foot is a line drawn between the third and fourth digits,
while in the Perissodactyles it is a line drawn down the centre of the
third digit. Distal articular surface of the astragalus divided into two
nearly equal facets, one for the navicular and the other for the cuboid
bone. The calcaneum with an articular facet for the lower end of the
fibula. Stomach almost always more or less complex. Colon convoluted.
Cæcum small. Placenta diffused or cotyledonary. Mammæ few and inguinal,
or numerous and abdominal.
In treating of many sections of mammals, it is only from the existing
species that our characters and classification can be derived, and to
these chiefly our observations upon the group must be directed, many of
the extinct forms being so little known that they can only be referred
to incidentally. With the Ungulata, however, it is quite otherwise. The
history of the Artiodactyla throughout the Tertiary period is now well
known, and throws great light upon the position and relations of the
existing groups.
The principal modifications which have taken place in the type from
its earliest known and most generalised manifestation have been the
following:—
1. As regards the teeth. Assumption by the grinding surfaces of the molar
teeth either of a bunodont or of a selenodont form. Modification of the
latter from a brachydont to a hypsodont type. Loss of upper incisors.
Development of canines into projecting tusks. Loss of anterior premolars.
2. As regards the limbs. Reduction of the ulna from a complete and
distinct bone to a comparatively rudimentary state, in which it coalesces
more or less firmly with the radius. Reduction of the fibula till nothing
but its lower extremity remains. Reduction and final loss of external
pair of digits (second and fifth), with coalescence of the metapodial
bones of the two middle digits. Union of the navicular and cuboid, and
sometimes the ectocuneiform, bones of the tarsus.
3. Change of form of the odontoid process of the axis vertebra from a
cone to a hollow half-cylinder.
4. Development of horns or antlers on the frontal bones, and gradual
complication of form of antlers.
5. By inference only, increasing complication of stomach with ruminating
function superadded. Modification of placenta from simple diffused to
cotyledonary form.
The primitive Artiodactyles, with the typical number (44) of incisor,
canine, and molar teeth, brachydont molars, conical odontoid process,
four distinct toes on each foot, with metapodium and all carpal bones
distinct, no frontal appendages, and (in all probability) simple stomach
and diffused placenta, were separated at a very early period into
Bunodonts and Selenodonts, although there is evidence of intermediate
forms showing a complete transition from the one modification to
the other. These and other fossil forms so completely connect the
four groups—Suina, Tylopoda, Tragulina, and Pecora—into which the
existing members of the suborder have become divided, that in a general
classification embracing both living and extinct forms these divisions
cannot be maintained. In the present work, however, it will be convenient
to retain them, mention being made of some of the chief annectant forms
in separate sections.
SUINA.
The existing members of this group are characterised by their bunodont
molars, and the absence of a complete fusion of the third and fourth
metapodials to form a “cannon-bone.” The full Eutherian dentition is very
frequently present.
Remains of very generalised swine-like animals have been abundantly
found in Tertiary formations both in America and Europe. In the former
continent they never (so far as present evidence indicates) underwent any
great diversity of modification, but gradually dwindled away and almost
died out, being only represented in the actual fauna by the two closely
allied species of Peccary, among the smallest and most insignificant
members of the group, which have existed almost unchanged since the
Miocene age at least, if the evidence of teeth alone can be trusted. In
the Old World, on the other hand, the swine have played a more important
part in recent times, having become widely distributed, and throwing
off some curiously specialised forms. At the present time, though not
very numerous in species, they range through the greater part of the Old
World, except within or near the Arctic Circle, although, in common with
all the other members of the great Ungulate order, they were completely
absent from the whole of the Australian region, until introduced by man
in very recent times.
The existing swine-like animals may be divided naturally into three
families:—I. _Hippopotamidæ_; II. _Suidæ_, or true Pigs; III.
_Dicotylidæ_, or Peccaries.[176]
_Family_ HIPPOPOTAMIDÆ.
[Illustration: FIG. 100.—Grinding surface of a worn molar of
_Hippopotamus amphibius_. (From Owen.)]
Muzzle very broad and rounded. Feet short and broad, having four
subequal toes, with short rounded hoofs, all reaching the ground in
walking. Incisors not rooted, but continuously growing; those of the
upper jaw curved and directed downwards; those of the lower straight and
procumbent. Canines very large, curved, continuously growing; those of
the upper jaw directed downwards. Stomach complex. No cæcum.
_Hippopotamus._[177]—This genus may be taken to include all the known
members of the family; it appears to have been always confined to the
Old World. The dentition may be expressed by the formula _i_ ²⁻³⁄₁₋₃,
_c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃. The crowns of the molars (Fig. 100) when worn
present trefoil-shaped surfaces of dentine; and those of the premolars
are sharp. The facial portion of the skull is much elongated, the orbits
are tubular and very prominent, and the mandible has a large rounded
descending flange at its angle. The ears are small, the tail is short,
and the legs are likewise so short that the belly is raised but a little
distance above the ground. The brain is not richly convoluted, and
differs very considerably from that of the Pigs, approximating in some
respects to that of the Camel and Giraffe, but on the whole standing
very much by itself. The stomach of the common species is of enormous
dimensions, having an axial length of 11 feet, and measuring upwards
of 15 feet along the greater curvature. Its axis is longitudinal, the
pylorus being situated almost in the pelvis, and it is divided into three
distinct compartments, of which the third is cylindrical. The liver of
the adult is of extremely simple form, elongated transversely, and narrow
from above downwards. With the exception of a few tufts of hair on the
lips, on the sides of the head and neck, and at the extremity of the
short compressed tail, the skin of the hippopotamus, some portions of
which are two inches in thickness, is entirely destitute of covering.
[Illustration: FIG. 101.—The Hippopotamus (_Hippopotamus amphibius_).]
The common Hippopotamus (_H. amphibius_), widely distributed in the
rivers and lakes of the African continent, is a huge bulky animal,
characterised by having only two incisors on either side of each jaw; the
central lower pair being very much larger than the outer ones. A male
from the Upper Nile which lived for nearly thirty years in the gardens of
the Zoological Society of London measured 12 feet along the back from the
nose to the root of the tail.
The Hippopotamus lives in herds of from twenty to forty individuals on
the banks and in the beds of rivers, in the neighbourhood of which it
finds its food. This consists chiefly of grass and aquatic plants, of
which it consumes enormous quantities, the stomach being capable of
containing from 5 to 6 bushels. These animals feed principally by night,
remaining in the water during the day, although in districts where
they are undisturbed by man they are less exclusively aquatic. In such
regions they put their heads boldly out of the water to blow, but when
rendered suspicious by persecution, they become exceedingly cautious,
only exposing their eyes and nostrils above the water, and even this they
prefer doing amid the shelter of water plants. In spite of their enormous
size and uncouth form, they are expert swimmers and divers, and can
remain under the water from five to eight minutes. They are said to walk
with considerable rapidity on the bottoms of rivers, beneath at least a
foot of water. At nightfall they come on land to feed; and when, as often
happens on the banks of the Nile, they reach cultivated ground, they do
immense damage to growing crops, destroying by their ponderous tread even
more than they devour.
A much smaller species, known as the Pigmy Hippopotamus (_H.
liberiensis_), inhabits some of the rivers of Western Africa, and is
characterised by having only a single pair of lower incisors. Mainly on
this account, it has been proposed to regard this species as representing
a distinct genus, under the name of _Chœropsis_; but since it agrees
so essentially in other characters with the common form, and sometimes
has two incisors on one side of the lower jaw, it appears preferable
to include it in the type genus. The greater relative size of the
brain-cavity as compared with the facial portion of the skull renders,
indeed, the contour of the skull decidedly different from that of _H.
amphibius_, but this is a feature generally found in young individuals of
larger species, and also in the adults of allied smaller forms.
Both the existing species are now exclusively confined to Africa, but
in the Pleistocene and Pliocene periods the genus was widely spread
over the Old World. Thus in the Upper Pliocene of the Continent and
the Pleistocene of England we meet with remains of a very large
fossil Hippopotamus which cannot be specifically distinguished from
_H. amphibius_. In the Pleistocene and Pliocene of India there are
two species having three pairs of incisors in both jaws. Of these _H.
palæindicus_ has the second pair in the lower jaw very minute, and
evidently just about to disappear; from which we learn that it is this
pair which is missing in _H. amphibius_. In the still more generalised
_H. sivalensis_ the three incisors in the lower jaw are of equal size.
Hexaprotodont species also occur in the Upper Tertiaries of Burma and
Algeria. Small tetraprotodont species (_H. pentlandi_ and _H. minutus_)
have left their remains in enormous quantities in the caves and fissures
of Sicily and Malta.
_Family_ SUIDÆ.
An elongated mobile snout, with an expanded, truncated, nearly naked,
flat, oval terminal surface in which the nostrils are placed. Feet
narrow; four completely developed toes on each. Hoofs of the two middle
toes with their contiguous surfaces flattened. The outer (second and
fifth) digits of existing forms not reaching to the ground in the
ordinary walking position. Teeth variable in number, owing to the
suppression in some forms of an upper incisor and one or more premolars.
Incisors rooted. Upper canines curving more or less outwards or upwards.
Stomach simple, except for a more or less developed pouch near the
cardiac orifice. A cæcum. Colon spirally coiled. Confined to the Old
World.
The mandible has no descending flange at the angle. The crowns of the
molars do not wear into such distinct trefoils as in the Hippopotamus,
and are oblong in shape. The last molar of both the upper and lower jaw
(Fig. 102) has an additional hinder lobe or talon, varying in size in the
different species. The upper premolars are simpler than the true molars.
[Illustration: FIG. 102.—Grinding surface of a worn third right lower
molar of the Wild Boar (_Sus scrofa_). After Owen.]
_Sus._[178]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃; total 44.
Upper incisors diminishing rapidly in size from the first to the third.
Lower incisors long, narrow, closely approximated, and almost horizontal
in position, their apices inclining towards the middle line; the second
slightly larger than the first, the third much smaller. Canines strongly
developed and with persistent roots and partial enamel-covering, those
of the upper jaw not having the usual downward direction, but curving
strongly outwards, upwards, and finally inwards, while those of the lower
jaw are directed upwards and outwards with a gentle backward curve,
their hinder edges working and wearing against the front edges of the
upper canines[179]. They appear externally to the mouth as tusks, the
form of the upper lip being modified to allow of their protrusion, but
are much less developed in the females than in the males. The teeth of
the molar series gradually increase in size and complexity from first
to last, and are arranged in contiguous series, except that the first
lower premolar is separated by an interval from the second. First and
second upper premolars with compressed crowns and two roots. The third
and fourth have an inner lobe developed on the crown, and an additional
pair of roots. The first and second true molars have quadrate crowns,
with four principal obtuse conical cusps, around which numerous accessory
cusps are clustered. The length of the third molar is nearly equal
(antero-posteriorly) to that of the first and second together, its crown
having, in addition to the four principal cusps, a large posterior talon
or heel, composed of numerous clustered conical cusps, and supported by
several additional roots. The lower molar teeth resemble generally those
of the upper jaw, but are narrower. Milk dentition: _i_ ³⁄₃, _c_ ¹⁄₁,
_m_ ³⁄₃; total 28,—the first permanent premolar having no predecessor in
this series. The third incisor, in both upper and lower jaws, is large,
developed before the others, and has much the size, form, and direction
of the canine. Vertebræ: C 7, D 13-14, L 6, S 4, C 20-24. The hairy
covering of the body varies much under different conditions of climate,
but when best developed, as in the European Wild Boar, consists of long
stiff bristles, mostly abundant on the back and sides, and of a close
softer curling undercoat.
The skull of the Pigs (Figs. 103-105) has the axis of the face bent down
upon the basicranial axis, as is also the case with the Sheep. Its most
striking feature is the elevation and backward slope of the occipital
crest formed by the union of the supraoccipital and parietals. The broad
and flat frontals have small postorbital processes, which do not join the
zygomata, so that the orbits are open behind. The nasals are very long
and narrow; and the premaxillæ send up long nasal processes, stopping
short of the frontals. A peculiar prenasal bone is developed at the
anterior extremity of the mesethmoid, which serves to strengthen the
cartilaginous snout. The palate is long and narrow, and extends behind
the last molar tooth. In most species the occipital crest is more nearly
vertical than in the skull represented in Fig. 104.
[Illustration: FIG. 103.—Left lateral view of the dentition of the Boar
(_Sus scrofa_), the roots of the teeth being exposed by removing the
external lamina of bone.]
[Illustration: FIG. 104.—Left lateral view of the skull of _Sus
longirostris_. ⅕ natural size. (From Nehring.)]
[Illustration: FIG. 105.—Frontal aspect of the cranium of _Sus
longirostris_, ⅕ natural size. (From Nehring.)]
This genus occurs at present under three principal modifications or
subgenera.
_A._—_Sus_ proper comprises a number of animals found in a wild state
throughout the greater part of Europe (except where exterminated by
human agency), the north of Africa, southern continental Asia, and
the great islands of the Malayan archipelago, Formosa, and Japan. The
following among others have been admitted by many zoologists as distinct
species:—_Sus scrofa_, the Wild Boar of Europe, Asia Minor, and North
Africa, once common throughout the British Isles; _S. sennaarensis_,
North-East Africa; _S. cristatus_, India; _S. vittatus_, Java, Borneo,
Amboyna, Batchian; _S. papuensis_, New Guinea; _S. timorensis_, Timor
and Rotti; _S. andamanensis_, Andaman Islands; _S. taëvanus_, Formosa;
_S. leucomystax_, Japan; _S. verrucosus_, Java, Borneo, Ceram; _S.
barbatus_, Borneo; _S. celebensis_, Celebes, Philippines, and Moluccas;
_S. longirostris_, Borneo and Java. The last four species form an
allied group in which the facial portion of the skull may be greatly
elongated; _S. barbatus_, and _S. celebensis_ being characterised by
the small size and simple structure of the talon of the third molars.
The skull of _S. longirostris_ is shown in Figs. 104 and 105. The small
_S. andamanensis_ also has very simple third molars. _S. vittatus_, _S.
leucomystax_, _S. cristatus_, _S. taëvanus_, and _S. papuensis_ form
another group, in which the third molar is generally of very complex
structure, more or less closely allied to the Wild Boar; and Dr. Nehring
is inclined to think that the whole five might be included under a
single specific name. This list will give some idea of the geographical
distribution of wild Pigs, but it must be borne in mind that through
the whole of this region, and in fact now throughout the greater part
of the habitable world, Pigs are kept by man in a domesticated state,
and it is still an open question whether some of the wild Pigs of the
islands named above may not be local races derived originally from, or
crossed with, imported domestic specimens. In New Zealand a wild or
rather “feral” race is already established, the origin of which is of
course quite recent, since it is well ascertained that no animal of the
kind ever lived upon the island until after its settlement by Europeans.
Whether the various breeds of domestic Pigs have been derived from
one or several sources is still unknown. As in so many similar cases,
there is no historic evidence upon the subject, and the researches of
naturalists, as Nathusius, Rütimeyer, Rolleston, Nehring, and others, who
have endeavoured to settle the question on anatomical evidence, have not
led to any satisfactory conclusions. It is, however, tolerably certain
that all the species or forms of wild Pigs enumerated above and all the
domestic races are closely allied, and it is probable (though of this
there has been no opportunity of proof) will breed freely together.
It is a curious circumstance that the young of all the wild kinds of
Pigs (so far as yet is known) present a uniform coloration, being dark
brown with longitudinal stripes of a paler colour, a character which
completely disappears after the first few months. On the other hand,
this peculiar marking is rarely seen in domestic Pigs in any part of
the world, although it has been occasionally observed. It is stated by
Darwin that the Pigs which have run wild in Jamaica and the semiferal
Pigs of New Granada have resumed this aboriginal character, and produce
longitudinally striped young; these must of course be the descendants
of domestic animals introduced from Europe since the Spanish conquest,
as before that time there were no true Pigs in the New World. Another
character by which the European domestic Pig differs from any of the wild
species is the concave outline of the frontal region of the skull, a form
still retained by the feral Pigs in New Zealand.
_B._—The diminutive Pig of the Nipal, Terai, and Bhutan, _Sus salvanius_,
has been separated from the rest by Hodgson under the generic name of
_Porcula_, but all the alleged distinctive characters prove on more
careful investigation to have little real value. Owing to its retired
habits and power of concealment under bushes and long grass in the depths
of the great Sal Forest, which is its principal home, very little has
been known of this curious little animal, scarcely larger than a hare.
The acquisition of living specimens in the London Zoological Gardens has,
however, afforded opportunities for careful anatomical observation.[180]
[Illustration: FIG. 106.—Wild Boar and Young.]
_C._—Two well-marked species of African Swine have been with more reason
separated under the name of _Potamochœrus_. The dentition differs
from that of the true _Sus_, inasmuch as the anterior premolars have
a tendency to disappear; sometimes in adult specimens the first upper
premolar is retained, but it is usually absent, as well as the first
and often the second lower premolars. The molar teeth are also less
complex: the last especially having a much less developed talon. There
are likewise characteristic cranial differences. The two species are very
distinct in outward appearance and coloration. One is _S. africanus_,
the South African River-Hog, or Bosch-Vark, of a gray colour, and the
other _S. porcus_, the West African Red River-Hog (Fig. 107), remarkable
for its vivid colouring and long pencilled ears. It should be noted that
the young of both these species, as well as of the pigmy _S. salvanius_,
present the striped character of the true _Sus_, a strong indication of
close affinities, whereas in all the following forms this is absent.
[Illustration: FIG. 107.—The Red River-Hog (_Sus porcus_). From Sclater,
_Guide to Animals in Zoological Society’s Gardens_, 1883, p. 183.]
The genus _Sus_, in the above extended sense, is well represented in
the Tertiaries of the Old World from the period of the Lower Pliocene
upwards. In the Pliocene and Pleistocene of India _S. falconeri_ and
_S. karnuliensis_ are characterised by the extremely complex structure
of the molars, in which they show decided signs of approximation to
the Wart-Hogs; the same feature being exhibited by _S. phacochœroides_
of the Algerian Pliocene. _S. titan_ and _S. giganteus_, of the Indian
Pliocene, together with _S. antiquus_ and _S. erymanthius_, of the
corresponding European deposits, are very large species characterised by
their comparatively simple molars; _S. titan_ being fully as large as a
Tapir. _S. hysudricus_ of the Pliocene of India, and _S. palæochœrus_
of that of Europe, are smaller allied species not improbably related
to _S. andamanensis_, with which they agree in molar structure. _S.
arvernensis_, of the Upper Pliocene of France, appears to be allied to
_S. africanus_; while in the diminutive _S. punjabiensis_ of the Pliocene
of North-Western India we probably have the direct ancestor of _S.
salvanius_.
[Illustration: FIG. 108.—Head of Babirusa (_Babirusa alfurus_).]
_Babirusa._[181]—Dentition: _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ²⁄₂, _m_ ³⁄₃; total 34.
The total number of teeth is therefore considerably reduced, the outer
upper incisor and the two anterior premolars of both jaws being absent.
The molars, especially the last, are smaller and simpler than in _Sus_;
but the great peculiarity of this genus is the extraordinary development
of the canines of the male. These teeth (Fig. 108) are ever-growing,
long, slender, and curved, and entirely without enamel covering. Those of
the upper jaw are directed upwards from their base, so that they never
enter the mouth, but piercing the skin of the face, resemble horns rather
than teeth, and curve backwards, downwards, and finally often forwards
again, almost or quite touching the skin of the forehead. Vertebra:
C 7, D 13, L 16, S 4. There is but one species (_B. alfurus_), found
only in the islands of Celebes and Buru. Its external surface is almost
entirely devoid of hair. With regard to the curiously modified dentition,
Wallace (_Malay Archipelago_, vol. i. p. 435) makes the following
observations:—“It is difficult to understand what can be the use of these
horn-like teeth. Some of the old writers supposed that they served as
hooks by which the creature could rest its head on a branch. But the
way in which they usually diverge just over and in front of the eye has
suggested the more probable idea, that they serve to guard these organs
from thorns and spines while hunting for fallen fruits among the tangled
thickets of rattans and other spiny plants. Even this, however, is not
satisfactory, for the female, who must seek her food in the same way,
does not possess them. I should be inclined to believe rather that these
tusks were once useful, and were then worn down as fast as they grew, but
that changed conditions of life have rendered them unnecessary, and they
now develop into a monstrous form, just as the incisors of the Beaver and
Rabbit will go on growing if the opposite teeth do not wear them away. In
old animals they reach an enormous size, and are generally broken off as
if by fighting.”
_Phacochœrus._[182]—The Wart-Hogs, so called from the large cutaneous
lobes projecting from each side of the face, have the teeth still more
remarkably modified than in _Babirusa_. The milk-dentition, and even
the early condition of the permanent dentition, is formed on the same
general type as that of _Sus_, except that certain of the typical teeth
are absent, the formula being _i_ ¹⁄₃, _c_ ¹⁄₁, _p_ ³⁄₂, _m_ ³⁄₃, total
34; but as age advances all the teeth have a tendency to disappear,
except the canines and the posterior molars, which in some cases are the
only teeth left in the jaws, and attain an extraordinary development.
The upper canines especially are of great size, and curve outwards,
forwards, and upwards. Their enamel covering is confined to the apex, and
soon wears away. The lower canines are much more slender, but follow the
same curve: except on the posterior surface, their crowns are covered
with enamel. Unlike those of the Babirusa, the canines of the Wart-Hog
are large in both sexes. The third molar tooth of both jaws is of great
size, and presents a structure at first sight unlike that of any other
mammal, being composed of numerous (22-25) parallel cylinders or columns,
each with pulp-cavity, dentine, and enamel covering, and packed together
with cement. Careful examination will, however, show that a similar
modification to that which has transformed the comparatively simple molar
tooth of the Mastodon into the extremely complex grinder of the Indian
Elephant has served to change the tooth of the common Pig into that of
_Phacochœrus_, and, as already mentioned, some of the fossil Indian and
African species of _Sus_ indicate the mode in which this transition came
about. The tubercles which cluster over the surface of the crown of the
molars of the common Pig are elongated and drawn out into columns in the
Wart-Hog, as the low transverse ridges of the Mastodon’s tooth become the
leaf-like plates of the Elephant’s.
Two species of this genus are commonly but rather doubtfully
distinguished:—_P. africanus_, Ælian’s Wart-Hog, widely distributed
over the continent; and _P. æthiopicus_, Pallas’s Wart-Hog, confined to
South-Eastern Africa. In specimens attributed to the latter species the
dentition reaches its most complete reduction, as in adult animals the
upper incisors are absent and the lower ones worn down to the roots.
_Family_ DICOTYLIDÆ.
Snout as in _Suidæ_. Dentition: _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total
38. Incisors rooted; upper canines directed downwards, with sharp cutting
hinder edges. Toes, four on the fore feet and three on the hind feet (the
fifth wanting). Stomach complex. A cæcum. Confined to the New World.
_Dicotyles._[183]—The teeth of the Peccaries (_Dicotyles_) differ from
those of the true Pigs (_Sus_) numerically in wanting the upper outer
incisor and the anterior premolar on either side of each jaw, and also
in the circumstance that the last premolar is nearly as complex as the
molars. The upper canines have their points directed downwards, not
outwards or upwards as in the Boars, and are very sharp, with cutting
hinder edges, and completely covered with enamel until worn. The lower
canines are large, directed upwards and outwards, and slightly curved
backwards. The premolar and molar teeth form a continuous series,
gradually increasing in size from the first to the last. The true molars
have square quadricuspidate crowns. The stomach is much more complex
than in the true Pigs, almost approaching that of the ruminants. In
the feet the two middle (third and fourth) metapodial bones, which are
completely separate in the Pigs, are united at their upper ends, as
in the ruminants. On the fore foot the two (second and fifth) outer
toes are equally developed as in Pigs, but on the hind foot, although
the inner (or second) is present, the outer (or fifth) toe is entirely
wanting, giving an unsymmetrical appearance of the member, very unusual
in Artiodactyles. Vertebræ: C 7, D 14, L 5, S 4, C 7. As in the Pigs,
the snout is truncated, and the nostrils are situated in its flat,
expanded, disc-like termination. The ears are rather small, ovate, and
erect; and there is no external appearance of a tail. The surface of
the body is well covered with thick bristly hair, and rather behind
the middle of the back is a large and peculiar gland, which secretes an
oleaginous substance with a powerful musky odour. This was mistaken by
the old travellers for a second navel, a popular error which suggested to
Cuvier the name of _Dicotyles_. When the animal is killed for food, it
is necessary speedily to remove this gland, otherwise it will taint the
whole flesh so as to render it uneatable.
[Illustration: FIG. 109.—The Collared Peccary (_Dicotyles tajacu_).]
There are two species,[184] so nearly allied that they will breed
together freely in captivity. Unlike the true Pigs, they never appear
to produce more than two young ones at a birth. The Collared Peccary
(_D. tajacu_, Linn., _torquatus_, Cuvier), Fig. 109, ranges from the
Red River of Arkansas through the forest districts of Central and South
America as far as the Rio Negro of Patagonia. Generally it is found
singly or in pairs, or at most in small herds of from eight to ten,
and is a comparatively harmless creature, not being inclined to attack
other animals or human beings. Its colour is dark gray, with a white
or whitish band passing across the chest from shoulder to shoulder.
The length of the head and body is about 36 inches. The White-lipped
Peccary or Warree (_D. labiatus_, Cuvier) is rather larger, being about
40 inches in length, of a blackish colour, with the lips and lower jaw
white. Its range is less extensive, since it is not found farther north
than British Honduras or south of Paraguay. It is generally met with in
large herds of from fifty to a hundred or more individuals, and is of
a more pugnacious disposition than the former species, and capable of
inflicting severe wounds with its sharp tusks. A hunter who encounters
a herd of them in a forest has often to climb a tree as his only chance
of safety. Both species are omnivorous, living on roots, fallen fruits,
worms, and carrion; and when they approach the neighbourhood of villages
and cultivated lands they often inflict great devastation upon the crops
of the inhabitants.
Remains of the two existing species of Peccary, as well as of one
much larger extinct form, are found in the cavern-deposits of Brazil;
while large Peccaries also occur in the Pleistocene of the United
States, which, although they have been referred to a distinct genus,
_Platygonus_, on account of their relatively smaller incisors and
somewhat simpler premolars, may well be included in _Dicotyles_.
[Illustration: FIG. 110.—The three left upper molars of _Hyotherium
perimense_, from the Pliocene of India.]
_Allied Extinct Genera._—In the Tertiary deposits of both the Old and
New World occur remains of Pig-like animals which, so far as we can
judge, appear to connect the Peccaries so closely with the true Pigs
as to render the _Dicotylidæ_ really inseparable from the _Suidæ_.
Of these the American genus _Chænohyus_ has the lower canine with a
triangular cross section and received into a notch in the upper jaw,
as in the Peccaries, but the fourth upper premolar is simpler than the
molars, as in the under-mentioned genus _Hyotherium_. The typical forms
have only three premolars, but in others, which it has been proposed
to separate generically as _Bothriolabis_, there are four of these
teeth. _Hyotherium_, of the Pliocene and Miocene of the Old World, is
a generalised form allied both to _Sus_ and _Dicotyles_ as well as to
certain extinct genera. The upper molars (Fig. 110) are characterised
by their square crowns, the last having no distinct third lobe, and
coming into use before the first is much worn, while the last premolar
is simpler than the true molars. The canines, which have an oval section
and are scarcely larger than the incisors, are not received into a notch
in the upper jaw. In the Pliocene of India there occurs an apparently
allied genus known as _Hippohyus_, in which the crowns of the molars
are much taller, and have lateral infoldings of the enamel, producing
a very complex pattern on the worn crowns. The European Miocene genus
_Listriodon_, with the dental formula _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_
³⁄₃, differs from all the preceding in having the anterior and posterior
pairs of tubercles of the molars united into ridges running across their
crowns, so that these teeth resemble the lower molars of the Tapir. The
genus is also found in the Lower Pliocene of India.
EXTINCT TRANSITIONAL ARTIODACTYLES.
In this place it will be convenient to notice briefly a few of the
extinct types of Tertiary Artiodactyles which connect the existing
bunodont Suina with the more specialised selenodont groups mentioned
below so closely as to show that in a strictly palæontological
classification such groups cannot be maintained. It should be mentioned
that while some of these extinct forms were in all probability actual
ancestral links between the bunodonts and selenodonts, others, like
the Anoplotheres, died out entirely without giving rise to any more
specialised descendants.
[Illustration: FIG. 111.—The imperfect third left upper molar of
_Hyopotamus giganteus_, Miocene, India. (From the _Palæontologia
Indica_.)]
_Chœropotamidæ._—In this family the molars are intermediate in
structure between those of the _Suidæ_ and the next family. The upper
ones have very broad crowns, with the five columns arranged as in
_Anthracotherium_; while the premolars are not secant, and may be
very large. The best known forms are the small _Cebochœrus_ of the
Phosphorites of Central France; _Chœropotamus_ of the Upper Eocene, the
type species of which was of the size of a large Pig, with the dental
formula _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₃, _m_ ³⁄₃, and no distinctly selenodont
structure in the molars; the much larger _Elotherium_, from the Upper
Eocene and Lower Miocene of both the Old and New Worlds, which presents
the very rare feature of the absence of a third lobe to the last lower
molar; and the equally large _Tetraconodon_ of the Pliocene of India,
in which this third lobe was present and the premolars were of enormous
size. The remarkable North American Eocene genus _Achænodon_ should
perhaps also be placed here.
[Illustration: FIG. 112.—A right upper molar of _Merycopotamus pusillus_,
Pliocene, India. (From the _Palæontologia Indica_.)]
_Anthracotheriidæ._—The genera _Anthracotherium_ and _Hyopotamus_, of
the upper Eocene and Miocene, have the typical Eutherian dental formula;
the upper molars (Fig. 111) carrying three columns on the anterior and
two on the posterior half of the crown, all of which are of a more or
less decidedly selenodont structure. The mandible has a descending
flange at the angle. The figured tooth (in which the antero-internal and
antero-median columns are imperfect) may be compared with the diagram
given in Fig. 5, p. 32, when the homology of the columns or tubercles
will be at once apparent, the broken antero-median column representing
the protoconule. Some of the species are of large size, while others are
comparatively small.
_Merycopotamus._—The genus _Merycopotamus_ of the lower Pliocene
of India may be regarded as an Anthracotheroid which has lost the
antero-median column to the upper molars (Fig. 112), so that these teeth
are consequently quadrituberculate; and may thus be regarded as typical
examples of the brachy-selenodont modification of molar structure.
_Cotylopidæ._—The Miocene genus _Cotylops_ (_Oreodon_[185]) is the type
of a large American family in which the upper molars are selenodont and
usually have four columns, while the lower canine is approximated to
the incisors and its form and function assumed by the first premolar.
The last upper premolar is simpler than the molars. There is no flange
to the angle of the mandible; and the feet have four digits. The
affinities of this peculiar family are probably widely spread, but they
may have been derived from the _Anthracotheriidæ_. The type genus has
the full Eutherian dentition, but in some of the more specialised forms
(_Cyclopidius_) the upper incisors may be wanting, and large vacuities
occur in the lachrymal region. The generalised genus _Protoreodon_, of
the Upper or Uinta Eocene, has five cusps on the upper molars, arranged
as in the _Anthracotheriidæ_. The pollex is retained in the manus of the
type genus.
[Illustration: FIG. 113.—Restoration of _Anoplotherium commune_ (Upper
Eocene). Cuvier.]
The family may be divided into subfamilies as follows:—
I. Upper molars with four columns.
1. Orbits open, no lachrymal fossa, a diastema, the last
upper premolar with two outer columns, outer wall of
upper molars concave and inclined inwards.—_Agriochœrinæ_
(_Agriochœrus_).
2. Orbits closed, a lachrymal fossa, no diastema, the last
upper premolar with one outer column; outer wall of upper
molars flattened.—_Cotylopinæ_ (_Cotylops_, _Eporeodon_,
_Merycochœrus_, _Cyclopidius_, etc.)
II. Upper molars with five columns.—_Protoreontinæ_ (_Protoreodon_).
_Anoplotheriidæ._—This family includes several Upper Eocene European
genera, with selenodont upper molars, carrying five columns arranged as
those in _Anthracotherium_. One of the earliest known, _Anoplotherium_,
was fully described by Cuvier from remains found in the Paris gypsum-beds
(Upper Eocene). Its forty-four teeth formed a series unbroken by a gap
or diastema, and were of uniform height (as in Man alone of existing
mammals). Its tail was long, with large chevron bones underneath, not
usually found in Ungulates, and there were either three or two toes on
each foot. It was in many respects a much-specialised form, apparently
not on the line of descent of any of the existing groups.
_Dacrytherium_ is an allied genus whose dentition leads on to that of the
smaller _Xiphodon_. The latter genus is characterised by the compressed
and elongated form of the crowns of the first three premolars, which thus
approximate to those of the Chevrotains. There were only two functional
digits to the feet. The so-called _Hyopotamus picteti_, of the Swiss
Eocene, is a species of _Dacrytherium_.
_Cænotheriidæ._—The typical representatives of this family are small
animals not larger than the Chevrotains, with the full complement of
teeth, generally no marked gap in the series, and the crowns of the upper
molars carrying two columns on the anterior and three on the posterior
half of the crown—precisely the reverse of the arrangement obtaining in
the _Anthracotheriidæ_. The known forms are from the Upper Eocene and
Lower Miocene of Europe. In _Cænotherium_ the molars are selenodont,
while they are bunodont in _Dichobunus_. _Homacodon_, of the Bridger
Eocene of the United States, is closely allied to the latter. The first
lower premolar of _Dichobunus_ assumes the form and function of a canine.
_Spaniotherium_ (_Metriotherium_) is a much larger form, in which the
molars are not unlike those of _Anthracotherium_, if the arrangement of
the cusps were reversed; it occurs in the Eocene Phosphorites of France.
It is suggested that the _Tylopoda_ may have originated from this group.
_Tapirulus_ is a small Eocene Artiodactyle with the columns of the upper
molars, which are somewhat like those of _Hyopotamus_, tending to form
transverse ridges; its family position is uncertain.
_Dichodontidæ._—The European genera included in this family all have
quadritubercular selenodont molars, and show signs of approximating
more or less closely to existing types. _Dichodon_, from the Upper
Eocene and Lower Miocene, has the full complement of teeth, which show
no diastema, and have low crowns. The fourth upper premolar has four
columns, like the true molars, and the corresponding lower tooth three
complete lobes; these features being unknown in any other Selenodonts.
In _Lophiomeryx_, of the same beds, the somewhat higher crowns of the
molars approximate to those of the _Cervidæ_, but the hinder lobes of
the upper ones are imperfectly developed; the genus may be allied,
to the _Tragulidæ_. In the small _Gelocus_, of the Lower Miocene,
the molars are not unlike those of _Dichodon_; but the navicular and
cuboid bones of the tarsus were fused together, and the metatarsals had
united to form a “cannon-bone,” although the metacarpals still remained
distinct. It is not improbable that upper incisors were wanting; and it
has been suggested that we have in this genus the ancestral type of the
_Tragulidæ_ and _Cervidæ_.
TYLOPODA.
_Family_ CAMELIDÆ.
This group is represented at the present day by the two species of
Camels of the Old World and the Llamas of South America, collectively
constituting the family _Camelidæ_. The special characters which
the Llamas and Camels have in common, and the combination of which
distinguishes them from the rest of the Artiodactyles, are as follows.
The premaxillæ have the full number of incisor teeth in the young state,
and the outermost is persistent through life as an isolated laniariform
tooth. The canines are present in both jaws, and those of the mandible
are differentiated from the long, procumbent, and spatulate incisors,
being suberect and pointed. The crowns of the true molars belong to the
crescentic or selenodont type, and are very hypsodont; but one or more
of the anterior premolars is usually detached from the series, and is of
simple pointed form. The auditory bulla is filled with cancellous tissue.
The hinder part of the body is much contracted, and the femur long and
vertically placed, so that the knee-joint is lower in position, and the
thigh altogether more detached from the abdomen than in most quadrupedal
mammals. The limbs are long, but with only the third and fourth digits
developed; no traces of any of the others being present. The trapezoid
and magnum of the carpus, and the cuboid and navicular of the tarsus
are distinct. The two metapodial bones of each limb are confluent for
the greater part of their length, though separated for a considerable
distance at the lower end. Their distal articular surfaces, instead of
being pulley-like, with deep ridges and grooves, as in other recent
Artiodactyles, are simple, rounded, and smooth. The proximal phalanges
are expanded at their distal ends, and the wide, depressed middle
phalanges are embedded in a broad cutaneous pad, forming the sole of the
foot, on which the animal rests in walking, instead of on the hoofs. The
ungual phalanges are very small and nodular, not flattened on their inner
or opposed surfaces, and not completely encased in hoofs, but bearing
nails on their upper surface only. The cervical region is long and
flexuous, and the vertebræ of which it is composed are remarkable for
the position of the canal for the transmission of the vertebral artery,
which does not perforate the transverse process, but passes obliquely
through the anterior part of the pedicle of the arch (a condition only
found in two other genera of mammals, _Macrauchenia_ and _Myrmecophaga_).
There are no horns or antlers. Though these animals ruminate, the
stomach differs considerably in the details of its construction from
that of the Pecora. The interior of the rumen or paunch has no villi
on its surface, and there is no distinct psalterium or manyplies. Both
the first and second compartments are remarkable for the presence of a
number of pouches or cells in their walls, with muscular septa, and a
sphincter-like arrangement of their orifices, by which they can be shut
off from the rest of the cavity, and into which the fluid portion only
of the contents of the stomach is allowed to enter.[186] The placenta
is diffuse, as in the Suina and Tragulina, not cotyledonary, as in the
Pecora. Finally, the _Camelidæ_ differ not only from other Ungulates,
but from all other mammals, in the fact that the red corpuscles of the
blood, instead of being circular in outline, are oval, as in the inferior
vertebrated classes.
_Camelus._[187]—Dentition of adult: _i_ ¹⁄₃, _c_ ¹⁄₁, _p_ ³⁄₂, _m_ ³⁄₃;
total 34. First upper premolar simple, placed immediately behind the
premaxillæ, and separated by a long diastema from the penultimate tooth
of that series. Lower incisors somewhat proclivous, the outermost the
largest. Skull elongated, with an overhanging occiput, orbits completely
surrounded by bone, and the premaxillæ not articulating with the
arched and somewhat elongated nasals. Vertebræ: C 7, D 12, L 7, S 4, C
13-15. Ears comparatively short and rounded. One or two dorsal adipose
humps. Feet broad, with the toes very imperfectly separated. Tail well
developed, tufted at the end. Hair nearly straight, and not woolly. Size
very large and bulky.
The genus is now represented by two species, viz. the single-humped
Arabian Camel (_Camelus dromedarius_), and the double-humped Bactrian
Camel (_C. bactrianus_, Fig. 114).[188] The former is quite unknown
in a wild state, but it is reported that wild Bactrian Camels occur
in the more remote parts of Turkestan. The latter species is found in
a domesticated state throughout a large portion of Turkestan and the
neighbouring region, extending as far as the Crimea in the west and
to Lake Baikal and Pekin in the east. It is a heavier and more clumsy
animal than the Arabian Camel, with thicker hair, shorter legs, and the
feet more callous and better adapted to a hard ground. The hair is most
developed upon the top of the head, neck, humps, arm, and wrist. Bactrian
Camels are occasionally brought over the stupendous mountain passes south
of Yarkand to within a few days’ journey of Leh, in Kashmir territory.
[Illustration: FIG. 114.—The Bactrian Camel (_Camelus bactrianus_).]
The Arabian Camel is commonly employed as a beast of burden in Africa
and India, and has of late years been introduced into Australia for
the same purpose; it is especially valuable in crossing long stretches
of arid desert from its power of existing for a considerable period of
time without water. The female goes fully eleven months with young, and
produces but a single calf at a birth, which is suckled for a whole
year. In disposition the Camel is surly and subject to furious outbursts
of temper, especially during the rutting season. At such periods the
male utters a peculiar and highly disagreeable bubbling noise in its
throat, well known to all who have travelled in India with Camels as
their transport. It has been said that the Camel is docile, but Palgrave
observes:—
“If docile means stupid, well and good; in such a case the Camel is the
very model of docility. But if the epithet is intended to designate an
animal that takes an interest in its rider so far as a beast can, that
in some way understands his intentions, or shares them in a subordinate
fashion, that obeys from a sort of submissive or half-fellow-feeling with
his master, like the horse or elephant, then I say that the camel is by
no means docile—very much the contrary. He takes no heed of his rider,
pays no attention whether he be on his back or not, walks straight on
when once set agoing, merely because he is too stupid to turn aside,
and then should some tempting thorn or green branch allure him out of
the path, continues to walk on in the new direction simply because he
is too dull to turn back into the right road. In a word, he is from
first to last an undomesticated and savage animal, rendered serviceable
by stupidity alone, without much skill on his master’s part, or any
co-operation on his own save that of an extreme passiveness. Neither
attachment nor even habit impress him; never tame, though not wide-awake
enough to be exactly wild.” The two species breed together freely,
and among the Yourouks of Asia Minor, hybrids, or mules, the produce
generally of a male Bactrian and a female Arabian camel are preferred to
either of the pure breeds.
Fossil remains of Camels are found in the Pliocene of the Siwalik Hills
in Northern India. These differ from the existing representatives of the
genus in having a vertical ridge at the antero-external angle of the
lower molars, whereby they resemble _Auchenia_; their cervical vertebræ
are also intermediate in structure between those of the latter and the
existing Camels. A fossil Camel is also found in the Pleistocene of
Algeria.
_Auchenia._[189]—Dentition of adults normally: _i_ ¹⁄₃, _c_ ¹⁄₁, _p_ ²⁄₂,
_m_ ³⁄₃; total 32—one of the lower premolars may, however, be wanting.
In the upper jaw there is a compressed, sharp, pointed laniariform
incisor near the hinder edge of the premaxilla, followed, in the male at
least, by a moderate-sized, pointed, curved true canine in the anterior
part of the maxilla. The isolated canine-like premolar which follows
in the Camels is not present. The teeth of the molar series, which are
in contact with each other, consist of two very small premolars (the
first almost rudimentary) and three broad molars, constructed generally
like those of _Camelus_. In the lower jaw the three incisors are long,
spatulate, and procumbent; the outer ones being the smallest. Next to
these is a curved, suberect canine, followed after an interval by an
isolated, minute, and often deciduous simple conical premolar; then a
contiguous series of one premolar and three molars, which differ from
those of existing species of _Camelus_ in having a small accessory
column at the anterior outer edge. The skull generally resembles that
of _Camelus_, the relatively larger brain-cavity and orbits and less
developed cranial ridges being due to its smaller size. The nasal bones
are shorter and broader, and are joined by the premaxillæ. Vertebræ:
C 7, D 12, L 7, S 4, C 15-20. Ears rather long and pointed. No dorsal
hump. Feet narrow, the toes being more separated than in the camels,
each having a distinct plantar pad. Tail short. Hairy covering long and
woolly. Size (in existing forms) smaller, and general form lighter than
in the Camels. At present and within historic times the genus is entirely
confined to the western side and southernmost parts of South America, but
fossil remains have been found in the caves of Brazil, in the pampas of
the Argentine republic, and in Central and North America.
[Illustration: FIG. 115.—Llama (_Auchenia glama_), from an animal living
in the Gardens of the Zoological Society of London.]
The word Llama, sometimes spelt Lama, is the name by which the Peruvians
designated one of a small group of closely allied animals, which, before
the Spanish conquest of America, were the only domesticated hoofed
mammals of the country, being kept, not only for their value as beasts
of burden, but also for their flesh, hides, and wool,—in fact, supplying
in the domestic economy of the people the place of the horse, the ox,
the goat, and the sheep of the Old World. The word is now sometimes
restricted to one particular species or variety of the group, and
sometimes used in a generic sense to cover the whole. Although they were
often compared by early writers to sheep, and spoken of as such, their
affinity to the camel was very soon perceived, and they were included
in the genus _Camelus_ in the _Systema Naturæ_ of Linnæus. They were,
however, separated by Cuvier in 1800 under the name of _Lama_, changed
by Illiger in 1811 to _Auchenia_ (in allusion to the great length of
neck, αὐχήν), a term afterwards adopted by Cuvier, and almost universally
accepted by systematic zoologists, although there has been of late a
disposition to revive the earlier name.
In essential structural characters, as well as in general appearance and
habits, all the animals of this genus very closely resemble each other,
so that the question as to whether they should be considered as belonging
to one, two, or more species has been one which has led to a large amount
of controversy among naturalists. The question has been much complicated
by the circumstances of the great majority of individuals which have come
under observation being either in a completely or partially domesticated
state, and descended from ancestors which from time immemorial have been
in like condition, one which always tends to produce a certain amount
of variation from the original type. It has, however, lost much of its
importance since the doctrine of the distinct origin of species has been
generally abandoned.
[Illustration: FIG. 116.—Head of Vicugna, from an animal living in the
Gardens of the Zoological Society of London.]
The four forms commonly distinguished by the inhabitants of South America
are recognised by some naturalists as distinct species, and have had
specific designations attached to them, though usually with expressions
of doubt, and with great difficulties in defining their distinctive
characteristics. These are (1) the Llama, _Auchenia glama_ (Linn.), or
_Lama peruana_ (Tiedemann); (2) the Alpaca, _A. pacos_ (Linn.); (3) the
Guanaco or Huanaco, _A. huanacus_ (Molina); and (4) the Vicugna, _A.
vicugna_ (Molina), or _A. vicunna_, (Cuv.) The first and second are only
known in the domestic state, and are variable in size and colour, being
often white, black, or piebald. The third and fourth are wild, and of
a nearly uniform light-brown colour, passing into white below. They
certainly differ from each other, the Vicugna being smaller, more slender
in its proportions, and having a shorter head (Fig. 116) than the Guanaco
(Fig. 117). It may therefore, according to the usual view of species,
be considered distinct. It lives in herds on the bleak and elevated
parts of the mountain range bordering the region of perpetual snow,
amidst rocks and precipices, occurring in various suitable localities
throughout Peru, in the southern part of Ecuador, and as far south as the
middle of Bolivia. Its manners very much resemble those of the Chamois
of the European Alps; and it is as vigilant, wild, and timid. The wool
is extremely delicate and soft, and highly valued for the purposes of
weaving, but the quantity which each animal produces is not great.
[Illustration: FIG. 117.—Head of Guanaco, from an animal living in the
Gardens of the Zoological Society of London.]
The Guanaco has an extensive geographical range, from the highlands of
the Andean region of Ecuador and Peru to the open plains of Patagonia,
and even the wooded islands of Tierra del Fuego. It constitutes the
principal food of the Patagonian Indians, and its skin is invaluable
to them, as furnishing the material out of which their long robes are
constructed. It is about the size of a European Red Deer, and is an
elegant animal, being possessed of a long, slender, gracefully curved
neck and fine legs. Dr. Cunningham,[190] speaking from observation on
wild animals, says:—
“It is not easy to describe its general appearance, which combines some
of the characters of a camel, a deer, and a goat. The body, deep at the
breast but very small at the loins, is covered with long, soft, very
fine hair, which on the upper parts is of a kind of fawn-colour, and
beneath varies from a very pale yellow to the most beautiful snow-white.
The head is provided with large ears, in general carried well back, and
is covered with short grayish hair, which is darkest on the forehead.
Occasionally the face is nearly black. As a rule it lives in flocks of
from half a dozen to several hundreds, but solitary individuals are now
and then to be met with. They are very difficult to approach sufficiently
near to admit of an easy shot, as they are extremely wary, but, on being
disturbed, canter off at a pace which soon puts a safe distance between
them and the sportsman, even though he should be mounted. Despite their
timidity, however, they are possessed of great curiosity, and will
sometimes advance within a comparatively short distance of an unknown
object, at which they will gaze fixedly till they take alarm, when they
effect a speedy retreat. Their cry is very peculiar, being something
between the belling of a deer and the neigh of a horse. It would be
difficult to overestimate their numbers upon the Patagonian plains; for
in whatever direction we walked we always came upon numbers of portions
of their skeletons and detached bones.”
Darwin, who has given an interesting account of the habits of the Guanaco
in his _Naturalist’s Voyage_, says that they readily take to the water,
and were seen several times at Port Valdes swimming from island to island.
The Llama is only known as a domestic animal, and is chiefly met with
in the southern part of Peru. Burmeister, a very competent writer
on the subject, says that he is perfectly satisfied that it is the
descendant of the wild Guanaco, an opinion opposed to that of Tschudi. It
generally attains a larger size than the Guanaco, and is usually white
or spotted with brown or black, and sometimes altogether black. The
earliest and often-quoted account of this animal by Agustin de Zarate,
treasurer-general of Peru in 1544, will bear repeating as an excellent
summary of the general character and uses to which it was put by the
Peruvians at the time of the Spanish conquest. He speaks of the Llama
as a sheep, observing, however, that it is camel-like in shape though
destitute of a hump:—
“In places where there is no snow the natives want water, and to supply
this they fill the skins of sheep with water and make other living sheep
carry them; for, it must be remarked, these sheep of Peru are large
enough to serve as beasts of burden. They can carry about one hundred
pounds or more, and the Spaniards used to ride them, and they would
go four or five leagues a day. When they are weary they lie down upon
the ground; and as there are no means of making them get up, either by
beating or assisting them, the load must of necessity be taken off.
When there is a man on one of them, if the beast is tired and urged to
go on, he turns his head round and discharges his saliva, which has an
unpleasant odour, into the rider’s face. These animals are of great
use and profit to their masters, for their wool is very good and fine,
particularly that of the species called Pacas, which have very long
fleeces; and the expense of their food is trifling, as a handful of maize
suffices them, and they can go four or five days without water. Their
flesh is as good as that of the fat sheep of Castile. There are now
public shambles for the sale of their flesh in all parts of Peru, which
was not the case when the Spaniards came first; for when one Indian had
killed a sheep his neighbours came and took what they wanted, and then
another Indian killed a sheep in his turn.”
The disagreeable habit here noticed of spitting in the face of persons
whose presence is obnoxious is common to all the group, as may be daily
witnessed in specimens in confinement in the menageries of Europe. One
of the principal labours to which the Llamas were subjected at the time
of the Spanish conquest was that of bringing down ore from the mines in
the mountains. Gregory de Bolivar estimated that in his day as many as
three hundred thousand were employed in the transport of the produce of
the mines of Potosi alone; but since the introduction of horses, mules,
and donkeys the importance of the Llama as a beast of burden has greatly
diminished.
The Alpaca, though believed by many naturalists to be a variety of the
Vicugna, is more probably, like the Llama, derived from the Guanaco,
having the naked callosities on the hind limbs, and the relatively
large skull of the latter. It is usually found in a domesticated or
semi-domesticated state, being kept in large flocks which graze on the
level heights of the Andes of southern Peru and northern Bolivia at an
elevation of from 14,000 to 16,000 feet above the sea-level, throughout
the year. It is smaller than the Llama, and, unlike that animal, is not
used as a beast of burden, but is valued only for its wool, of which the
Indian blankets and ponchas are made. Its colour is usually dark brown or
black.
Mention has already been made of the occurrence of fossil Llamas in
America, but some diversity of view obtains as to the generic position
of some of these forms, owing to variations in their dental formula.
Remains apparently referable to the existing species occur in the
cavern-deposits of Brazil. In the Pleistocene of Mexico we meet with
_A. (Palauchenia) magna_, which attained the size of a Camel, and had
always two, and occasionally three, lower premolars; while in one South
American Pleistocene species, which has been generically separated as
_Hemiauchenia_, there were invariably three premolars in each jaw. In _A.
(Holomeniscus) hesterna_, from the Pleistocene of North America, which
was equal in size to _A. magna_, the premolars were reduced to one in
each jaw; and the same condition obtains in _A. (Eschatius) vitakeriana_,
where, however, the upper one is of simpler structure.
_Extinct Cameloids._—Until within the last few years the existence of
two genera having so very much in common as the Camels and the Llamas,
and yet so completely isolated geographically, had not received any
satisfactory explanation; for the old idea that they in some way
“represented” each other in the two hemispheres of the world was a mere
fancy without philosophical basis. The discoveries made mostly within
the past twenty years of a vast and previously unsuspected extinct fauna
in the American continent of the Tertiary period, as interpreted by
Leidy, Cope, Marsh, and others, has thrown a flood of light upon the
early history of this family, and upon its relations to other mammals.
There have been found in these regions many Camel-like animals exhibiting
different generic modifications; and, what is more interesting, a gradual
series of changes, coinciding with the antiquity of the deposits in which
they are found, have been traced from the thoroughly differentiated
species of the modern epoch down through the Pliocene to the early
Miocene beds, where, their characters having become by degrees more
generalised, they have lost all that specially distinguishes them as
_Camelidæ_, and are merged into forms common to the ancestral type of all
the other sections of the Artiodactyles. Hitherto none of these annectant
forms have been found in any of the fossiliferous strata of the Old
World; and it may therefore be fairly surmised (according to the evidence
at present before us) that America was the original home of the Tylopoda,
and that the true Camels have passed over into the Old World, probably by
way of the north of Asia, where we have every reason to believe there was
formerly a free communication between the continents, and then, gradually
driven southward, perhaps by changes of climate, having become isolated,
have undergone some further special modifications; while those members
of the family that remained in their original birthplace have become,
through causes not clearly understood, restricted solely to the southern
or most distant part of the continent. The occurrence in the dentition of
the fossil Siwalik Camels of a feature now found only in _Auchenia_ is
especially interesting from this point of view.
Briefly referring to some of these fossil types, we may note that
_Pliauchenia_, of the Loup Fork beds (Lower Pliocene) of the United
States, has three lower premolars, while in _Procamelus_ there were four
of these teeth. In _Protolabis_ of the Miocene we have a more generalised
form, in which the dental formula is _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_
³⁄₃; and from this type a transition may be traced to _Poëbrotherium_,
which, while having the same dental formula, was no larger than a Fox,
and had the third and fourth metacarpals separate, with rudiments of the
fourth and fifth. The earliest undoubted representative of the group is
_Leptotragulus_, of the Uinta Eocene, which appears to have been closely
allied to _Poëbrotherium_. It is, however, probable that the first
lower premolar was wanting; while the other premolars of the mandible
were much shorter antero-posteriorly than in the last-named genus. The
manus, moreover, appears to have been less reduced, the second metacarpal
retaining its connection with the magnum. It is suggested that
_Leptotragulus_ may have been derived from the Bunodont genus _Homacodon_
of the Bridger Eocene, mentioned among the _Cænotheriidæ_.
TRAGULINA.
_Family_ TRAGULIDÆ.
No teeth in premaxillæ. Upper canines well developed, especially in
the males; narrow and pointed. Lower canines incisiform. No caniniform
premolars in either jaw, all the premolars except the last in the upper
jaw being secant. Molariform teeth in a continuous series, consisting
of _p_ ³⁄₃, _m_ ³⁄₃. Odontoid process of axis vertebra conical. Fibula
complete. Four complete toes on each foot. The middle metapodials
generally confluent, the outer ones (second and fifth) very slender
but complete, _i.e._ extending from the carpus or tarsus to the digit.
Navicular, cuboid, and ectocuneiform bones of tarsus united. Tympanic
bullæ of skull filled with cancellar tissue. No frontal appendages.
Ruminating, but the stomach with only three distinct compartments, the
manyplies or third cavity of the stomach of the Pecora being rudimentary.
Placenta diffused.
This section is represented only by the single family _Tragulidæ_,
containing a few animals of small size, commonly known as Chevrotains,
intermediate in their structure between the Deer, the Camels, and the
Pigs. The large size of the canines of the male and the absence of
horns caused them to be associated formerly with _Moschus_, one of the
_Cervidæ_; hence they are often spoken of as “Pigmy Musk-Deer,” although
they have no musk-secreting gland, or, except in the above-named trivial
external characters, no special affinities with the true Musk-Deer.
There has scarcely been a more troublesome and obdurate error in zoology
than in this association of animals so really distinct. It has been
troublesome, not only in preventing a just conception of the relations of
existing Artiodactyles, but also in causing great confusion and hindrance
in palæontological researches among allied forms; and most obdurate,
inasmuch as all that has been recently done in advancing our knowledge
of both groups has not succeeded in eradicating it, not only from nearly
every one of our zoological text-books, whether British or Continental,
but even from works of the highest scientific pretensions.
The family is now generally divided into two genera.
_Tragulus_,[191] containing the smallest of the existing Ungulates,
animals having more of the general aspects and habits of some Rodents,
as the Agoutis, than of the rest of their own order. The best-known
species are _T. javanicus_, _T. napu_, _T. stanleyanus_, and _T.
memmina_. The first three are from the Malay Peninsula, or the islands of
the Indo-Malayan Archipelago, the last from Ceylon and India. A fossil
species occurs in the Pliocene of the latter country.
_Dorcatherium_[192] is distinguished chiefly by the feet being stouter
and shorter, the outer toes better developed, and the two middle
metacarpals not ankylosed together. Its dental formula (as that of
_Tragulus_) is usually _i_ ⁰⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃ = 34. Vertebræ:
C 7, D 13, L 6, S 5, C 12-13. The only existing species, _D. aquaticum_
(Fig. 118), from the west coast of Africa, is rather larger than any of
the Asiatic Chevrotains, which it otherwise much resembles, but it is
said to frequent the banks of streams, and have much the habits of Pigs.
It is of a rich brown colour, with back and sides spotted and striped
with white. It is evidently the survivor of a very ancient form, as
remains of the type species (_D. naui_), only differing in size, occur in
the lower Pliocene and Miocene of Europe; fossil species are also found
in the Indian Pliocene. In _D. naui_ there are, at least frequently, four
lower premolars, while the existing species has but three of these teeth.
[Illustration: FIG. 118.—The African Water-Chevrotain (_Dorcatherium
aquaticum_).]
_Extinct Traguloids._—A number of small selenodont Artiodactyles from
various Miocene and Pliocene deposits appear to connect the modern
Tragulina so closely with _Gelocus_ (p. 294), and thus with the ancestral
_Cervidæ_, that their classification is almost an impossibility. Thus
_Leptomeryx_, from the Miocene of the United States, is regarded as a
Traguloid, having four premolars in each jaw and with the metatarsals
fused into a cannon-bone. _Prodremotherium_, of the Upper Eocene
Phosphorites of France, differs in that the metacarpals also form a
cannon-bone; while in the American _Hypertragulus_, both metacarpals and
metatarsals remain separate. _Bachitherium_, of the French Phosphorites,
apparently presents affinity with _Gelocus_, _Prodremotherium_, and
_Dorcatherium_. In this genus the first of the four lower premolars
assumes the character and function of a canine, the true canine being
incisor-like, and there are traces of minute upper incisors.
PECORA, OR COTYLOPHORA.
No premaxillary teeth or caniniform premolars. Upper canines generally
absent, though sometimes largely developed. Inferior incisors, three on
each side with an incisiform canine in contact with them. Molariform
teeth consisting of _p_ ³⁄₃, _m_ ³⁄₃, in continuous series. Auditory
bullæ simple and hollow within. Odontoid process in the form of a
crescent, hollow above. Distal extremity of the fibula represented by a
distinct malleolar bone of peculiar shape, articulating with the outer
surface of the lower end of the tibia. Third and fourth metacarpals and
metatarsals confluent. Outer or lateral toes small and rudimentary, or
in some cases entirely suppressed; their metapodial bones never complete
in existing forms. Navicular and cuboid bones of tarsus united. Horns or
antlers usually present, at least in the male sex. Left brachial artery
arising from a common innominate trunk, instead of coming off separately
from the aortic arch as in the preceding sections. Stomach with four
complete cavities. Placenta cotyledonous.[193]
[Illustration: FIG. 119.—A shed right antler of the Red Deer (_Cervus
elaphus_), found in an Irish lake. _a_, Brow tine; _b_, bez tine; _c_,
tres tine; _d_, crown or royal tine. (After Owen.)]
The Pecora or true Ruminants form at the present time an extremely
homogeneous group, one of the best-defined and most closely united of any
of the Mammalia. But, though the original or common type has never been
departed from in essentials, variation has been very active among them
within certain limits; and the great difficulty which all zoologists have
felt in subdividing them into natural minor groups arises from the fact
that the changes in different organs (feet, skull, frontal appendages,
teeth, cutaneous glands, etc.) have proceeded with such apparent
irregularity and absence of correlation that the different modifications
of these parts are most variously combined in different members of the
group. It appears, however, extremely probable that they soon branched
into two main types, represented in the present day by the _Cervidæ_ and
the _Bovidæ_,—otherwise the antlered and horned Ruminants. Intermediate
smaller branches produced the existing Musk-Deer and Giraffe, as well as
the extinct _Helladotherium_ inclining to the first-named group, and the
extinct _Sivatherium_, _Brahmatherium_, _Hydaspitherium_, and others more
allied to the latter, although upon the true relationship of these forms
there is a difference of opinion.
[Illustration: FIG. 120.—Head of Deer (_Cervus schomburgki_), showing
antlers. From Sclater, _Proc. Zool. Soc._ 1877, p. 682.]
The earliest forms of true Pecora, as _Palæomeryx_, generally had no
frontal appendages, and some few forms continue to the present day in a
similar case. In the very large majority, however, either in both sexes
or in the male only, a pair or occasionally two pairs (_Tetraceros_ and
the extinct _Sivatherium_) of processes are developed from the frontal
bones as weapons of offence and defence, these being almost always formed
on one or other of two types.
1. “Antlers” are outgrowths of true bone, covered during their growth
with vascular, sensitive integument coated with short hair. When the
growth of the antler is complete, the supply of blood to it ceases, the
skin dies and peels off, leaving the bone bare and insensible, and after
a time, by a process of absorption near the base, it becomes detached
from the skull and is “shed” (Fig. 119). A more or less elongated portion
or “pedicle” always remains on the skull from the summit of which a new
antler is developed. In the greater number of existing species of Deer
this process is repeated with great regularity at the same period of each
year. The antler may be simple, straight, subcylindrical, tapering and
pointed, but more often it sends off one or more branches called “tines”
or “snags” (Fig. 119). In this case the main stem is termed the “beam.”
Commonly all the branches of the antler are cylindrical and gradually
tapering. Sometimes they are more or less expanded and flattened, the
antler being then said to be “palmated.” In young animals the antlers
are always small and simple, and in those species in which they are
variously branched or palmated, this condition is only gradually acquired
in several successive annual growths. An interesting parallel has been
observed here, as in so many other cases, between the development of the
race and that of the individual. Thus the earliest known forms of Deer,
those of the Lower Miocene, generally have no antlers, as in the young of
the existing species. The Deer of the Middle Miocene have simple antlers,
with not more than two branches, as in existing Deer of the second
year; but it is not until the Pliocene and Pleistocene times that Deer
occur with antlers developed with that luxuriance of growth and beauty
of form characteristic of some of the existing species in a perfectly
adult state. Among recent _Cervidæ_, antlers are wanting in the genera
_Moschus_ and _Hydropotes_; they are present in both sexes in _Tarandus_
(the Reindeer), and in the male sex only in all others.
In those forms with the most complex antlers (Figs. 119, 120) the tine
immediately over the forehead is termed the _brow tine_, the next one
the _bez tine_, and the third one the _tres tine_; the mass of points at
the summit of the antler being termed either the _royal_ and _surroyal
tines_, or collectively the _crown_. The nodulated bony ring at the base
of the antler, just above the point at which it separates from the
pedicle when it is shed, is termed the _burr_.
[Illustration: FIG. 121.—Head of Antelope (_Gazella granti_), showing
horns. From Sir V. Brooke, _Proc. Zool. Soc._ 1878, p. 724.]
2. The horns of the _Bovidæ_ consist of permanent, conical, usually
curved bony processes, into which air-cells continued from the frontal
sinuses often extend, called “horn-cores,” ensheathed in a case of
true horn, an epidermic development of fibrous structure, which grows
continuously, though slowly, from the base, and wears away at the apex,
but is very rarely shed entire. The only existing species in which
the latter process occurs regularly and periodically is the American
Prong-Buck (_Antilocapra_), in which the horns also differ from those of
all others in being bifurcated. Horns are not present at birth, but begin
to grow very soon afterwards. The males of all existing _Bovidæ_ possess
them, and they are also present (though usually not so fully developed)
in the females of all except the genera _Boselaphus_, _Strepsiceros_,
_Tragelaphus_, _Antilope_, _Æpyceros_, _Saiga_, _Cobus_, _Cervicapra_,
_Pelea_, _Nanotragus_, _Neotragus_, _Cephalophus_, and _Tetraceros_; as
well as in some species of _Gazella_, such as _G. picticandata_ and _G.
walleri_.
[Illustration: FIG. 122.—Crown surface of a worn left upper molar
of _Palæomeryx sivalensis_, to show brachydont type. (From the
_Palæontologia Indica_.)]
Another character by which different members of the _Pecora_ can be
distinguished among themselves is derived from the nature of the molar
teeth. Although there is nothing in the general mode and arrangement of
the enamel-folds, or in the accessory columns, absolutely distinctive
between the two principal families, existing species may generally be
distinguished, inasmuch as the true molars of the _Cervidæ_ are more or
less brachydont, and those of the _Bovidæ_ generally hypsodont, _i.e._,
the teeth of the former have comparatively short crowns (Fig. 122),
which, as in most mammals, take their place at once with the neck (or
point where the crown and root join) on a level with or a little above
the alveolar border, and remain in this position throughout the animal’s
life; whereas in the other forms (Fig. 123), the crown being lengthened
and the root small, the neck does not come up to the alveolar level
until a considerable part of the surface has worn away, and the crown
of the tooth thus appears for the greater part of the animal’s life
partially buried in the socket. In this form of tooth (which is almost
always most developed in the posterior molars of the permanent series)
the constituent columns of the crown are necessarily nearly parallel,
whereas in the first-described they diverge from the neck towards the
free or grinding surface of the tooth. In the completely hypsodont form
the interstices of the lengthened columnar folds of enamel and dentine
are filled up with cement, which gives stability to the whole organ,
and is entirely or nearly wanting in the short-crowned teeth. The same
modification from low to high crowns without essential alteration of
pattern is seen in an even still more marked manner in some of the
Perissodactyle Ungulates, the tooth of the Horse bearing to that of
_Anchitherium_ the same relation as that of an Ox does to the early
selenodont Artiodactyles. A parallel modification has also taken place in
the molar teeth of the Proboscidea.
[Illustration: FIG. 123.—Inner and outer aspects of an almost unworn left
upper molar of the Nilghai (_Boselaphus tragocamelus_), to show hypsodont
type. (From the _Palæontologia Indica_.)]
As the hypsodont tooth is essentially a modification of, and, as it were,
an improvement upon, the brachydont, it is but natural to expect that
all intermediate forms may be met with. Even among the Deer themselves,
as pointed out by Lartet, the most ancient have very short molars, and
the depressions on the grinding surface are so shallow that the bottom
is always visible; while in the _Cervidæ_ of the more recent Tertiary
periods, and especially the Pleistocene and living species, these same
cavities are so deep that whatever be the state of the dentition the
bottom cannot be seen. Some existing Deer, as the Axis, are far more
hypsodont than the majority of the family; and, on the other hand,
many of the Antelopes (as _Tragelaphus_) retain much of the brachydont
character, which is, however, completely lost in the more modern and
highly specialised Sheep and Oxen.
[Illustration: FIG. 124.—Stomach of Ruminant opened to show internal
structure. _a_, Œsophagus; _b_, rumen or paunch; _c_, reticulum or
honey-comb bag; _d_, psalterium or manyplies; _e_, abomasum or reed; _f_,
duodenum.]
The complicated stomach of the Pecora (Fig. 124), which is necessary for
the performance of the peculiar function known as “chewing the cud”—a
function common also to the Tragulina and Tylopoda—is divided into four
well-defined compartments, known as (1) the Rumen or Paunch, (2) the
Reticulum or Honey-comb Bag, (3) the Psalterium or Manyplies, (4) the
Abomasum or Reed. The paunch is a very capacious receptacle, shaped
like a blunted cone bent partly upon itself. Into its broader base
opens the œsophagus or gullet at a spot not far removed from its wide
orifice of communication with the second stomach or honey-comb bag. Its
inner walls are nearly uniformly covered with a pale mucous membrane,
which is beset with innumerable close-set, short, and slender villi,
resembling very much the “pile” on velvet. The honey-comb bag is very
much smaller than the paunch. It is nearly globose in shape, and receives
its name on account of the peculiar arrangement of its mucous membrane
which forms shallow hexagonal cells all over its inner surface. Running
along its upper wall there is a deep groove, coursing from the first to
the third stomach. This groove plays an important part in the act of
rumination. Its walls are muscular, like those of the viscus with which
it is associated, which allows its calibre to be altered. Sometimes it
completely closes round so as to become converted into a tube by the
opposition of its edges. At others it forms an open canal. The manyplies
is globular in form, and its lining membrane is raised into longitudinal
folds or laminæ arranged very much like the leaves of a book, and very
close together. Their surfaces are roughened by the presence of small
projections or papillæ. The reed is the proper digestive stomach,
corresponding with the same organ in man. Its shape is somewhat pyriform,
and its walls are formed of a smooth mucous membrane, which secretes the
gastric juice.
When the food is first swallowed it is conveyed into the paunch, and
after undergoing a softening process there it is regurgitated into
the mouth, and undergoes a further trituration by the molar teeth and
mixture with the secretion of the salivary and buccal glands. It is then
swallowed again, but now passes directly through the before-mentioned
groove into the manyplies, and, after filtering through the numerous
folds of the lining membrane of this cavity, finally reaches the fourth
or digestive stomach.
The placenta of the Pecora is characterised by the fœtal villi being
collected into groups or cotyledons, which may present either a convex
or a concave surface to the uterus. These cotyledons are received into
permanent elevations in the mucous membrane of the uterus, the surfaces
of which present a curvature which is the reverse of the cotyledons.
_Family_ CERVIDÆ.
Frontal appendages, when present, in the form of antlers. First molar,
at least, in both jaws brachydont. Two orifices to the lachrymal duct,
situated on or inside the rim of the orbit. An antorbital or lachrymal
vacuity of such dimensions as to exclude the lachrymal bone from
articulation with the nasal. Upper canines usually present in both
sexes and sometimes attaining a very great size in the male (see Fig.
134). Lateral digits of both fore and hind feet, almost always present,
and frequently the distal ends of the metapodials. Placenta with few
cotyledons. Gall-bladder absent (except in _Moschus_). This family
contains numerous species, having a wide geographical distribution,
ranging in the New World from the Arctic Circle as far south as Chili,
and in the Old World throughout the whole of Europe and Asia, though
absent in the Ethiopian and Australian regions.
It may be divided into two subfamilies.
Subfamily =Moschinæ=.—This subfamily is represented solely by the
Musk-Deer, which differs so remarkably from the true Deer that it is
considered by several writers as the representative of a separate family.
The late Professor Garrod even suggested that it should be regarded as an
extremely aberrant member of the _Bovidæ_.
[Illustration: FIG. 125.—The Musk-Deer (_Moschus moschiferus_).]
_Moschus._[194]—The Musk-Deer (Fig. 125) in many respects stands by
itself as an isolated zoological form, retaining characters belonging
to the older and more generalised types of ruminants before they were
distinctly separated into the horned and the antlered sections now
dominant upon the earth. One of these characters is that both sexes are
entirely devoid of any sort of frontal appendage. In this, however,
it agrees with one existing genus of true Deer (_Hydropotes_); and,
as in that animal, the upper canine teeth of the males are remarkably
developed, long, slender, sharp pointed, and gently curved, projecting
downwards out of the mouth with the ends turned somewhat backwards.
Vertebræ: C 7, D 14, L 5, S 5, C 6. Among the anatomical peculiarities in
which it differs from all true Deer and agrees with the _Bovidæ_ is the
presence of a gall-bladder. The hemispheres of the brain are but slightly
convoluted, and the cotyledons of the placenta are arranged in a peculiar
linear manner.[195]
Although, owing to variations of colour presented by different
individuals in different localities and seasons, several nominal species
have been described, zoologists are now generally agreed that there is
but one, the _Moschus moschiferus_ of Linnæus. In size it is rather
less than the European Roe Deer, being about 20 inches high at the
shoulder. Its limbs, especially the hinder ones, are long. The feet are
remarkable for the great development of the lateral pair of hoofs, and
for the freedom of motion they all present, so that they appear to have
the power of grasping projecting rocky points,—a power which must be
of great assistance to the animal in steadying it in its agile bounds
among the crags of its native haunts. The ears are large, and the tail
quite rudimentary. The hair covering the body is long, coarse, and of a
peculiarly brittle and pith-like character, breaking with the application
of an extremely slight force; it is generally of a grayish-brown colour,
sometimes inclined to yellowish-red, and often variegated with lighter
patches. The Musk-Deer has a wide distribution over the highlands
of central and eastern Asia, including the greater part of southern
Siberia, and extends to Kashmir on the south-west and Cochin-China on
the south-east, always, however, at considerable elevations,—being
rarely found in summer below 7000 feet above the sea-level, and ranging
as high as the limits of the thickets of birch or pines, among which
it mostly conceals itself in the daytime. It is a hardy, solitary, and
retiring animal, chiefly nocturnal in its habits, and almost always found
alone, rarely in pairs, and never in herds. It is exceedingly active
and sure-footed, having few equals in traversing rocky and precipitous
ground; and it feeds on moss, grass, and leaves of the plants which grow
on the mountains among which it makes its home.
Most of the animals of the group to which the Musk-Deer belongs, in
fact the large majority of mammals, have some portion of the cutaneous
surface peculiarly modified and provided with glands secreting some
odorous and oleaginous substance specially characteristic of the species.
This, correlated with the extraordinary development of the olfactory
organs, appears to offer the principal means by which animals in a
state of nature become aware of the presence of other individuals of
their own species, or of those inimical to them, even at very great
distances, and hence it is of extreme importance both to the well-being
of the individual and to the continuance of the race. The situation of
this specially modified portion of skin is extremely various, sometimes
between the toes, as in Sheep, sometimes on the face in front of the
eyes, as in many Deer and Antelopes. Sometimes it is in the form of a
simple depression or shallow recess, often very deeply involuted, and in
its fullest state of development it forms a distinct pouch or sac with
a narrow tubular orifice. In this sac a considerable quantity of the
secretion can accumulate until discharged by the action of a compressor
muscle which surrounds it. This is the form taken by the special gland of
the Musk-Deer, which has made the animal so well known, and has proved
the cause of an unremitting persecution to its possessor. It is found
in the male only, and is a sac about the size of a very small orange,
situated beneath the skin of the abdomen, the orifice being immediately
in front of the preputial aperture. The secretion with which the sac is
filled is of dark-brown or chocolate colour, and when fresh described as
being of the consistence of “moist gingerbread,” but becoming dry and
granular after keeping. It has a peculiar and very powerful scent, which
when properly diluted and treated forms the basis of many of our most
admired perfumes. When the animal is killed the whole gland or “pod” is
cut out and dried, and in this form reaches the market of the Western
World, chiefly through China.
Subfamily =Cervinæ.=—This subfamily includes all the true Deer. According
to the arrangement proposed by Sir V. Brooke[196] the existing _Cervinæ_
may be divided into the sections Plesiometacarpalia and Telemetacarpalia.
=Plesiometacarpalia.=—In this section, which is mainly characteristic of
the Old World, the proximal portions of the lateral (second and fifth)
metacarpals persist, and the vomer is never so ossified as to divide the
posterior osseous nares into two distinct passages. The premaxillæ nearly
always articulate with the nasals.
_Cervulus._[197]—Antlers half the length of the head, placed on pedicles
nearly equal to them in length. Brow tine short, inclined inwards and
upwards; terminal extremity of beam unbranched, and curved downwards and
inwards. Lachrymal fossa of skull very large, and extending into facial
part of jugal; lachrymal (antorbital) vacuity moderate. Ascending portion
of premaxillæ at least as long as nasals. A permanent ridge extending
from each pedicle over the orbit, lachrymal fossa and vacuity. Auditory
bulla much inflated. Upper canines of males very large. Ectocuneiform
united with naviculo-cuboid of tarsus. No traces of the phalanges of the
lateral digits.
The native name Muntjac has been generally adopted in European languages
for a small group of Deer indigenous to the southern and eastern parts
of Asia and the adjacent islands, which are separated by very marked
characters from all their allies. They are also called “Kijang” or
“Kidjang,” and constitute the genus _Cervulus_ of Blainville and most
zoologists;—_Styloceros_ of Hamilton-Smith, and _Prox_ of Ogilby. They
are all of small size compared with the majority of Deer, and have long
bodies and rather short limbs and neck. The antlers, which as in most
Deer are present in the male only, are small and simple, and the main
stem or beam, after giving off a very short brow tine, inclines backwards
and upwards, is unbranched and pointed, and when fully developed curves
inwards and somewhat downwards at the tip. These small antlers are
supported upon pedicles or permanent processes of the frontal bones,
longer than in any other Deer, and the front edges of which are continued
downwards as strong ridges passing along the sides of the face above the
orbits, and serving to protect the large supraorbital glands lying on
their inner sides. The lachrymal fossa of the skull, in which is lodged
the large suborbital gland or crumen, is of great depth and extent. The
upper canine teeth of the males are strongly developed and sharp, curving
downwards, backwards, and outwards, projecting visibly outside the mouth
as tusks, and loosely implanted in their sockets. In the females they are
very much smaller. The limbs exhibit several structural peculiarities
not found in other Deer. The lateral digits of both fore and hind feet
are very little developed, the hoofs alone being present and their bony
supports (found in all other Deer) wanting. There is a tufted gland on
the outer side of the metatarsus.
The Muntjacs are solitary animals, very rarely even two being seen
together. They are fond of hilly ground covered with forests, in the
dense thickets of which they pass most of their time, only coming to
the skirts of the woods at morning and evening to graze. They carry the
head and neck low and the hind-quarters high, their action in running
being peculiar and not very elegant, somewhat resembling the pace of a
sheep. Though with no power of sustained speed or extensive leap, they
are remarkable for flexibility of body and facility of creeping through
tangled underwood. They are often called by Indian sportsmen “Barking
Deer,” a name given on account of their alarm cry, a kind of short shrill
bark, like that of a fox but louder, which may often be heard in the
jungles they frequent both by day and by night. When attacked by dogs the
males use their sharp canine teeth with great vigour, inflicting upon
their opponents deep and even dangerous wounds.
There is some difference of opinion among zoologists as to the number of
species of the genus _Cervulus_. Sir Victor Brooke, who investigated this
question in 1878 (see _Proceedings of the Zoological Society of London_
for that year, p. 898), came to the conclusion that there are certainly
three which are quite well marked, viz.—
_C. muntjac_ (Fig. 126), found in British India, Burma, the Malay
Peninsula, Sumatra, Java, Hainan, Banca, and Borneo. The general colour
is a bright yellowish-red, darker in the upper parts of the back; the
fore legs from the shoulder downwards and the lower part of the hind
legs, dark bluish-brown; anterior parts of the face from the muzzle to
between the eyes, brown—a blackish line running up the inside of each
frontal ridge; chin, throat, inside of hind legs, and under surface of
tail white. The female has a black bristly tuft of hair on the spot from
which the pedicles of the antlers of the male grow. The average length
of the male, according to Jerdon, is 3½ feet, tail 7 inches, height 26
to 28 inches. The female is a little smaller. The specimens from Java,
Sumatra, and Borneo are of larger size than those from the mainland, and
may possibly be of distinct species or race.
[Illustration: FIG. 126.—The Muntjac (_Cervulus muntjac_).]
_C. lacrymans_ of Milne-Edwards, or Sclater’s Muntjac of Swinhoe, from
Moupin, and near Hangchow, China.
_C. reevesi_, a very small species from southern China.
Subsequently the name _C. crinifrons_ has been applied to a Muntjac
from Ningpo, China, readily distinguished from all other species by its
bushy forehead and long tail. Another species from Tenasserim has been
described as _C. feæ_.
Small Deer from the European Pliocene have been provisionally referred
to _Cervulus_, but the so-called _Prox furcatus_, of the Miocene, is now
included in _Palæomeryx_.
_Elaphodus._[198]—Antlers very small, unbranched, supported on long,
slender, converging pedicles. Ascending rami of premaxillæ shorter than
nasals. No supraorbital ridges or frontal glands. Upper canines of male
long, but not everted. A distinct frontal tuft of hair. Other characters
as in _Cervulus_.
This genus (which has also received the name of _Lophotragus_) is
represented by a small Deer (Fig. 127) from China of about the same
size as the Indian Muntjac. The male has minute simple antlers and very
large canine teeth. There are no supraorbital glands, nor is there a
tufted gland on the metatarsus. The limbs have the same peculiarities
as in _Cervulus_, but the mesocuneiform may also ankylose with the
ectocuneiform, and traces of the metacarpals may remain. The hair is
coarse and somewhat quill-like.
[Illustration: FIG. 127.—Male of _Elaphodus michianus_. From Sclater
_Proc. Zool. Soc._ 1876, p. 273.]
_Cervus._[199]—The great majority of the Deer of the Old World may be
included in this large genus, which is one not easy of definition. The
antlers of the male are, however, large, and two or three times the
length of the head, and may be either rounded or palmate; the canines are
never large; the ectocuneiform of the tarsus remains distinct from the
naviculo-cuboid; the lateral digits are represented by their phalanges;
and the skull does not carry prominent frontal ridges. Vertebræ: C 7, D
13, L 6, S 4, C 11-14. The size of the lachrymal fossa and vacuity, and
the degree of inflation of the auditory bulla, are subject to variation
in the different groups into which the genus may be divided.
The _Rusine_ group is characteristic of the Oriental region, where it is
typically represented by the Sambur (_C. aristotelis_) of India, Burma,
and China. The antlers are rounded, and often strongly grooved, without a
bez tine, and with the beam simply forked at the extremity, upright, and
but slightly curved; the angle formed by the brow tine, which rises close
to the burr, being acute. The molars are markedly hypsodont, with small
accessory columns. The lachrymal fossa is deep and the vacuity large; the
auditory bulla is slightly inflated and rugose. Tail moderate; neck maned.
The Sambur, which is abundant in hilly districts, is a fine animal,
standing nearly 5 feet in height, and of massive build; the general
colour being deep brown. _C. equinus_, of Borneo, Sumatra, and Singapore,
_C. swinhoei_, of Formosa, _C. philippinus_, and _C. alfredi_ of the
Philippines, are closely allied species, of which the two latter are
of smaller dimensions. The Indian Hog Deer (_C. porcinus_) is a still
smaller form, not larger than the Roe. _C. hippelaphus_ of Java, _C.
timoriensis_, and _C. moluccensis_ are distinguished by the posterior
branch of the beam of the antler being considerably larger than the
anterior.
The _Rucervine_ group is another strictly Oriental one, and is
represented by the Swamp Deer (_C. duvaucelli_) of India, the closely
allied _C. schomburgki_ of Siam, of which the antlers are shown in Fig.
119 (p. 309), and _C. eldi_ of Burma and Hainan. The beam of the antler
is somewhat flattened, and more curved than in the Rusine group; the
large brow tine is given off from the beam at an obtuse angle and curves
upwards; the beam bifurcates into two branches, which again divide. Skull
as in the Rusine group, but relatively narrower. Tail short; neck maned.
The Swamp Deer is somewhat smaller than the Sambur, and of a full
yellowish colour. Fossil representatives of this group occur in the
Pliocene of India.
The _Elaphurine_ group is represented only by the very aberrant _C.
davidianus_ of Northern China. In size and proportions this species
approximates to the Swamp Deer, but the antlers are peculiar in rising
straight from the brow and then giving off a long and straight back tine
(correlated by Sir V. Brooke with the posterior branch of the Rusine
antler); the summit of the beam is forked, and in old individuals the
two tines of the fork may again branch. Nasals long, and much expanded
between the lachrymal vacuities, of which they form the inner border;
lachrymal fossa large and deep. Tail long; neck maned.
The _Axine_ group includes only the well-known Axis of India, readily
distinguished by the white spots with which the body is marked. Antlers
of a Rusine type, the beam being much curved, and the brow tine usually
given off at an acute or right angle. Molars very hypsodont. The
coloration of the Axis is more brilliant than that of any other member of
the family.
Here may be noticed a group of Deer mainly characteristic of the
eastern Palæarctic region, frequently known as the _Pseudaxine_ group,
which appears to connect the Axine with the Elaphine type. Well-known
representatives of this group are _C. sika_ (Fig. 128) of Japan, _C.
mantchuricus_ of China, and _C. taëvanus_ of Formosa. The antlers have a
brow and tres tine, and then a forked beam, of which the posterior tine
is the smaller. The lachrymal vacuity and fossa are of moderate size;
and the auditory bulla is only moderately inflated, and quite smooth
externally. Tail moderate; neck maned. In summer the coat is spotted, but
is plain in winter. A herd of _C. sika_ have been acclimatised in Ireland
by Viscount Powerscourt, at Powerscourt, County Wicklow. A number of Deer
from the Pliocene of Europe, such as _C. perrieri_ and _C. etueriarum_,
appear to be allied both to the Pseudaxine and Axine groups.
[Illustration: FIG. 128.—The Japanese Deer (_Cervus sika_). From Lord
Powerscourt, _Proc. Zool. Soc._ 1884, p. 209.]
The _Elaphine_ or typical group is at once characterised by the presence
of a bez tine to the antlers (Fig. 129), in which the beam is rounded,
and splits up near the summit into a larger or smaller number of snags,
often arranged in a cup-like manner. Skull as in the preceding group. All
the species large. The Red Deer, _C. elaphus_, which is dark brown in
colour, with a light patch on the rump, inhabits Europe, Western Asia,
and Northern Africa—the so-called Barbary Deer not being specifically
distinct. A full-grown Scotch Stag is fully 4 feet in height at the
withers. The antlers are shed between the end of February and the early
part of April; old animals shedding earlier than younger ones. The young,
which (as in all the members of the genus except some of the Rusine
species) are spotted, are born at the end of May or the beginning of
June. The points on the antlers increase in number with the age of the
creature, and when twelve are present it is known in Scotland as a “royal
stag.” This number, however, is sometimes exceeded, as in the case of a
pair of antlers, weighing 74 lbs., from a stag killed in Transylvania,
which had forty-five points. The antlers during the second year consist
of a simple unbranched stem, to which a tine or branch is added in each
succeeding year, until the normal development is attained, after which
their growth is somewhat irregular. Many of the antlers dug up in British
peat-beds (as Fig. 118) are larger than those of living individuals,
and in the cave-deposits of England and the Continent antlers are met
with rivalling those of the Wapiti in size; these large fossil antlers
probably indicating the ancestral form from which the Red Deer and
several of the allied species are descended.
[Illustration: FIG. 129.—Head of the Wapiti (_Cervus canadensis_).]
The North American Wapiti (_Cervus canadensis_, Fig. 129), the Persian
Maral (_C. maral_), the Kashmir Stag (_C. cashmeerianus_), as well as
_C. affinis_ of Tibet, are all closely allied to the Red Deer, but are
of larger size, this being especially the case with the first two. A
fine example of the antlers of the Wapiti is shown in the accompanying
woodcut, and exhibits the absence of a cup at the surroyals, by which
this species is distinguished from the Red Deer.
The last, or _Damine_ group of existing Deer includes the Common and the
Persian Fallow Deer. These are readily characterised by the palmation
of the antlers in the region of the surroyals and the spotted coat.
The Common Fallow Deer (_C. dama_) stands about three feet in height.
The Persian Fallow Deer (_C. mesopotamicus_) is very closely allied,
differing only in its slightly larger size and the form of the antlers,
the two breeding together. The common species, although now kept in
English parks, does not appear to be a native of this country, having
probably been introduced from the regions bordering the Mediterranean.
The fur is of a yellowish-brown colour (whence the name “fallow”), marked
with white spots; there is, however, a uniformly dark brown variety found
in Britain. The bucks and does live apart, except during the pairing
season; and the doe produces one or two, and sometimes three fawns at
a birth. The Fallow Deer from the Pleistocene and Pliocene deposits
of the East Coast described under the names of _C. browni_ and _C.
falconeri_ appear to have been closely allied to the existing species.
The remarkable _C. verticornis_, of the Norfolk Forest-bed, is regarded
as an aberrant member of this group, in which the antlers are very short
and thick, with the brow tine cylindrical and downwardly curved, and the
beam expanded above the tres tine into a crown with two points.
The extinct Irish Deer (_Cervus giganteus_), of which the skeleton is
shown in the woodcut (Fig. 130), is the only representative of the
_Megacerotine_ group. The antlers, which may have a span of over 11
feet, are enormously palmated, and have a bifurcated brow tine, a small
bez tine, and a third posterior tine. The skeleton measures upwards of
6 feet at the withers. Remains of this species are especially common in
the peat-bogs of Ireland, but are also met with in Pleistocene deposits
over a large part of Europe. In addition to the forms already mentioned
there are many other fossil species of _Cervus_, some of which, like the
English Pleistocene _C. sedgewicki_, cannot be included in any of the
existing groups. There is no conclusive evidence of the existence of any
species of _Cervus_ before the Lower Pliocene period.
=Telemetacarpalia.=—This section includes all the Deer of the New World,
together with some Old World forms, and is characterised by retaining the
distal extremities of the lateral (second and fifth) metacarpals. With
the exception of _Alces_, _Capreolus_, and _Hydropotes_ (which are either
partly or entirely Old World types), the vomer is so much ossified as to
divide the posterior bony nares into two distinct orifices (Fig. 132).
[Illustration: FIG. 130.—Skeleton of the Gigantic Irish Deer (_Cervus
giganteus_). After Owen.]
_Rangifer._[200]—The Reindeer, or Caribou as it is termed in North
America, is the sole representative of the genus _Rangifer_, which is
sufficiently distinguished from all its allies by the presence of antlers
in both sexes. The lachrymal vacuity is small. This animal is distributed
over the northern parts of Europe, Asia, and America; the differences
which may be observable in specimens from different regions not being
sufficient to allow of specific distinction. The Reindeer is a heavily
built animal, with short limbs, in which the lateral hoofs are well
developed, and the cleft between the two main hoofs is very deep, so that
these hoofs spread out as the animal traverses the snow-clad regions in
which it dwells. The antlers (Fig. 131) are of very large relative size.
There is a bez as well as a brow tine, which are peculiar in being either
branched or palmated. In the American race (Caribou), as well as in some
of the specimens found fossil in the English Pleistocene (Fig. 131), one
of the brow tines is generally aborted to allow of the great development
of the other. The dentition of the Reindeer is frequently remarkable
for the very small size of the posterior lobe of the last lower molar.
Vertebræ: C 7, D 14, L 5, S 5, C 11.
[Illustration: FIG. 131.—Skull and antlers of the Reindeer (_Rangifer
tarandus_), from an English Pleistocene deposit. _br_, Brow tine; _bz_,
bez tine. (After Owen.)]
The Reindeer has long been domesticated in Scandinavia, and is of
especial value to the Laplanders, whom it serves as a substitute for
the Horse, Cow, Sheep, and Goat. It is capable of drawing a weight of
300 lbs., and its fleetness and endurance are remarkable. Harnessed to
a sledge it will travel without difficulty 100 miles a day over the
frozen snow, on which its broad and deeply cleft hoofs are admirably
adapted for travelling. During the summer the Lapland Reindeer feeds
chiefly on the young shoots of the willow and birch; and since at this
season migration to the coast seems necessary to the well-being of this
animal, the Laplander, with his herds, sojourns for several months in
the neighbourhood of the sea. In winter its food consists chiefly of the
so-called reindeer-moss and other lichens which the animal makes use
of its hoofs in seeking for beneath the snow. The wild Reindeer grows
to a much greater size than the tame breed; but in Northern Europe the
former are being gradually reduced through the natives entrapping and
domesticating them. The tame breed found in Northern Asia is much larger
than the Lapland form, and is there used to ride on. Remains referable
to the existing species are found in the cavern and other Pleistocene
deposits of Europe.
[Illustration: FIG. 132.—Hinder part of the base of the cranium of the
Virginian Deer (_Cariacus virginianus_). From Garrod, _Proc. Zool. Soc._
1877, p. 13.]
_Alces._[201]—The Elk or Moose (_Alces machlis_) has the same general
distribution as the Reindeer, and is likewise the single existing
representative of its genus. It is the largest existing member of the
family, attaining sometimes a height of 8 feet at the withers. The
antlers (Fig. 133) have neither brow nor bez tine, but form an enormous
basin-shaped palmation, primarily composed of an anterior and a posterior
branch; their weight may be as much as 60 lbs. The nasal bones are very
short, and the narial aperture of great size. The Elk is covered with a
thick coarse fur of a brownish colour, longest on the neck and throat.
Its legs are long and its neck short, and as it is thus unable to feed
close to the ground, it browses on the tops of low plants, the leaves of
trees, and the tender shoots of the willow and birch. Its antlers attain
their full length by the fifth year, but in after years they increase in
breadth and in the number of snags, until fourteen of these are produced.
Although spending a large part of their lives in forests, Elks do not
suffer much inconvenience from the great expanse of their antlers, as in
making their way among trees they are carried horizontally to prevent
entanglement with the branches. Their usual pace is a shambling trot, but
when frightened they break into a gallop. The natural timidity of the
Elk forsakes the male at the rutting season, and he will then attack
whatever animal comes in his way. The antlers and hoofs are his principal
weapons, and with a single blow from the latter he has been known to kill
a wolf. The female often gives birth to two fawns, and with these she
retires into the deepest recesses of the forest, the young remaining with
her till their third year. The Elk ranges, but in scanty numbers, over
the whole of Northern Europe and Asia, as far south as East Prussia, the
Caucasus, and North China, and over North America from the New England
States westward to British Columbia. Fossil species are found in the
Pleistocene deposits of Europe.
_Cervalces._[202]—A remarkable extinct Deer from the Pleistocene of North
America, described as _Cervalces_, appears in some respects (although
a true Telemetacarpalian) to connect _Alces_ with _Cervus_. Thus the
palmated antlers are divided into anterior and posterior branches, but
below this division there are two tines apparently corresponding to the
bez and posterior tines of _Cervus giganteus_ (Fig. 130).
[Illustration: FIG. 133.—Head of Elk (_Alces machlis_).]
_Capreolus._[203]—Antlers (in the existing species) less than twice the
length of the head, usually with three tines on each. Brow tine developed
from the anterior surface of the upper half of the antler, and directed
upwards. Lachrymal vacuity small. Premaxillæ not always articulating with
nasals. Auditory bullæ slightly inflated, rugose externally. Vertebræ: C
7, D 13, L 6, S 6, C 8. Tail very short. Glands in fore feet rudimentary;
large in hind feet.
The Roe, or Roe Deer (_Capreolus caprea_), is a small form distributed
over Europe and Western Asia, being one of the species found in the
British Isles. The male is somewhat over two feet in height at the
withers, of a dark reddish-brown colour in summer, with a white patch
on the rump. The small antlers are approximated at their bases, and
consist of a rugged beam rising vertically for some distance, then
bifurcating, and the posterior branch again dividing. The Roe dates from
the Pleistocene period. Extinct Deer from the Continental Pliocene have
been provisionally referred to _Capreolus_.
_Hydropotes._[204]—No antlers in either sex. Lachrymal fossa deep and
short (Fig. 134); lachrymal vacuity of moderate size. Orbits small and
but slightly prominent. Auditory bulla much inflated. Angle of mandible
much produced backwardly (Fig. 134); alveolar margins of mandible in
diastema sharp and everted. Canines of male very large, and slightly
convergent. Vertebræ: C 7, D 12, L 6, S 4, C 10. No tufts on metatarsals.
Foot glands small in fore feet, deep in hind ones.
[Illustration: FIG. 134.—The left lateral view of the skull of a male
Chinese Water Deer (_Hydropotes inermis_), with the wall of the maxilla
cut away to show the root of the canine. ½ natural size. (From Sir V.
Brooke, _Proc. Zool. Soc._ 1872, p. 524.)]
[Illustration: FIG. 135.—Upper surface of the brain of _Hydropotes
inermis_. (From Garrod, _Proc. Zool. Soc._ 1877, p. 792.)]
The Chinese Water Deer (_H. inermis_) is the sole representative of this
genus. In the absence of antlers and the large canines of the male it
resembles _Moschus_, although very different in other respects. Thus
the brain (Fig. 135) has the hemispheres much convoluted, as in other
_Cervinæ_, and approximates to that of _Pudua_; while the placenta
and viscera likewise agree with those of the true Deer. In the total
absence of any ossification of the vomer to divide the posterior nares
_Hydropotes_ resembles _Capreolus_ and differs from all the following
genera. The Chinese Water-Deer is nearly of the same size as the Indian
Muntjac. It has short legs and a long body, the hair covering the latter
being of a light reddish-brown. It is a remarkably prolific animal,
differing from all other Deer in producing five or six young at a time.
The mandible of a ruminant from the Middle Miocene of Gers in France,
described under the name of _Platyprosopus_, presents such a marked
resemblance to _Hydropotes_ in the form of the angle as to suggest a more
or less intimate affinity.
_Cariacus._[205]—Skull (Fig. 132) with the vomer dividing the posterior
nares into two distinct chambers; premaxillæ not reaching nasals. Antlers
never greatly exceeding the length of the head. Lachrymal vacuity very
large, and lachrymal fossa small. Auditory bullæ slightly inflated.
Vertebræ: C 7, D 13, L 6, S 4, C 13. Tail long or short. Colour uniform
in adult.
This genus, which agrees with the Reindeer in the division of the
posterior nares by the ossified vomer, comprises a number of species
confined to the New World, none of which attain very large dimensions,
and the antlers of which are relatively smaller than in the existing
species of _Cervus_. The genus may be divided into groups.
The typical _Cariacine_ group, as represented by _C. virginianus_, has
well-developed antlers, with a short brow tine rising from the inner side
of the beam, and directed upwards, and several branches; a long tail; and
no upper canines. In this species, as well as in _C. mexicanus_ and other
forms, the antlers do not divide dichotomously, and the lachrymal fossa
is of moderate depth. The Mule Deer (_C. macrotis_) of North America is
distinguished by the dichotomous branching of the antlers and the deeper
lachrymal fossa. The Virginian Deer is somewhat smaller than the Fallow
Deer, and of a uniform reddish-yellow colour in summer, and light gray in
winter.
The _Blastocerine_ group of South America is represented by _C.
paludosus_ and _C. campestris_, and has dichotomous antlers, with no
brow tine, and the posterior branch the larger, a short tail, and no
upper canines. The _Furciferine_ group includes _C. chilensis_ and
_C. antisiensis_, confined to western South America. The antlers are
not longer than the head, with a large anterior tine curving forwards
at right angles to the simple posterior one. Auditory bullæ slightly
inflated, and rugose. Upper canines may be present. The species are of
medium size. _C. clavatus_, of Central America, while resembling this
group in the characters of the skull and the arrangement of the hair on
the face, agrees with the next one in having simple spike-like antlers.
The South American _Coassine_ group comprises the small forms known as
Brockets, in which the antlers form simple spikes not exceeding half the
length of the head. Some six species are known.
Remains of _Cariacus_, mostly or entirely referable to existing species,
are of common occurrence in the Brazilian cave-deposits. _Blastomeryx_,
of the Pliocene of North America, is believed to be an allied type.
_Pudua._[206]—Antlers in the form of minute simple spikes. Distinguished
from the Coassine group of _Cariacus_ by the articulation of the
premaxillæ with the nasals (as in the _Furciferine_ group), and the
coalescence of the ectocuneiform with the naviculo-cuboid, as well as by
various external characters. No upper canines. Represented only by the
very small _P. humilis_ of the Chilian Andes.
_Extinct Genera._—In the European and other Tertiary deposits several
genera of extinct _Cervidæ_ occur, of which the more important may
be briefly mentioned. _Amphitragulus_, of the Lower Miocene of the
Continent, has four lower premolars, brachydont molars, and no antlers;
the largest species being somewhat bigger than the Musk-Deer. The closely
allied _Palæomeryx_ (_Dremotherium_ or _Micromeryx_) generally has but
three lower premolars, and the brachydont upper molars (Fig. 122), like
those of _Amphitragulus_, want the small accessory inner column[207]
found in modern Deer. In _P. feignouxi_, of the Lower Miocene, the
lateral metacarpals, although slender, were complete, and the males had
large canines, but no antlers. _P. furcatus_, of the Middle Miocene, had
small antlers, and the canines appear to have been reduced in size. This
genus, besides being represented in the European Miocene, also occurs in
the Pliocene of India and China; some of the species being as large as
the Red Deer.
_Family_ GIRAFFIDÆ.
In the existing genus the frontal appendages consist of a pair of
short, erect, permanent bony processes placed over the union of the
frontal and the parietal bones, ossified from distinct centres, though
afterwards ankylosed to the skull, covered externally with a hairy
skin, present in both sexes, and even in the new-born animal. Anterior
to these is a median protuberance on the frontal and contiguous parts
of the nasal bones, which increases with age, and is sometimes spoken
of as a third horn. Skull with a lachrymal vacuity. No upper canines.
Molars brachydont, with rugose enamel; the upper ones having no inner
accessory column. Lateral digits entirely absent on both fore and hind
feet, even the hoofs not developed. Humerus with double bicipital groove.
Vertebræ: C 7, D 14, L 5, S 3, C 20. Gall-bladder generally absent. Male
reproductive organs and placenta of a Bovine type. Dentition: _i_ ⁰⁄₃,
_c_ ⁰⁄₁, _p_ ³⁄₃, _m_ ³⁄₃.
[Illustration: FIG. 136.—The Giraffe (_Giraffa camelopardalis_).]
_Giraffa._[208]—The Giraffe (_G. camelopardalis_) is the sole existing
representative of the genus, now confined to the Ethiopian region.
In addition to the characters noticed above, the Giraffe is characterised
by its great size and peculiar proportions; the neck and limbs being
of great length, and the back inclining upwards from the loins to the
withers.
To produce the extremely elongated neck the seven cervical vertebræ are
proportionately long, which gives a somewhat stiff and awkward motion
to the neck. The ears are large, the lips long and thin, the nostrils
closable at the will of the animal, the tongue very long and extensile,
and the tail of considerable length, with a large terminal tuft. An adult
male may have a total height of 16 feet. The coloration consists of large
blotches of darker or lighter chestnut-brown on a paler ground, the
lower limbs and under parts being of a uniform pale colour. The Giraffe
feeds almost exclusively on the foliage of trees, showing a preference
for certain varieties of mimosa, and for the young shoots of the prickly
acacia, for browsing on which its prehensile tongue and large free lips
are specially adapted. It is gregarious in its habits, living in small
herds of about twenty individuals, although Sir S. Baker, who hunted it
in Abyssinia, states that he has seen as many as a hundred together.
Fossil species of _Giraffa_ occur in Pliocene deposits over Greece,
Persia, India, and China, thus affording one of many striking instances
of the former wide distribution of the generic types now confined to the
Ethiopian region.
_Allied Extinct Types._—The Pliocene deposits of many parts of the Old
World yield remains of a number of large Ruminants which show such
evident signs of affinity with the Giraffe that it is difficult to draw
up a definition by which they can be separated in characters of family
value from that genus. On the other hand, some of these forms approximate
in the characters of the skull to some of the brachydont members of the
_Bovidæ_, although it is quite clear from the nature of the cranial
appendages that they cannot be included in that family. All these forms
have brachydont molars, with rugose enamel, like those of the Giraffe;
while several of them have limb-bones approximating to those of the
latter—the humerus, when known, having a double bicipital groove. The
nature of the cranial appendages (when present) is not fully understood,
but it appears that in some cases these approximated more to the type of
an antler than to that of a horn; although, from the absence of a “burr,”
they appear never to have been shed. A gradual diminution in the length
of the limbs and neck can be traced from the more Giraffoid to the more
Bovoid forms of this extinct group; and it is manifest that if these
animals be included in the _Giraffidæ_ the definition of that family as
given above must be somewhat modified. Only brief mention can be made of
the more important genera.
The imperfectly known _Vishnutherium_, of the Pliocene of India and
Burma, seems to make the nearest approach to the Giraffe, but the limbs
and cervical vertebræ were decidedly shorter, although of a similar
slender type. _Helladotherium_, of the Pliocene of Greece and India, is
represented by a species of considerably larger size than the Giraffe,
with no appendages or lachrymal vacuity to the skull, and with shorter
and stouter limbs and neck.
_Hydaspitherium_, _Bramatherium_, and _Sivatherium_ are Indian genera,
characterised by the presence of large palmated and antler-like cranial
appendages, varying considerably in arrangement. The former genus has a
large lachrymal vacuity which is absent in the two latter. In the first
and second genera all the appendages rise from a common base; but in
_Sivatherium_ there is a pair of simple horn-like projections on the
orbits in addition to the posterior palmated antlers. _Sivatherium_ was
an animal of huge bulk, being the largest known representative of the
Pecora.
Another apparently allied type is _Samotherium_, of the Pliocene of
the Isle of Samos, which appears also to have some affinity with the
Antelopes. The skull is nearly as large as that of the Giraffe, and is
of the same elongated shape, although depressed between the conical
horn-cores, which rise vertically above the orbits, and without a median
bony prominence on the frontals. The horn-cores form mere processes of
the frontals. The diastema and the mandibular symphysis are shorter than
in the Giraffe, and the latter is less deflected. The teeth, although
larger, are almost indistinguishable from those of the Giraffe, the only
well-marked difference being that the last lower premolar has a double in
place of a single postero-internal column.
_Family_ ANTILOCAPRIDÆ.
Closely allied to the _Bovidæ_, but the horns deciduous and branched.
_Antilocapra._[209]—The Prong-buck, or Prong-horned Antelope
(_Antilocapra americana_), as the single existing member of this family
is called, is an animal of nearly the same size as the Fallow Deer, but
of a lighter and more graceful build. It is an inhabitant of the prairies
of North America, where it is one of the few representatives of the
Cavicorn Pecora. The bony horn-cores are unbranched, and form vertical,
blade-like projections immediately above the orbit. The horns themselves
are compressed, and nearly one foot in length, having a gentle backward
curvature, the short branch arising somewhat above the middle of its
height, and inclining forwards. When the horn is about to be cast off
it becomes loosened, and a new one is formed upon the bony core beneath
it. The ears are long and pointed, and the tail is short. The neck has a
thick mane of long chestnut-coloured hair, and there is a white patch on
the rump.
_Family_ BOVIDÆ.
Frontal appendages, when present, in the form of non-deciduous horns.
Molars frequently hypsodont. Usually only one orifice to the lachrymal
canal, situated inside the rim of the orbit. Lachrymal bone almost always
articulating with the nasal. Canines absent in both sexes. The lateral
toes may be completely absent, but more often they are represented by
the hoofs alone, supported sometimes by a very rudimentary skeleton,
consisting of mere irregular nodules of bone. Distal ends of the lateral
metapodials never present. Gall-bladder almost always present. The number
of cotyledons in the placenta generally varies from 60 to 100; whereas
in the _Cervidæ_ the number is usually from 5 to 12, _Capreolus_ and
_Hydropotes_ having the fewest. In _Giraffa_ the number is upwards of
180. The nature of the horns and horn-cores has been already explained;
in the majority of genera these appendages are present in both sexes,
although much larger in the male (see p. 310).
The _Bovidæ_, or hollow-horned Ruminants (Cavicornia), form a most
extensive family, with members widely distributed throughout the Old
World, with the exception of the Australian region; but in America they
are less numerous, and confined to the Arctic and northern temperate
regions, no species being indigenous either to South or Central America.
There is scarcely any natural and well-defined group in the whole
class which presents greater difficulties of subdivision than this;
consequently zoologists are as yet very little agreed as to the extent
and boundaries of the genera into which it should be divided. For the
present the genera provisionally adopted may be arranged under a number
of sections or groups, which some writers regard as subfamilies. The
series may be commenced with the Antelopes, the greater number of which
are now characteristic of the Ethiopian region.
_Alcelaphine Section._—Includes large African Antelopes, of which the
type genus ranges into Syria; generally characterised by their great
height at the withers as compared with the rump. Skull with large frontal
sinuses, extending into the horn-cores, and the horns lyre-shaped or
recurved, and more or less approximated at the base. No large pits at
apertures of supraorbital foramina in frontals; upper molars hypsodont
and narrow. Horns in both sexes. General colour mostly uniform.
_Alcelaphus._[210]—If _Damalis_ be included, this genus is represented
by some nine or ten living species. Head more or less long and narrow,
with the muffle moderately broad and naked. Nostrils approximated, edged
with stiff hairs. Horns compressed and ringed at the base, more or less
lyrate, and bent back at the tips. Hoofs small. Tail of moderate length,
and heavy. Two mammæ.
[Illustration: FIG. 137.—The Harte-beest (_Alcelaphus caama_).]
In the typical forms, such as the Bubaline Antelope (_A. bubalinus_), the
Harte-beest (_A. caama_, Fig. 137), and the Tora Antelope (_A. tora_,
Fig. 138), the horns, which present the peculiar curvature shown in the
figures, are situated on a crest at the vertex of the skull, and the
facial portion of the cranium is greatly elongated. The Harte-beest,
which is found throughout Central and Southern Africa, stands nearly 5
feet high at the withers, and is a somewhat ungainly looking animal, with
short hair, which is grayish-brown above and nearly white beneath. In
the Pliocene of the Siwalik Hills in Northern India there occur remains
of an _Alcelaphus_ (_A. palæindicus_) in which the skull had the long
facial portion characteristic of the typical group, while the horns
approximate to those of the Bontebok. The Blessbok (_A. albifrons_)
and Bontebok (_A. pygargus_), belonging to the genus _Damalis_ of many
authors, have the facial portion of the skull shorter, the horns situated
more in advance of the plane of the occiput, and inclining regularly
backwards. Of the Blessbok Mr. C. J. Anderson observes that “it is of a
beautiful violet colour, and is found in company with black Wildebeests
and Springboks in countless thousands on the vast green plains of short
crisp, sour grass occupying a central position in South Africa. Cattle
and horses refuse to pasture on the grassy products of these plains,
which afford sustenance to myriads of this Antelope, whose skin emits a
most delicious and powerful perfume of flowers and sweet-smelling herbs.”
Since the time this was written these Antelopes have been greatly reduced
in number. _A. (Damalis) hunteri_, from East Africa, appears to be allied
to _A. senegalensis_, but in the more elongated facial portion of the
skull approximates to the Harte-beest, and thus confirms the view that
_Damalis_ should not form a distinct genus.
[Illustration: FIG. 138.—Head of _Alcelaphus tora_. From Sclater, _Proc.
Zool. Soc._ 1873, p. 762.]
_Connochætes._[211]—Head short and massive, with the muffle very broad
and bristly. Nostrils widely separated, hairy within. Horns on the
vertex of the skull, immediately over the occiput, approximated at base,
cylindrical, bent outwards, and recurving upwards at the tip. Extremities
of premaxillæ much expanded laterally, and firmly ankylosed. Vertebræ:
C 7, D 14, L 6, S 4, C 16. Hoofs very narrow. Tail very long, covered
throughout with long hairs. Four mammæ. Two species, _C. taurina_ and
_C. gnu_ (Fig. 139), both from South Africa. The former, or Brindled
Gnu, is distinguished by the absence of long hair on the face, the black
(instead of white) tail, and the presence of dark vertical streaks on the
shoulders; it is never found to the south of the Orange River.
The White-tailed Gnu stands about 4 feet 6 inches at the withers. These
animals were formerly found in large herds, and are remarkable not only
on account of their peculiar form, but also for their grotesque actions
when alarmed. Some interesting observations have recently been published
upon the mode of development of the horns of the Gnu,[212] from which
it appears that in very young individuals the horns are straight and
divergent, situated some distance below the vertex of the head, and
separated by a wide hairy interval. These young horns form the straight
tips of those of the adult, the basal downwardly curved portion being
subsequently developed. In the fully adult animal the base of the horns
forms a helmet-like mass on the forehead which completely obliterates the
hairy frontal space of the young.
[Illustration: FIG. 139.—The White-tailed Gnu (_Connochætes gnu_).]
_Cephalophine Section._—Small or medium-sized African and Indian
Antelopes, with simple horns present only in the males, a more or less
elongated suborbital gland, a lachrymal depression in the skull, and
square-crowned upper molars (Fig. 140). Lateral hoofs well developed.
_Cephalophus._[213]—One pair of horns, arising far back on the frontals,
conical, short, angulated at the base, and erect or recurved. Suborbital
gland opening in the form of a slit, or as a row of pores. Auditory bulla
divided by a distinct septum. Muffle large and moist. Tail very short.
Head tufted. Upper molars of larger species with an accessory internal
column. Dorsal vertebræ fourteen in number. Some sixteen species,
confined to southern and tropical Africa.
The Duikerboks, as the members of this genus are called, are among
the most graceful of the African Antelopes, the smallest species not
being larger than a rabbit. The West African _C. sylvicultor_ and _C.
longiceps_ are the largest species.
_Tetraceros._[214]—Two pairs of conical horns, of which the anterior are
much the smaller. Suborbital gland elongated, and lachrymal fossa very
large. Upper molars (Fig. 140) without accessory internal column. One
existing Indian species (_T. quadricornis_).
[Illustration: FIG. 140.—Palatal and outer aspects of the three right
upper premolars and first molar of the Four-horned Antelope (_Tetraceros
quadricornis_). From the _Palæontologia Indica_.]
The Four-horned Antelope is found throughout the peninsula of India in
jungle. The general colour is brown, lighter beneath and on the inside of
the limbs. Remains of this species are found fossil in the cave-deposits
of Madras, and a small Ruminant from the Pliocene of the Siwalik Hills
has been provisionally referred to this genus.
_Cervicaprine Section._—Small or large Antelopes now confined to the
Ethiopian region, with horns present only in the males, lachrymal vacuity
generally large, more or less distinct pits at the apertures of the
supraorbital foramina in the frontals, and narrow upper molars in which
there is no accessory internal column.
_Neotragus._[215]—Distinguished from the next genus by having the crown
of the head tufted, muzzle hairy, premaxillæ long and reaching the
lachrymals, nasals very short, mesethmoid much ossified, third lobe of
last lower molar either absent or very small, and the hinder lobe of the
corresponding upper molar much reduced.
Three species, Salt’s Antelope (_N. saltianus_), from Abyssinia, and
also _N. kirki_ and _N. damarensis_; the two latter having a small
third lobe to the last molar. Writing of the first-named species, Mr.
W. T. Blanford[216] observes that “the _Beni-Israel_, or _Om-dig-dig_,
one of the smallest Antelopes known, abounds on the shores of the Red
Sea and throughout the tropical and subtropical regions of Abyssinia.
It is occasionally, but rarely, found at higher elevations; I heard of
instances of its being shot both at Serafie and Dildi, but it is not
often seen above about 6000 feet. It inhabits bushes, keeping much to
heavy jungle on the banks of water-courses, and is usually single, or
in pairs, either a male and female or a female and young being found
together; less often the female is accompanied by two young ones, which
remain with her until full grown.”
_Nanotragus._[217]—Horns small, parallel with frontals, and rising
immediately above postorbital process of frontals, in front of the
fronto-parietal suture. Lachrymal fossa very large, suddenly descending
in front of the orbit, and extending on to the maxilla; lachrymal vacuity
small. Auditory bulla large and smooth, without internal septum. Nasals
of moderate length. Crown of the head smooth; naked part of muffle small;
aperture of suborbital gland small. Lateral hoofs small or absent. Nine
species.[218]
The typical species is the Royal Antelope (_N. pygmæus_) of Guinea, the
smallest existing representative of the Pecora. This species, together
with _N. moschatus_ and _N. tragulus_ have no lateral hoofs, or tufts on
the knees. In the _Scopophorine_ group, comprising _N. scoparia_, _N.
montanus_, and _N. hastatus_, both these appendages are present; while in
the _Oreotragine_ group (_N. melanotis_ and _N. oreotragus_) the former
are present and the latter absent.
_Pelea._[219]—Horns rather small, compressed, upright, scarcely
diverging, and placed immediately over the orbits. No suborbital gland,
nor lachrymal fossa; premaxillæ not reaching nasals. Tail short and
bushy. Colour uniform. One species—the Rehbok (_P. capreola_), South
Africa, is nearly of the size of a Fallow Deer, although more resembling
a Chamois in build and habits. The colour is of a uniform light gray.
This animal inhabits bare rocky districts, and thus differs widely from
the Water-buck and its allies.
_Cobus._[220]—Large Antelopes, with the horns large, elongate, sublyrate,
and ringed at the base, and with rudimentary suborbital glands. Skull
with a deep frontal hollow, no lachrymal depression, large lachrymal
vacuity, and the premaxillæ reaching the very long nasals. Tail long,
with a ridge of hair above, and slightly tufted at the end. Colour
uniform. Six species, African.
The Antelopes of this genus are water-loving animals, the Water-buck
(_C. ellipsiprymnus_) and the Singsing (_C. defassus_) being well-known
examples. Both these species are much alike, standing as much as 4 feet
6 inches at the withers. The Water-buck of South and Eastern Africa is
characterised by the coarseness of its long hair; while in the Singsing
of West and Central Africa the hair is remarkably fine and soft.
Fossil Antelopes from the Pliocene of India are referred to _Cobus_.
_Helicophora_, from the Lower Pliocene of Attica, is regarded as allied
to _Cobus_, but it has no distinct supraorbital pits.
_Cervicapra._[221]—An allied South African genus in which the tail is
short and bushy and the premaxillæ do not reach the nasals. Three species.
The Reitbok (_C. arundineum_) is of a grizzly ochre colour; it stands
nearly 3 feet in height, and has horns about 1 foot in length. The Nagor
(_C. redunca_) is about 6 inches shorter, with horns of half the length,
and fulvous brown above and white below; the West African _C. bohor_
being rather larger.
_Antilopine Section._—A large group of moderate-sized or small Antelopes,
most abundant in the deserts bordering the Palæarctic, Oriental, and
Ethiopian regions. Horns generally compressed and lyrate, or recurved, or
cylindrical and spiral, ringed at base, sometimes present in both sexes.
Skull with large pits at apertures of supraorbital foramina of frontals,
and generally a distinct lachrymal fossa. Molars of upper jaw narrow,
without inner accessory column, and resembling those of the Sheep and
Goats. Tail moderate, compressed, hairy above.
_Antilope._[222]—Horns, present only in the male, long, cylindrical,
subspiral, and diverging. Suborbital gland large, with a somewhat linear
opening; lachrymal depression of skull very large, and a small lachrymal
fissure. Glands in the feet; lateral hoofs present. One species, India.
The well-known Black-buck (_A. cervicapra_) is found on open plains
all over India, except in lower Bengal and Malabar. Old males are deep
blackish-brown in colour on the back and sides and the outer surfaces of
the limbs, the under parts and inner surfaces of the limbs white, and
the back of the head, nape, and neck yellowish. Young males and females
are fawn-coloured above. Very large herds are seen in the plains about
Delhi and Mattra, which are said in some instances to reach to thousands.
Horn-cores are found in the Pleistocene deposits of the valley of the
Jumna which cannot be distinguished from those of the existing species.
_Æpyceros._[223]—Horns compressed, lyrate, and wide-spreading; present
only in male. No suborbital gland, or lachrymal depression in the skull.
No lateral hoofs. Two species; one from South and the other from West
Africa.
The Palla (_Æ. melampus_) is a large Antelope standing over 3 feet
high at the withers, and readily distinguished by its dark red colour,
gradually shading to white below. It is usually found on or near hills in
herds of from twenty to thirty. _Æ. petersi_ is from the Congo.
_Saiga._[224]—Nose very large, convex, and inflated. Supraorbital gland
present. Lachrymal fossa of skull small, and fissure absent; narial
aperture very large; nasals extremely short; supraorbital pits rather
small. Horns yellow, lyrate, of moderate length; present only in male.
Vertebræ: C 7, D 13, L 6, S 4, C 10. One species, Eastern Europe and
Western Asia.
The Saiga (_S. tatarica_) is a clumsily built and somewhat sheep-like
Antelope inhabiting the steppes; it occurs fossil in the Pleistocene of
France and England.
_Pantholops._[225]—Allied in the characters of the head and skull to
_Saiga_, but the nose less convex, the nostrils of the male more swollen,
and the horns of that sex black, very long, compressed, and lyrate; those
of female very short. One species, Central Asia.
The Chiru (_P. hodgsoni_) inhabits the highlands of Western Tibet and
Turkestan. In the former area it generally goes in small herds of from
three to six, and in the summer may be found grazing in early morning on
the level spaces frequently found in the river valleys at elevations of
about 15,000 feet. It is excessively shy and difficult to approach. The
large size of the narial aperture in the skull of Chiru is suggestive of
a connection with respiration at a high altitude, but this appears to be
negatived by the occurrence of the same feature in the Saiga.
_Gazella._[226]—Delicately built and sandy-coloured Antelopes, with
lyrate or recurved horns, which may be absent in the female, and are
always smaller and simpler in that sex than in the male. Skull with
moderate lachrymal fossa, and a distinct lachrymal fissure. Vertebræ: C
7, D 13, L 6, S 4, C 14. Suborbital gland frequently small, and covered
with hair. Face with a white streak running from the outer side of the
base of each horn nearly down to the upper end of each nostril, cutting
off a dark triangular central patch, and bordered externally by a
diffused dark line (see Fig. 121, p. 310). The Gazelles, of which there
are some twenty-four existing species, are typically Palæarctic desert
forms, the Springbok (_G. euchore_) being an outlying South African
species. _G. picticaudata_ and _G. gutturosa_ are respectively found in
Western Tibet and Mongolia, the former at great elevations. The majority
of the Gazelles do not exceed 30 inches in height, although _G. mohr_ is
36. Sir Victor Brooke classifies[227] the Gazelles as follows:—
A. No stripe on back; three lower premolars.
_a._ White of rump not encroaching on the fawn of the haunches.
I. Female with horns.
1. Horns lyrate or sublyrate—_G. dorcas_, _G. isabella_,
_G. rufifrons_, _G. lævipes_, _G. tilonura_, _G. naso_.
2. Horns non-lyrate—_G. cuvieri_, _G. leptoceros_, _G.
spekei_, _G. arabica_, _G. bennetti_, _G. fuscifrons_,
_G. muscatensis_.
II. Female without horns.
_G. subgutturosa_, _G. gutturosa_, _G. picticaudata_.
_b._ White of rump projecting forwards in an angle into the
fawn colour of the haunches. Horns in both sexes.
_G. dama_, _G. mohr_, _G. soemmerringi_, _G. granti_
(Fig. 121), _G. thomsoni_.
B. A white stripe down the back, two lower premolars. Horns in
both sexes.—_G. euchore._
The East African _G. walleri_ is an aberrant species, in which the
females are hornless, which has been made the type of the genus
_Lithocranius_. It is characterised by the extreme density of the horns
and skull, the slenderness of the mandible, and the small size of the
cheek-teeth, the upper molars being relatively broader and lower than
usual. The cranium is remarkable for the shortness of its facial portion,
the large size and production backwards of the supraoccipital, and for
the circumstance that the long basicranial axis is nearly parallel with
the plane of the palate.
Fossil species of _Gazella_ are found in the Pliocene and Pleistocene
deposits of Europe and India. _G. deperdita_ (_brevicornis_), of the
Lower Pliocene of France and Greece, appears to be a generalised species
in which the lower molars frequently have accessory columns, traces of
which are found in some of the existing forms.
_Hippotragine Section._—Includes very large African Antelopes, with long
horns, present in both sexes, which are placed over or behind the orbit,
and are either recurved, straight, or subspiral. Skull with no distinct
pits at apertures of supraorbital foramina in frontals, no lachrymal
fossa, and only a small lachrymal fissure. No suborbital gland. Tail
long, cylindrical, and tufted at the end. Upper molars extremely
hypsodont, very broad, and with large accessory columns, thus closely
resembling those of the Oxen. Some authorities divide this section into
two. In the Pliocene it occurs in India and Europe.
_Hippotragus._[228]—Horns stout, rising vertically from a crest over
the orbit at an obtuse angle to the plane of the nasals, then recurved;
lachrymal fissure in some instances almost obliterated. Neck with an
erect recurved mane. Tail very distinctly tufted. Four species, tropical
Africa and south to the Cape.
The Sable Antelope (_H. niger_) is one of the best-known examples of this
genus, occurring in South and East Africa. It stands upwards of 4½ feet
in height at the withers, and, except for some white streaks on the face
and the whole of the under surface of the body, is of a black colour.
The Blaubok (_H. leucophæus_) is distinguished by the glaucous hue of
the hair. The other species are the Equine Antelope (_H. equinus_) and
Baker’s Antelope (_H. bakeri_) from the Sudan, both closely allied, but
the latter distinguished by its pale fulvous colour, pencilled ears, and
black stripes on the shoulder.
Skulls of fossil Antelopes from the Pliocene of India have been referred
to _Hippotragus_ (_H. sivalensis_), and Sir V. Brooke suggests that the
European Pliocene _Antilope recticornis_ is not generically separable.
_Oryx._[229]—Horns long, slender, nearly straight or somewhat recurved,
rising behind the orbit, and inclining backwards in the plane of the
nasals; lachrymal fossa distinct. Nape maned; tail long, and more haired
than in _Hippotragus_. Four species, ranging over all the African deserts
to Arabia and Syria.
The Gemsbok (_O. gazella_, Fig. 141), is a South African species
characterised by its straight horns, the presence of a tuft of hair on
the throat, as well as by the large patches and stripes of black on the
head, back, limbs, and flanks. It stands nearly 4 feet in height at the
shoulder, and the horns are 2 feet 9 inches in length. The colour of the
upper part of the body is a rusty gray, and of the under part white,
while these are separated from each other by a well-defined black band
on either side. These bands unite on the breast, and are continued as a
single black band until reaching the lower jaw, where they again divide
and form two transverse bands on the head, terminating at the base of
the horns. The head otherwise is white, as also are the limbs, with the
exception of the thighs, which are black. The Gemsbok generally goes
in pairs, or in small herds of three or four. The Beisa (_O. beisa_)
of Abyssinia is distinguished by the absence of the tuft of hair on
the throat. Writing of this species in his _Geology and Zoology of
Abyssinia_, Mr. W. T. Blanford observes that “the appearance of a herd of
Oryx is very imposing. They are some of the most elegant and symmetrical
of animals, the motions being those of a wild Horse rather than of an
Antelope. Their favourite pace appears to be either a steady quick walk
or a trot; they rarely break into a gallop unless greatly alarmed. When
frightened they dash off, sometimes snorting and putting their heads down
as if charging, raising their long tails, and looking very formidable.
They are wary animals, though far less so than some other Antelopes. It
is said that they frequently attack when wounded, and their long straight
horns are most deadly weapons.” The Arabian Beatrix Antelope (_O.
beatrix_) is a much smaller animal, with the black markings confined to
the head, fore limbs, and flanks. Finally, the Leucoryx (_O. leucoryx_)
of North Africa, while agreeing in size with the Beatrix, differs by its
curved horns and uniform coloration.
[Illustration: FIG. 141.—The Gemsbok (_Oryx gazella_).]
The extinct _Palæoryx_, of the Lower Pliocene of Europe and the Isle of
Samos, appears to have been an ancestral form of _Oryx_, said to show
some signs of affinity with _Hippotragus._
_Addax._[230]—Horns with the same inclination as in _Oryx_, but with a
slight spiral twist. No mane on nape, but a slight one on the throat.
Hoofs rounded. One species (_A. nasomaculatus_), from North Africa and
Arabia, the colour of which is nearly white.
_Tragelaphine Section._—Includes large, so-called Bovine, Antelopes now
mainly characteristic of the Ethiopian region, but with one Oriental
genus. Horns usually present in the male only (if developed in the female
smaller), with a more or less distinct ridge in front, and usually
twisted spirally, the front ridge twisting outwards from the base of the
horn. Skull without lachrymal fossa, but with a large or small lachrymal
fissure; usually large pits at the apertures of the supraorbital foramina
on the frontals; premaxillæ reaching nasals. Muffle large and moist;
nostrils approximated. Molars hypsodont or brachydont. Vertical white
stripes frequently present on the body.
_a._ _Hind limbs much shorter than the fore. Horns behind the orbit,
short, conical, faintly angulated. Nose bovine. Body without vertical
stripes. Molars_ (Fig. 123, p. 311) _hypsodont, with a large accessory
column in those of the upper jaw. One Oriental genus._
_Boselaphus._[231]—The one genus of this subsection is represented only
by the well-known Nilghai (_B. tragocamelus_) of India. The male stands
over 4 feet in height at the shoulder, with horns about 8 inches in
length; the hornless female being about one third smaller. Both sexes
have a short erect mane, and the male has also a tuft of hair upon the
throat. When adult the sexes are very different in colour, the male being
of a dark iron gray or slate colour, approaching black on the head and
legs, while the female and young are of a bright light brown or fawn
colour. In both male and female at all ages the lips, chin, and under
parts, as well as two transverse stripes on the inner sides of the ears
and rings on the fetlocks, are white, and the mane and tip of the tail
black. The Nilghai is one of the few Antelopes occurring in India, where
it is found from near the foot of the Himalaya to the south of Mysore,
though rare to the north of the Ganges and also in the extreme south. It
is most abundant in Central India, and does not occur in Assam or the
countries to the east of the Bay of Bengal. It frequents forests and low
jungles, though often found in tolerably open plains, associating in
small herds. One, or very often two, young produced at a birth. Fossil
remains of species of this genus occur in the Pleistocene and Pliocene
deposits of India.
_b._ _Fore and hind limbs equal. Horns long, and spirally twisted. Nose
cervine, and aperture of suborbital gland very small. Body generally
striped. Molars brachydont, those of the upper jaw in existing forms with
a smaller inner accessory column. Three existing Ethiopian genera._
_Tragelaphus._[232]—Female hornless. Horns of males (Fig. 142) over
orbit, with one or two spiral turns, obscurely ridged, the posterior
ridge being more developed than the anterior. Skull with small
supraorbital pits, very small lachrymal fissure, and no deep intercornual
depression in the frontals. Neck maned or smooth. Hoofs short or long.
Coloration usually brilliant, differing markedly in the two sexes, and
the white bands on the body, when present, numerous and distinct. Seven
species.
[Illustration: FIG. 142.—Head of _Tragelaphus gratus_. From Sclater,
_Proc. Zool. Soc._ 1883, p. 36.]
The Harnessed Antelopes are among the handsomest of the whole group. The
small Guib (_T. scriptus_) is not larger than a Goat, but _T. angasi_ is
3 feet 4 inches in height at the shoulder. In _T. scriptus_, _T. angasi_,
and _T. euryceros_, the two sexes differ in colour, the body is marked by
white stripes descending from a white dorsal streak, and the hoofs are
short; the third species differing from the others by the absence of a
mane on the neck, back, and belly. _T. gratus_ agrees with this group in
coloration (the mane being absent), but differs in the extreme elongation
of its hoofs. The Nakong, _T. spekei_, while having the long hoofs of
_T. gratus_, has a perfectly plain body coloration, with a mane on the
neck. The two species with elongated hoofs inhabit swampy districts, for
which this peculiar structure is admirably adapted; and the Nakong, when
frightened, will rush into the water and leave only its nostrils and the
tips of the horns above the surface. The small Bushbuck (_T. sylvaticus_)
of South Africa has no stripes, and short hoofs.
[Illustration: FIG. 143. The Kudu (_Strepsiceros kudu_). From Sclater,
_List of Animals in Zoological Society’s Gardens_, 1883, p. 136.]
_Strepsiceros._[233]—Females hornless. Horns (Fig. 143) more twisted
than in _Tragelaphus_, forming an open spiral, with the anterior ridge
very strongly developed, and rising at an obtuse angle to the plane of
the nasals. Skull with large supraorbital pits, large lachrymal fissure,
and deep intercornual depression. Hoofs short. Body with white vertical
stripes descending from a longitudinal dorsal streak. Two existing
species.
The Kudu (_S. kudu_, Fig. 143) extends from South Africa to Abyssinia,
and is only inferior in size to the Eland. The horns are about 4 feet
in length, and form a very open spiral, and there is a fringe of long
hair down the front of the neck. The Lesser Kudu (_S. imberbis_), of
Somali-land is a much smaller form, without the fringe of hair on the
neck, and with a much smaller axis formed by the spiral of the horns.
An imperfect skull from the Pliocene of Northern India has been referred
to _Strepsiceros_.
_Oreas._[234]—Females horned. Horns twisted on their own axis, with very
strong ridges, inclining upwards and outwards in the plane of the nasals.
General characters of skull as in preceding genus. Stripes on body, if
present, very faintly marked. One existing species.
The Eland (_O. canna_) is the largest of all the Antelopes, the males
standing nearly 6 feet at the withers. One variety from South Africa
is of a uniform pale fawn colour, while the Central African form is of
a bright tan colour, marked by a number of thin pale vertical stripes
descending from a dark dorsal ridge—these markings fading more or less in
the adults. The males have a large dewlap, a tuft of brown hair on the
forehead, and a small mane on the neck. The straight black horns of the
male are usually about 18 inches long. Elands were formerly extremely
abundant in Southern and Eastern Africa, but their destruction has been
so relentless that they have totally disappeared from extensive areas,
and are daily becoming scarcer.
Portions of upper jaws from the Pliocene deposits of India appear to
indicate the former existence in that area of large Antelopes closely
allied to the Eland, but distinguished from the living species by the
greater size of the inner accessory column in the upper molars.
_Allied Extinct Types._—Large Antelopes with spirally twisted horns
appear to have been common over Southern Europe in Pliocene times, but
their exact affinity is in many cases difficult to determine. Of these,
_Palæoreas_, which occurs in the Lower Pliocene of Europe and Algeria,
appears to present affinities both to _Oreas_ and _Strepsiceros_, and may
have been the ancestral type from which these two genera are derived; the
upper molars have well-developed accessory columns.
The so-called _Antilope torticornis_, of the French Pliocene, resembles
_Tragelaphus_ in the greater development of the posterior as compared
with the anterior ridge of the horn-cores, and has accordingly been
referred to that genus. _Protragelaphus_, of the Lower Pliocene of
Attica, differs from all the other types in the absence of the anterior
ridge on the horn-cores and of the supraorbital pits, while it has a
distinct lachrymal fossa.
In this place it will be convenient to notice certain fossil forms which
do not accord with any of the existing sections of the family, and for
the reception of which the _Palæotragine_ section has been formed. In
these types the horn-cores are laterally compressed like those of the
modern Goats, but the upper molars resemble those of the brachydont
Antelopes. The earliest of these genera, and the first representative
of the Antelopes yet known, is _Protragoceros_, of the Middle Miocene
of France, first described as _Antilope clavata_; _Palæotragoceros_ and
_Tragoceros_, of the Lower Pliocene, are distinguished by their larger
horns and wider molars.
A remarkable large Antelope from the Lower Pliocene of the Isle of Samos,
in the Turkish Archipelago, proposed to be described as _Criotherium_,
appears to be unlike any other form. The horns, which are placed on the
extreme vertex of the skull, are very short, tightly twisted, and project
in front of the forehead. The upper molars have short and broad crowns,
with no accessory column on the inner side.
_Rupicaprine Section._—The Caprine Antelopes, as the typical members of
this section may be termed, appear to connect the true Antelopes with the
Goats. They are mostly small or medium-sized forms, inhabiting portions
of the Palæarctic and Oriental regions, with one outlying North American
genus. The typical forms present the following features. Horns present,
and of nearly equal size in both sexes, rising behind the orbits, short,
ringed at the base, conical or somewhat compressed, and recurved.
Suborbital gland generally present, in some cases small. Build clumsy;
hoofs large; tail short, tapering, hairy above. Skull with lachrymal
fossa, but no fissure. Molars as in the Caprine section.
_Rupicapra._[235]—Horns short and cylindrical, rising perpendicularly
from the forehead for some distance, then bending sharply backwards and
downwards, forming hooks with pointed tips. Premaxillæ not reaching the
nasals. One species, Palæarctic.
The Gemse, or Alpine Chamois (_R. tragus_), inhabits the high mountains
of Europe from the Pyrenees to the Caucasus. It stands about 2 feet in
height at the withers. The body is covered in winter with long hair of a
chestnut-brown colour, that of the head being paler, with a dark brown
streak on each side. At other seasons the colour is somewhat lighter, in
spring approaching to gray. Underneath the external covering the body is
further protected from cold by a coat of short thick wool of a grayish
colour. The tail is black; the ears are pointed and erect; the hoofs have
the outer edges higher than the soles, and are thus admirably adapted for
laying hold of the slightest projection or roughness on the face of the
rocky precipices it frequents. The Chamois is gregarious, living in herds
of fifteen or twenty, and feeding generally in the morning or evening.
The old males, however, live alone, except in the rutting season, which
occurs in October, when they join the herds, driving off the young males,
and engaging in contests with each other that often end fatally. The
period of gestation is twenty weeks, when the female, beneath the shelter
of a projecting rock, produces one and sometimes two young. In summer the
Chamois ascends to the limits of perpetual snow, being only outstripped
in the loftiness of its haunts by the Ibex; and during that season it
shows its intolerance of heat by choosing such browsing grounds as have a
northern exposure.
[Illustration: FIG. 144.—_Nemorhædus crispus._ From Sclater, _List of
Animals in Zoological Society’s Gardens_, 1883, p. 151.]
_Nemorhædus._[236]—Horns rounded, gradually recurving, without distinct
hook at the end. Suborbital gland small or wanting; ears large; skull
with a large lachrymal depression, and the premaxillæ not quite reaching
the nasals. Some nine species, ranging from the Eastern Himalayas to
North China and Japan, and southwards to Formosa, the Malay Peninsula,
and Sumatra. The smallest species is the Himalayan Goral (_N. goral_). Of
the larger forms we may mention the Himalayan Serow (_N. bubalinus_) the
Cambing-Utan (_N. sumatrensis_) of Sumatra, and the Japanese _N. crispus_
(Fig. 144). Of the Serow, Colonel Kinloch remarks that “it is a large and
powerful beast. The body is covered with very coarse hair, which assumes
the form of a bristly mane on the head and shoulders, and gives the
beast a ferocious appearance, which does not belie its disposition. The
colour is a dull black on the back, bright red on the sides, and white
underneath, the legs also being dirty white. The ears are very large, the
muzzle is coarse. The Serow has an awkward gait, but in spite of this can
go over the worst ground; and it has perhaps no superior in going down
steep hills. It is a solitary animal, and nowhere numerous.”
_Haploceros._[237]—The Rocky-Mountain Goat (_Haploceros montanus_),
inhabiting the northern parts of California, appears to be very closely
allied to _Nemorhædus_. The horns are somewhat compressed at the base;
there is no suborbital gland; and the ears are small. The hair, which is
whitish in colour, is very long, and especially abundant in the region of
the throat, shoulders, flanks, and tail. The animal is about the size of
a large Sheep.
_Budorcas._[238]—The Takin (_B. taxicolor_) of the Mishmi Hills in Assam,
and an allied species from Eastern Tibet, are larger forms apparently
related to _Nemorhædus_, but with a much greater development of the
horns. The horns of what is considered to be the male[239] arise from
the vertex of the skull, and are nearly in contact in the middle line;
they first bend outwards and downwards, and then suddenly upwards
and backwards. Those regarded by Mr. Hume as referable to the female
are directed at first outwards, and then gradually curve upwards and
backwards, without any downward flexure or angulation. The horns of
the male may be 2 feet in length, with a basal diameter of 13 inches.
The muzzle is hairy, with a small naked muffle. There appear to be
considerable seasonal and sexual variations in colour; the body being in
some cases of a yellow dun, while in others it is a dusky, reddish-brown,
with much black intermingled. The heads of large males are blackish.
Scarcely anything is known of the habits of the Takin, which never
appears to have been seen alive by Europeans.
_Caprine Section._—Both sexes with horns, but those of the female small.
Horns usually compressed, triangular, with transverse ridges, and either
curving backwards or spiral. Muzzle hairy, without naked muffle.
Suborbital gland small or absent; lachrymal fossa of skull present or
absent. Tail short and flattened. Foot-glands frequently present. Molars
very hypsodont; those of the upper jaw being narrow, without an accessory
internal column. Mainly Palæarctic, but with some outlying forms.
This section includes the Goats and Sheep, which are so closely connected
that it is difficult to give well-marked generic characters that will
hold good for all the species. They seem to be one of the latest
developments of the _Bovidæ_, since they are unknown before the Pliocene
period; and are essentially mountain forms.
[Illustration: FIG. 145.—The Alpine Ibex (_Capra ibex_).]
_Capra._[240]—Horns flattened from side to side, and either curving
backwards (Fig. 145) or spirally twisted. No suborbital gland, and no
lachrymal fossa in the skull. Foot-glands, if present, only in the fore
feet. Chin more or less bearded. Males with a strong odour. Vertebræ:
C 7, D 13, L 6, S 4, C 9-13. Some dozen species, ranging over all the
higher mountains of Southern Europe, from Spain to the Caucasus; also
found in Abyssinia, Persia, Sind, and Baluchistan, thence through the
higher Himalaya, and so on to Tibet and Northern China. One outlying
species occurs in the Nilgherries of Southern India.
The European Ibex or Steinbok (Fig. 145), which may be taken as a typical
Goat, stands about 2½ feet in height at the shoulder. In summer the hair
is short and smooth, and of an ashy-gray colour, but a long coat is
developed in winter. The horns of the male rise in a bold backward sweep
from the forehead, and are characterised by the strong transverse ridges
on the broad and flat anterior surface. They are said to be not more
than some 2 feet in length, but these dimensions are greatly exceeded
by the horns of the Himalayan Ibex. The Alpine Ibex lives at a greater
height than the Chamois, spending the day just at the limit of perpetual
snow, and descending at night to graze at lower levels. Both this and the
Himalayan species generally live in small herds of from five to fifteen
or more; they are wary animals, although not so much so as many of the
wild Sheep. The following list, mainly taken from two papers by Mr.
Sclater,[241] gives the distribution of the various species of Goats,
with some remarks on their peculiarities:—
(1) _C. ibex_, confined to the Alps of Switzerland, Savoy, and the
Tyrol, and now nearly extinct, except where artificially preserved.
(2) _C. sibirica_, closely allied to the preceding, but with larger
horns, occurs in the Altai Mountains, and throughout the Himalaya from
Kashmir to Nipal, and northward towards Turkestan. (3) _C. sinaitica_,
of the mountains of Upper Egypt, the Sinaitic Peninsula, and Palestine,
is allied to the two preceding species, but has the horns somewhat
more compressed, with a difference in the ridges on the front. (4) _C.
caucasica_, a very distinct species, confined to the Caucasus, where
it inhabits the western part of the Great Caucasus; with thick horns
curving backwards and outwards in one plane, with the exception of their
tips, which incline inwards.[242] (5) _C. pallasi_ is an allied species
from the Eastern Caucasus, distinguished, among other features, by the
curvature of the horns, which lie flatter and twist more outward from
the forehead, with a greater terminal inward bend. (6) _C. pyrenaica_,
of the Pyrenees, and the higher ranges of Central Spain, Andalusia, and
Portugal, is another nearly related species. (7) _C. ægagrus_, formerly
abundant over the Grecian Archipelago, but now restricted in Europe to
Crete and some of the Cyclades, is found throughout the mountains of
Asia Minor and Persia, and thence to Baluchistan and Sind. The horns
are thinner and sharper in front than in the Ibexes, and this species
is generally regarded as the ancestral stock of the various breeds of
domestic Goats. (8) _C. dorcas_, a Goat from the island of Jura, near
Eubœa, has been described under this name, and is apparently nearly
allied to _C. ægagrus_. (9) _C. walie_, an apparently well-characterised
species from the highest ranges of Abyssinia. (10) _C. falconeri_; the
Markhoor differs from all the preceding species by the spiral twisting of
its horns, which attain enormous dimensions. It occurs in the Pir-Panjal
range south of Kashmir, and thence into Afghanistan and the Suleiman
range, and northwards to Astor, Gilgit, and Scardo (Baltistan). The
specimens from the Suleiman range have the spiral of the horns very
close, somewhat as in the Eland; while in those from Astor, Gilgit, and
Scardo it is very open, as in the Kudu. The Pir-Panjal race occupies a
somewhat intermediate position in this respect. (11) _C. jemlaica_, the
Thar, inhabits suitable regions along the whole range of the Himalaya
from Kashmir to Bhutan. Together with the next species, it differs from
the more typical Goats in its short, thick, and much compressed horns,
the anterior border of which is keeled, and the moist naked muffle. There
are no glands in the fore feet. It was generically separated by Gray as
_Hemitragus_. (12) _C. hylocrius_, the so-called Ibex of the Nilgherries,
Anamallays, and other adjoining ranges of Southern India, is an outlying
species, apparently allied to the preceding, but with somewhat different
horns, in which the external angle in front is much rounded off.
Of fossil Goats we have but little knowledge. Remains of _C. pyrenaica_
are found in cave-deposits at Gibraltar; and it is not improbable that
the genus is represented in the Upper Pliocene of France. Several species
occur in the Pliocene of India, _C. sivalensis_ being apparently closely
allied to _C. jemlaica_, while another has horns resembling those of _C.
falconeri_, and it is possible that a third may be more nearly related to
the Ibexes.
_Ovis._[243]—Horns curving backwards and downwards in a bold sweep,
with the tips everted, generally with more or less prominent transverse
ridges, and brownish in colour. Suborbital gland and lachrymal fossa
usually present, but generally small. Foot-glands in all the feet. Chin
not bearded;[244] males without a strong odour. Vertebræ: C 7, D 13, L
6, S 4, C 10-14. Some twelve species, mainly Palæarctic, but extending
into the adjacent portions of the Oriental region, and with one outlying
species in North America.
The more typical Sheep are closely connected with the Goats by the
Himalayan Bharal (_O. nahura_) and the Aoudad (_O. tragelaphus_) of
Northern Africa, both these species having no suborbital gland and no
lachrymal fossa, while their comparatively smooth and olive-coloured
horns show a decided approximation to those of the Goats. Both present,
however, the ovine character of glands in all the feet. In the typical
Sheep the basioccipital of the skull is wider in front than behind,
with the anterior pair of tubercles widely separated and much larger
than the posterior pair. The Bharal, however, resembles the Goats in
having an oblong basioccipital, with the posterior tubercles larger and
more prominent than the anterior ones, both being situated in the same
antero-posterior line. These transitions towards the caprine type are,
however, not sufficient to support the view that the Bharal should form
the type of a distinct genus (_Pseudois_), more especially since some of
the typical Sheep, like _O. canadensis_, have the lachrymal fossa of the
skull very much reduced in size.
The distinction of the various permanent modifications under which wild
Sheep occur is a matter of considerable difficulty. Trivial characters,
such as size, slight variations in colour, and especially the form and
curvature of the horns, are relied upon by different zoologists who have
given attention to the subject in the discrimination of species, but no
complete accord has yet been established. The most generally recognised
forms are enumerated below.
The geographical distribution of wild Sheep is interesting. The immense
mountain ranges of Central Asia, the Pamir and Thian-Shan of Turkestan,
may be looked upon as the centre of their habitat. Here, at an elevation
of 16,000 feet above the sea-level, is the home of the magnificent
_Ovis poli_, named after the celebrated Venetian traveller Marco Polo,
who met with it in his adventurous travels through this region in the
thirteenth century. It is remarkable for the great size of the horns of
the old rams and the wide open sweep of their curve, so that the points
stand boldly out on each side, far away from the animal’s head, instead
of curling round nearly in the same plane, as in most of the other
species. A Sheep from the same region, in which the horns retain their
more normal development, has received the name of _O. karelini_, but,
according to Mr. W. T. Blanford,[245] is not distinct specifically from
_O. poli_. Eastward and northward is found the Argali (_O. argali_),
with a wide and not very well determined range; it formerly occurred in
the Altai, but is now found in Northern Mongolia. Still farther north,
in the Stanovoi Mountains and Kamschatka, is _O. nivicola_, and away on
the other side of Behring’s Strait, in the Rocky Mountains and adjacent
highlands of western North America, is the “Bighorn” or Mountain Sheep
(_O. canadensis_), the only member of the genus found in that continent,
and indeed—except the Bison, Musk-Ox, Mountain Goat (_Haploceros_), and
the Prong-buck (_Antilocapra_)—the only hollow-horned Ruminant, being
like the rest obviously a straggler from the cradle of its race. The two
last-named species are nearly allied, and are characterised by the slight
development of the ridges on their horns and the very shallow lachrymal
fossa. Turning southward from the point from which we started, and
still a little to the east, in Nipal and Western Tibet, is the Himalayan
Argali (_O. hodgsoni_), having massive and strongly curved horns, with
bold ridges, like those of the true Argali. Indeed, were it not for their
isolated areas there would appear to be no grounds for distinguishing
these two closely allied forms, and it is not improbable that they
are really identical. _O. brookei_, appears to have been founded on a
hybrid between _O. hodgsoni_ and _O. vignei_. In the same districts,
and also in Southern Ladak, there occurs the Bharal (_O. nahura_), with
smaller, smoother, and more spreading horns. Passing in a south-westerly
direction we find a series of smaller forms, _O. vignei_ of Ladak, _O.
cycloceros_ of Northern India, Persia, and Baluchistan. _O. gmelini_ of
Asia Minor and Persia, _O. ophion_, confined to the elevated pine-clad
Troodos Mountains of the island of Cyprus, and said at the time of the
British occupation in 1878 to have been reduced to a flock of about
twenty-five individuals, and _O. musimon_, the Moufflon of Corsica and
Sardinia (see Fig. 146), believed to have been formerly also a native of
Spain. In the three latter species the females are hornless. Lastly, we
have the somewhat aberrant, Goat-like Aoudad (_O. tragelaphus_), of the
great mountain ranges of North Africa, in which, as already mentioned,
the skull and horns resemble those of the Bharal, although the tail is
longer, and there is a thick fringe of long hair on the throat, chest,
and fore legs.
[Illustration: FIG. 146.—The Moufflon (_Ovis musimon_). From a living
animal in the London Zoological Gardens.]
We thus find that Sheep are essentially inhabitants of high mountainous
parts of the world, for dwelling among which their wonderful powers of
climbing and leaping give them special advantages. No species frequent
by choice either level deserts, open plains, dense forests, or swamps.
By far the greater number of species are inhabitants of the continent of
Asia, one extending into North America, one into Southern Europe, and one
into North Africa. No wild Sheep exist in any other part of the world,
unless the so-called Musk-Ox of the Arctic regions, the nearest existing
ally to the true Sheep, may be considered as one. Geologically speaking,
Sheep appear to be very modern animals, or perhaps it would be safer to
say that no remains that can be with certainty referred to the genus
have been met with in the hitherto explored true Tertiary beds, which
have yielded such abundant modifications of Antelopes and Deer. They are
generally considered not to be indigenous in the British Isles, but to
have been introduced by man from the East in prehistoric times. A fossil
Sheep (_Ovis savigni_), apparently allied to the Argali, has, however,
been described from the so-called Forest-bed of the Norfolk coast.
The Sheep was a domestic animal in Asia and Europe before the dawn of
history, though quite unknown as such in the New World until after the
Spanish conquest. It has now been introduced by man into almost all
parts of the world where settled agricultural operations are carried on,
but flourishes especially in the temperate regions of both hemispheres.
Whether our well-known and useful animal is derived from any one of the
existing wild species, or from the crossing of several, or from some
now extinct species, is quite a matter of conjecture. The variations of
external characters seen in the different domestic breeds are very great.
They are chiefly manifested in the form and number of the horns, which
may be increased from the normal two to four or even eight, or may be
altogether absent in the female alone, or in both sexes; in the form and
length of the ears, which often hang pendent by the side of the head;
in the peculiar elevation or arching of the nasal bones in some Eastern
races; in the length of the tail, and the development of great masses of
fat at each side of its root, or in the tail itself; and in the colour
and quality of the fleece.
_Ovibos._[246]—This genus is generally considered to be a connecting link
between the Caprine and Bovine sections, but should rather be regarded as
an aberrant type of the former. Horns of adult male rounded, smooth, and
closely approximated at their bases, where they are depressed and rugose;
curving downwards, and then upwards and forwards. Muzzle caprine; no
suborbital gland, no lachrymal fossa or fissure in skull; orbits tubular;
a large narial aperture and very short nasals; premaxillæ not reaching
nasals. Tail short, and molar teeth caprine. One existing and two fossil
species, Palæarctic and Nearctic.
[Illustration: FIG. 147.—The Musk-Ox (_Ovibos moschatus_).]
The animal commonly known as the Musk-Ox (_Ovibos moschatus_), though
approaching in size the smaller varieties of Oxen, is in structure and
habits closely allied to the Sheep, its affinities being well expressed
by the generic name _Ovibos_ bestowed upon it by De Blainville. The
specific name, as also the common English appellatives “Musk-Ox,”
“Musk-Buffalo,” or “Musk-Sheep,” applied to it by various authors, refer
to the musky odour which the animal exhales. This does not appear to be
due to the secretion of a special gland, as in the case of the Musk-Deer;
but it must be observed that, except as regards the osteology, very
little is known of the anatomy of this species. It about equals in size
the small Welsh and Scotch cattle. The head is large and broad. The horns
in the old males have extremely broad bases, meeting in the median line,
and covering the brow and whole crown of the head. They are directed
at first downwards by the side of the face and then turn upwards and
forwards, ending in the same plane as the eye. Their basal halves are of
a dull white colour, oval in section and coarsely fibrous; their middle
part smooth, shining, and round; their tips black. In the females and
young males the horns are smaller, and their bases are separated from
each other by a space in the middle of the forehead. The ears are small,
erect, and pointed, and nearly concealed in the hair. The space between
the nostrils and the upper lip is covered with short close hair, as in
Sheep and Goats, without any trace of the bare muffle of the Oxen.
The greater part of the animal is covered with long brown hair, thick,
matted, and curly on the shoulders, so as to give the appearance of a
hump, but elsewhere straight and hanging down,—that of the sides, back,
and haunches reaching as far as the middle of the legs and entirely
concealing the very short tail. There is also a thick woolly under-fur,
shed in the summer. The hair on the lower jaw, throat, and chest is long
and straight, and hangs down like a beard or dewlap, though there is no
loose fold of skin in this situation as in Oxen. The limbs are stout
and short, terminating in unsymmetrical hoofs, the external one being
rounded, the internal pointed, and the sole partially covered with hair.
The Musk-Ox is at the present day confined to the most northern parts of
North America, where it ranges over the rocky barren grounds between the
60th parallel and the shores of the Arctic Sea. Its southern range is
gradually contracting, and it appears that it is no longer met with west
of the Mackenzie River, though formerly abundant as far as Eschscholtz
Bay. Northwards and eastwards it extends through the Parry Islands and
Grinnell Land to North Greenland, reaching on the west coast as far south
as Melville Bay; and it was also met with in abundance by the German
polar expedition of 1869-70 at Sabine Island on the east coast. No trace
of it has been found in Spitzbergen or Franz Joseph Land. As proved
by the discovery of fossil remains, it ranged during the Pleistocene
period over northern Siberia and the plains of Germany and France, its
bones occurring very generally in river deposits along with those of
the Reindeer, Mammoth, and Woolly Rhinoceros. It has also been found in
Pleistocene gravels in several parts of England, as Maidenhead, Bromley,
Freshfield near Bath, Barnwood near Gloucester, and also in the lower
brick-earth of the Thames valley at Crayford, Kent.
It is gregarious in habit, assembling in herds of twenty or thirty head,
or, according to Hearne, sometimes eighty or a hundred, in which there
are seldom more than two or three full-grown males. The Musk-Ox runs with
considerable speed, notwithstanding the shortness of its legs. Major
H. W. Feilden, naturalist to the Arctic expedition of 1875, says: “No
person watching this animal in a state of nature could fail to see how
essentially ovine are its actions. When alarmed they gather together like
a flock of sheep herded by collie dog, and the way in which they pack
closely together and follow blindly the vacillating leadership of the old
ram is unquestionably sheep-like. When thoroughly frightened they take
to the hills, ascending precipitous slopes and scaling rocks with great
agility.” They feed chiefly on grass, but also on moss, lichens, and
tender shoots of the willow and pine. The female brings forth a single
young one in the end of May or beginning of June after a gestation of
nine months. According to Sir J. Richardson, “when this animal is fat
its flesh is well tasted, and resembles that of the Caribou, but has
a coarser grain. The flesh of the bulls is highly flavoured, and both
bulls and cows when lean smell strongly of musk, their flesh at the same
time being very dark and tough, and certainly far inferior to that of
any other ruminating animal existing in North America.” The carcase of
a Musk-Ox weighs, exclusive of fat, above 3 cwt. On this subject, Major
Feilden[247] says: “The cause of the disagreeable odour which frequently
taints the flesh of these animals has received no elucidation from my
observations. It does not appear to be confined to either sex, or to any
particular season of the year; for a young unweaned animal, killed at
its mother’s side and transferred within an hour to the stew-pans, was
as rank and objectionable as any. The flesh of some of these animals of
which I have partaken was dark, tender, and as well flavoured as that of
four-year old Southdown mutton.”
Remains of two fossil species of this genus (_O. bombifrons_ and _O.
cavifrons_) have been described from Pleistocene beds in the United
States, the one from Kentucky and the other from the Arkansas River. Both
(if indeed they be valid species) appear closely allied to the living
form.
_Bovine Section._—Horns present and of nearly equal size in both sexes;
in form rounded or angulated, placed on or near the vertex of the
skull, extending more or less outwards, and curving upwards near the
extremities; external surface comparatively smooth and never marked by
prominent transverse ridges or knobs. Muzzle broad, with large naked
muffle; nostrils lateral; no suborbital gland. Skull without any trace of
lachrymal fossa or fissure. Tail long and cylindrical; generally tufted
at the extremity, rarely hairy throughout. Males usually with a dewlap on
the throat. No foot-glands. Molar teeth extremely hypsodont; those of the
upper jaw with a nearly square cross-section, and a large accessory inner
column.
The section is abundantly represented in the Palæarctic, Oriental, and
Ethiopian regions, with one Nearctic species and an outlying and aberrant
species in Celebes.
_Bos._[248]—The whole of the species of Oxen were included by Linnæus in
the single genus _Bos_, and although the species have been distributed
by modern zoologists in several genera—such as _Anoa_, _Bubalus_,
_Bison_, _Poëphagus_, _Bibos_, and _Bos_—the characters by which they are
separated are so slight that it seems, on the whole, preferable to retain
the old genus in its original wide sense. Using then the term _Bos_ in
this sense, it will include all the representatives of the section—about
a dozen in number—and may be divided into several groups.
The first group includes the Buffaloes (genus _Bubalus_), chiefly
characterised by their more or less flattened and angulated horns, which
incline upwards and backwards, with an inward curve towards their tips,
and are placed below the plane of the occiput, or vertex of the skull.
The premaxillæ reach to the nasals, and the vomer is peculiar in being
so much ossified as to join the posterior border of the palate. The back
has a distinct ridge in the region of the withers; and the forehead is
frequently convex. Oriental and Ethiopian region, and Celebes.
The most generalised representative of this group is the small Anoa
(_B. depressicornis_) of Celebes, the type of the genus _Anoa_ or
_Probubalus_, which has the same cranial structure as in the more
typical Buffaloes, to the young of which (as was pointed out by the
late Professor Garrod) it presents a striking resemblance. Its colour
is black; and the short and prismatic horns are directed upwards from
the forehead. In the Pliocene Siwaliks of India there occur the remains
of larger Buffaloes (_B. occipitalis_ and _B. acuticornis_) closely
allied to the Anoa, but with longer and more distinctly angulated horns.
The still larger _B. platyceros_ of the last-named deposits, in which
the horns are wide-spreading and much flattened, appears to be in some
respects intermediate between the preceding and following forms. The
typical Indian Buffalo (_Bos buffelus_), which has been domesticated
over South-East Asia, Egypt, and Southern Europe, is, in the wild state,
a gigantic animal with enormous horns. These horns are longer, more
slender, and more outwardly directed in the female than in the male;
and in the former sex may have a length of more than 6 feet from base
to tip. They are widely separated at their bases, the forehead is very
convex, and the ears are not excessively large, and have no distinct
fringe. These Buffaloes frequent swampy and moist districts in several
parts of India, but it is in many instances difficult to decide whether
they belong to really wild or to feral races. Very large skulls,
specifically indistinguishable from those of the existing form, occur in
the Pleistocene deposits of the Narbada valley in India; while an allied,
if not specifically identical form, occurs in the Pliocene of the same
country. There is some doubt whether _B. antiquus_ of the Pleistocene of
Algeria is most nearly related to the Indian or to the African species.
In Africa two species of Buffalo are recognised by Sir Victor
Brooke,[249] namely the large _B. caffer_, occurring typically at the
Cape, but said by this writer to range to Abyssinia, and the smaller
_B. pumilus_, which seems to have a very wide distribution. The skulls
of both these forms are shorter than in the Indian species, while the
horns are also shorter, much more curved inwardly, and more approximated
on the forehead. In the large typical form of _B. caffer_ from South
Africa the colour is black, the horns of the male are very thick, much
reflected, and closely approximated on the forehead, where they form
a helmet-like mass.[250] The large northern form described as _B.
æquinoctialis_ has the horns somewhat less thick, and thus approximates
to the so-called _B. pumilus_.
The latter occurs typically in Western Africa, where it has also been
described as _B. brachyceros_. In the typical form the horns are thinner
and less reflected than in _B. caffer_, and in some specimens they are
more widely separated on the forehead, and are marked at their bases by
distinct rugæ. The colour is ruddy brown, inclining to rufous in one
specimen. The skulls of Buffaloes from West Africa, probably referable to
the form described as _B. centralis_, appear to connect _B. pumilus_ with
_B. caffer_, as shown by their larger size and the form of their horns;
so that further observations are required to show whether the smaller
form is really entitled to rank as a distinct species, or merely as a
well-marked local race.
The second group comprises the Bisons, which are more nearly allied to
the true Oxen, having similar rounded horns, but the skull being less
massive, with a longer and more tapering frontal region, and a wider
frontal diameter. The superior part of the forehead is transversely
arched, the intercornual space elevated in the middle, the horns situated
below the plane of the occiput, and the orbits more or less prominent.
The premaxillæ do not extend upwards to reach the nasals. The Bisons
(Fig. 148) have the body covered with short, crisp, woolly hair, while on
the head and neck there is an abundance of much longer and darker hair,
which forms a mane concealing the eyes, ears, and the bases of the horns.
There is also a long beard beneath the chin; while a line of long hair
extends from the head nearly to the tail, the latter being tufted at the
extremity. The withers are much higher than the hind quarters, so that
there is a kind of hump at the shoulders.
The group is represented by two species—the European and the American
Bison. The former is the _Bos bonasus_ of Linnæus, and is also identical
with the _Bos bison_ of Ray. The German name _Wisent_ is the equivalent
of the Greek _Bison_. The American species is the _Bos americanus_ of
Gmelin. Both species are closely allied, but the American Bison is
slightly the smaller animal of the two, and is shorter and weaker in
the hind quarters, with a smaller pelvis; its body is, however, more
massive in front; and the hair on the head, neck, and fore quarters is
longer and more luxuriant. A large bull American Bison, preserved in the
Museum at Washington, stands 5 feet 8 inches in height at the withers.
The European Bison appears to have been formerly abundant over a large
portion of Europe in the Pleistocene period—the fossil race described as
_B. priscus_ not being specifically distinct; but at the present day it
exists only in the primeval forests of Lithuania, Moldavia, Wallachia,
and the Caucasus, where it is artificially preserved.
[Illustration: FIG. 148.—The American Bison (_Bos americanus_). After
Hornaday.]
The American Bison formerly ranged over about one-third of the North
American continent. Thus, to quote from Mr. Hornaday,[251] “starting
almost at tide-water on the Atlantic coast, it extended across the
Alleghany mountain system to the prairies along the Mississippi, and
southward to the delta of that great system. Although the great plain
country of the West was the natural home of the species, where it
flourished most abundantly, it also wandered south across Texas to
the burning plains of North-Eastern Mexico, westward across the Rocky
Mountains into New Mexico, Utah, and Idaho, and northward across a
vast treeless waste to the bleak and inhospitable shores of the Great
Slave Lake itself.” In consequence of the settlement of the country by
Europeans the area inhabited by the Bison was gradually contracted, till
about 1840 one mighty herd occupied the centre of its former range.
The completion of the Union Pacific Railway in 1869 divided this great
herd into a southern and a northern division, the former comprising
a number of individuals estimated at nearly four millions, while the
latter contained about a million and a half. Before 1880 the southern
herd had, however, practically ceased to exist; while the same fate
overtook the northern one in 1883. In 1889 some twenty stragglers in
Texas represented the last of the southern herd; while there were a few
others in Colorado, Wyoming, Montana, and Dakota. A herd of some two
hundred wild individuals, derived from the northern herd, is preserved by
the United States Government in the Yellowstone National Park; and it is
believed that some five hundred of the race known as Wood-Bison exist in
British territory; but with these exceptions this magnificent species is
exterminated. The multitudes in which the American Bison formerly existed
are almost incredible; the prairies being absolutely black with them as
far as the eye could reach, and the numbers in the herds being, as we
have said, reckoned by millions. Mr. Hornaday even considers that the
whole of the game in South Africa was never equal to the number of Bison
on an equal area of the American prairies.
[Illustration: FIG. 149.—The Yak (_Bos grunniens_), domestic variety.]
An extinct Bison from the Pleistocene of Texas, known as _Bos latifrons_,
was probably the ancestor of the recent American species.
The Yak (_Bos grunniens_) appears to be allied both to the Bisons and the
true Oxen, being distinguished from the former by the different position
occupied by the long hair, which forms a fringe investing the shoulders,
flanks, and thighs, and grows over the whole of the tail. In the skull
the orbits are less tubular, the forehead flatter, and the premaxillæ
less widely separated from the nasals. There is no distinct dewlap.
Wild Yaks inhabit the higher regions of Chinese Tibet and the region of
the Karakoram, as well as the more outlying parts of Ladak, such as the
Changchemo valley. Owing, however, to incessant pursuit those now found
within the territories of the Maharaja of Kashmir are stragglers from
Chinese Tibet. The height of the Yak is somewhat lower than that of the
larger domestic cattle. The colour of the wild race is black, tending
to brown on the flanks; but many of the tame breeds which have been
crossed with ordinary cattle have more or less white (Fig. 149), and it
is the white tails of these half-breeds that are so esteemed in India as
“chowries.” Yaks are exceedingly intolerant of heat, and the wild ones
always live at very great elevations. Tame Yaks are extensively used as
beasts of burden in Tibet, where they are extremely valuable in crossing
the high and desolate wastes of that region; they have, however, the
great drawback that they refuse to eat corn, so that in districts where
there is no grass it is frequently necessary to make forced marches
with wearied beasts in order to prevent them (and thus the whole party)
perishing from starvation.
The skull of an extinct species from the Pliocene of Northern India,
described as _Bos sivalensis_, appears to indicate a species allied to
the Yak.
With the Bibovine group we come to the consideration of three Oriental
species which connect the preceding forms with the typical Oxen. The
three species are the Gaur (_B. gaurus_) the Gayal (_B. frontalis_,
Fig. 150) of India, and the Banteng (_B. sondaicus_) of Burma, Java,
Bali, and Lambok. In this group, as in the true Oxen, there are thirteen
pairs of ribs, against fourteen in the Bisons. All the three species
are characterised by the great height of the spines of the anterior
dorsal vertebræ, causing a prominent ridge down the back. The horns,
which are of a greenish colour in the Gaur, are somewhat flattened, and
after running outwards are directed upwards instead of backwards; they
occupy the vertex of the skull. The frontals are more or less concave,
the premaxillæ do not join the nasals, and the occipital aspect of
the skull is characterised by the deep incisions made by the temporal
fossæ. The lower part of the legs is white (Fig. 150), and the hoofs are
comparatively small and pointed. The Gaur (_B. gaurus_) is the largest
of the three species, and inhabits all the large forests of India from
near Cape Comorin to the foot of the Himalaya; it is commonly known
to sportsmen as the Indian Bison. It stands fully 6 feet in height
at the withers, which are much elevated; and since the whole back is
arched the line from the nose to the root of the tail forms an almost
continuous curve. The most characteristic feature of the animal is,
however, the large and convex intercornual frontal crest, which curves
forward, and thus gives a concave profile to this part of the skull. As
a rule the Gaur prefers hilly regions, although it is sometimes met with
on the flat. It is very shy and readily frightened; and it has never
been domesticated. The Gayal, or Mithan, of which a figure is given in
woodcut 150, is at once distinguished from the Gaur by the straight line
between the horns (which are black in colour), owing to the absence of
the intercornual crest of the latter. The horns are also shorter, more
rounded, and less curved. In the Indian Museum, Calcutta, there are,
however, skulls which are to a great extent intermediate between those
of typical Gaurs and those of typical Gayals, but these may belong to
hybrids. The Gayal occurs in Assam, Chittagong, and adjacent districts,
but it appears that these animals exist in a semi-domesticated condition,
no wild race being known to Europeans, although it is probable that such
may exist in the unexplored Mishmi Hills.
[Illustration: FIG. 150.—The Gayal (_Bos frontalis_). From Sclater, _List
of Animals in Zoological Society’s Gardens_, 1883.]
The Banteng (_B. sondaicus_) is a smaller and lighter built animal
than either of the preceding, with a longer and sharper head, and more
rounded and slender horns. The dorsal ridge is, moreover, but slightly
developed; while the bright dun colour of the body of the female readily
distinguishes it from the darker hue of the Gaur and Gayal.
A fossil skull from the Pleistocene deposits of the Narbada valley,
India, described as _Bos palæogaurus_, is believed to indicate a species
nearly allied to the Gaur, if indeed it be specifically distinct.
The true Oxen, or Taurine group, are now represented solely by _Bos
taurus_ and _Bos indicus_. Both of these species are now known only
by domesticated races, unless the herds of the former preserved at
Chillingham and some other British parks are the survivors of an original
wild race. The dorsal ridge of the Bibovine group is here wanting;
the horns are rounded, with their extremities directed backwards, and
are placed at the extreme vertex of the skull; while the long frontal
region is nearly flat; the temporal fossæ scarcely intrude upon the
occipital aspect of the skull; and the premaxillæ reach the nasals. The
hoofs are large and rounded. It is known that wild Oxen were abundant
in the forests of Europe at the time of Julius Cæsar, by whom they were
described as the Urus, equal to the German Aurochs; and the large skulls
found in turbary and Pleistocene deposits, and described under the name
of _Bos primigenius_, can only be regarded as having belonged to the
large original race of _B. taurus_, of which it has been thought the
Chillingham cattle are smaller descendants.[252] The subfossil skulls
described as _B. longifrons_ and _B. frontosus_ must also be looked upon
as referable to smaller races of the same species. That the domestic
cattle of Europe are descendants from the various races of the same
original species there can be no doubt, but in the case of the humped
cattle of India (_B. indicus_) it is quite probable that their origin
may be, at least in part, different. The extinct _Bos namadicus_, of the
Pleistocene deposits of India, was a species with the general characters
of the Taurine group, but with an inclination to a flattening of the
horns, and with an approximation to a Bibovine type of occiput, as well
as with the separation of the premaxillæ from the nasals.
The earliest representatives of this group occur in the Pliocene of the
Siwalik Hills in Northern India. One of these species (_B. planifrons_)
appears to be allied to _B. namadicus_; but the other (_B. acutifrons_)
was a gigantic species characterised by the sharp median angulation of
the frontal region, and the pyriform section of the enormous horn-cores.
The extinct _B. elatus_, from the Upper Pliocene of France and Italy,
is the representative of a generalised type, which may be known as the
Leptobovine group. The males had rounded horn-cores widely separated at
their bases, and placed low down on the forehead. The females (which have
been described as _Leptobos_) were often or always hornless. The limbs
were unusually slender. This group also occurs in the Pliocene of the
Siwalik Hills.
_Suborder_ PERISSODACTYLA.
This is a perfectly well-defined group of Ungulate mammals, represented
in the actual fauna of the world by only three distinct types or
families—the Tapirs, the Rhinoceroses, and the Horses—poor in genera
and species, and (except in the case of the two domesticated species of
_Equus_, which have been largely multiplied and diffused by man’s agency)
not generally numerous in individuals, though widely scattered over the
earth’s surface. Palæontological records, however, show very clearly that
these are but the surviving remnants of a very extensive and much-varied
assemblage of animals, which flourished upon the earth through the
Tertiary geological period, and which, if it could be reconstructed in
its entirety, would not only show members filling up structurally the
intervals between the existing apparently isolated forms, but would also
show several marked lines of specialisation which have become extinct
without leaving any direct successors.
[Illustration: FIG. 151.—Bones of right fore foot of existing
Perissodactyles. A, Tapir (_Tapirus indicus_), × ⅕; B, Rhinoceros
(_Rhinoceros sumatrensis_), × ⅙; C, Horse (_Equus caballus_), × ⅛. _U_,
ulna; _R_, radius; _c_, cuneiform; _l_, lunar; _s_, scaphoid; _u_,
unciform; _m_, magnum; _td_, trapezoid; _tm_, trapezium.—From Flower,
_Osteology of Mammalia_.]
The following are the principal characters distinguishing them from
the Artiodactyla. Premolar and molar teeth in continuous series, with
massive, quadrate, transversely ridged or complex crowns,—the posterior
premolars often resembling the true molars in size and structure. Crown
of the last lower molar commonly bilobed, and if a third lobe is present
in this tooth it is wanting in the last lower milk-molar. Dorso-lumbar
vertebræ never fewer than twenty-two, usually twenty-three in the
existing species. Nasal bones expanded posteriorly. An alisphenoid
canal. Femur with a third trochanter.[253] The middle or third digit on
both fore and hind feet larger than any of the others, and symmetrical
in itself, the free border of the ungual phalanx being evenly rounded
(see Fig. 151). This may be the only functional toe, or the second and
fourth may be subequally developed on each side of it. In the Tapirs
and many extinct forms, the fifth toe also remains on the fore limb,
but its presence does not interfere with the symmetrical arrangement of
the remainder of the foot around the median line of the third or middle
digit. Traces of a hallux have only been found in some extremely ancient
and primitive forms. The astragalus has a pulley-like surface above
for articulation with the tibia, but its distal surface is flattened
and unites to a much greater extent with the navicular than with the
cuboid, which bone is of comparatively less importance than in the
Artiodactyla. The calcaneum does not articulate with the lower or distal
extremity of the fibula. The stomach is always simple, the cæcum is large
and capacious, the placenta diffused, and the mammæ are inguinal. The
gall-bladder is invariably absent.
As regards the dentition, the whole of the premolar series may be
preceded by milk-teeth; and it has been demonstrated in _Rhinoceros_
that when there is no displacement of the first cheek-tooth that tooth
is a persistent milk-molar; the same condition apparently holding
good in _Palæotherium._ This feature indicates considerable dental
specialisation, the milk-molars, according to the theory generally
accepted by the leading English zoologists, being the acquired, and the
premolars the original series. Another peculiar feature of the dentition
of the Perissodactyla, very rarely met with among the Artiodactyla,
is that the premolars tend to resemble the true molars; this feature
occurring in all the existing genera, although not found in the earlier
generalised types. The cheek-teeth of all the members of the suborder
are primarily constructed on some modification of what is known as the
lophodont plan. Thus the upper molars (Fig. 155, p. 375) have an outer
antero-posterior wall from which proceed two transverse ridges, formed
by the coalescence of the primitive inner and outer columns, towards
the inner aspect of the crown; while in the lower molars there may be
either two simple transverse ridges, or these ridges may be curved into
crescents, coming into contact with one another at their extremities.
Those forms having brachydont teeth show this plan of structure in its
simplest modification; but in cases, as in the Horse, where the teeth
assume an extremely hypsodont form, the original plan is so obscured by
infoldings of the enamel that it can only be traced with difficulty.
At the present day the Perissodactyla are sharply differentiated into
Horses, Tapirs, and Rhinoceroses, but the knowledge already gained of
the extinct representatives of the suborder shows such a close alliance
between these groups that it is exceedingly difficult to make any
satisfactory classification of the whole. This is of course exactly what
might have been expected; and the same would doubtless be the case with
all other groups if we knew as much of their past history as we do of
that of the Perissodactyles.
The detailed account of the anatomy of the Horse given in the sequel will
afford much information as to the general structure of the members of the
suborder.
_Family_ TAPIRIDÆ.
Both upper and lower cheek-teeth brachydont and simply bilophodont;
hinder premolars as complex as the molars; last lower molar without third
lobe; first upper cheek-tooth with a milk-predecessor.[254] Outer columns
of upper molars conical. Four digits in the manus, and three in the pes.
_Tapirus._[255]—Dentition _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₃, _m_ ³⁄₃; total 42.
Of the upper incisors, the first and second are nearly equal, with short,
broad crowns; the third is large and conical, considerably larger than
the canine, which is separated from it by an interval. Lower incisors
diminishing in size from the first to the third; the canine, which is
in contact with the third incisor, large and conical, working against
(and behind) the canine-like third upper incisor. In both jaws there
is a diastema between the canines and the commencement of the teeth of
the cheek-series, which are all in contact. First upper premolar with a
triangular crown, narrow in front owing to the absence of the anterior
inner cusp. The other upper premolars and molars all formed on the same
plan and of nearly the same size, with four roots and quadrate crowns,
rather wider transversely than from before backwards, each having four
cusps, connected by a pair of transverse ridges, anterior and posterior.
The first lower premolar compressed in front; the others composed of a
simple pair of transverse crests, with a small anterior and posterior
circular ridge.
Skull elevated and compressed. Orbit and temporal fossa widely
continuous, there being no true postorbital process from the frontal
bone. Anterior narial apertures very large, and extending high on the
face between the orbits; nasal bones short, elevated, triangular, and
pointed in front. Vertebræ: C 7, D 18, L 5, S 6, C about 12. Limbs short
and stout. Forefeet with four toes, having distinct hoofs: the first
is absent, the third the longest, the second and fourth nearly equal,
the fifth the shortest and scarcely reaching the ground in the ordinary
standing position. Hind feet with the typical Perissodactyle arrangement
of three toes,—the middle one being the largest, the two others nearly
equal. Nose and upper lip elongated into a flexible, mobile snout or
short proboscis, near the end of which the nostrils are situated. Eyes
rather small. Ears of moderate size, ovate, erect. Tail very short. Skin
thick and but scantily covered with hair.
The existing species of Tapir may be grouped into two sections, the
distinctive characters of which are only recognisable in the skeleton.
(A) With a great anterior prolongation of the ossification of the nasal
septum (mesethmoid), extending in the adult far beyond the nasal bones,
and supported and embraced at the base by ascending plates from the
maxillæ (genus _Elasmognathus_, Gill). Two species, both from Central
America, _Tapirus bairdi_ and _T. dowi_. The former is found in Mexico,
Honduras, Nicaragua, Costa Rica, and Panama; the latter in Guatemala,
Nicaragua, and Costa Rica. (B) With ossification of the septum not
extending farther forward than the nasal bones (_Tapirus_ proper).
Three species, _T. indicus_, the largest of the genus, from the Malay
Peninsula (as far north as Tavoy and Mergui), Sumatra, and Borneo,
distinguished by its peculiar coloration, the head, neck, fore and hind
limbs, being glossy black, and the intermediate part of the body white;
_T. americanus_ (_T. terrestris_, Linn.), the common Tapir of the forests
and lowlands of Brazil and Paraguay (Fig. 152); and _T. roulini_, the
Pinchaque Tapir of the high regions of the Andes. All the American
species are of a nearly uniform dark brown or blackish colour when adult;
but it is a curious circumstance that when young (and in this the Malay
species conforms with the others) they are conspicuously marked with
spots and longitudinal stripes of white or fawn colour on a darker ground.
The habits of all the kinds of Tapirs appear to be very similar. They are
solitary, nocturnal, shy, and inoffensive, chiefly frequenting the depths
of shady forests and the neighbourhood of water, to which they frequently
resort for the purpose of bathing, and in which they often take refuge
when pursued. They feed on various vegetable substances, as shoots of
trees and bushes, buds, and leaves. They are hunted by the natives of the
lands in which they live for the sake of their hides and flesh.
The singular fact of the existence of so closely allied animals as the
Malayan and the American Tapirs in such distant regions of the earth,
and in no intervening places, is accounted for by what is known of
the geological history of the race; for the Tapirs must once have had
a very wide distribution. There is no proof of their having lived in
the Eocene epoch, but in deposits of Miocene and Pliocene date remains
undistinguishable generically from the modern Tapirs, and described as
_T. priscus_, _T. arvernensis_, etc., have been found in France, Germany,
and in the Red Crag of Suffolk. Tapirs appear, however, to have become
extinct in Europe before the Pleistocene period, since none of their
bones or teeth have been found in any of the caverns or alluvial deposits
in which those of Elephants, Rhinoceroses, and Hippopotamuses occur in
abundance; but in other regions their distribution at this age was far
wider than at present, as they are known to have extended eastward to
China (_T. sinensis_, Owen) and westwards over the greater part of the
southern United States of America, from South Carolina to California.
Lund also distinguished two species or varieties from the caves of
Brazil, one of which appears identical with _T. americanus_. Thus we
have no difficulty in tracing the common origin in the Miocene Tapirs of
Europe of the now widely separated American and Asiatic species. It is,
moreover, interesting to observe how very slight an amount of variation
has taken place in forms isolated during such an enormous period of time.
[Illustration: FIG. 152.—The American Tapir (_Tapirus americanus_).]
The anatomy of the soft parts of the Tapirs[256] conforms to the general
Perissodactyle type, as exemplified in the Rhinoceros and the Horse,
although on the whole (as might have been expected) presenting a closer
resemblance to the former. _T. americanus_ differs from _T. indicus_
by the absence, or at any rate the less development, of the intestinal
valvulæ conniventes, the presence of a moderator band in the heart,
the shape of the glans penis, and the more elongated cæcum, which is
sacculated by four distinct longitudinal fibrous bands. The convolutions
of the hemispheres of the brain of the Tapirs are simpler than in other
Perissodactyles, thus tending to confirm the inferences which may
be drawn from the skeleton and teeth as to the comparatively low or
generalised organisation of these animals.
_Palæotapirus._—This name has been applied to an imperfectly known form
from the Upper Eocene Phosphorites of Central France, which is regarded
by Dr. Filhol as referable to this family.
_Family_ LOPHIODONTIDÆ.
Molars brachydont and bilophodont, those of the lower jaw with either
straight or imperfectly crescentoid ridges; premolars smaller and usually
simpler than the molars; last lower molar generally with a third lobe.
Outer columns of upper molars conical or flattened. Digits usually as in
the preceding family.
[Illustration: FIG. 153.—Right side of skull of _Hyracotherium
leporinum_, from the London Clay. ½ natural size. (After Owen.) 3,
Occiput; 7, sagittal crest; 11, frontals; 15, nasals; 21, maxilla; 22,
premaxilla; _d_, mandibular condyle; _a_, aperture of facial nerve; _p_
1-4, premolars; _m_ 1-3, molars.]
This family includes a number of more or less imperfectly known
forms, all of which are extinct and apparently confined to the Eocene
period, and ranging from the size of a Rabbit to that of a Rhinoceros.
Although some of these appear to have died out without giving rise to
more specialised forms, it is probable that this family contained the
ancestral types from which most or all of the modern Perissodactyles
have been derived. Only very brief mention can be made here of some
of the leading genera. _Lophiodon_, of the Middle and Upper Eocene of
Europe, with the dental formula, _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃,
includes the largest representatives of the family, and is generally
regarded as a stock which has died out without giving rise to later
forms. The ridges of the lower molars are straight, and the last of these
teeth has a third lobe; while the second transverse ridge of the last
upper premolar is usually incomplete; the outer columns of the upper
molars are flattened, as in the next genus. _Hyrachyus_, of the Upper
Eocene of the United States, and probably also occurring in the French
Eocenes, is an allied genus, with four premolars and no third lobe to
the last lower molar; the fourth upper premolar having the two ridges
uniting internally to form a crescent. This genus has been regarded as
the ancestor of the Rhinocerotic _Hyracodon_. The genus _Hyracotherium_
was established in 1839 by Owen for a small animal no larger than a
Hare, the skull of which was found in the London Clay at Herne Bay.
A more nearly perfect specimen, apparently of the same species, was
afterwards (in 1857) described under the name of _Pliolophus vulpiceps_,
of which the skull is figured in the accompanying woodcut. Other forms
referable to the same genus have been obtained from the Wasatch Eocene
of the United States, and were described by Professor Marsh under the
name of _Eohippus_. There were four premolars, the fourth being unlike
the molars, and in the upper jaw having only one inner cusp. The upper
molars are of the general type of those of _Lophiodon_, but have conical
outer columns, and the anterior transverse ridge imperfect, while
the ridges of the lower molars are crescentoid. _Systemodon_ differs
from _Hyracotherium_ by the absence of a diastema between the first
and second premolars; it occurs in the Wasatch Lower Eocene of the
United States. In _Pachynolophus_ (_Lophiotherium_, _Orotherium_, or
_Orohippus_), which is common to the Middle and Upper Eocene of Europe
and the Bridger Eocene of North America, the outer columns of the upper
molars are flattened, and in some cases, at least, the last premolar
resembles the molars, that of the upper jaw having two inner cusps.[257]
This genus, indeed, so closely connects _Hyracotherium_ with the genera
_Epihippus_ and _Anchilophus_ as to show that the distinction between
the _Lophiodontidæ_ and _Palæotheriidæ_ is really an arbitrary one.
_Epihippus_, of the Upper Eocene of the United States, has both the third
and fourth upper premolars as complex in the molars, and is distinguished
from _Anchilophus_ by the lower cusps and more imperfect transverse
ridges of these teeth. The so-called _Orohippus agilis_ belongs to this
genus. _Isectolophus_ is another American Eocene genus which may be
provisionally placed in this family; it is regarded by Professors Scott
and Osborn as connecting _Systemodon_ with the _Tapiridæ_; the fourth
and probably the third upper premolar approximating in structure to the
molars; the upper molars have conical outer columns. _Helaletes_ is
another closely allied form, with similar premolars, but with the outer
columns of the upper molars flattened.
[Illustration: FIG. 154.—Restoration of _Palæotherium_ (Upper Eocene).
After Cuvier.]
_Family_ PALÆOTHERIIDÆ.
[Illustration: FIG. 155.—A half-worn right upper molar of _Palæotherium
magnum_. (After Owen.) _f_, _f_, External surfaces of outer columns;
_a_, postero-external column (metacone); _b_, antero-external column
(paracone); _c_, postero-internal column (hypocone); _d_, antero-internal
column (protocone); _i_, anterior intermediate column (protoconule); _e_,
median valley; _g_, posterior valley.]
Molars (Fig. 155) brachydont, with the valleys between the ridges never
filled with cement; upper premolars either simpler than or as complex
as the molars; lower molars with crescentoid ridges, and the last of
the series with or without a third lobe. Outer columns of upper molars
flattened. Orbit (at least usually) confluent with temporal fossa. Three
digits on each foot. This family includes extinct genera ranging from
the Middle and Upper Eocene to the Miocene, and passes so gradually into
the following one that the maintenance of the two can only be supported
on the ground of convenience. The typical genus, _Palæotherium_, was
made known to science in the early part of the present century by
Cuvier, who restored the skeleton (Fig. 154) with a short neck like that
of the Tapirs, although it has been subsequently found that the neck
was considerably longer. This genus (which may be taken to include
_Paloplotherium_) ranges from the Middle to the Upper Eocene of Europe,
and usually has the full typical dentition, although the first premolar
may disappear. The last lower molar has a third lobe; and in the typical
forms the last premolar is as complex as the molars, the diastema is
short, and the canines are not large. In other forms, however, the
hinder ridge of the fourth upper premolar may be aborted. The first
upper cheek-tooth is generally a well-developed tooth, which may have
a deciduous predecessor. _Anchilophus_, of the Upper Eocene of Europe,
and _Anchitherium_, of the Miocene of Europe and North America, connect
the preceding forms with the _Equidæ_. In the latter genus there is the
full number of teeth, the last lower molar has almost completely lost
the third lobe of _Anchilophus_, and the surfaces of the two outer lobes
of the upper molars (Figs. 157, 158) lack the median vertical ridges of
that genus. In the American species of _Anchitherium_ (which have been
described as _Mesohippus_ and _Miohippus_) the lateral digits are larger
than in the European Middle Miocene _Anchitherium aurelianense_; a mere
splint represents the fifth metacarpal, and the meso- and ento-cuneiform
of the tarsus do not unite as they do in the latter.
_Family_ EQUIDÆ.
Molars hypsodont, with the outer columns of the upper ones flattened, the
valleys completely filled with cement, and the enamel thrown into folds
and plications; upper premolars as complex as molars, which they slightly
exceed in size; ridges of lower molars crescentoid, and complicated by
enamel-foldings; no distinct third lobe to last lower molar; summits of
incisors with a central infolding of enamel. Orbit completely surrounded
by bone. Digits three or one, but in the former case the median one is
alone of functional importance; ulna and fibula incomplete; meso- and
ento-cuneiform of tarsus united.
Such are the leading characters which serve to distinguish the existing
Horses and their nearest fossil allies from the _Palæotheriidæ_. The
Horse, as being the best known of the Perissodactyle Ungulates, is
selected for a somewhat detailed description; but before proceeding
to this it will be advisable to take a brief survey of the relations
of the _Equidæ_ to the extinct forms already noticed, and also of the
modifications of the family at present existing.
The earliest form which can be certainly included in this line of descent
is the American Lower Eocene genus _Phenacodus_ (noticed below under the
head of the suborder Condylarthra), in which there were five complete
digits to the feet. From this form there is but a step to _Systemodon_
and _Hyracotherium_, in which the functional digits of the manus were
reduced to four, as in _Pachynolophus_ (Fig. 156, _a_), although one
species retained a rudiment of the metacarpal of the pollex.
[Illustration: FIG. 156.—Successive stages of modification of the feet
of extinct forms of Horse-like animals (chiefly from Marsh), showing
gradual reduction of the outer and enlargement of the middle toe (III).
_a_, _Pachynolophus_ (Eocene); _b_, _Anchitherium_ (Early Miocene); _c_,
_Anchitherium_ (Late Miocene); _d_, _Hipparion_ (Pliocene); _e_, _Equus_
(Pleistocene).]
The transition from these animals of the Eocene period to the Horses of
modern times has been accompanied by a gradual increase in size. The
diminutive _Hyracotherium_ of the Lower, and _Pachynolophus_ of the
Middle and Upper Eocene were succeeded in the Miocene period by the
forms to which the name of _Anchitherium_ has been given, of the size of
sheep; these again in Pliocene times by _Hipparion_ and _Protohippus_, as
large as the modern donkeys; and it is mainly in the Pleistocene period
that _Equidæ_ occur which approach in size the existing Horse. Important
structural modifications have also taken place, with corresponding
changes in the mode of life of the animal. Thus the neck has become
elongated, the skull altered in form, the teeth greatly modified, and
the limbs have undergone remarkable changes. The last two require to be
described more in detail.
[Illustration: FIG. 157.—_a_, Grinding surface of unworn molar tooth
of _Anchitherium_; _b_, corresponding surface of unworn molar of young
Horse; _c_, the same tooth after it has been some time in use. The
uncoloured portions are the dentine or ivory, the shaded parts the
cement filling the cavities and surrounding the exterior. The black line
separating these two structures is the enamel or hardest constituent of
the tooth.]
The teeth in the Eocene forms had, as mentioned above, the characteristic
number of forty-four. This number has been retained throughout the
series, at least theoretically; but one tooth on either side of each jaw,
the anterior premolar, which in all the Eocene and Miocene species was
well developed, persisting through the lifetime of the animal, is in all
modern Horses rudimentary, functionless, and generally lost at an early
period of life, evidently passing through a stage which must soon lead
to its complete disappearance. The canines have also greatly diminished
in size, and are rarely present in the female sex, so that practically
a very large number of adult Horses of the present day have eight teeth
less than the number possessed by their predecessors. The diastema or
interval between the incisor and premolar teeth (of essential importance
in the domesticated Horse to his master, as without it there would be no
room for inserting the special instrument of subjugation to his commands,
the bit) already existed in the earliest known forms, but has gradually
increased in length. The incisors have undergone in comparatively recent
times that curious change producing the structure more fully described
hereafter, which distinguishes the Horse’s incisors from those of all
other known animals, with the exception of the extinct _Macrauchenia_.
Lastly, the molars have undergone a remarkable series of modifications,
much resembling in principle those that have taken place in several other
groups of herbivorous animals. Distinctions in form which existed between
the premolars, at least in the anterior part of the series, and the true
molars have gradually disappeared, the teeth becoming all very uniform
in the shape and structure of their grinding surface. The crowns of all
these teeth in the early forms were very short (see Fig. 158, _a_); there
was a distinct constriction, or neck, between the crown and roots; and
when the tooth was developing, as soon as the neck once rose fairly above
the alveolar margin, the tooth remained permanently in this position.
The term “brachydont” expresses this condition of teeth, the mode of
growth of which may be illustrated by those of man. The free surface had
two nearly transverse curved ridges, with valleys between (Fig. 157,
_a_); but the valleys were shallow and had no deposit of cement filling
them, the whole exposed surface of the unworn tooth being formed of
enamel. When the ridges became worn down the dentine of the interior was
exposed, forming islands surrounded by enamel. With the progress of time
the crowns of the teeth gradually became longer, the valleys deeper,
and the ridges not only more elevated but more curved and complex in
arrangement. To give support to these high ridges and save them from
breaking in use, the valleys or cavities between them became filled up to
the top with cement, and as the crown wore down an admirable grinding
surface consisting of patches and islands of the two softer substances,
dentine and cement, separated by variously reduplicated and contorted
lines of intensely hard enamel, resulted (Fig. 157, _c_). The crown
continued lengthening until in the modern Horses it has assumed the form
called “hypsodont” (Fig. 158, _b_). Instead of contracting into a neck,
and forming roots, its sides continue parallel for a considerable depth
in the socket, and as the surface wears away, the whole tooth slowly
pushes up, and maintains the grinding edge constantly at the same level
above the alveolus, much as in the perpetually growing Rodent’s teeth.
But in existing Horses there is still a limit to the growth of the
molar. After a length is attained which in normal conditions supplies
sufficient grinding surface for the lifetime of the animal, a neck and
roots are formed, and the tooth is reduced to the condition of that of
the brachydont ancestor. It is perfectly clear that this lengthening
of the crown adds greatly to the power of the teeth as organs of
mastication, and enables the animals in which it has taken place to find
their sustenance among the comparatively dry and harsh herbage of the
open plains, instead of being limited to the more succulent vegetable
productions of the marshes and forests in which their predecessors
probably dwelt.
[Illustration: FIG. 158.—_a_, Outer view of second upper molar teeth
of _Anchitherium_ (brachydont form); _b_, corresponding tooth of Horse
(hypsodont form).]
The modifications of the limbs which took place _pari passu_ with those
of the teeth must have been associated with increased speed, especially
over firm and unyielding ground. Short, stout legs, and broad feet, with
numerous toes, spreading apart from each other when the weight of the
creature is borne on them, are sufficiently well adapted for plodding
deliberately over marshy and yielding surfaces, and the Tapirs and the
Rhinoceroses, which in the structure of the limbs have altered but little
from the primitive Eocene forms, still haunt the borders of streams and
lakes and the shady depths of the forests, as was probably the habit
of their ancient representatives, while the Horses are all inhabitants
of the open plains, for life in which their whole organisation is in
the most eminent degree adapted. The length and mobility of the neck,
position of the eye and ear, and great development of the organ of smell,
give them ample means of becoming aware of the approach of enemies,
while the length of their limbs, the angles the different segments form
with each other, and especially the combination of firmness, stability,
and lightness in the reduction of all the toes to a single one, upon
which the whole weight of the body and all the muscular power are
concentrated, give them speed and endurance surpassing that of almost any
other animal. When surprised, however, they are by no means helpless,
both fore and hind feet becoming at need powerful weapons of defence.
If we were not so habituated to the sight of the Horse as hardly ever
to consider its structure, we should greatly marvel at being told of a
mammal so strangely constructed that it had but a single toe on each
extremity, on the end of the nail of which it walked or galloped. Such
a conformation is without a parallel in the vertebrate series, and is
one of the most remarkable instances of specialisation, or deviation
from the usual type, in accordance with particular conditions of life.
It is clear, both from the structure of the foot itself, and also by an
examination of the intermediate forms, that this toe corresponds to the
middle or third digit of the complete typical or pentadactyle foot; and
there is very strong evidence to show that by a gradual concentration of
all the power of the limb upon this toe, and the concurrent dwindling
away and final disappearance of all the others, the present condition of
the Horse’s foot has been produced.
_Protohippus._[258]—In this Lower Pliocene North American genus (also
described as _Merychippus_) the cheek-teeth resemble those of the
generalised species of _Equus_, but have shorter crowns; while the
milk-molars approximate to the permanent molars of _Anchitherium_. Each
foot has three digits.
[Illustration: FIG. 159.—Three right upper cheek-teeth of _Hipparion_.
_a_, Antero-external column; _b_, postero-external column; _c_,
postero-internal column, or posterior pillar; _d_, antero-internal
column, or anterior pillar; _f_, posterior intermediate column; _i_,
anterior intermediate column. (From the _Palæontologia Indica_.)]
_Hipparion._[259]—Upper cheek-teeth (Fig. 159), with the antero-internal
column, or anterior pillar as it may be conveniently termed in this
family, detached throughout the greater part of its height from the
adjacent column. Either a single or three digits in each foot. First
upper premolar large and persistent. This genus was very widely
distributed in the Pliocene, occurring in Europe, Asia, and North
America. In the typical European forms, and also in those of North
America, there were three digits in the feet (Fig. 156, _d_); but in
the Indian _H. antilopinum_ (separated by Cope as _Hippodactylus_) the
lateral digits seem to have disappeared. There is some doubt whether or
no _Hipparion_ should occupy a place in the direct ancestry of the Horse,
and Professor Cope suggests that while in America the intermediate place
between _Anchitherium_ and _Equus_ was held by _Protohippus_, in Europe
the same position was occupied by _Hipparion_—a view which involves the
dual origin of the Horses of the New and Old Worlds.
_Equus._[260]—Upper cheek-teeth with the anterior pillar (except in
a very early stage of wear) joined by a narrow neck to the adjacent
column (Fig. 157, _c_). Each foot with a single complete digit, but with
remnants of the proximal portions of the second and fourth metapodials
(Fig. 156, _e_); some extinct forms having claw-like rudiments of the
terminal phalangeals of the lateral digits. First upper premolar very
small or altogether absent in existing species, but in some fossil
species larger and persistent; first lower premolar only occasionally
developed in some fossil forms. Ears long. Tail long, with long hairs
either at the end or throughout. A callosity on the inner side of the
fore limb above the carpus.
_Fossil Species._—In the Pleistocene Horses of South America described
as _Hippidium_, as well as in the closely allied ones from North America
for which the name _Pliohippus_ has been proposed, the upper molars
are shorter and more curved than in the existing species, while their
anterior pillar is not longer antero-posteriorly than in _Hipparion_;
the lateral claw-like hoofs persisting. Some of the European Pliocene
species (like _E. stenonis_) agree with these species in the form of
the grinding surface of the anterior pillar of the upper molars. In one
of the species from the Lower Pliocene of India (_E. sivalensis_)—which
was a contemporary of _Hipparion_—and in all the existing species, the
grinding surface of the pillar in question is greatly elongated in the
antero-posterior direction, as in Fig. 157, _c_.
Fossil remains of Horses are found abundantly in deposits of the most
recent geological age in almost every part in America, from Eschscholtz
Bay in the north to Patagonia in the south. In that continent, however,
they became quite extinct, and no Horses, either wild or domesticated,
existed there at the time of the Spanish conquest, which is the more
remarkable as, when introduced from Europe, the Horses that ran wild
proved by their rapid multiplication in the plains of South America
and Texas that the climate, food, and other circumstances were highly
favourable for their existence. The former great abundance of _Equidæ_
in America, their complete extinction, and their perfect acclimatisation
when reintroduced by man, form curious but as yet unsolved problems in
geographical distribution.
_Existing Species._—The existing species of the genus are the following:—
The Horse, _Equus caballus_, is distinguished from the others by the long
hairs of the tail being more abundant and growing quite from the base as
well as the end and sides, and also by possessing a small bare callosity
on the inner side of the hind leg, just below the “hock” or heel joint,
in addition to the one on the inner side of the fore limb above the
carpus, common to all the genus. The mane is also longer and more
flowing, and the ears are shorter, the limbs longer, the hoofs broader,
and the head smaller.
Though the existing Horses are not usually marked in any definite manner,
or only irregularly dappled, or spotted with light surrounded by a darker
ring, many examples are met with showing a dark median dorsal streak
like that found in all the other members of the genus, and even with
dark stripes on the shoulders and legs indicating “the probability of
the descent of all the existing races from a single dun-coloured, more
or less striped, primitive stock, to which our horses still occasionally
revert.”[261]
In Europe wild Horses were extremely abundant in the Neolithic or
polished-stone period. Judging from the quantity of their remains
found associated with those of the men of that time, the chase of
these animals must have been among man’s chief occupations, and they
must have furnished him with one of his most important food supplies.
The characters of the bones preserved, and certain rude but graphic
representations carved on bones or reindeers’ antlers, enable us to know
that these Horses were rather small in size, and heavy in build, with
large heads and rough shaggy manes and tails, much like, in fact, the
present wild horses of the steppes of the south of Russia. They were
domesticated by the inhabitants of Europe before the dawn of history, but
it is doubtful whether the majority of the animals now existing on the
Continent are derived directly from them, as it is more probable that
they are descendants from Horses imported through Greece and Italy from
Asia, derived from a still earlier domestication, followed by gradual
improvement through long-continued attention bestowed on their breeding
and training. Horses are now diffused by the agency of man throughout
almost the whole of the inhabited parts of the globe, and the great
modifications they have undergone in consequence of domestication and
selective breeding are well exemplified by comparing such extreme forms
as the Shetland pony, dwarfed by uncongenial climate, the thoroughbred
racer, and the London dray-horse. In Australia, as in America, horses
imported by the European settlers have escaped into the unreclaimed
lands, and multiplied to a prodigious extent, roaming in vast herds over
the plains where no hoofed animal ever trod before.
A wild Horse from Central Asia, named _E. prezevalskii_,[262] is
described as having callosities on both limbs and broad hoofs like _E.
caballus_; but the long hairs of the tail do not begin until about half
way down its length. It also differs from _E. caballus_ in having a short
erect mane and no forelock; neither is there any dorsal stripe. The
ears are of moderate size; the whole body is of a whitish-gray, paler
beneath, and reddish on the head and upper parts of the limbs. If rightly
described this form would appear to be intermediate between the true
Horses and the Asses.
The second species is the domestic Ass (_E. asinus_), and the wild Asses
of Africa (_E. asinus_, var. _africanus_ and var. _somalicus_[263]). The
domestic Ass, which is now nearly as widely diffused and useful to man as
the Horse, was known in Egypt long before the latter, and is doubtless
of African origin. The ears are long, the mane erect, the tail without
long hairs at the base, and there are no callosities on the hind limbs.
There is a dark dorsal stripe, and another across the shoulders; while
the limbs are frequently banded. Of the wild forms the Nubian race (var.
_africanus_) has distinct dorsal and shoulder stripes, but the rings on
the limbs are often very indistinct; while in the Somali race the dorsal
stripe is indistinct, and the shoulder stripe wanting, but the rings on
the limbs are very boldly marked. Teeth and bones from a Pleistocene
cavern deposit in Madras have been referred to _E. asinus_.
The Asiatic wild Asses, which roam in small herds in the open plains
of Syria, of many parts of Persia, of the north-west of India, and
the highlands of Tartary and Tibet, from the shores of the Caspian
to the frontiers of China, differ from the last in being of a more
rufous or isabelline colour, instead of pure gray, in wanting the dark
streak across the shoulder, and having smaller ears. They have all a
dark-coloured median dorsal stripe. Though it is considered probable by
many zoologists that they form but a single species[264] (_E. hemionus_),
they present such marked variations in size and form that they have
commonly been divided into three—the Syrian Wild Ass (_E. hemippus_), the
Onager (_E. onager_) from Persia, Baluchistan, the Punjab, Sind, and the
desert of Kach, and the Kiang or Dzeggetai (_E. hemionus_) of the high
table-lands of Tibet, where it is usually met with at an elevation of
15,000 feet and upwards above the sea-level. The last is considerably
larger than either of the others, and differs from them in external
appearance, having more the aspect of the horse. They are all remarkably
swift, having been known to outstrip the fleetest Horse in speed.
[Illustration: FIG. 160.—The Quagga (_Equus quagga_).]
Lastly, there are four striped species, all inhabitants of Africa. These
constitute the genus _Hippotigris_ of Hamilton-Smith, but they are
not separable except by their coloration from the true Asses, and one
of them, the Quagga (_E. quagga_), may be considered as intermediate.
This animal was formerly met with in vast herds on the great plains of
South Africa, between the Cape Colony and the Vaal River, but now, in
common with most of the larger wild animals of that region, is becoming
extremely scarce, owing to the encroachments of European civilisation,
if, indeed, it is not already extinct. In length of ears and character of
tail it more resembles the Horse than it does the Ass, although it agrees
with the latter in wanting the callosity on the inner side of the hind
leg, just below the hock, characteristic of the Horse. The colour of the
head, neck, and upper parts of the body is reddish-brown, irregularly
banded and marked with dark brown stripes, stronger on the head and neck
and gradually becoming fainter until lost behind the shoulder. There
is a broad dark median dorsal stripe. The under surface of the body,
the legs, and tail are nearly white, without stripes. The crest is very
high, surmounted by a standing mane, banded alternately brown and white.
Though never really domesticated, Quaggas have occasionally been trained
to harness. The accompanying figure is reduced from a painting made from
one of a pair which were driven in Hyde Park in the early part of the
present century. The name is an imitation of the shrill barking neigh of
the animal—“ouag-ga, ouag-ga,” the last syllable very much prolonged. It
must be remembered, however, in reading books of African travel that the
same word is very commonly applied by hunters to Burchell’s Zebra.
Of the Zebras proper, the one which was first known to Europeans, and
was formerly considered the most common, is the True Zebra (_E. zebra_),
sometimes called the Mountain Zebra. It inhabits the mountainous regions
of the Cape Colony; but now, owing to the advances of civilised man into
its somewhat restricted range, it has become very scarce, and is even,
like the Quagga, threatened with extermination at no distant date. The
second species, Burchell’s Zebra (_E. burchelli_), still roams in large
herds over the plains to the north of the Orange River, but in yearly
diminishing numbers. Both species are subject to considerable individual
variations in marking, but the following are the principal characters by
which they can be distinguished.
[Illustration: FIG. 161.—True or Mountain Zebra (_Equus zebra_).]
_E. zebra_ (Fig. 161) is the smaller of the two (about 4 feet high at
the shoulders), and has longer ears, a tail more scantily clothed with
hair, and a shorter mane. The general ground colour is white, and the
stripes are black; the lower part of the face is bright brown. With the
exception of the abdomen and the inside of the thighs, the whole of the
surface is covered with stripes, the legs having narrow transverse
bars reaching quite to the hoofs, and the base of the tail being also
barred. The outsides of the ears have a white tip and a broad black mark
occupying the greater part of the surface, but are white at the base.
Perhaps the most constant and obvious distinction between this species
and the next is the arrangement of the stripes on the hinder part of the
back, where there are a number of short transverse bands passing from the
median longitudinal dorsal stripe towards, and sometimes joining with,
the uppermost of the broad stripes which run obliquely across the haunch
from the flanks towards the root of the tail. There is often a median
longitudinal stripe under the chest.
[Illustration: FIG. 162.—Burchell’s Zebra (_Equus burchelli_).]
_E. burchelli_ (Fig. 162) is a rather larger and more robust animal, with
smaller ears, a longer mane, and fuller tail. The general ground colour
of the body is pale yellowish-brown, the limbs nearly white, the stripes
dark brown or black. In the typical form they do not extend on to the
limbs or the tail; but there is a great variation in this respect, even
in animals of the same herd, some being striped quite down to the hoofs
(this form has been named _E. chapmani_). There is a strongly marked
median longitudinal ventral black stripe, to which the lower ends of the
transverse side stripes are usually united, but the dorsal stripe (also
strongly marked) is completely isolated in its posterior half, and the
uppermost of the broad haunch stripes runs nearly parallel to it. A much
larger proportion of the ears is white than in the other species. In
the middle of the wide intervals between the broad black stripes of the
flanks and haunches fainter stripes are generally seen.
_E. grevyi._—Under this name a Zebra has been described which was sent in
1882 to Paris from the Galla country, lying to the south of Abyssinia,
the most northern locality in which Zebras have previously been met
with. In many of its characters it resembles _E. zebra_, but the stripes
are much finer and more numerous than in the typical examples of that
species, and it has a strong, black, and isolated dorsal stripe. Even
allowing for the great variations that are met with in the markings of
animals of this group, the aberrant characters of this individual are
quite sufficient to separate it specifically from the true Zebra of South
Africa. Other similar specimens have been recently brought from the
Somali country.
The flesh of the Zebras is relished by the natives as food, and their
hides are very valuable for leather. Although the many attempts that
have been made to break in and train these animals for riding or driving
have sometimes been rewarded with partial success, they have never been
domesticated in the true sense of the word.
There are thus at least seven modifications of the Horse type at
present existing, sufficiently distinct to be reckoned as species by
all zoologists, and easily recognised by their external characters.
They are, however, all so closely allied that each will, at least in a
state of domestication or captivity, breed with perfect freedom with
any of the others. Cases of cross breeds are recorded between the Horse
and the Quagga, the Horse and Burchell’s Zebra, the Horse and the
Hemionus or Asiatic wild Ass, the common Ass and the Zebra, the common
Ass and Burchell’s Zebra, the common Ass and the Hemionus, the Hemionus
and the Zebra, and the Hemionus and Burchell’s Zebra. The two species
which are perhaps the farthest removed in general structure, the Horse
and the Ass, produce, as is well known, hybrids or Mules, which in
some qualities useful to man excel both their progenitors, and in some
countries, and for certain kinds of work, are in greater requisition
than either. Although occasional instances have been recorded of female
Mules breeding with the males of one or other of the pure species, it is
doubtful if any case has occurred of their breeding _inter se_, although
the opportunities of doing so must have been great, as Mules have been
reared in immense numbers for at least several thousands of years. We may
therefore consider it settled that the different species of the group are
now in that degree of physiological differentiation which enables them
to produce offspring with each other, but does not permit of the progeny
continuing the race, at all events unless reinforced by the aid of one of
the pure forms.
The several members of the group show mental differences quite as
striking as those exhibited by their external form, and more than
perhaps might be expected from the similarity of their cerebral
organisation. The patience of the Ass, the high spirit of the Horse, the
obstinacy of the Mule, have long been proverbial. It is very remarkable
that, out of so many species, two only should have shown any aptitude for
domestication, and that these two should have been from time immemorial
the universal and most useful companions and servants of man, while all
the others remain in their native freedom to this day. It is, however,
still a question whether this really arises from a different mental
constitution causing a natural capacity for entering into relations
with man, or whether it may not be owing to their having been brought
gradually into this condition by long-continued and persevering efforts
when the need of their services was keenly felt. It is quite possible
that one reason why most of the attempts to add new species to the list
of our domestic animals in modern times have ended in failure is that it
does not answer to do so in cases in which existing species supply all
the principal purposes to which the new ones might be put. It can hardly
be expected that Zebras and Quaggas fresh from their native mountains
and plains can be brought into competition as beasts of burden and
draught with Horses and Asses, whose naturally useful qualities have been
augmented by the training of thousands of generations of progenitors.
Not unfrequently instances occur of domestic Horses being produced with
a small additional toe with complete hoof, usually on the inside of the
principal toe, and, though far more rarely, three or more toes may be
present. These malformations are often cited as instances of reversion to
the condition of some of the earlier forms of equine animals previously
mentioned. Such explanations, however plausible they appear at first
sight, are nevertheless very doubtful. All the feet of polydactyle horses
which we have examined bear little resemblance to those of _Hipparion_
or _Anchitherium_, but look rather as if due to that tendency to
reduplication of parts which occurs so frequently as a teratological
condition, especially among domestic animals, and, whatever its origin,
certainly cannot in many instances, as the cases of entire limbs
superadded, or of six digits in man, be attributed to reversion.
_Anatomy._—The anatomical structure of the Horse has been described in
great detail in several works devoted to the subject, which will be
mentioned in the bibliography, though these have generally been written
from the point of view of the veterinarian rather than of the comparative
anatomist. The limits of the present work will only admit of the most
salient points being indicated, particularly those in which the Horse
differs from the other Ungulata. Unless otherwise specified, it must be
understood that all that is stated here, although mostly derived from
observation upon the Horse, applies equally well to the other existing
members of the group.
[Illustration: FIG. 163.—Side view of skull of Horse, with the bone
removed so as to expose the whole of the teeth. _PMx_, Premaxilla;
_Mx_, maxilla; _Na_, nasal; _Ma_, malar or jugal; _L_, lachrymal; _Fr_,
frontal; _Sq_, squamosal; _Pa_, parietal; _oc_, occipital condyle; _pp_,
paroccipital process; _i¹_, _i²_, and _i³_³, the three incisors; _c_, the
canine; _pm¹_, the situation of the rudimentary first premolar, which has
been lost in the lower, but is present in the upper jaw; _pm²_, _pm³_,
and _pm⁴_, the three fully developed premolars; _m¹_, _m²_, and _m³_, the
three true molars.]
_Skeleton._—The skull (Fig. 163) as a whole is greatly elongated, chiefly
in consequence of the immense size of the face as compared with the
hinder or true cranial portion. The basal line of the cranium from the
lower border of the foramen magnum to the incisor border of the palate is
very nearly straight. The orbit, of nearly circular form, though small in
proportion to the size of the whole skull, is distinctly marked, being
completely surrounded by a strong ring of bone with prominent edges.
Behind it, and freely communicating with it beneath the osseous bridge
(the postorbital process of the frontal) forming the boundary between
them, is the small temporal fossa occupying the whole of the side of
the cranium proper, and in front is the great flattened expanse of the
“cheek,” formed chiefly by the maxilla, giving support to the long row of
cheek-teeth, and having a prominent ridge running forward from below the
orbit for the attachment of the masseter muscle. The lachrymal occupies
a considerable space on the flat surface of the cheek in front of the
orbit, and below it the jugal or malar does the same. The latter sends
a horizontal or slightly ascending process backwards below the orbit to
join the under surface of the zygomatic process of the squamosal, which
is remarkably large, and, instead of ending as usual behind the orbit,
runs forwards to join the greatly developed postorbital process of the
frontal, and even forms part of the posterior and inferior boundary of
the orbit, an arrangement not met with in other mammals. The closure
of the orbit behind distinguishes the skull of the Horse from that of
the Rhinoceros and Tapir, and also from all of the Perissodactyles of
the Eocene period. In front of the cerebral cavity, the great tubular
nasal cavities are provided with well-developed turbinal bones, and are
roofed over by very large nasals, broad behind, and ending in front in
a narrow decurved point. The opening of the anterior nares is prolonged
backwards on each side of the face between the nasals and the elongated
slender premaxillæ. The latter expand in front, and are curved downwards
to form the semicircular alveolar border supporting the large incisor
teeth. The palate is narrow in the interval between the incisor and
cheek-teeth, in which are situated the large anterior palatine foramina.
Between the cheek-teeth it is broader, and it ends posteriorly in a
rounded excavated border opposite the hinder edge of the penultimate
molar. It is mainly formed by the maxillæ, as the palatines are very
narrow. The pterygoids are delicate slender slips of bone attached to
the hinder border of the palatines, and supported externally by, and
generally ankylosed to, the rough pterygoid plates of the alisphenoid,
with no pterygoid fossa between. They slope very obliquely forwards,
and end in curved, compressed, hamular processes. There is a distinct
alisphenoid canal for the passage of the internal maxillary or main
branch of the external carotid artery. The base of the cranium is long
and narrow; the alisphenoid is very obliquely perforated by the foramen
rotundum, but the foramen ovale is confluent with the large foramen
lacerum medium behind. The glenoid surface for the articulation of the
mandible is greatly extended transversely, concave from side to side,
convex from before backwards in front, and hollow behind, and is bounded
posteriorly at its inner part by a prominent post-glenoid process. The
squamosal enters considerably into the formation of the temporal fossa,
and, besides sending the zygomatic process forwards, it sends down
behind the meatus auditorius a post-tympanic process which aids to hold
in place the otherwise loose tympano-periotic bone. Behind this the
exoccipital gives off a very long paroccipital process. The periotic
and tympanic are ankylosed together, but not with the squamosal. The
former has a wide but shallow floccular fossa on its inner side, and
sends backwards a considerable “pars mastoidea,” which appears on the
outer surface of the skull between the post-tympanic process of the
squamosal and the exoccipital. The tympanic forms a tubular meatus
auditorius externus directed outwards and slightly backwards. It is not
dilated into a distinct bulla, but ends in front in a pointed styliform
process; and completely embraces the truncated cylindrical tympanohyal,
which is of great size, in correspondence with the large development of
the whole anterior arch of the hyoid. This consists mainly of a long
and compressed stylohyal, expanded at the upper end, where it sends
off a triangular posterior process. The basihyal is remarkable for the
long, median, pointed, compressed “glossohyal” process, which it sends
forward from its anterior border into the base of the tongue. A similar
but less developed process is found in the Rhinoceros. The mandible is
largely developed, especially the region of the angle, which is expanded
and flattened, giving great surface for the attachment of the masseter
muscle. The condyle is greatly elevated above the alveolar border; its
articular surface is very wide transversely, and narrow and convex
from before backwards. The coronoid process is slender, straight, and
inclined backwards. The horizontal ramus, long, straight, and compressed,
gradually narrows towards the symphysis, where it expands laterally to
form with the ankylosed opposite ramus the wide, semicircular, shallow
alveolar border for the incisor teeth.
The vertebral column consists of seven cervical, eighteen dorsal, six
lumbar, five sacral, and fifteen to eighteen caudal vertebræ. There
may be nineteen rib-bearing vertebræ, in which case five only will be
reckoned as belonging to the lumbar series. The odontoid process of the
atlas is wide, flat, and hollowed above, as in the Ruminants. The bodies
of the cervical vertebræ are elongated, strongly keeled, and markedly
opisthocœlous, or concave behind and convex in front. Their neural laminæ
are very broad, the spines almost obsolete, except in the seventh, and
the transverse processes not largely developed. In the trunk vertebræ the
opisthocœlous character of the centrum gradually diminishes. The spinous
processes of the anterior thoracic region are high and compressed. To
these is attached the powerful elastic ligament, _ligamentum nuchæ_, or
“paxwax,” which passing forwards in the middle line of the neck above the
neural arches of the cervical vertebræ, to which it is also connected,
is attached to the occiput and supports the weight of the head. The
transverse processes of the lumbar vertebræ are long, flattened, and
project horizontally outwards or slightly forwards from the arch. The
metapophyses are moderately developed, and there are no anapophyses.
The caudal vertebræ, except those quite at the base, are slender and
cylindrical, without processes and without chevron-bones beneath. The
ribs are eighteen or nineteen in number on each side, flattened, and
united to the sternum by short, stout, tolerably well ossified sternal
ribs. The sternum consists of six pieces; the anterior or presternum
being extremely compressed, and projecting forwards like the prow of a
boat. The segments which follow gradually widen, and the hinder part of
the sternum is broad and flat.
As in all other Ungulates, there are no clavicles. The scapula is
long and slender; the suprascapular border is rounded, and slowly and
imperfectly ossified. The spine is very slightly developed; rather above
the middle its edge is thickened and somewhat turned backwards, but it
gradually subsides at the lower extremity without forming any acromial
process. The coracoid process is a prominent rounded nodule. The humerus
is stout and rather short, and has a double bicipital groove. The ulna
is quite rudimentary, being only represented by little more than the
olecranon. The shaft gradually tapers below, and is firmly ankylosed to
the radius. The latter bone is of nearly equal width throughout. The
three bones of the first row of the carpus (the scaphoid, lunar, and
cuneiform) are subequal in size. The second row consists of a very broad
and flat magnum, supporting the great third metacarpal, having to its
radial side the trapezoid, and to its ulnar side the unciform, which
are both small, and articulate distally with the rudimentary second and
fourth metacarpals. The pisiform is large and prominent, flattened,
and curved; articulating partly with the cuneiform and partly with the
lower end of the radius. The large metacarpal is called in veterinary
anatomy “cannon-bone”; the small lateral metacarpals, which gradually
taper towards their lower extremities, and lie in close contact with
the large one, are called “splint-bones.” The single digit consists of
a moderate-sized proximal (_os suffraginis_, or large pastern), a very
short middle (_os coronæ_, or small pastern), and a wide, semilunar,
ungual phalanx (_os pedis_, or coffin-bone). There is a pair of large
nodular sesamoids behind the metacarpo-phalangeal articulation, and a
single large transversely extended sesamoid behind the joint between the
second and third phalanx, called the “navicular bone.”[265]
The carpal joint, corresponding to the wrist of man, is commonly called
the “knee” of the Horse, the joint between the metacarpal and the first
phalanx the “fetlock,” that between the first and second phalanges
the “pastern,” and that between the second and third phalanges the
“coffin-joint.”
In the hind limb the femur is marked, as in other Perissodactyles, by the
presence of a “third trochanter,” a flattened process, curving forwards,
arising from the outer side of the bone, about one-third of the distance
from the upper end. The fibula is reduced to a mere styliform rudiment
of the upper end; its lower part being absent or completely fused with
the tibia. The calcaneum has a long and compressed calcaneal process. The
astragalus has a large flat articular surface in front for the navicular,
and a very small one for the cuboid. The navicular and the external
cuneiform bones are very broad and flat. The cuboid is small, and the
internal and middle cuneiform bones are small and united together. The
metapodials and phalanges resemble very closely those of the fore limb,
but the principal metatarsal is more laterally compressed at its upper
end than is the corresponding metacarpal. The joint between the femur and
tibia, corresponding to the knee of man, is called the “stifle joint”;
while that between the tibia and tarsus, corresponding to the ankle of
man, is termed the “hock.” The bones and joints of the foot have the
same names as in the fore limb. The Horse is eminently “digitigrade,”
standing on the extremity of the single digit of each foot, which is kept
habitually in a position approaching to vertical.
The muscles[266] of the limbs are modified from those of the ordinary
mammalian type in accordance with the reduced condition of the bones
and the simple requirements of flexion and extension of the joints, no
such actions as pronation and supination, or opposition of digits, being
possible or needed. The muscles, therefore, which perform these functions
in other mammals are absent or rudimentary.
[Illustration: FIG. 164.—Section of foot of Horse. 1, Metacarpal bone;
2, first phalanx (_os suffraginis_); 3, second phalanx (_os coronæ_);
4, third or ungual phalanx (_os pedis_, or coffin-bone); 5, one of the
upper sesamoid bones; 6, lower sesamoid or “navicular” bone; 7, tendon
of anterior extensor of the phalanges; 8, tendon of superficial flexor
(_fl. perforatus_); 9, tendon of deep flexor (_fl. perforans_); 10,
suspensory ligament of fetlock; 11, inferior or short sesamoid ligament;
12, derma or skin of the foot, covered with hair, and continued into 13,
the coronary cushion, 14, the podophyllous or laminar membrane, and 15,
the keratogenous membrane of the sole; 16, plantar cushion; 17, hoof; 18,
fatty cushion of fetlock.]
Below the carpal and tarsal joints the fore and hind limbs correspond
almost exactly in structure as well as function. On the anterior or
extensor surface of the limb a powerful tendon (7 in Fig. 164), that of
the anterior extensor of the phalanges (corresponding to the _extensor
communis digitorum_ of the arm and _extensor longus digitorum_ of the
foot of man) passes down over the metacarpal bone and phalanges, to be
inserted mainly into the upper edge of the anterior surface of the last
phalanx or pedal bone. There is also a much smaller second extensor
on the outer side of this in each limb, the lateral extensor of the
phalanges. In the fore leg the tendon of this muscle (which corresponds
with the _extensor minimi digiti_ of man) receives a slip from that of
the principal extensor, and is inserted into the first phalanx. In the
hind leg (where it is the homologue apparently of the _peroneus brevis_
of man) the tendon becomes blended with that of the large extensor.
A very strong ligamentous band behind the metapodium, arising from near
the upper extremity of its posterior surface, divides into two at its
lower end, and each division, being first connected with one of the
paired upper sesamoid bones, passes by the side of the first phalanx to
join the extensor tendon of the phalanges. This is called in veterinary
anatomy the “suspensory ligament of the sesamoids,” or of the “fetlock”
(10 in Fig. 164); but its attachments and relations, as well as the
occasional presence of muscular fibres in its substance, show that it
is the homologue of the short flexor muscle of other mammals, curiously
modified both in structure and function to suit the requirements of the
Horse’s foot. Behind or superficial to this are placed the two strong
tendons of the long flexor muscles, the most superficial, or _flexor
perforatus_ (8), dividing to allow the other to pass through, and then
inserted into the middle phalanx. The _flexor perforans_ (9) is as
usual inserted into the terminal phalanx. In the fore leg these muscles
correspond with those similarly named in man. In the hind leg, the
perforated tendon is a continuation of that of the plantaris, passing
pulley-wise over the tuberosity of the calcaneum. The perforating tendon
is derived from the muscle corresponding with the long flexor of man, and
the smaller tendon of the oblique flexor (_tibialis posticus_ of man) is
united with it.
The hoof of the Horse corresponds to the nail or claw of other mammals,
but is so constructed as to form a complete and very solid case to the
expanded termination of the toe, giving a firm basis of support formed of
a nonsensitive substance, which is continually renewed by the addition of
material from within as its surface wears away by friction against the
ground. The terminal phalanx of the toe is greatly enlarged and modified
in form to support this hoof, and the size of the internal framework of
the foot is further increased by a pair of lateral fibro-cartilaginous
masses attached on each side to the hinder edges of the bone, and by a
fibro-cellular and adipose plantar cushion in the median part. These
structures are all enclosed in the keratogenous membrane or “subcorneous
integument,” a continuation of the ordinary derma of the limb, but
extremely vascular, and having its superficial extent greatly increased
by being developed into papillæ or laminæ. From this the horny material
which constitutes the hoof is exuded. A thickened ring encircling the
upper part, called coronary cushion (13), and the sole (15), are covered
with numerous thickly set papillæ or villi, and take the greatest share
in the formation of the hoof; the intermediate part constituting the
front and side of the foot (14), corresponding with the wall of the
hoof, is covered with parallel, fine longitudinal laminæ, fitting into
corresponding depressions in the inner side of the horny hoof.
The horny hoof is divided into a wall or crust consisting of the front
and sides, the flattened or concave sole, and the “frog,” a triangular
median prominence, notched posteriorly, with the apex turned forwards,
situated in the hinder part of the sole. It is formed of pavement
epithelial cells, mainly grouped in a concentric manner around the
vascular papillæ of the keratogenous membrane, so that a section near the
base of the hoof, cut transversely to the long axis of these papillæ,
shows a number of small circular or oval orifices, with cells arranged
concentrically round them. The nearer the surface of the hoof, or farther
removed from the seat of growth, the more indistinct the structure
becomes.
Small round or oval plates of horny epidermis called “chestnuts,” growing
like the hoof from enlarged papillæ of the skin, are found on the
inner face of the fore limb, above the carpal joint, in all species of
_Equidæ_, and in the Horse (_E. caballus_) alone similar formations occur
near the upper extremity of the inner face of the metatarsus. Their use
is unknown.
Behind the joint between the metapodium and the first phalanx is a
prominence formed by the fatty cushion of the fetlock (18 in Fig. 164).
On the middle of this is a small bare patch covered with thickened
epidermis, the _ergot_ or spur, generally concealed beneath the long hair
which grows around it. This is the functionless vestige of the large
callous pad found in this situation in the Tapir, and in fact in all
mammals in which this part reaches the ground in walking.
[Illustration: FIG. 165.—Longitudinal and transverse section of upper
incisor of Horse. _p_, Pulp cavity; _d_, dentine or ivory; _e_, enamel;
_c_, outer layer of cement; _c′_, inner layer of cement, lining _a_, the
pit or cavity of the crown of the tooth.]
_Dentition._—The dentition of the Horse, when all the teeth are in place,
is, as stated before, expressed by the formula _i_ ³⁄₃, _c_ ¹⁄₁, _p_
⁴⁄₃, _m_ ³⁄₃ = 42. The incisors of each jaw are placed in close contact,
forming a semicircle. The crowns are broad, somewhat awl-shaped, and of
nearly equal size. They have all the great peculiarity, not found in
the teeth of any other living mammal, of an involution of the external
surface of the tooth (see Fig. 165) forming a deep fossa or pit, the
bottom of which becomes partially filled up with cement. As the tooth
wears, the surface, besides the external enamel layer as in an ordinary
simple tooth, shows in addition a second inner ring of the same hard
substance surrounding the pit, thus of course adding greatly to the
efficiency of the tooth as an organ for biting tough, fibrous substances.
This pit, generally filled in the living animal with particles of food,
is conspicuous from its dark colour, and constitutes the “mark” by which
the age of the horse is judged, as in consequence of its extending only
to a certain depth, it becomes obliterated as the crown wears away,
when the tooth assumes the character of an ordinary incisor, consisting
only of a core of dentine surrounded by the external enamel layer. It
is not quite so deep in the lower as in the upper teeth. The canines
are either quite rudimentary or entirely absent in the female. In the
male they are compressed, pointed, and smaller than the incisors, from
which they are separated by a slight interval. The teeth of the cheek
series are all in contact with each other, but separated from the canines
by a considerable toothless space. The anterior premolars are quite
rudimentary, often, especially in the lower jaw, not developed at all,
and generally fall by the time the animal attains maturity, so that there
are but six functional grinding teeth—three that have predecessors in
the milk-dentition, and hence are considered as premolars, and three
true molars, but otherwise, except the first and last of the series,
not distinguishable in form or structure. These teeth in both upper and
lower jaws are extremely long-crowned or hypsodont (Fig. 158), successive
portions being pushed out as the surface wears away;—a process which
continues until the animal becomes advanced in age. The enamelled surface
is infolded in a complex manner (a modification of that found in other
Perissodactyles, see Figs. 155, 167), the folds extending quite to the
base of the crown, and the interstices being filled and the surface
covered with a considerable mass of cement, which binds together and
strengthens the whole tooth. As the teeth wear, the folded enamel,
being harder than the other constituents—the dentine and cement—forms
projecting ridges on the surface arranged in a definite pattern, which
give it great efficiency as a grinding instrument (see Fig. 157, _b_ and
_c_). The free surfaces of the upper teeth are quadrate, except the first
and last, which are nearly triangular. The lower teeth are much narrower
than the upper.
The milk dentition consists of _i_ ³⁄₃, _c_ ⁰⁄₀, _m_ ³⁄₃ = 24,—the
canines and first or rudimentary premolars having apparently no
predecessors. In form and structure they much resemble the permanent
teeth, having the same characteristic enamel-foldings. Their eruption
commences a few days after birth, and is complete before the end of the
first year, the upper teeth usually appearing somewhat earlier than those
of the lower jaw. The first teeth to appear are the first and second
milk-molars (about five days), then the central incisor (from seven to
ten days); this is followed by the second incisor (at one month), then
by the third molar, and finally by the third incisor. Of the permanent
teeth the first true molar appears a little after the end of the first
year, followed by the second molar before the end of the second year. At
about two and a half years the first premolar replaces its predecessor.
Between two and a half and three years the first incisor appears. At
three years the second and third premolars and the third true molar have
appeared; at from three and a half to four years the second incisor; at
four to four and a half years the canine; and, finally, at five years the
third incisor, completing the permanent dentition. Up to this period the
age of the horse is clearly shown by the state of the dentition, and for
some time longer indications can be obtained from the wear of the incisor
teeth, though this depends to a certain extent upon the hardness of the
food or other accidental circumstances. As a general rule, the depression
caused by the infolding of the surface of the incisor (the “mark”), is
obliterated in the first or central incisor at six years, in the second
at seven years, and in the third at eight years. In the upper teeth, as
the depressions are deeper, this obliteration does not take place until
about two years later. After this period no certain indications can be
obtained of the age of the horse from the teeth.
_Digestive Organs._—The lips are flexible and prehensile. The membrane
that lines them and the cheeks is quite smooth. The palate is long and
narrow; its mucous surface has seventeen pairs of not very sharply
defined oblique ridges, extending as far back as the last molar tooth,
beyond which the velum palati extends for about 3 inches, having a soft
corrugated surface, and ending posteriorly in an arched border without
uvula. This embraces the base of the epiglottis, and shuts off all
communication between the cavity of the mouth and the nasal passages,
respiration being, under ordinary circumstances, carried on exclusively
through the nostrils. Between the mucous membrane and the bone of the
hard palate is a dense vascular and nervous plexus. The membrane lining
the fauces is soft and corrugated. An elongated raised glandular mass,
3 inches long and 1 inch from above downwards, extending backwards from
the root of the tongue along the side of the fauces, with openings on the
surface leading into crypts with glandular walls, represents the tonsil.
The tongue, corresponding to the general form of the mouth, is long and
narrow. It consists of a compressed intermolar portion with a flat upper
surface, broad behind and becoming narrower in front; and of a depressed
anterior part rather shorter than the former, which is narrow behind but
widens towards the evenly rounded apex. The dorsal surface generally is
very soft and smooth. There are two large circumvallate papillæ near the
base, rather irregular in form, about a quarter of an inch in diameter
and half an inch apart. The conical papillæ are very small and close set,
though longer and more filamentous on the intermolar portion. There are
no fungiform papillæ on the dorsum, but a few not very conspicuous ones
scattered along the sides of the organ.
Of the salivary glands the parotid is by far the largest; elongated in
the vertical direction, and narrower in the middle than at either upper
or lower extremity. Its upper extremity embraces the lower surface of
the cartilaginous ear-conch; its lower end reaches the level of the
inferior margin of the mandible, along the posterior margin of which it
is placed. Its duct leaves the inferior anterior angle, at first descends
a little, and runs forward under cover of the rounded inferior border of
the mandibular ramus, then curves up along the anterior margin of the
masseter muscle, becoming superficial, pierces the buccinator, and enters
the mouth by a simple aperture opposite the middle of the crown of the
third premolar tooth. It is not quite so thick as a goose-quill when
distended, and nearly a foot in length.
The submaxillary gland is of very similar texture to the last, but much
smaller; it is placed deeper, and lies with its main axis horizontal.
It is elongated and slender, and flattened from within outwards. Its
posterior end rests against the anterior surface of the transverse
process of the atlas, from which it extends forwards and downwards,
slightly curved, to beneath the ramus of the jaw. The duct which runs
along its upper and internal border passes forwards in the usual course,
lying in the inner side of the sublingual gland, to open on the outer
surface of a distinct papilla, situated on the floor of the mouth, half
an inch from the middle line, and midway between the lower incisor teeth
and the attachment of the frænum linguæ. The sublingual is represented by
a mass of glands lying just beneath the mucous membrane of the floor of
the mouth on the side of the tongue, causing a distinct ridge, extending
from the frænum backwards, and the numerous ducts opening separately
along the summit of the ridge. The buccal glands are arranged in two rows
parallel with the molar teeth. The upper ones are the largest, and are
continuous anteriorly with the labial glands, the ducts of which open on
the mucous membrane of the upper lip.
The stomach of the Horse is simple in its external form, with a largely
developed right _cul de sac_, and is a good deal curved on itself,
so that the cardiac and pyloric orifices are brought near together.
The antrum pyloricum is small and not very distinctly marked off. The
interior is divided by the character of the lining membrane into two very
distinct portions, right and left. Over the latter the dense white smooth
epithelial lining of the œsophagus is continued, terminating abruptly
by a raised crenellated border. Over the right part (rather the larger
portion) the mucous membrane has a grayish-red colour and a velvety
appearance, and contains very numerous peptic glands, which are wanting
in the cardiac portion. The œsophageal orifice is very small, and is
guarded by a strong crescentic or rather horse-shoe-like band of muscular
fibres, which is supposed to be the cause of the difficulty of vomiting
in the Horse. The small intestine is of great length (80 to 90 feet),
its mucous membrane being covered with numerous fine villi. The cæcum is
of conical form, about 2 feet long and nearly a foot in diameter; its
walls are sacculated, especially near the base, having four longitudinal
fibrous bands; and its capacity is about twice that of the stomach. It
lies with its base near the lower part of the abdomen, and its apex
directed towards the thorax. The colon is about one-third the length
of the small intestine, and very capacious in the greater part of its
course. As usual, it may be divided into an ascending, transverse, and
descending portion; but the middle or transverse portion is folded into a
great loop, which descends as low as the pubis; so that the colon forms
altogether four folds, generally parallel to the long axis of the body.
The descending colon is much narrower than the rest, and not sacculated,
and being considerably longer than the distance it has to traverse, is
thrown into numerous folds.
The liver (Fig. 166) is tolerably symmetrical in its general arrangement,
being divided nearly equally into segments by a well-marked umbilical
fissure. Each segment is again divided by lateral fissures, which do
not extend quite to the posterior border of the organ; of the central
lobes thus cut off, the right is rather the larger, and has two fissures
in its free border subdividing it into lobules. The extent of these
varies, however, in different individuals, being not usually so marked
as in the figure, which is from a fœtal specimen. The two lateral lobes
are subtriangular in form. The Spigelian lobe is represented by a
flat surface between the portal fissure and the posterior border, not
distinctly marked off from the left lateral by a fissure of the ductus
venosus, as this vessel is buried deep in the hepatic substance, but
the caudate lobe is distinct and tongue-shaped, its free apex reaching
nearly to the border of the right lateral lobe. In most works on the
anatomy of the Horse this has been confounded with the Spigelian lobe of
man. There is no gall-bladder (as in all other Perissodactyles), and the
biliary duct enters the duodenum about 6 inches from the pylorus. The
pancreas has two lobes or branches—a long one passing to the left and
reaching the spleen, and a shorter right lobe. The principal duct enters
the duodenum with the bile-duct, and there is often a second small duct
which opens separately near to this.
[Illustration: FIG. 166.—Under surface of the liver of the Horse. _u_,
Umbilical fissure; _ll_, left lateral lobe; _lc_, left central lobe;
_rc_, right central lobe; _rl_, right lateral lobe; _s_, Spigelian lobe;
_c_, caudate lobe.]
_Circulatory and Respiratory Organs._—The heart has the form of a rather
elongated and pointed cone. There is one anterior vena cava, formed by
the union of the two jugular and two axillary veins. The aorta gives off
a large branch (the anterior aorta) very near its origin, from which
arise—first, the left axillary, and afterwards the right axillary and the
two carotid arteries.
Under ordinary circumstances the Horse breathes entirely by the nasal
passages, the communication between the larynx and the mouth being
closed by the velum palati. The nostrils are placed laterally, near
the termination of the muzzle, and are large and very dilatable, being
bordered by cartilages upon which several muscles act. Immediately within
the opening of the nostril, the respiratory canal sends off on its upper
and outer side a diverticulum or blind pouch (called “false nostril”) of
a conical form, and curved, 2 to 3 inches in depth, lying in the notch
formed between the nasal and premaxillary bones. It is lined by mucous
membrane continuous with that of the nasal passage, but its use is not
apparent. It is longer in the Ass than in the Horse. A similar structure
is found in the Rhinoceros, and in a much more developed condition in
the Tapir. Here may be mentioned the guttural pouches, large air sacs,
diverticula from the Eustachian tubes, and lying behind the upper part
of the pharynx. These are likewise found in other Perissodactyles,
but their use is also still not clearly understood. The larynx has the
lateral sacculi well developed, though entirely concealed within the alæ
of the thyroid cartilage. The trachea divides into two bronchi, one for
each lung.
_Nervous System._—The brain differs little, except in details of
arrangement of convolutions, from that of other Ungulates. The cerebral
hemispheres are rather elongated and subcylindrical, the olfactory
lobes are large and project freely in front of the hemispheres, and the
greater part of the cerebellum is uncovered. The eye is provided with a
nictitating membrane or third eyelid, at the base of which the ducts of
the Harderian gland open.
_Reproductive System._—The testes are situated in a distinct sessile or
slightly pedunculated scrotum, into which they descend from the sixth
to the tenth month after birth. The accessory generative glands are
the two vesiculæ seminales, with the median third vesicle, or _uterus
masculinus_, lying between them, the single bilobed prostate, and a pair
of globular Cowper’s glands. The penis is large, cylindrical, with a
truncated, expanded, flattened termination. When in a state of repose it
is retracted by a muscle arising from the sacrum, within the prepuce, a
cutaneous fold attached below the symphysis pubis.
The uterus is bicornuate. The vagina is often partially divided by a
membraneous septum or hymen. The mammæ (as in other members of the
suborder), are two, inguinally placed. The surface of the chorion is
covered evenly with minute villi, constituting a diffuse non-deciduate
placenta. The period of gestation is eleven months.
_Bibliography._—M. S. Arloing, “Organisation du pied chez le
cheval,” _Ann. Sci. Nat._ 1867, viii. pp. 55-81; H. Burmeister,
_Los caballos fosiles de la Pampa Argentina_, Buenos Ayres,
1875; Chanveau and Arloing, _Traité d’anatomie comparée des
animaux domestiques_, Paris, 1871, and English edition by G.
Fleming, 1873; E. Cuyer and E. Alix, _Le Cheval_, 1886; A.
Ecker, “Das Europäische Wildpferd und dessen Beziehungen zum
domesticirten Pferd,” _Globus_, Bd. xxxiv. Brunswick, 1878;
Forsyth-Major, “Beiträge zur Geschichte der fossilen Pferde
besonders Italiens,” _Abh. Schw. Pal. Ges._ iv. pp. 1-16, pt.
iv.; George, “Études zool. sur les Hémiones et quelques autres
espèces chevalines,” _Ann. Sci. Nat._ 1869, xii. p. 5; E. F.
Gurlt, _Anatomische Abbildungen der Haussäugethiere_, 1824,
and _Hand. der vergleich. Anat. der Haussäugethiere_, 2 vols.
1822; Huet, “Croisement des diverses espèces du genre cheval,”
_Nouv. Archives du Muséum_, 2d sér. tom. ii. p. 46, 1879;
Leisering, _Atlas der Anatomie des Pferdes_, Leipsic, 1861;
J. M’Fadyean, _The Anatomy of the Horse_, 1884; O. C. Marsh,
“Notice of New Equine Mammals from the Tertiary Formation,”
_Am. Journ. of Science and Arts_, vol. vii. March 1874; Id.
“Fossil Horses in America,” _Amer. Naturalist_, vol. viii.
May 1874; Id. “Polydactyle Horses,” _Am. Journ. of Science
and Arts_, vol. xvii. June 1879; Franz Müller, _Lehrbuch der
Anatomie des Pferdes_, Vienna, 1853; R. Owen, “Equine Remains
in Cavern of Bruniquel,” _Phil. Trans._ vol. clix. (1870), p.
535; W. Percivall, _The Anatomy of the Horse_, 1832; G. Stubbs,
_Anatomy of the Horse_, 1766. F. H. Huth’s _Bibliographical
Record of Hippology_ (1887) contains a list of nearly four
thousand works on Horses and Equitation, published in the
various languages of the civilised world.
_Family_ RHINOCEROTIDÆ.
Although the existing members of this family are readily distinguished
from the other living representatives of the suborder by the simple
crescentoid form assumed by the ridges of the lower cheek-teeth, yet
it is exceedingly difficult to give a definition by which they can be
distinguished from the _Lophiodontidæ_, from some members of which they
are, indeed, probably derived. The outer columns of the upper molars
(Fig. 167) are, however, so excessively flattened as to produce a
continuous thick and nearly straight outer wall, which is often produced
in advance of the anterior transverse ridge; both transverse ridges
being but little curved, and intimately connected with the outer wall.
The upper premolars are in most cases nearly or quite as complex as the
molars, and the ridges of the lower cheek-teeth are crescentoid. The
last lower molar has no third lobe. The height of the crowns of the
cheek-teeth is variable. The skull is large, with the orbit confluent
with the temporal fossa. There are either three or four digits in the
manus, and three in the pes. One or more dermal horns are attached to
the fronto-nasal region of the skull of existing forms, but these were
wanting in some of the fossil species.
[Illustration: FIG. 167.—A partially worn second right upper molar of
_Rhinoceros antiquitatis_. Letters as in Fig. 155 (p. 375), except _k_,
which indicates a prolongation of the median valley. (After Owen.)]
_Rhinoceros._[267]—Incisors variable, reduced in number, often quite
rudimentary, and early deciduous. Upper canines absent. Molar series,
consisting of the full number of four premolars and three molars above
and below, all in contact and closely resembling each other, except
the first, which is much smaller than the rest and often deciduous;
and the last, in which the hinder lobe is partly aborted, so that the
contour of the crown is triangular. Head large, skull elongated, elevated
posteriorly into a transverse occipital crest. No postorbital processes.
Nasal bones large and stout, co-ossified, and standing out freely above
the premaxillæ, from which they are separated by a deep and wide fissure;
the latter small, generally not meeting in the middle line in front,
often quite rudimentary. Tympanics small, not forming a bulla. Brain
cavity very small for the size of the skull. Vertebræ: C 7, D 19-20, L 3,
S 4, C about 22. Limbs stout, and of moderate length. Three completely
developed toes, with distinct broad rounded hoofs on each foot (Fig. 151,
p. 368), some fossil forms having a fourth in the manus. Eyes small. Ears
of moderate size, oval, erect, prominent, placed near the occiput. Skin
very thick, in many species thrown into massive folds. Hairy covering
scanty. When one horn is present it is situated over the conjoined nasal
bones; when two, the hinder one is over the frontals. These horns, which
are of a more or less conical form and usually recurved, often grow to
a great length (three or even four feet), and are composed of a solid
mass of hardened epidermic cells growing from a cluster of long dermal
papillæ. The cells formed on each papilla constitute a distinct horny
fibre, like a thick hair, and the whole are cemented together by an
intermediate mass of cells which grow up from the interspaces between
the papillæ. It results from this that the horn has the appearance of a
mass of agglutinated hairs, which, in the newly growing part at the base,
readily fray out on destruction of the softer intermediate substance; but
the fibres differ from true hairs in growing from a free papilla of the
derm, and not within a follicular involution of the same.
[Illustration: FIG. 168.—A partially worn second right upper molar of
(_A_) _Rhinoceros sondaicus_, and (_B_) _R. unicornis_. _k_, Fossette cut
off from median valley; _m_, crotchet; _n_, crista, or combining-plate;
_e_, anterior valley; _l_, anterior intermediate column. Other letters as
in Fig. 155, p. 375.]
The large lower cutting teeth of the typical Rhinoceroses have been
very generally regarded as incisors, but comparison with fossil allied
types, in which three lower incisors and canines are present, leaves
little doubt but that they are really canines. The upper molar teeth
present some amount of specific variation; thus while one type (Fig.
168, _A_) has only a simple “crotchet” projecting from the posterior
transverse ridge into the median valley, in others (Fig. 168, _B_)
this crotchet joins a “crista,” or “combing-plate,” projecting from
the outer wall to cut off a distinct fossette from the median valley.
Occasionally, however (as in Fig. 167), the crotchet and combing-plate
do not completely join, although the fossette is distinctly indicated.
The first upper premolar may occasionally be preceded by a milk-tooth.
The Rhinoceroses differ from the Horses and agree with the Tapirs in the
direction of the cæcum.
The living species of _Rhinoceros_ are all animals of large size, but
of little intelligence, generally timid indisposition, though ferocious
when attacked and brought to bay, using the nasal horns as weapons, by
which they strike and toss their assailant. Their sight is dull, but
their hearing and scent are remarkably acute. They feed on herbage,
shrubs, and leaves of trees, and, like so many other large animals which
inhabit hot countries, sleep the greater part of the day, being most
active in the cool of the evening or even during the night. They are fond
of bathing and wallowing in water or mud. None of the species have been
domesticated. Animals of the group have existed in both the Old and New
Worlds since the latter part of the Eocene period. In America they all
became extinct before the end of the Pliocene period. In the Old World
their distribution has become greatly restricted, and they are no longer
found in Europe and North Asia, but only in Africa and portions of the
Indian and Indo-Malayan region.
_Existing Species._—The existing (as well as many of the extinct) species
of Rhinoceroses naturally divide into three groups, which are regarded by
some zoologists as of generic value.
_Rhinocerotic, or Typical Group._—The adults with a single large
compressed incisor above on each side, and occasionally a small lateral
one; below, a very small incisor and a very large, procumbent, pointed
canine. Nasal bones pointed in front. A single nasal horn. Skin very
thick, and raised into strong, definitely arranged ridges or folds.
[Illustration: FIG. 169.—Indian Rhinoceros (_Rhinoceros unicornis_). This
figure, and also figures 170, 172, are reduced from drawings by J. Wolf,
from animals living in the London Zoological Society’s Gardens.]
There are two well-marked species of one-horned Rhinoceroses. (1) The
Indian Rhinoceros, _R. unicornis_ (Fig. 169) of Linnæus,[268] the
largest and best known, from being the most frequently exhibited alive
in England, is at present only met with in a wild state in the terai
region of Nipal and Bhutan, and in the upper valley of the Brahmaputra
or province of Assam, though it formerly had a wider range. The first
Rhinoceros seen alive in Europe since the time when these animals, in
common with nearly all the large remarkable beasts of both Africa
and Asia, were exhibited in the Roman shows, was of this species. It
was sent from India to Emmanuel, King of Portugal, in 1513; and from
a sketch of it, taken in Lisbon, Albert Dürer composed his celebrated
but rather fanciful engraving, which was reproduced in so many old
books on natural history. Both in this and the following species the
post-glenoid and post-tympanic processes of the squamosal bone of the
skull unite below so as to completely surround the external auditory
meatus. The molar teeth are hypsodont, and have a horizontal plane of
wear; those of the upper jaw (Fig. 168, _b_) being characterised by the
presence of a combing-plate joining the crotchet, and the absence of
a distinct buttress at the antero-external angle. The stomach departs
from the ordinary Perissodactyle type. The small intestine is beset
over most of its surface with long and fine villi; and the Spigelian
lobe of the liver is well developed. There is a gland behind the foot.
Teeth from the Pleistocene of the Narbada valley in India apparently
indicate the existence of the Indian Rhinoceros at that epoch. (2) The
Javan Rhinoceros (_R. sondaicus_, Fig. 170) is a smaller form, readily
distinguished by dental and internal characters, as well as by the
different arrangement of the plications of the skin (as seen in the
figures); the horn in the female appears to be very little developed, if
not altogether absent. This species has a more extensive geographical
range, being found in the Bengal Sunderbans near Calcutta, Burma, the
Malay Peninsula, Java, Sumatra, and probably Borneo. The molar teeth have
shorter crowns than in the preceding species, and wear into ridges;
those of the upper jaw (Fig. 168, _a_) having no combing-plate, and a
strongly marked buttress at the antero-external angle (not distinctly
shown in the figure). The visceral anatomy, according to Beddard,[269]
does not differ materially from that of the next species. In respect
to its dentition and anatomical characters this species is indeed more
nearly allied to the Sumatran than to the Indian Rhinoceros; and thereby
indicates that the division of the existing Rhinoceroses into separate
genera is not advisable.
[Illustration: FIG. 170.—Javan Rhinoceros (_Rhinoceros sondaicus_).]
_Ceratorhine Group._—The adults with a moderate-sized compressed incisor
above, and a laterally placed, pointed, procumbent canine below, which is
sometimes lost in old animals. Nasal bones narrow and pointed anteriorly.
A well-developed nasal, and a small frontal horn separated by an
interval. The skin thrown into folds, but these not so strongly marked
as in the former group. The smallest living member of the family, the
Sumatran Rhinoceros, _R. sumatrensis_, Cuvier, now represents this group.
Its geographical range is nearly the same as that of the Javan species,
though not extending into Bengal; but it has been found in Assam,
Chittagong, Burma, the Malay Peninsula, Sumatra, and Borneo. So far as
can be determined during the life of the type specimen, it appears that
the hairy form from Chittagong, described as _R. lasiotis_, is only a
variety of this species.[270] The molar teeth of the Sumatran Rhinoceros
are almost indistinguishable from those of the Javan species, and
reference has already been made to the resemblance between the visceral
anatomy of these species.[271] The form of the stomach is very similar to
that of the Horse. The liver (Fig. 171) has a comparatively large caudate
lobe, but is chiefly remarkable for the peculiar shape of the Spigelian
lobe, which mainly consists of a thin strip of tissue, 8 inches long, ¾
inch wide, and ¼ inch deep. The small intestine, in place of the villi of
_R. unicornis_, has throughout the greater part of its length a uniform
series of thin and nearly or quite continuous transverse foldings, like
the valvulæ conniventes of the human small intestine. There is no gland
behind the foot. The post-glenoid and post-tympanic processes of the
squamosal do not unite below the auditory meatus. The presence of a
lateral nasal diverticulum, like that of the Horses and Tapirs, has been
verified only in this species, although it doubtless occurs in the others.
[Illustration: FIG. 171.—Posterior aspect of the liver of _Rhinoceros
sumatrensis_. _rc_, Right central lobe; _rl_, right lateral lobe; _lc_,
left central lobe; _ll_, left lateral lobe; _c_, caudate lobe; _sp_,
Spigelian lobe. (From Garrod, _Proc. Zool. Soc._ 1873, p. 102.)]
_Atelodine Group._—In the adults the incisors and canines quite
rudimentary or entirely wanting. Nasal bones thick, rounded and truncated
in front. Well-developed anterior and posterior horns in close contact.
Skin without any definite permanent folds.
The two well-marked existing species are peculiar to the African
continent.
[Illustration: FIG. 172.—Common African Rhinoceros (_Rhinoceros
bicornis_).]
The common Two-horned Rhinoceros, _R. bicornis_, is the smaller of the
two, with a pointed prehensile upper lip, and a narrow compressed deep
symphysis of the lower jaw. It ranges through the wooded and watered
districts of Africa, from Abyssinia in the north to the Cape Colony, but
its numbers are yearly diminishing, owing to the inroads of European
civilisation, and especially of English sportsmen. It feeds exclusively
upon leaves and branches of bushes and small trees, and chiefly frequents
the sides of wood-clad rugged hills. Specimens in which the posterior
horn has attained a length as great as, or greater than, the anterior
have been separated under the name of _R. keitloa_, but the characters of
these appendages are too variable to found specific distinctions upon.
The Common African Rhinoceros is far more rarely seen in menageries in
Europe than either of the three Oriental species, but one has lived in
the gardens of the London Zoological Society since 1868. The molar teeth
of this species are of the general type of those of _R. sondaicus_,
having no combing-plate to join the crotchet in those of the upper jaw.
The conch of the ear is much rounded at its extremity, and edged by a
fringe of short hairs; while the nostrils are somewhat rounded. The eye
is placed immediately below the posterior horn.[272] Both in this and the
following species the post-glenoid and post-tympanic processes of the
squamosal do not unite below the auditory meatus. Nothing is known of the
anatomy of the soft parts of either of them.
Burchell’s or the Square-mouthed Rhinoceros (_R. simus_), sometimes
called the White Rhinoceros, though the colour (dark slate) is not
materially different from that of the last species, is the largest of the
whole group, and differs from all the others in having a square truncated
upper lip and a wide, shallow, spatulate symphysis to the lower jaw. In
conformity with the structure of the mouth, this species lives entirely
by browsing on grass, and is therefore more partial to open countries
or districts where there are broad grassy valleys between the tracts of
bush. It is only found in Africa south of the Zambesi, and of late years
has become extremely scarce, owing to the persecutions of sportsmen;
indeed, the time of its complete extinction cannot be far off. No
specimen of this species has ever been brought alive to Europe. Mr. F. C.
Selous[273] gives the following description of its habits from extensive
personal observation:—
“The square-mouthed rhinoceros is a huge ungainly-looking beast, with
a disproportionately large head, a large male standing 6 feet 6 inches
at the shoulder. Like elephants and buffaloes they lie asleep during
the heat of the day, and feed during the night and in the cool hours of
early morning and evening. Their sight is very bad; but they are quick of
hearing, and their scent is very keen; they are, too, often accompanied
by rhinoceros birds, which, by running about their heads, flapping their
wings, and screeching at the same time, frequently give them notice of
the approach of danger. When disturbed they go off at a swift trot, which
soon leaves all pursuit from a man on foot far behind; but if chased by
a horseman they break into a gallop, which they can keep up for some
distance. However, although they run very swiftly, when their size and
heavy build is considered, they are no match for an average good horse.
They are, as a rule, very easy to shoot on horseback, as, if one gallops
a little in front of and on one side of them, they will hold their
course, and come sailing past, offering a magnificent broadside shot,
while under similar circumstances a prehensile-lipped rhinoceros will
usually swerve away in such a manner as only to present his hind-quarters
for a shot. When either walking or running, the square-mouthed rhinoceros
holds its head very low, its nose nearly touching the ground. When a
small calf accompanies its mother it always runs in front, and she
appears to guide it by holding the point of her horn upon the little
animal’s rump; and it is perfectly wonderful to note how in all sudden
changes of pace, from a trot to a gallop or _vice versâ_, the same
position is always exactly maintained. During the autumn and winter
months (_i.e._ from March to August) the square-mouthed rhinoceros is
usually very fat; and its meat is then most excellent, being something
like beef, but yet having a peculiar flavour of its own. The part in
greatest favour among hunters is the hump, which, if cut off whole and
roasted just as it is in the skin, in a hole dug in the ground, would, I
think, be difficult to match either for juiciness or flavour.”
The molar dentition is of the type obtaining in _R. unicornis_, so that
in this respect _R. simus_ has the same relation to _R. bicornis_ as
is presented by _R. unicornis_ to _R. sondaicus_. The ear-conch of the
Square-mouthed Rhinoceros is very large, elongated, and pointed at its
extremity, which bears only a slight tuft of hair; it is much expanded
in the middle, and the lower portion has its edges united to form a
short tube. The nostrils have a long slit-like aperture; and the eye is
situated behind the posterior horn.
_Extinct Species._—Using the generic term _Rhinoceros_ in its widest
signification, a very large number of fossil forms may be referred to it,
the earliest of which date from the Upper Eocene (Oligocene) Phosphorites
of Central France. Only a few of the more important of these types can,
however, be even mentioned in this place.
In the Pliocene Siwaliks of India _R. sivalensis_ appears to have been
the direct ancestor of _R. sondaicus_; while _R. palæindicus_ was
probably nearly related to _R. unicornis_, although the upper molars had
not developed a combing-plate.
_R. schleirmacheri_, of the Lower Pliocene of Europe, falls into the
Ceratorhine group, although differing from _R. sumatrensis_ by the union
of the post-glenoid and post-tympanic processes of the squamosal beneath
the auditory meatus. The Middle Miocene _R. sansaniensis_ was a closely
allied if not identical form.
The Atelodine group was very widely spread in past epochs. Thus the
huge _R. platyrhinus_ of the Indian Pliocene, and the equally large _R.
antiquitatis_ of the Pleistocene of Europe, were specialised forms with
a dentition resembling that of _R. simus_, to which they were probably
allied. An upper molar of _R. antiquitatis_—the so-called Tichorine, or
Woolly Rhinoceros—is shown in the woodcut on p. 402. Of this species
nearly whole carcases, with the thick woolly external covering, have been
discovered associated with those of the Mammoth, preserved in the frozen
soil of the north of Siberia. In common with some other extinct species
it had a solid median wall of bone supporting the nasals, from which it
is inferred that the horns were of a size and weight surpassing that of
the modern species. In the Lower Pliocene of Attica _R. pachygnathus_
appears to have been closely allied to _R. bicornis_. Several species
such as _R. leptorhinus_ (Fig. 173), _R. megarhinus_, and _R. etruscus_,
occur in the European Pleistocene which do not present a marked
relationship to any of the living forms. This group is also represented
in the Pleistocene of Southern India by the small _R. deccanensis_ and
_R. karnuliensis_.
In the Upper Miocene, or Lower Pliocene, of North America numerous
Rhinoceroses with incisor teeth occur which have no nasal horn, although
in those forms of which the limbs are known the fore feet resembled
those of existing species in having only three digits. These species
have been generically separated as _Aphelops_, but so closely do they
resemble existing Rhinoceroses that at one time Professor Cope proposed
to refer the hornless female of _R. sondaicus_ (described by Lesson as
_R. inermis_) to the same genus. If these American types be included in
_Rhinoceros_ there seems no valid reason for separating the European
Lower Pliocene and Miocene forms described as _Aceratherium_, at least
some of which have four digits in the manus. This group is represented
in the Upper Eocene Phosphorites of France, and also by a very large
species in the Pliocene of India. Lastly, _R. minutus_, of the Lower
Miocene of France, and an allied North American species are distinguished
by carrying a pair of very small horns placed transversely across the
nasals, from which feature it has been proposed that they should be
separated genetically as _Diceratherium_.
[Illustration: FIG. 173.—Skull of _Rhinoceros leptorhinus_, from the
Pleistocene of Essex. About ⅛ natural size.]
_Extinct Generic Types._—The Tertiary deposits of different parts of the
world have yielded remains of many extinct forms more or less closely
related to the Rhinoceroses, and some of which should certainly be
included in the same family; although others perhaps form the types
of one or more distinct families. One of the most remarkable of these
extinct types is the huge _Elasmotherium_, from the Pleistocene of
Siberia, in which the dentition was reduced to two premolars and three
molars on either side of each jaw. The structure of the skeleton is
essentially rhinocerotic, the skull having an ossified nasal septum,
and a huge frontal prominence for the support of a very large horn. The
teeth are extremely hypsodont, with the enamel plicated to a remarkable
degree, and unlike those of _Rhinoceros_. The genus is evidently a very
specialised one.
The other genera we have to notice are more generalised types. Of these
the North American _Hyracodon_, with the full typical number of teeth,
and without nasal horn, appears to connect the Rhinoceroses with the
Lophiodont _Hyrachyus_. The genera _Amynodon_ and _Metamynodon_ (Fig.
174), from the American Tertiaries, are forms allied to the Rhinoceroses,
with the full number of incisors and canines, and the hinder lobe of the
last upper molar not aborted. The lower canines are either upright, or
less proclivous than in the Rhinoceroses; in _Metamynodon_ the premolars
are reduced to ³⁄₂. Molar teeth from the Phosphorites of Central France,
described under the name of _Cadurcotherium_, are constructed on the
general plan of those of the Rhinoceroses, although distinguished by
their extreme narrowness; this type of tooth being very similar to that
found in _Homalodontotherium_ from Tertiary deposits in Patagonia. The
latter has the full number of teeth, without any diastema in the series.
Until we have some knowledge of the skeleton of these remarkable forms
nothing definite can be said as to their serial position.
[Illustration: FIG. 174.—Right half of the palatal surface of the cranium
of _Metamynodon planifrons_, from the Upper Miocene of North America.
(After Scott and Osborn.)]
_Families_ LAMBDOTHERIIDÆ, CHALICOTHERIIDÆ, AND TITANOTHERIIDÆ.
These families contain a large number of more or less nearly related
extinct types from Tertiary beds of both the Old and New Worlds, some
of which present most remarkable deviations from the ordinary Ungulate
structure. All are characterised by their brachydont molars, which depart
widely from the normal lophodont type. The upper molars consist of four
columns, of which the two external ones are expanded to form an outer
wall; the posterior pair being connected in some cases by an oblique
transverse ridge, while there may be traces of an anterior ridge. The
premolars are simpler.
_Lambdotheriidæ._—This family is confined to the Upper Eocene and
Miocene of North America, where it is represented by _Lambdotherium_,
_Palæosyops_, and _Limnosyops_; it presents the normal type of foot
structure, and all the genera except the first have the full complement
of teeth. There were four digits in the manus. The last lower molar has
a third lobe. _Limnosyops_ differs from _Palæosyops_ in having two inner
columns to the last upper molar.
[Illustration: FIG. 175.—Anterior and distal aspects of a phalangeal bone
of _Chalicotherium sivalense_. (From the _Palæontologia Indica_.)]
_Chalicotheriidæ._—The genus _Chalicotherium_, which is found in the
Tertiaries of Europe, Asia, and North America, differs so remarkably
in the structure of the feet from all other Ungulates that it has
been proposed to regard it as the representative of a distinct order,
Ancylopoda. The molars are, however, almost indistinguishable from those
of the preceding and following families; while the cervical vertebræ
and portions of the limbs are of a Perissodactyle type. On the other
hand, the femur has lost its third trochanter; while the phalanges are
strangely modified, the terminal ones forming long curved claws, while
the others (Fig. 175) have strong ginglymoid distal articulations.
These phalanges were, indeed, long regarded as referable to Edentates,
being described in Europe as _Macrotherium_, and in the United States
as _Morotherium_ and _Moropus_. _Ancylotherium_, of the Grecian Pikermi
beds, is founded upon phalanges which indicate an allied genus. The
Indian species of _Chalicotherium_ is distinguished by the loss of the
incisors and the upper canine; while all the species want the first
premolar.
_Titanotheriidæ._—This exclusively North American family includes
gigantic forms closely allied to the _Lambdotheriidæ_, but with the last
upper premolar as complex as the molars, and frequently with large bony
protuberances in the nasal region. The best known genus, _Titanotherium_
(_Menodus_,[274] _Brontotherium_, _Symborodon_, _Allops_, etc.), may
either have the full complement of teeth, or the incisors may be reduced
to ²⁄₀. The canines and incisors are small, and there is no diastema
when the full dental series is developed. The skull is very like that of
the Rhinoceroses; but has a transverse pair of large bony prominences
on the nasal region, varying considerably in shape and size in the
different species, which in the living animal were probably covered with
horny sheaths. The third trochanter of the femur was aborted. These
huge animals—inferior in size only to the Elephant—appear to have been
abundant in the United States during the Miocene period.
_Family_ MACRAUCHENIIDÆ.
This extinct South American family is best known by the genus
_Macrauchenia_, as represented by _M. patachonica_ and _M. boliviensis_,
which are apparently from Pleistocene formations. They are very singular
and specialised forms, quite out of the line of descent of any of the
existing Perissodactyles, and the steps by which they are connected
with the rest of the group have not yet been discovered. Of the larger
species, _M. patachonica_, the skeleton is completely known. It had the
full number of forty-four teeth, forming an almost uninterrupted series.
The cervical vertebræ resemble those of the Camels in the position of
the vertebrarterial canal, but the ends of the centra are flat, and not
opisthocœlous as in the allied forms. In some of the limb characters it
resembles the _Equidæ_, but in the articulation of the fibula with the
calcaneum it agrees with the Artiodactyles. The structure of the feet is,
however, distinctly Perissodactylate, there being three toes on each. The
teeth approximate to a Rhinocerotine structure; and the incisors have an
infolding of the enamel of their crowns, as in those of the Horses. The
nares open on the top of the skull, and it is probable that the muzzle
was produced into a short proboscis. Several other South American forms
have been referred to this family, some of which have received distinct
generic names, but further evidence is required before many of them can
be accepted. Possibly _Homalodontotherium_ should be placed here.
_Family_ PROTEROTHERIIDÆ.
_Proterotherium._—Here may be noticed certain very remarkable
Perissodactyles from the South American Tertiaries, for which the name
_Proterotherium_ has been proposed. The cheek-teeth are so like those
of _Anchitherium_ that they have been described under that name. The
upper jaw has one pair of canine-like incisors and no canines, while the
lower jaw carries two pairs of incisors. In the skull the orbits were
completely closed, as in the Horses. The feet were tridactyle, like those
of _Hipparion_, but the tarsus was constructed on an Artiodactyle type.
SUBUNGULATA.
By far the greater number of the Subungulata are extinct, and of many of
those whose former existence has been revealed, chiefly by the labours
of the American palæontologists, our knowledge is at present necessarily
imperfect, though daily extending. It will only be possible here to give
details of some of the more interesting or best-known forms.
The characters by which the skeleton of the feet of the Subungulata
are distinguished from those of the Ungulata Vera have been already
mentioned on p. 275. In addition to these it may be observed that the
feet frequently have five functional digits, and may be plantigrade;
while the upper surface of the astragalus is generally flattened, instead
of presenting the strongly-marked pulley-like ridges and groove so
characteristic of the Ungulata Vera.
_Suborder_ HYRACOIDEA.
_Family_ HYRACIDÆ.
[Illustration: FIG. 176.—_Hyrax capensis._]
This division is constituted to receive a single family of mammals, the
affinities of which have long constituted a puzzle to zoologists. They
were first placed among the Rodents, to which animals their small size
and general appearance and habits give them much superficial resemblance.
Cuvier’s investigations into their anatomical structure, and especially
their dental characters, led him to place them among the Ungulates, near
the genus _Rhinoceros_, a position long accepted by many zoologists.
Further knowledge of their organisation and mode of development caused
Milne-Edwards, Huxley, and others to disassociate them from this
connection, and, failing to find any agreement with any other known
forms, to place them in an order entirely apart. Palæontology has thrown
no light upon the affinities of this anomalous and isolated group, as no
extinct animals possessing their distinctive characters have as yet been
discovered.
[Illustration: FIG. 177.—Skull and dentition of _Dendrohyrax dorsalis_. ×
⅔.]
The dentition, according to the usual interpretation, consists only of
incisors and molars, the formula in all known species being _i_ ¹⁄₂,
_c_ ⁰⁄₀, _p_ ⁴⁄₄, _m_ ³⁄₃. The upper incisors have persistent pulps,
and are curved longitudinally, forming a semicircle as in Rodents. They
are, however, not flattened from before backwards as in that order, but
prismatic, with an antero-external, an antero-internal, and a posterior
surface, the first two only being covered with enamel; their apices are
consequently not chisel-shaped, but sharp pointed. They are preceded by
functional, rooted milk-teeth. The outer lower incisors, which should
perhaps be regarded rather as canines, have long tapering roots, but not
of persistent growth. They are straight, procumbent, with awl-shaped,
trilobed crowns. Behind the incisors is a considerable diastema. The
molars and premolars are all contiguous, and formed almost exactly on
the pattern of some of the Perissodactyle Ungulates. The hyoid arch is
unlike that of any known mammal. The dorsal and lumbar vertebræ are very
numerous, 28 to 30, of which 21 or 22 bear ribs. The tail is extremely
short. There are no clavicles. In the fore foot the three middle toes are
subequally developed, the fifth is present, but smaller, and the hallux
is rudimentary, although, in one species at least, all its normal bones
are present. The ungual phalanges of the four outer digits are small,
somewhat conical, and flattened in form. The carpus has a distinct os
centrale. There is a slight ridge on the femur in the place of a third
trochanter. The fibula is complete, thickest at its upper end, where
it generally ankyloses with the tibia. The articulation between the
tibia and astragalus is more complex than in other mammals, the end
of the malleolus entering into it. The hind foot is very like that of
_Rhinoceros_, having three well-developed toes. There is no trace of a
hallux, and the fifth metatarsal is represented only by a small nodule.
The ungual phalanx of the inner (or second) digit is deeply cleft, and
has a peculiar long curved claw, the others have short broad nails. The
stomach is formed upon much the same principle as that of the Horse
or Rhinoceros, but is more elongated transversely and divided by a
constriction into two cavities—a large left _cul de sac_, lined by a very
dense white epithelium and a right pyloric cavity, with a very thick,
soft, vascular lining. The intestinal canal (Fig. 178) is long, and has
an arrangement perfectly unique among mammals, indeed among vertebrated
animals, for, in addition to the ordinary short, but capacious and
sacculated cæcum (_cm_) at the commencement of the colon, there is, lower
down, an additional pair of large, conical, pointed, supplemental cæca
(_c_). The liver is much subdivided, and there is no gall-bladder. The
brain resembles that of the typical Ungulates far more than the Rodents.
The testes are permanently abdominal. The ureters open into the fundus
of the bladder, as in some Rodents. The female has six teats, of which
four are inguinal and two axillary; and the placenta is zonary, as in the
Elephant and Carnivora.
[Illustration: FIG. 178.—Diagrammatic view of the alimentary canal
of _Hyrax capensis_, the intestines being somewhat abbreviated. _d_,
Duodenum; _i_, ileum; _cm_, cæcum; _c_, supplemental colic cæca; _r_,
rectum.]
There are two distinct forms of Hyrax, differing both in structure and
habits, which may be accorded generic rank.
_Hyrax._[275]—Molar teeth having the same pattern as those of
_Rhinoceros_. Interval between upper incisors less than the width of the
teeth. Lower incisors slightly notched at the cutting edge. Vertebræ:
C 7, D 22, L 8, S 6, C 6. Of this form the earliest known species, _H.
capensis_ (Fig. 176) is the type. There are several other species, as _H.
habessinicus_ and _syriacus_, from Eastern Africa and Syria. They inhabit
mountainous and rocky regions, and live on the ground.
_Dendrohyrax._[276]—Molar teeth having the same pattern as _Palæotherium_
(except that the third lower molar has but two lobes). Interval between
upper incisors exceeding the width of the teeth. Lower incisors with very
distinctly trilobed crowns. Vertebræ: C 7, D 21, L 7, S 5, C 10. The
members of this section frequent the trunks and large branches of trees,
sleeping in holes. There are several species, not distinctly defined,
from western and south Africa, as _D. arboreus_ and _D. dorsalis_. The
members of both groups appear to have a power like that possessed by the
Lizards called Geckos of clinging to vertical surfaces of rocks and trees
by the soles of their feet.
It should be added that some writers separate three of the African
species usually included in _Hyrax_ (viz. _H. bocagei_, _H. bakeri_, and
_H. blainvillei_) under the designation of _Heterohyrax_.[277]
_Suborder_ PROBOSCIDEA.
This name has been appropriated to a well-marked group of animals,
presenting some very anomalous characters, allied in many respects to
the typical Ungulata, but belonging neither to the Artiodactyle nor
Perissodactyle type of that order. It has been thought that they possess
some, though certainly not very close, affinities with the Rodentia, and
also with the Sirenia. It is certain, however, that the two species of
Elephant, which are the sole living representatives of the group, stand
quite alone among existing mammals, differing widely from all others
in many points of their structure. In some respects, as the skull,
proboscis, and dentition, they are highly specialised; but in others,
as in the presence of two anterior venæ cavæ and in the structure of
the limbs, they retain a low or generalised condition. A considerable
series of extinct forms, extending back through the Pliocene and Miocene
epochs, show the same type under different modifications, and in still
more generalised outlines; and certain forms from the Eocene of North
America, if their affinities are rightly interpreted, appear to link the
true Proboscidea to some unknown primitive type of Ungulata.
The following are the principal characters common to existing, and, by
inference, to the extinct, Proboscidea. The nose extended into a long,
muscular, very flexible and prehensile proboscis, at the end of which
the nostrils are situated, and from which the name given to the group
is derived. The teeth consisting of ever-growing incisors of very great
size, but never exceeding one pair in each jaw, and often present in
one jaw only; no canines; large and transversely ridged molars. No
clavicles. Limbs strong, the upper segment, especially in the hind limb,
the longer. Radius and ulna distinct, the latter articulating extensively
with the carpus. Fibula and tibia distinct. Astragalus very flat on both
surfaces. Manus and pes short, broad, and massive, each with five toes,
though the outer pair may be more or less rudimentary, all encased in
a common integument, though with distinct, broad, short hoofs. Third
digit the largest. Two anterior venæ cavæ entering the right auricle.
Stomach simple. A capacious cæcum. Testes permanently abdominal. Uterus
bicornuate. Placenta non-deciduate and zonary. Mammæ two, pectoral.
With regard to the teeth, the incisors,[278] which project largely out
of the mouth, and are commonly called “tusks,” are of an elongated
conical form, and generally curved. They are composed mainly of solid
dentine, the fine elastic quality and large mass of which renders it
invaluable as “ivory” for commerce and the arts. A peculiarity of the
dentine of most Proboscidea is that it shows, in transverse fractures or
sections, striæ proceeding in the arc of a circle from the centre to the
circumference in opposite directions, and forming by their decussations
curvilinear lozenges, as in the “engine-turning” of the case of a watch.
The enamel-covering in existing species is confined to the extreme
apex, and very soon wears off, but in some extinct species it forms
persistent longitudinal bands of limited breadth. The tusks have small
milk-predecessors, shed at an early age.
The molar teeth present a remarkable series of modifications, from the
comparatively simple form in _Dinotherium_, with two or three strongly
pronounced transverse ridges and a normal mode of succession, to the
extremely complex structure and anomalous mode of replacement found in
the true Elephants. The intermediate conditions occur in the various
species of _Mastodon_. In this genus the enamel-covered transverse
ridges of each tooth are generally more numerous than in _Dinotherium_,
and often complicated by notches dividing their edge or by accessory
columns attached to them, but in the unworn tooth they stand out freely
on the surface of the crown, with deep valleys between (Fig. 179, I).
In the Elephants the ridges are still further increased in number, and
consequently narrower from before backwards, and are greatly extended
in vertical height, so that, in order to give solidity to what would
otherwise be a laminated or pectinated tooth, it becomes necessary to
envelop and unite the whole in a large mass of cement, which completely
fills up the valleys, and gives a general smooth appearance to the organ
when unworn; but as the wear consequent upon the masticating process
proceeds, the alternate layers of tissue of different hardness—cement,
dentine, and enamel—which are disclosed upon the surface form a fine and
very efficient triturating instrument. The modification of the tooth of
a Mastodon into that of an Elephant is therefore precisely the same in
principle as that of the molar of a Palæotherium into that of a Horse,
or of the corresponding tooth of one of the primitive Artiodactyles into
that of an Ox. The intermediate stages, moreover, even in the present
state of our knowledge, are so numerous that it is not possible to draw a
definite line between the two types of tooth structure (see Fig. 179, I,
II, III, IV).
[Illustration: FIG. 179.—Longitudinal sections of the crown of a
molar tooth of various Proboscideans, showing stages in the gradual
modification from the simple to the complex form. I, _Mastodon
americanus_; II, _Elephas insignis_; III, _Elephas africanus_; IV,
_Elephas primigenius_. The dentine is indicated by transverse lines, the
cement by a dotted surface, and the enamel is black.]
As regards the mode of succession, that of modern Elephants is, as
before mentioned, very peculiar. During the complete lifetime of the
animal there are but six molar teeth on either side of each jaw, with
occasionally a rudimentary one in front, completing the typical number
of seven. The last three represent the true molars of ordinary mammals;
those in front appear to be milk-molars, which are never replaced by
permanent successors, but the whole series gradually moves forwards in
the jaw, and the teeth become worn away and their remnants cast out in
front, while development of others proceeds behind. The individual teeth
are so large, and the processes of growth and destruction by wear take
place so slowly, that not more than one, or portions of two, teeth are
ever in place and in use on either side of each jaw at one time, and the
whole series of changes coincides with the usual duration of the animal’s
life. On the other hand, the Dinotherium, the opposite extreme of the
Proboscidean series, has the whole of the molar teeth in place and use
at one time, and the milk-molars are vertically displaced by premolars
in the ordinary fashion. Among Mastodons transitional forms occur in
the mode of succession as well as in structure, many species showing a
vertical displacement of one or more of the milk-molars, and the same has
been observed in one extinct species of Elephant (_E. planifrons_) as
regards the posterior of these teeth.
All known Proboscideans are animals of comparatively large dimensions,
and some are the most colossal of land mammals. The head is of great
proportionate size; and, as the brain case increases but little in bulk
during growth, while the exterior wall of the skull is required to
be of great superficial extent to support the trunk and the huge and
ponderous tusks, and to afford space for the attachment of muscles of
sufficient size and strength to wield the skull thus heavily weighted,
an extraordinary development of air-cells takes place in the cancellous
tissue of nearly all the bones of the cranium (Fig. 180). These cells
are not only formed in the walls of the cranium proper, but are also
largely developed in the nasal bones and upper part of the premaxillæ and
maxillæ, the bones forming the palate and the basicranial axis, and even
extend into the interior of the ossified mesethmoid and vomer. Where two
originally distinct bones come into contact, the cells pass freely from
one to the other, and almost all the sutures become obliterated in old
animals. The intercellular lamellæ in the great mass which surrounds
the brain cavity superiorly and laterally mostly radiate from the inner
to the outer table, but in the other bones their direction is more
irregular. Like the similar but less developed air-cells in the skulls
of many other mammals, they all communicate with the nasal passages,
and they are entirely secondary to the original growth of the bones,
their development having scarcely commenced in the new-born animal, and
they gradually enlarge as the growth of the creature proceeds towards
maturity. The nasal bones are very short, and the anterior narial
aperture is situated high in the face. The zygomatic arch is slender and
straight, the jugal bone being small, and forming only the middle part of
the arch, the anterior part of which (unlike that of typical Ungulates)
is formed only by the maxilla. The maxillo-turbinals are but rudimentary,
the elongated proboscis supplying their place functionally in warming and
clearing from dust the inspired air.
[Illustration: FIG. 180.—A vertical section of the skull of the African
Elephant (_Elephas africanus_) taken to the left of the middle line, and
including the vomer (_Vo_) and the mesethmoid (_ME_). _an_, Anterior,
and _pn_, posterior narial aperture. ¹⁄₁₂ natural size. (From Flower’s
_Osteology of the Mammalia_.)]
The neck is very short. The limbs are long and stout, and remarkable for
the great length of the upper segment (especially the femur) as compared
with the distal segment, the manus, and pes. It is owing to this and
the vertical position of the femur that the knee-joint in the hind leg
is placed much lower, and is more conspicuous externally than in most
quadrupedal mammals; and this having been erroneously compared with the
hock-joint or ankle of typical Ungulates, the popular fallacy that the
joints of the Elephant’s leg bend in a contrary direction to that of
other mammals has arisen. There is no round ligament in the hip-joint,
or third trochanter to the femur. The radius and ulna are distinct,
though fixed in a crossed or prone position. The fibula also is quite
distinct from the tibia. The feet are short and broad, the carpal and
tarsal bones being very square, with flattened surfaces for articulation;
the astragalus especially differs from that of typical Ungulates in its
flatness, in the absence of a distinct pulley-like articular surface
at either extremity, and in having no articular facet for the cuboid.
The fibula articulates with the calcaneum, as in Artiodactyles. Of
the five toes present on each extremity (see Fig. 98), the middle one
is somewhat the largest, and the lateral ones smallest, and generally
wanting (especially in the hind foot) the complete number of phalanges.
The ungual phalanges are all small, irregular in form, and late in
ossification. The whole are encased in a common integument, with a flat,
subcircular, truncated sole, the only external indication of the toes
being the broad oval nails or hoofs arranged in a semicircle around the
front edge of the sole. The hind foot is smaller and narrower than the
front. The liver is small and simple, and there is no gall-bladder. In
form the brain resembles that of the Rodents and other lower orders
of mammals, the cerebellum being entirely behind and uncovered by the
cerebrum, but the hemispheres of the latter are richly convoluted.
The Proboscidea are exclusively vegetable feeders, living chiefly on
leaves and young branches of forest trees and various kinds of herbage,
which they gather and convey to their mouth by the very mobile proboscis,
an organ which combines in a marvellous manner strength with dexterity
of application, and is a necessary compensation for the shortness and
inflexibility of the neck, as by it many of the functions of the lips
of other animals are performed. By its means the Elephant is enabled
to drink without bending the head or limbs; the end of the trunk being
dipped into the stream or pool, a forcible inspiration fills the two
capacious air-passages in its interior with water, which, on the tip of
the trunk being turned upwards and inserted into the mouth, is ejected
by a blowing action, and swallowed; or if the animal wishes to refresh
and cool its skin, it can throw the water in a copious stream over any
part of its surface. Elephants can also throw dust and sand over their
bodies by the same means and for the same purpose, and wild animals
have been frequently observed fanning themselves with leafy boughs held
in the trunk. The species are at present limited in their geographical
distribution to the Ethiopian and Oriental regions, but they formerly had
a far more extensive range.
_Family_ ELEPHANTIDÆ.
Cheek-teeth succeeding one another in an arc of a circle, and portions of
only two, or at most three, of the hinder teeth in use at any one time.
Premolars frequently lost, and in any case of no functional importance.
_Elephas._[279]—Dentition: _i_ ¹⁄₀, _c_ ⁰⁄₀, _dm_ ³⁄₃, _m_ ³⁄₃ = 26. The
incisors variable, but usually of very large size, especially in the
male sex, directed somewhat outwards, and curved upwards, without enamel
except on the apex before it is worn. The molars composed of numerous
flattened enamel-covered plates or ridges of dentine, projecting from
a common many-rooted base, surrounded and united together by cement,
and extending straight across the crown, without (in most forms) any
median division into inner and outer columns. The number of plates
increases from the anterior to the posterior molar in regular succession,
varying in the different species, but the third and fourth (or the last
milk-molar and the first true molar), and these only, have the same
number of ridges, which always exceeds five. Premolars nearly always
wanting. Skull of adult very high and globular. Mandible ending in front
in a short, deflected, and spout-like symphysis. Vertebræ: C 7, D 19-21,
L 3-4, S 4, C 26-33.
The existing species of the genus differ so much that they have been
referred by some writers to distinct genera; fossil forms show, however,
such a transition from the one to the other that it is scarcely possible
to regard them even as the representatives of distinct groups.
[Illustration: FIG. 181.—Grinding surface of a half-worn lower molar of
the Indian Elephant (_Elephas indicus_). _d_, Dentine; _e_, enamel; _c_,
cement. (From Owen.)]
In the well-known Indian or Asiatic Elephant (_E. indicus_) the average
number of plates of the six successive molar teeth is expressed by the
“ridge-formula,” 4, 8, 12, 12, 16, 24. The plates are compressed from
before backwards, the anterior and posterior surfaces (as seen in the
worn grinding face of the tooth, Fig. 181) being nearly parallel. Ears of
moderate size. Upper margin of the end of the proboscis developed into
a distinct finger-like process, much longer than the lower margin. Five
nails on the fore feet, and four (occasionally five) on the hind feet.
[Illustration: FIG. 182.—Grinding surface of a partially worn right upper
molar of the African Elephant (_Elephas africanus_). Letters as in the
preceding figure. The left side of the figure is the front of the tooth,
and the lower side the outer border. (From Owen.)]
This species inhabits in a wild state the forest lands of India, Burma,
the Malay Peninsula, Cochin China, Ceylon, and Sumatra. The elephants
from the last-named islands, presenting some variations from those of
the mainland, have been separated under the name of _E. sumatranus_, but
the distinction has not been satisfactorily established. The appearance
of the Asiatic Elephant is familiar to all. Though rarely breeding in
captivity, it has been domesticated from the most remote antiquity, and
is still extensively used in the East as a beast of burden. In the wild
state it is gregarious, associating in herds of ten, twenty, or more
individuals, and though it may, under certain circumstances, become
dangerous, it is generally inoffensive and even timid, fond of shade and
solitude and the neighbourhood of water. The height of the male at the
shoulder when full grown is usually from 8 to 10 feet, but occasionally
as much as 11. The female is somewhat smaller.
[Illustration: FIG. 183.—African Elephant (_Elephas africanus_). From a
young specimen in the London Zoological Gardens.]
In the African Elephant (_E. africanus_) the molars (Fig. 182) are of
coarse construction, with fewer and larger plates and thicker enamel.
Ridge-formula: 3, 6, 7, 7, 8, 10. The plates not flattened, but thicker
in the middle than at the edges, so that their worn grinding surfaces
are lozenge-shaped. Ears very large. The upper and lower margins of the
end of the trunk forming two nearly equal prehensile lips. But three
hoofs on the hind foot. This species now inhabits the wooded districts
of the whole of Africa south of the Sahara, except where it has been
driven away by human settlements. Fossil remains of Pleistocene age,
undistinguishable specifically, have been found in Algeria, Spain, and
Sicily. It was trained for war and show by the ancient Carthaginians and
Romans, and recent experience of the species in captivity in England
shows that it is as intelligent as its Asiatic relative, if not more so,
while surpassing it in courage, activity, and obstinacy. Nevertheless,
in modern times, no people in Africa have been sufficiently civilised
or enterprising to care to train it for domestic purposes. It is hunted
chiefly for the sake of the ivory of its immense tusks, of which it
yields the principal source of supply to the European market, and the
desire to obtain which is rapidly leading to the extermination of the
species. In size the male African elephant often surpasses that of Asia,
but the female is usually smaller. The circumference of the fore foot is
half the height at the shoulder, a circumstance which enables the hunters
to judge from the footprints the exact size of the animals of which
they are in pursuit. The African Elephant also differs from its Indian
congener in having tusks in both sexes, whereas in the latter the male
only is so armed. Moreover, the eye is relatively larger, the forehead
more convex, and the colour somewhat darker. Whereas the Indian Elephant
frequents the depths of forests and seldom leaves their shade during the
daytime, the following account by Sir Samuel Baker indicates different
habits in the African species. This traveller observes: “In Africa, the
country being generally more open than in Ceylon, the Elephant remains
throughout the day either beneath a solitary tree or exposed to the sun
in the vast prairies, where the thick grass attains a height of from
nine to twelve feet. The general food of the African Elephant consists
of the foliage of trees, especially mimosas. Many of the mimosas are
flat-headed, about thirty feet high, and the richer portion of the
foliage confined to the crown. Thus the Elephant, not being able to
reach to so great a height, must overturn the tree to obtain the coveted
food. The destruction caused by a herd of Elephants in a mimosa forest
is extraordinary, and I have seen trees uprooted of so large a size that
I am convinced no single elephant could have overturned them. I have
measured trees four feet six inches in circumference and about thirty
feet high uprooted by elephants. The natives have assured me that the
elephants mutually assist each other, and that several engage together in
the work of overturning a large tree.”
[Illustration: FIG. 184.—Restored skeleton of the Mammoth (_Elephas
primigenius_). From Tilesius in _Mém. Acad. Imp. Sc. St. Pétersbourg_,
vol. v. (1815). _s_, Scapula; _h_, humerus; _r_, radius; _u_, ulna;
_c_, carpus; _rs_, ischium; _f_, femur; _t_, tibia; _fi_, fibula; _ta_,
tarsus.]
_Extinct Species of Elephant._—Abundant remains of Elephants are found
embedded in alluvial gravels, or secreted in the recesses of caves,
into which they have been washed by streams and floods, or dragged as
food by Hyænas and other carnivorous inhabitants of these subterranean
dens. Such remains belonging to the Pleistocene and Pliocene periods
have been found in many parts of Europe, including the British Isles,
in North Africa, throughout the North American continent from Alaska to
Mexico, and extensively distributed in Asia, where the deposits of the
sub-Himalayan Siwalik Hills, and equivalent deposits in the Punjab, Perim
Island,[280] and Burma, belonging to the earliest Pliocene, are rich
in the remains of Elephants of varied form. These species are chiefly
known and characterised at present by the skulls and teeth; some of the
latter resemble the existing Indian and some the African type, but the
majority are between the two, and make the distinction between the two
existing species as of generic importance quite impracticable. Others
again approach so closely in the breadth and coarseness of the ridges
and paucity of cement to _Mastodon_ as to have been placed by some
zoologists in that genus. These form the subgenus called _Stegodon_ by
Falconer, and may be regarded as a distinct group of the genus.
Among the best known extinct Elephants is _E. primigenius_, the
Mammoth,[281] very closely resembling the existing Indian species, and
one of the most recently extinct and extensively distributed of all the
fossil forms. Probably no animal which has not survived to the historic
period has left such abundant and well-preserved evidence of its former
existence. The discovery of immense numbers, not only, as in the case
of most extinct creatures, in the form of fragmentary bones and teeth,
but often as more or less nearly entire carcases, or “mummies,” as they
may be called, with the flesh, skin, and hair _in situ_, in the frozen
soil of the tundras of Northern Siberia, has for a long time given great
interest to the species, and been the cause of many legendary stories
among the natives of the lands in which they occur. Among these one of
the most prevailing is that the Mammoth was, or still is, an animal which
passes its life habitually in burrows below the surface of the ground,
and immediately dies if by any chance it comes into the upper air.
Of the whole group the Mammoth is in many respects, as in the size and
form of the tusks, and especially the characters of the molar teeth,
the farthest removed from the primitive Mastodon-like type, while its
nearest surviving relative, _E. indicus_, has retained the slightly more
generalised characters of the Mammoth’s contemporaries of more southern
climes, _E. columbi_ of America, and _E. armeniacus_ of the Old World,
if, indeed, it can be specifically distinguished from them.
The tusks or upper incisor teeth were doubtless present in both sexes,
but probably of smaller size in the female. In the adult males they
often attained the length of from 9 to 10 feet measured along the outer
curve. Upon leaving the head they were directed at first downwards and
outwards, then upwards and finally inwards at the tips, and generally
with a tendency to a spiral form not seen in other species of Elephant.
Different specimens, however, present great variations in curve, from
nearly straight to an almost complete circle.
It is chiefly by the characters of the molar teeth that the various
extinct modifications of the Elephant type are distinguished. Those of
the Mammoth (Fig. 185) differ from the corresponding organs of allied
species in the great breadth of the crown as compared with the length,
the narrowness and close approximation of the ridges, the thinness of the
enamel and its straightness, parallelism, and absence of “crimping,”
as seen on the worn surface, or in a horizontal section of the tooth.
Dr. Falconer gave the prevailing “ridge-formula” as 4, 8, 12, 12, 16,
24. Dr. Leith Adams, working from more abundant materials, has shown,
however, that the number of ridges of each tooth, especially those at
the posterior end of the series, is subject to very great individual
variation, ranging in each tooth of the series within the following
limits: 3 to 4, 6 to 9, 9 to 12, 9 to 15, 14 to 16, 18 to 27, excluding
the small plates called talons at each end of the tooth. Besides these
variations in the number of ridges or plates of which each tooth is
composed, the thickness of the enamel varies so much as to have given
rise to a distinction between a “thick-plated” and a “thin-plated”
variety—the latter being most prevalent among the specimens from the
Arctic regions, and most distinctively characteristic of the species.
From the specimens with thick enamel plates the transition to the other
species or varieties mentioned above, including _E. indicus_, is almost
imperceptible.
[Illustration: FIG. 185.—Grinding surface of upper molar of the Mammoth
(_Elephas primigenius_). _c_, Cement; _d_, dentine; _e_, enamel. (From
Owen.)]
The bones of the skeleton generally more resemble those of the Indian
Elephant than of any other known species, but the skull differs in the
narrower summit, narrower temporal fossæ, and more prolonged incisive
sheaths required to support the roots of the enormous tusks. Among the
external characters by which the Mammoth was distinguished from either
of the existing species of Elephant was the dense clothing, not only
of long coarse outer hair, but also of close woolly under hair, of a
reddish-brown colour, evidently in adaptation to the colder climate
which it inhabited. This character, for a knowledge of which we are
indebted to the well-preserved remains found in Northern Siberia, is also
represented in the rude but graphic drawings of prehistoric age found in
caverns in the south of France.[282] In size different individuals varied
considerably, but the average height does not appear to have exceeded
that of either of the existing species of Elephant.
The geographical range of the Mammoth was very extensive. There is
scarcely a county in England in which some of its remains have not been
found either in alluvial deposits of gravel or in caverns, and numbers
of its teeth are from time to time dredged up from the bottom of the sea
by the fishermen who ply their trade in the German Ocean, having been
washed out of the water-worn cliffs of the eastern counties of England.
In Scotland and Ireland its remains are less abundant, but they have been
found in vast numbers at various localities throughout the greater part
of Central Europe (as far south as Santander in Spain and Rome), Northern
Asia, and the northern part of the American continent, though the exact
distribution of the Mammoth in the New World is still a question of
debate. It has not hitherto been met with in any part of Scandinavia or
Finland.
In point of time, the Mammoth belongs exclusively to the Pleistocene
epoch, and it was undoubtedly contemporaneous with man in France, and
probably elsewhere. There is evidence to show that it existed in Britain
before, during, and after the glacial period.
As before indicated, it is in the northern part of Siberia that its
remains have been found in the greatest abundance, and in quite
exceptional conditions of preservation. For a very long period there
has been from that region a regular export of Mammoth ivory in a state
fit for commercial purposes, both eastward to China and westward to
Europe. In the middle of the tenth century an active trade was carried
on at Khiva in fossil ivory, which was fashioned into combs, vases, and
other objects, as related by Abu’l Kásim, an Arab writer of that period.
Middendorff reckoned that the number of tusks which have yearly come into
the market during the last two centuries has been at least a hundred
pairs, and Nordenskiöld, from personal observation, considers this
calculation as probably rather too low than too high. They are found at
all suitable places along the whole line of the shore between the mouth
of the Obi and Behring Straits, and the farther north the more numerous
do they become, the islands of New Siberia being now one of the most
favourite collecting localities. The soil of Bear Island and of Liachoff
Islands is said to consist only of sand and ice with such quantities of
Mammoth bones as almost to compose its chief substance. The remains are
not only found around the mouths of the great rivers, as would be the
case if the carcases had been washed down from more southern localities
in the interior of the continent, but are imbedded in the frozen soil in
such circumstances as to indicate that the animals had lived not far from
the localities in which they are now found, and they are exposed either
by the melting of the ice in unusually warm summers or by the washing
away of the sea cliffs or river banks by storms or floods. In this way
the bodies of more or less nearly perfect animals, often standing in the
erect position, with the soft parts and hairy covering entire, have been
brought to light.
References to the principal recorded discoveries of this kind, and to the
numerous speculations to which they have given rise, both among ignorant
peasants and learned academicians, will be found in Nordenskiöld’s
_Voyage of the Vega_ (English translation, vol. i. 1881, p. 398 _sq._)
and a series of papers in the _Geological Magazine_ for 1880 and 1881,
by H. H. Howorth, as well as in a separate work on the Mammoth by the
same writer. For the geographical distribution and anatomical characters,
see Falconer’s _Palæontological Memoirs_, vol. ii. 1868; Boyd Dawkins,
“_Elephas primigenius_, its Range in Space and Time,” _Quart. Journ.
Geol. Soc._ xxxv. p. 138 (1879); and Leith Adams, “Monograph of British
Fossil Elephants,” part ii., _Palæontographical Society_ (1879).
_E. antiquus_, of the European Pleistocene, has a lower ridge-formula
than in the Mammoth, the molars being narrower, and approximating to
those of the African Elephant in structure. Small allied forms occur in
the rock-fissures and caverns of Malta, and have been described as _E.
mnaidriensis_ and _E. melitensis_; some of the individuals of the latter
not exceeding 3 feet in height. The European _E. meridionalis_ is a
southern form of somewhat earlier age, very common in the Upper Pliocene
of Italy and France, and also in the so-called Forest-bed of the Norfolk
coast. It attained very large dimensions, its height being estimated at
upwards of 15 feet. The ridge-formula is lower than in _E. antiquus_, the
molars are broad, with the worn enamel-discs generally expanded in the
middle, and the enamel itself is crenulated.
Elephant remains are very abundant in the Pleistocene and Pliocene
deposits of India, those from the latter beds being the oldest
representatives of the genus. Of these the Pleistocene _E. namadicus_
appears closely allied to _E. antiquus_, from which it is distinguished
by a bold ridge across the forehead. Among the Pliocene forms _E.
hysudricus_ may be an ancestral type allied to the Indian Elephant;
while _E. planifrons_ is closely related to _E. meridionalis_, although
retaining the ancestral feature of developing premolars.
The Stegodont group is peculiar to the eastern parts of the Old World,
and, as already observed, connects the true Elephants intimately with
the Mastodons. The molars (Fig. 179, II) are characterised by the
lowness of the ridges, while the intervening valleys may have but little
cement, and there may be a more or less distinct longitudinal groove
in the crown dividing each ridge into an inner and an outer moiety. In
species like _E. insignis_ the ridge-formula is nearly the same as in
_E. meridionalis_, but in _E. clifti_ some of the molars carry only six
ridges, and premolars were present, so that we thus have such a complete
transition to the next genus that it is very difficult to know where to
draw the line between the two.
_Mastodon._[283]—Dentition: _i_ ¹⁄₁₋₀, _c_ ⁰⁄₀, _dm_ ³⁄₃, _m_ ³⁄₃. Upper
incisors large, as in _Elephas_, sometimes with longitudinal bands of
enamel, more or less spirally disposed. Lower incisors variable; when
present comparatively small and straight, sometimes persistent, sometimes
early deciduous, and in some species never present. Grinding surface of
molars with transverse ridges, the summits of which are divided more
or less into conical or mammillary cusps, and often with secondary or
additional cusps between and clustering against the principal ridges;
enamel thick; cement very scanty, never filling up the interspaces
between the ridges. The third, fourth, and fifth cheek-teeth (_i.e._ the
last milk-molar, and the first and second molars) having the same number
of ridges,[284] which never exceeds five.
In the upper jaw the incisors, though of large size, were apparently
never so much curved as in some species of Elephant, and they often
have longitudinal bands of enamel, more or less spirally disposed upon
their surface, which are not met with in Elephants. Lower incisors were
present throughout life in some species, which have the symphysis of the
lower jaw greatly elongated to support them (as in _M. angustidens_, _M.
pentilici_, and _M. longirostris_). In the common North American species
(_M. americanus_) the mandibular symphysis is short, but it may have a
small incisor on one side. In other species no inferior tusks have been
found, at all events in adult life (see figure of _M. arvernensis_).
The molar teeth increase in size from before backwards, but as many as
three of these teeth may be in place in each jaw at one time. There is
in many species a true vertical succession, affecting either the third,
or the third and second, or (in _M. productus_) the first, second, and
third of the six molariform teeth. These three are therefore reckoned as
milk-molars, and their successors as premolars, while the last three,
which are never changed, correspond to the true molars of those animals
in which the typical dentition is fully developed. The study of the mode
of succession of the teeth in the different species of Mastodons is
particularly interesting, as it exhibits so many stages of the process
by which the very anomalous dentition of the modern Elephants may have
been derived by gradual modification from the typical heterodont and
diphyodont dentition of the ordinary mammal. It also shows that the
anterior molars of Elephants do not correspond to the premolars of other
Ungulates, but to the milk-molars, the early loss of which in consequence
of the peculiar process of horizontal forward-moving succession does
not require, or allow time for, their replacement by premolars. It must
be noted, however, that, in the Mastodon in some respects the least
specialised in tooth-structure, the _M. americanus_ of North America, no
vertical succession of the molars has yet been observed, although vast
numbers of specimens have been examined.
[Illustration: FIG. 186.—Restoration of the skeleton of _Mastodon
arvernensis_, from the Pliocene of Europe, (After Sismonda.)]
The Mastodons have fewer ridges on their molar teeth than the
Elephants; the ridges are also less elevated, wider apart, have a
thicker enamel-covering, and scarcely any cement filling up the space
between them. Sometimes (as in _M. americanus_) the ridges are simple
transverse wedge-shaped elevations, with straight or concave edges. In
other species the summits of the ridges are more or less subdivided into
conical cusps, and may have accessory cusps clustering around them (as
in _M. americanus_, see Fig. 187). When the apices of these are worn by
mastication, their surfaces present circles of dentine, surrounded by a
border of enamel, and as the attrition proceeds different patterns are
produced by the union of the bases of the cusps, a trilobed or trefoil
form being characteristic of some species (Fig. 188).
[Illustration: FIG. 187.—Oblique side and crown view of the last upper
molar of _Mastodon arvernensis_. (From Owens.)]
As already mentioned, certain of the molariform teeth of the middle of
the series in Mastodons have the same number of principal ridges, those
in front of them having fewer and those behind a greater number. These
teeth were distinguished as “intermediate” molars by Dr. Falconer, and
are three in number, namely the last milk-molar and the first and second
true molars (or the third, fourth, and fifth of the whole series). The
number of ridges on these intermediate molars is nearly always three or
four, and the tooth in front has usually one fewer and that behind one
more, so that the ridge-formula of most Mastodons can be reduced either
to 1, 2, 3, 3, 3, 4, or 2, 3, 4, 4, 4, 5. The former characterises the
section called _Trilophodon_ (of which an intermediate molar is shown in
Fig. 188), and the latter that called _Tetralophodon_ by Dr. Falconer.
These divisions are very useful, as under one or the other all the
present known species of Mastodon can be ranged, but observations upon a
larger number of individuals have shown that the number of ridges upon
the teeth is not quite so constant as implied by the formulæ given above.
Their exact enumeration is even difficult in many cases, as “talons” or
small accessory ridges at the hinder end of the teeth occur in various
stages of development, until they take on the character of true ridges.
Transitional conditions have also been shown, at least in some of the
teeth, between the trilophodont and the tetralophodont forms, and again
between the latter and what has been called a “pentalophodont” type,
which leads on towards the condition of dental structure characteristic
of the true Elephants.
[Illustration: FIG. 188.—Grinding surface of the partially worn last left
lower milk-molar of _Mastodon angustidens_, from the Upper Miocene of
India. The lower side of the figure is the outer border of the tooth.]
The range of the genus _Mastodon_ in time was from the middle of the
Miocene period to the end of the Pliocene in the Old World, when it
became extinct; but in America several species—especially the one best
known, owing to the abundance of its remains, which has been variously
called _M. americanus_, _M. ohioticus_, and _M. giganteus_—survived to a
late Pleistocene period.
The range in space will be best indicated by the following list
of some of the better known species. (1) Trilophodont series—_M.
angustidens_,[285] _borsoni_, _pentelici_, _turiensis_, from Europe; _M.
falconeri_ and _pandionis_, from India; _M. americanus_, _obscurus_, and
_productus_, North America; and _M. cordillerum_ and _humboldti_, South
America. (2) Tetralophodont series—_M. arvernensis_, _M. longirostris_,
from Europe; _M. latidens_, _sivalensis_, and _perimensis_, from
India; _M. mirificus_, from North America. _Mastodon arvernensis_ and
_M. longirostris_, together with a trilophodont species, occur in the
crag-deposits of Norfolk and Suffolk.
_Family_ DINOTHERIIDÆ.
An extinct family distinguished from the _Elephantidæ_ by the whole
series of permanent cheek-teeth being in use at the same time.
[Illustration: FIG. 189.—Skull of _Dinotherium giganteum_, from the
Lower Pliocene of Eppelsheim, Hessen-Darmstadt. (After Kaup.) _p_, 3, 4,
premolars; 1, 2, 3, molars.]
_Dinotherium._[286]—Dentition of adult: _i_ ⁰⁄₁, _c_ ⁰⁄₀, _p_ ²⁄₂,
_m_ ³⁄₃ = 22; all present at the same time, there being no horizontal
succession, but the premolars replacing milk-teeth in the ordinary
manner. The presence or absence of upper incisors has not yet been
clearly ascertained. Lower incisors large, conical, descending, and
slightly curved backwards, implanted in a greatly thickened and deflected
beak or prolongation of the symphysis. In section they do not show the
decussating striæ characteristic of Mastodons and Elephants. Crowns of
molars carrying strong transverse, crenulated ridges, with deep valleys
between, much resembling the lower ones of the Tapirs. Ridge-formula of
the permanent molar series: 2, 2, 3, 2, 2. The three ridges of the first
true molar are constant in both upper and lower jaws, although it is
quite an anomalous character among Proboscideans for this molar to have
more ridges than those which come behind it. The last milk-molar has also
three ridges, the penultimate but two. The cranium is much depressed,
with comparatively little development of air-cells. The remainder of
the skeleton is imperfectly known, but apparently agrees in its general
character with that of the other Proboscideans.
Remains of _Dinotherium giganteum_, an animal of elephantine proportions,
strikingly characterised by the pair of huge tusks descending nearly
vertically from the front of the lower jaw, were first discovered at
Eppelsheim, near Darmstadt, and described by Kaup. They have since been
met with in various Lower Pliocene and higher Miocene formations in the
south of Germany, France, Greece, and Asia Minor. Closely allied forms
also occur in the Lower Pliocene and Upper Miocene of India, but none are
known from America.
_Suborder_ AMBLYPODA.
_Uintatherium._[287]—Among the most remarkable of the comparatively
recent discoveries in the higher Eocene formations of the western
states of North America has been one of a group of animals of huge
size, approaching that of the largest existing Elephants, presenting a
combination of characters quite unlike those known among other recent or
extinct creatures, and of which there were evidently many species living
contemporaneously, but all of which became extinct before the close of
the Eocene period. To form some idea of their appearance, we must imagine
animals very elephantine in general proportions and in the structure of
their limbs. The feet had five short toes. The tail, as in the Elephants,
was long and slender, but the neck, though still short, was not so much
abbreviated as in the Proboscideans, and there is no evidence that these
animals possessed a trunk. The head differed greatly from that of the
Elephants, being long and narrow, more like that of a Rhinoceros, and,
as in that animal, was elevated behind into a great occipital crest,
and it had developed upon its upper surface three pairs of conspicuous,
laterally diverging protuberances—one pair in the parietal region,
one on the maxillaries in front of the orbits, and one (much smaller)
near the fore part of the elongated nasal bones. Whether these were
merely covered by bosses of callous skin, as the rounded form and
ruggedness of their extremities would indicate, or whether they formed
the bases of attachment for horns of still greater extent, like those
of the Rhinoceros or of the Cavicorn Ruminants, can only be a matter
of conjecture. There were no upper incisors, but usually three on each
side below, of comparatively small size, as was also the lower canine.
A huge, compressed, curved, sharp-pointed canine tusk, very similar in
form and position to that of the Musk-Deer, descended from each side of
the upper jaw. These were present in both sexes, but very much smaller
in the female, as was also the flange-like process of the lower jaw by
which they were guarded. Behind these, and at some distance from them,
were on each side above and below six cheek-teeth, of comparatively
small size, placed in continuous series, each with a pair of oblique
ridges conjoined internally and diverging externally in a V-like manner,
and provided with a stout basal cingulum. The normal dental formula was
therefore _i_ ⁰⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃ = 34; and the dentition had
thus already attained a remarkable degree of specialisation, although the
brain was smaller and more rudimentary in characters than in almost any
other known mammal. In its comparative length and the absence of a third
trochanter the femur of these animals resembles that of the Proboscidea.
The first discovered evidences of the existence of animals of this group
were described by Leidy in 1872, under the name of _Uintatherium_ (from
the Uinta mountains, near which they were found). Subsequently the
names _Dinoceras_, _Tinoceras_, _Loxolophodon_, etc., have been applied
to various members of the group, but the characters by which they are
distinguished do not seem of sufficient importance to allow of their
separation from the type genus _Uintatherium_.[288]
[Illustration: FIG. 190.—Skeleton of _Uintatherium mirabile_. ¹⁄₃₀
natural size. (From Marsh, _Am. Journ. Sci._ vol. xii. p. 2.)]
_Coryphodon._[289]—Another interesting form referred to this suborder is
_Coryphodon_, which appears to connect the _Uintatheriidæ_ with the most
primitive Perissodactyla. It was first described by Owen in 1846 from a
fragment of a jaw from the London Clay. Other remains were afterwards
discovered in France, and lately in great abundance, indicating many
species from the size of a Tapir to that of a Rhinoceros, in the Lower
and Middle Eocenes of New Mexico and Wyoming in the United States.
_Coryphodon_ had forty-four teeth; the canines of both jaws were large
and sharp pointed, and the molars had strongly pronounced oblique
ridges. The general proportions were those of a Bear, but the tail was
of moderate length, and the feet short and wide. The femur had a third
trochanter; and the cranium was devoid of protuberances. The genus should
be regarded as the type of a distinct family _Coryphodontidæ_.
[Illustration: FIG. 191.—Palatal aspect of the cranium of _Coryphodon
hamatus_, from the Wasatch Eocene of New Mexico. ²⁄₉ natural size. (After
Cope.)]
_Suborder_ CONDYLARTHRA.
The term Condylarthra has been proposed by Professor Cope for a number
of generalised and mostly comparatively small Ungulates, which were
probably allied both to the Perissodactyla and Artiodactyla, but present
characters separating them from those divisions as commonly defined. In
the structure of the carpus and tarsus these forms (which are chiefly
known to us from the Eocene of the United States) come nearer to the
Hyracoidea than to any other existing type. As a rule they have the full
dental formula; the molars are brachydont, generally bunodont, and in
many instances also tritubercular; while the premolars are always simpler
than the molars.
The humerus is quite peculiar among Ungulates in having an entepicondylar
foramen; the femur has a third trochanter; and the form and relations of
the astragalus are similar to those obtaining in the Carnivora. The feet
are usually furnished with five functional digits, of which the ungual
phalanges are pointed. In many respects the skeleton of these remarkably
generalised Ungulates approximates so decidedly to a Carnivorous type as
to have led palæontologists to conclude that the Ungulata and Carnivora
are branches of an original common stock.
In this work space only permits of allusion to a few of the more
important types of this group. _Periptychus_, which occurs in the lowest
Eocene of New Mexico, is a bunodont type readily distinguished by the
vertical flutings of the premolars, and the small size of the incisors
and canines. It has been suggested that this genus is closely related to
the stock of the bunodont Artiodactyla. Of greater interest is the genus
_Phenacodus_, which is regarded as the lowest factor in the series from
which the modern Horse has been evolved, where it holds the position
immediately below _Hyracotherium_ or, _Systemodon_ (see p. 374). One of
the species was about the size of a Bull-dog, while another might be
compared to a small Leopard. The structure of the cheek-teeth is such
as might readily be modified into that obtaining in _Hyracotherium_;
all the feet had five fully developed digits, and the tail was long.
_Meniscotherium_ and _Hyracodontotherium_ are more specialised forms of
somewhat later age, with a lophodont dentition: the latter genus being
European.
_Suborder_ TOXODONTIA.
In addition to the _Macraucheniidæ_ and certain other forms noticed
under the head of the Perissodactyla, the Tertiaries of South America
have yielded some very remarkable forms of mammalian life, the nature
and affinities of which have greatly puzzled all zoologists who have
attempted to unravel them.
_Nesodon_ and _Toxodon_.—Among these _Nesodon_, from Patagonia, has the
full typical Eutherian number of teeth; the crowns of the incisors being
short, and the molars having a complex rhinocerotic type of structure
somewhat intermediate between _Homalodontotherium_ (p. 412) and the
following genus _Toxodon_. The typical species of _Nesodon_ was about
as large as a Sheep, but nothing more is known of it than the teeth and
portions of the skull.
_Toxodon_ is an animal about the size of a Hippopotamus; it was first
discovered by Darwin, and many specimens have since been found in
Pleistocene deposits near Buenos Ayres, and described by Owen, Gervais,
and Burmeister. The teeth consist of large incisors, very small lower
canines, and strongly curved molars, all with persistent roots, the
formula being apparently _i_ ²⁄₃, _c_ ⁰⁄₁, _p_ ⁴⁄₃, _m_ ³⁄₃ = 38.
The cranial characters exhibit a combination of those found in both
Perissodactyles and Artiodactyles, but the form of the hinder part of the
palate and the absence of an alisphenoid canal belong to the latter; and
the tympanic, firmly fixed in between the squamosal and the exoccipital,
ankylosed to both, and forming the floor of a long upward-directed meatus
auditorius, is so exactly like that of the Suina that it is difficult
to believe it does not indicate some real affinity to that group. These
characters seem to outweigh in importance those by which some zoologists
have linked _Toxodon_ to the Perissodactyla, and the absence of the third
trochanter and the articulation of the fibula with the calcaneum tell in
the same direction. According to the recent observations of Ameghino the
hind feet were certainly tridactylous, and the front feet probably so.
The earlier allied genera _Protoxodon_ and _Adinotherium_ are definitely
known to have tridactylous front and hind feet, which conform to the
Perissodactylate type, the bones of the proximal and distal rows of the
carpus interlocking. _Acrotherium_, which has similar feet, differs
from all other Ungulates, and indeed from all Eutherians except some
individuals of the existing carnivorous genus _Otocyon_, in having eight
cheek-teeth, five of which have been reckoned as premolars.
[Illustration: FIG. 192.—Cranium and Lower Jaw of _Typotherium
cristatum_. ¹⁄₃ natural size. From Gervais.]
_Typotherium._—_Typotherium_ (Fig. 192), also called _Mesotherium_,
from the same locality as _Toxodon_, was an animal rather larger than
a Capybara, and of much the same general appearance. Its skeleton is
completely known, and shows a singular combination of characters,
resembling _Toxodon_ or a generalised Ungulate on the one hand, and the
Rodents, especially the _Leporidæ_, on the other. In the presence of
clavicles it differs from all known Ungulates, and in having two pairs of
lower incisors from all Rodents. The teeth are _i_ ¹⁄₂, _c_ ⁰⁄₀, _p_ ²⁄₁,
_m_ ³⁄₃ = 24.
From the Tertiaries of various parts of South America a number of forms
more or less closely allied to _Toxodon_ and _Typotherium_ have been
recently described, but as many of them are very imperfectly known, and
there is much doubt as to their generic position, it will be unnecessary
to refer to them further.
It will thus be seen that, although our knowledge of many of these
forms is still very limited, we may trace among them a curious chain of
affinities, which would seem to unite the Ungulates on the one hand with
the Rodents on the other; but further materials are required before we
can establish with certainty so important a relationship, one which,
if true, would alter materially some of the prevailing views upon the
classification of mammals.
_Group_ TILLODONTIA.
[Illustration: FIG. 193.—Skull of _Tillotherium fodiens_. ⅙ natural size.
From Marsh.]
Here may be noticed a remarkable group of animals, called by Marsh,
Tillodontia, the remains of which are found abundantly in the Lower and
Middle Eocene beds of North America. They seem to combine the characters
of the Ungulata, Rodentia, and Carnivora. In the genus _Tillotherium_ of
Marsh (probably identical with the previously described _Anchippodus_ of
Leidy) the skull (Fig. 193) resembled that of the Bears, but the molar
teeth were of the Ungulate type, while the large incisors were very
similar to those of the Rodents. The dental formula is _i_ ²⁄₂, _c_ ¹⁄₁,
_p_ ³⁄₄, _m_ ³⁄₃. The first pair of incisors was very small; the upper
molars were tritubercular, while the lower ones had crescentoid ridges as
in _Palæotherium_. The skeleton resembled that of the Carnivores, but the
scaphoid and lunar bones were distinct, and there was a third trochanter
on the femur. The feet were plantigrade, and each had five digits, all
with long pointed claws. In the allied genus _Stylinodon_ all the teeth
were rootless. Some forms were as large as a Tapir.
These, with other more or less closely allied animals, such as
_Calamodon_ and _Psittacotherium_, constituting a group called
Tæniodonta, are included by Cope in his large order Bunotheria, to which
also the existing Insectivora are referred. The dentition of some of
these forms makes a remarkable approximation towards a Rodent type,
while it has been suggested that there are also signs of remote Edentate
affinities. The constantly increasing knowledge of these annectant forms
adds to the difficulty so often referred to in this work of establishing
anything like a definite classification of the heterodont mammals.
An incisor tooth from the Swiss Eocene has recently been referred to
_Calamodon_.
_Bibliography of Ungulata._—In addition to the works and
memoirs mentioned under the different sections of the order,
the following may be referred to:—W. Kowalevsky, “Monographie
des genus Anthracotherium,” _Palæontographica_ 1873; Id. “Sur
l’Anchitherium aurelianense et sur l’histoire paléontologique
des Chevaux,” _Mém. de l’Acad. Imp. des Sciences de St.
Pétersbourg_, 1873; Id. “On the Osteology of the Hyopotamidæ,”
_Philosophical Transactions_, 1873; L. Rütimeyer, “Versuch
einer natürlichen Geschichte des Rindes.” etc., _Neue Denks.
der allgem. Schweiz. Gesellsch. für Naturwissenschaften_, 1867;
Id. “Die Rinder der Tertiär-Epoche,” _Abhand. der Schweiz.
Paläont. Gesellsch._ 1877 and 1878; Id. “Beiträge zu einer
Natürliche Geschichte der Hirsche,” _ibid._ 1880-1881; C. J.
Forsyth-Major, “Beiträge zur Geschichte der Fossilen Pferde,”
_ibid._ 1880; M. Schlosser, “Beiträge zur Kenntniss der
Stammesgeschichte der Hufthiere und Versuch einer Systematik
der Paar- und Unpaarhufer,” _Morph. Jahrb._ 1886; E. D. Cope,
“The Perissodactyla,” _Amer. Natural._ 1887; M. Pavlow, “Études
sur l’histoire paléontologique des Ongulés,” _Bull. Soc. Imp.
Naturalistes Moscow_, 1887-1890. W. B. Scott and H. F. Osborn,
“The Mammalia of the Uinta Formation,” _Trans. Amer. Phil.
Soc._ vol. xvi. (1889).
CHAPTER X
THE ORDER RODENTIA
The Rodentia, or Rodents, form a well-defined order, readily
distinguished by their large scalpriform incisors and the absence of
any trace of canines. The existing forms are mostly of comparatively
small size, and are generally of terrestrial habits, although a few are
arboreal or natatorial. The dentition is diphyodont; the mandible never
has more than a single pair of incisors; the premolars are always below
the full number, being very generally ¹⁄₁, or altogether wanting. The
feet are plantigrade or semi-plantigrade, generally with five digits,
and usually unguiculate, although occasionally of a subungulate type.
Clavicles are present as a rule, although they may be imperfect or
rudimentary.
The upper incisors resemble the lower in growing uninterruptedly from
persistent pulps, and, except in the suborder Duplicidentata, agree with
them in number; the premolars and molars may be rooted or rootless, with
tuberculated or laminated crowns, and are arranged in an unbroken series.
The orbits communicate freely with the temporal fossæ; the condyle of the
mandible is elongated in the antero-posterior direction, and, through the
absence of a post-glenoid process to the squamosal, admits of a backward
and forward motion of the jaw. The intestine (except in the _Myoxidæ_)
has a large cæcum; the testes are inguinal or abdominal; the uterus is
two-horned, the cornua either opening separately into the vagina or
uniting to form a corpus uteri; the placenta is discoidal and deciduate;
and the smooth cerebral hemispheres do not extend backwards so as to
cover any part of the cerebellum.
[Illustration: FIG. 194.—Skull of _Hystrix cristata_ (juv.) _t_, Temporal
muscle; _m_, masseter; _m′_, portion of masseter transmitted through
the infraorbital foramen, the superior maxillary nerve passing outwards
between it and the maxillary bone.]
The Rodents include by far the greatest number of species, and have the
widest distribution of any of the orders of terrestrial mammals, being in
fact cosmopolitan, although more abundant in some parts than in others.
The total number of known existing species exceeds 900. South America may
be regarded as their headquarters at the present day; while in Australia
and Madagascar they are represented only by a few genera. All the Rodents
are exclusively herbivorous, and the whole of them gather their food
by gnawing. They present considerable diversity of habits. Thus the
Squirrels are arboreal, and some of them provided with a parachute for
taking flying leaps from tree to tree; the Hares are cursorial; the
Jerboas agile jumpers; the Mole-Rats fossorial; while the Beavers and
Water-Voles are aquatic. In spite, however, of this diversity of habits
the Rodents present a remarkable similarity in general structure; so
much so, indeed, that the characters employed for distinguishing the
various families and genera are comparatively trivial, and of slight
structural importance. The skull of the Rodents is characterised by the
invariable presence of the zygomatic arch, of which the middle portion
is formed by the jugal (Fig. 7, p. 37); and, as already mentioned, the
orbit communicates freely with the temporal fossa. There is invariably
a long diastema separating the incisors from the cheek-teeth; and, with
the exception of the Duplicidentata, the glenoid cavity of the squamosal
is elongated antero-posteriorly. Postorbital processes of the frontals
exist only in the Squirrels, Marmots, and Hares; in all other genera they
are rudimentary or altogether absent; the zygoma never sends upwards a
corresponding process; the lachrymal foramen is always within the orbital
margin; in many species the infraorbital foramen is very large (in some
as large as the orbit), and transmits part of the great masseter muscle
(Fig. 194, _m_), by means of which the jaws are worked. The zygomatic
arch varies in its degree of development, and the position of the jugal
therein is used as a distinguishing character for grouping the families;
the nasals are, with few exceptions, large, and extend far forwards; the
parietals are moderate, and there is generally a distinct interparietal.
The palate is narrow from before backwards—this being especially
pronounced in the Hares, where it is reduced to a mere bridge between the
premolars; while in other cases, as in the Mole-Rats (_Bathyerginæ_), it
is extremely narrow transversely, its width being less than that of one
of the molar teeth. Auditory bullæ are always present, and generally
large; in some genera, as in the Gerbilles and Jerboas, there are also
supplemental mastoid bullæ forming great hemispherical bony swellings at
the back of the skull (see Fig. 7, _Per_); and in these genera, and in
the true Hares, the meatus auditorius is tubular and directed upwards
and backwards. The mandible is characterised by the abruptly narrowed
and rounded symphysial part supporting the large incisors, as well as by
the small size of the coronoid process and the great development of the
angular portion.
The dental formula varies from _i_ ²⁄₁, _c_ ⁰⁄₀, _p_ ³⁄₂, _m_ ³⁄₃ (total
28) in the Duplicidentata to _i_ ¹⁄₁, _c_ ⁰⁄₀, _p_ ⁰⁄₀, _m_ ²⁄₂ (total
12) in _Hydromys_, _Xeromys_, and one species of _Heterocephalus_; but
in the great majority of forms it is very constant, _i_ ¹⁄₁, _c_ ⁰⁄₀,
_p_ ⁰⁻¹⁄₀₋₁, _m_ ³⁄₃ being very typical. Only in the Duplicidentata is
there a second pair of upper incisors, which are of very small size, and
situated immediately behind the large normal pair. This group is also
peculiar in that the enamel of the incisors is not confined to their
anterior surfaces, but extends partially on to their sides. It is by
reason of the thick layer of enamel on their anterior surface and its
absence from the posterior surface that the incisors maintain their
sharp chisel-like edge, which is so essentially characteristic of the
order. Both the upper and the lower incisors are regularly curved—the
curvature being somewhat greater in the upper ones—and since they grew
continuously from persistent pulps, it is quite evident that should any
accident, such as the loss of one of them, or displacement by fracture
of the jaw, prevent the regulation of the length by attrition against
one another, the unopposed tooth will gradually curve upon itself until
a complete circle or more has been formed, the tooth, perhaps, passing
during its growth through some part of the animal’s head. The molars, as
already mentioned, may be rooted or rootless, tuberculated or laminated;
this diversity of structure occurring even in the same family. When there
are more than three cheek-teeth those in front of the last three have
succeeded milk-teeth, and must therefore be considered premolars. In some
species, as in the Agoutis (_Dasyproctidæ_), the milk-teeth are long
retained, while in the allied Cavies (_Caviidæ_) they are shed before
birth.
[Illustration: FIG. 195.—Vertical and longitudinal section through
skull of the Beaver (_Castor fiber_) showing the cerebral cavity, the
greatly developed turbinal lamellæ, the mode of implantation of the large
incisor, and the curved, rootless molars.]
There are generally nineteen dorso-lumbar vertebræ (thirteen dorsal and
six lumbar), their form varying in the different genera. In the cursorial
and leaping species the lumbar transverse processes are generally
very long, and in the Hares there are large compressed hypapophyses.
The caudal vertebræ exhibit great variety in structure, being in a
rudimentary condition in the Guinea-Pig, while in the Jumping Hares
and prehensile-tailed Porcupines they are of very large dimensions.
The scapula is usually narrow, with a long acromion; the clavicles may
be altogether absent or imperfect, as in the Porcupines, Cavies, and
Hares, but in most species they are well developed. In all existing
forms the humerus has no entepicondylar foramen, and the radius and
ulna are distinct. In most species the manus has five digits, with
phalanges normally developed; the pollex being rarely rudimentary or
absent. The pelvis has well-developed ischia and pubes, meeting in a
long, and usually bony, symphysis. The femur varies considerably in form,
but generally has a well-defined third trochanter; in the Sciurine and
Hystricine Rodents the tibia and fibula are distinct, but in the Rats
and other Murines, and in the Hares, these bones are united, often high
up; the pes is much more variable than the manus, the digits varying
in number from five, as in the Squirrels and Rats, to four, as in the
Hares, or even three, as in the Capybara, Viscacha, and Agouti; in the
_Dipodidæ_ the metatarsals are greatly elongated, and in some of the
species, as in the Jerboas, they are ankylosed together.
The mouth is divided into two cavities communicating by a constricted
orifice, an anterior one containing the large incisors, and a posterior
one in which the molars are placed; the hairy integument of the face
being continued inwards behind the incisors. This peculiar arrangement
evidently prevents substances not intended for food getting into the
mouth, as when the animal is engaged in gnawing through an obstacle.
In the Hares and Pacas the inside of the cheeks is hairy, and in some
species, as in the Pouched Rats and Hamsters, there are large internal
cheek-pouches lined with the hairy integument, which open near the angles
of the mouth and extend backwards behind the ears. In the New World
Pouched Rats (_Geomyidæ_) the pouches open externally on the cheeks. The
tongue presents little variability in length, being always short and
compressed, with an obtuse apex never protruded beyond the incisors. In
most species there are three circumvallate papillæ at the base; and the
apical portion is generally covered with small filiform papillæ, some
of which in the Porcupines (_Hystrix_) become greatly enlarged, forming
toothed spines. The stomach varies in form from the simple oval sac of
the Squirrel to the complex ruminant-like organ of the Lemming. In the
Water-Vole (_Arvicola amphibius_) and the Agouti (_Dasyprocta aguti_)
it is strongly constricted between the œsophagus and pylorus. In the
common Dormouse the œsophagus immediately before entering the stomach is
much dilated, forming a large egg-shaped sac with thickened glandular
walls; and in some other species, as in _Lophiomys imhausi_ and in the
Beaver, glandular masses are attached to and open into the cardiac or
pyloric pouches. The alimentary canal (Fig. 196) of all Rodents, with
the exception of the Dormice (_Myoxidæ_), has a cæcum, which is often
of great length and sacculated, as in the Hares, Water-Voles, and
Porcupines. In some instances, as in the Hamster and Water-Vole, the long
colon is spirally twisted upon itself near its commencement. The liver is
typically divided in all, but the lobes are variously subdivided in the
different species (in _Capromys_ they are divided into minute lobules);
and the gall-bladder, though present in most, is absent in a few. In most
species the penis (which is generally provided with a bone) can be more
or less completely retracted within the fold of integument surrounding
the anus, where it lies curved backwards upon itself under cover of the
integument. It may, however, be carried forward some distance in front
of the anal orifice, from which in the breeding season, as in the Voles
and Marmots, the prominent testicular mass separates it. The testes
in the rutting season form projections in the groins, but (except in
the Duplicidentata) do not completely leave the cavity of the abdomen.
Prostatic glands and, except in the Duplicidentata, vesiculæ seminales
are present in all. The uterus may be double, each division opening by
a separate aperture into a common vagina, as in _Leporidæ_, _Sciuridæ_,
and _Hydrochœrus_, or completely two-horned, as in most species. The
mammæ vary in number and position from the single abdominal pair of the
Guinea-Pig to the ten thoracico-abdominal pairs found in some of the
Rats. In the _Octodontidæ_ the mammæ are placed high up on the sides of
the body.
[Illustration: FIG. 196.—Alimentary canal of Rat (_Mus decumanus_), the
greater part of the small intestine being omitted. _o_, Œsophagus; _d_,
duodenum; _i_, ileum; _cm_, cæcum; _c_, colon.]
The peculiar odour evolved by many Rodents is due to the secretions of
special glands, which may open either into the prepuce, as in _Mus_,
_Arvicola_, _Cricetus_, etc., or into the rectum, as in _Arctomys_ and
_Aulacodus_ or into the passage common to both, as in the Beaver, or
again, into pouches opening near the anus, as in the Hare, Agouti, and
Jerboa.
The integument is generally thin, and the panniculus carnosus (the sheet
of muscle underlying the skin) rarely much developed. The fur varies
exceedingly in character. Thus it may be very fine and soft, as in the
Chinchillas and Hares, in others more or less replaced by spines on the
upper surface, as in the Spiny-Rats and Porcupines; in several genera, as
in _Xerus_, _Acanthomys_, _Platacanthomys_, _Echinothrix_, _Loncheres_,
and _Echinomys_, the spines are flattened. In the muscular structures
the chief peculiarities are noticeable in the comparatively small size
of the temporal muscles, and in the great double masseters (Fig. 194),
which are the principal agents in gnawing; the digastrics also are
remarkable for their well-defined central tendon, and in many species
their anterior bellies are united between the mandibular rami; the
cleidomastoid generally arises from the basioccipital, and the pectoralis
major is connected with the latissimus dorsi; in the Porcupines and Hares
the tendons of the flexor digitorum longus and flexor hallucis longus are
connected in the foot, while in the Rats and Squirrels they are separate,
and the flexor digitorum longus is generally inserted into the metatarsal
of the hallux.[290]
Rodents are tolerably well represented in a fossil condition from the
period of the Upper Eocene, while if _Decticadapis_, of the Lower Eocene
of Rheims, is rightly referred to it the order dates from the oldest
Tertiary. All the fossil forms at present known are, however, essentially
true Rodents, and afford no clue as to the relations of the order with
other mammals. The remote affinities of the Rodents to the Proboscidea,
as well as their more marked resemblances to _Typotherium_, have been
already mentioned. Whether there is a real genetic affinity (as Professor
Cope suggests) with the Tillodontia cannot be decided with the evidence
at present available.
_Suborder_ SIMPLICIDENTATA.
Only one pair of upper incisors, having their enamel confined to their
front surfaces. Incisive foramina moderate and distinct; fibula not
articulating with the calcaneum. Testes abdominal, and descending
periodically only into a temporary sessile scrotum.
_Section_ SCIUROMORPHA.
Zygomatic arch slender, chiefly formed by the jugal, which is not
supported by a long maxillary process extending backwards beneath it;
postorbital processes of frontal present or absent; infraorbital opening
small (except in _Anomalurus_); mandible with the angular part arising
from the inferior surface of the bony socket of the lower incisor;
clavicles well developed; fibula distinct.
_Family_ ANOMALURIDÆ.
Arboreal forms, having their limbs connected by a cutaneous expansion
supported by a cartilaginous process arising from the olecranon; tail
long and hairy, with large imbricated scales on its inferior surface
near the root; sixteen pairs of ribs; no postorbital processes on the
frontals; _p_ ¹⁄₁; molars not tuberculate, with transverse enamel-folds.
Confined to the Ethiopian region.
[Illustration: FIG. 197.—_Anomalurus fulgens._ From Alston, _Proc. Zool.
Soc._ 1875.]
_Anomalurus_,[291] with several species from West and Central Africa,
alone represents the family. The peculiar caudal scales, which evidently
assist the animal in climbing, and the position of the cartilaginous
support of the parachute, are well shown in Fig. 197. All the species
but two are from Western Africa; _A. orientalis_ occurs near Zanzibar,
and _A. pusillus_ is from the equatorial regions of that continent.
According to Mr. O. Thomas,[292] the latter “little animal is most nearly
allied to the West-African _A. beecrofti_, but differs from that species
in its duller and less yellow upper side, in the entire absence of rufous
on its neck and belly, and, as from all the other described species, in
its diminutive size.”
_Family_ SCIURIDÆ.
Arboreal or terrestrial forms, with cylindrical hairy tails, without
scales, and with twelve or thirteen pairs of ribs. Skull (Figs. 198, 199)
with distinct postorbital processes; infraorbital opening small; palate
broad; _p_ ²⁄₁; first upper premolar very small or deciduous; molars
rooted, tubercular.
Subfamily =Sciurinæ=.—Incisors compressed; form slender; tail long and
hairy. Cosmopolitan (excluding Australian region).
[Illustration: FIG. 198.—Lateral view of skull of American Marmot
(_Arctomys monax_).]
This subfamily includes the true Squirrels, of which seven existing
genera are usually recognised.
_Sciurus._[293]—Tail long and bushy; ears generally well developed,
pointed, often tufted; feet adapted for climbing, the anterior having
four digits and a rudimentary pollex, and the posterior with five digits,
all of which have long, curved, and sharp claws. Mammæ, from four to
six. Skull (Fig. 199) lightly built, with long postorbital processes.
Penultimate upper premolar, when present, minute.
[Illustration: FIG. 199.—Palatal Aspect of cranium of Squirrel (_Sciurus
bicolor_). Natural size.]
True Squirrels are found in most of the temperate and tropical regions of
the world, exclusive of Madagascar and the Australian region. They are,
however, most abundant in the Malayan part of the Oriental region, and
attain their largest size and most brilliant coloration in the tropics.
Their size is very variable, so that whereas _S. soricinus_, of Borneo,
is no larger than a Mouse, _S. bicolor_, of the Malayan region, is nearly
as large as a Cat. The common English Squirrel (_S. vulgaris_) is found
over the whole of the Palæarctic region, reaching in one direction from
Ireland to Japan, and in the other from the north of Italy to Lapland;
its remains occur in the Norfolk “Forest-bed.” In the Malayan region
“nearly all the numerous species are brilliantly marked, and many are
ornamented with variously coloured longitudinal stripes along their
bodies. One of the commonest and best known of the striped species is
the little Indian Palm-Squirrel (_S. palmarum_), which in large numbers
runs about every Indian village. Another Oriental species (_S. caniceps_)
presents almost the only known instance among mammals of the temporary
assumption during the breeding season of a distinctly ornamental coat,
corresponding to the breeding-plumage of birds. For the greater part of
the year the animal is of a uniform gray colour; but about December its
back becomes a brilliant orange-yellow, which lasts until about March,
when it is again replaced by gray. The Squirrel shown in Fig. 200 is a
native of Burma and Tenasserim, and is closely allied to _S. caniceps_,
but goes through no seasonal change of colour.
[Illustration: FIG. 200.—Burmese Squirrel (_Sciurus pygerythrus_). After
Anderson.]
“The number of species in the genus is about 75, of which 3 belong to the
Palæarctic, 15 to the Ethiopian, about 40 to the Oriental, and 16 to the
combined Nearctic and Neotropical regions” (Thomas).
Fossil species referred to _Sciurus_ are found in the European Tertiaries
down to the Phosphorites of Central France, while others occur in the
White River Miocene of the United States.
_Rhithrosciurus._[294]—A very striking Squirrel, confined to Borneo,
and as yet only known from three or four examples, has been separated
generically under this name. The general shape of its skull is
very different from that of other Squirrels; but its most peculiar
characteristic is the presence of from seven to ten minute parallel
vertical grooves running down the front face of its incisors; no other
Squirrel having really grooved incisors, and no other member of the
whole order incisive grooves resembling these. Its premolars number ¹⁄₁,
and its molars are simpler and less ridged than in the other genera.
This Squirrel (_R. macrotis_) is far larger than the English, with an
enormously long bushy tail, long tufted ears, and black and white bands
down its sides.
_Xerus._[295]—Fur coarse and spiny. Claws long and comparatively
straight. Ear-conchs minute or absent. Skull with the postorbital
processes short and directed backwards, the bony palate prolonged
considerably behind the tooth-row, and the external ridge on the front
face of the anterior zygomatic root more developed, and continued much
farther upwards than in _Sciurus_. Premolars ²⁄₁; molars as in _Sciurus_.
Mammæ two. This genus contains four well-marked species, known as Spiny
Squirrels, all natives of Africa. They are terrestrial in their habits,
living in burrows which they dig for themselves. _X. getulus_, a striped
species of North Africa, has much the size and appearance of the Indian
Palm-Squirrel; all the others are a little larger than the English
Squirrel.
_Tamias._[296]—All the members of this genus are characterised by the
possession of internal cheek-pouches, and by their style of coloration;
being ornamented on the back with alternate light and dark bands. Their
skulls are slenderer and lighter than those of the true Squirrels, from
which they differ in several unimportant details. There is only one
functional premolar—the small anterior one usually found in _Sciurus_
being either absent altogether or quite small and functionless. There
are some four well-defined species, all found in North America, one (_T.
asiaticus_) extending also through Siberia into Eastern Europe.[297]
They are generally known as Ground-Squirrels, but in America, where
they are among the commonest and best known of the indigenous Rodents,
as “Chipmunks.” The members of this genus seem to lead into the genus
_Spermophilus_, so that the division of the _Sciuridæ_ into two
subfamilies, although convenient for classification, is rather artificial.
Remains of _Tamias_, probably belonging to existing species, occur in the
Pleistocene deposits of Europe and Nebraska.
_Pteromys_[298] and _Sciuropterus_.[299]—The Flying Squirrels, although
incapable of true flight, can yet float through the air for considerable
distances by the aid of an extension of skin connecting their fore and
hind limbs, and forming a sort of parachute. This parachute is merely a
lateral extension of the ordinary skin of the body, which passes outwards
between the limbs and terminates at the wrists and ankles. In addition
to the lateral membrane there is a narrow and inconspicuous one passing
from the cheek along the front of the shoulder to the front of the wrist,
and another—at least in the larger species—stretching across behind the
body from ankle to ankle and involving the base of the tail. The Flying
Squirrels are divided into three genera. Of those with a normal dentition
_Pteromys_ contains the larger and _Sciuropterus_ the smaller species.
The two differ in certain details of dentition, as well as in the greater
development in the former of the expanded membranes, especially of the
“interfemoral” or posterior membrane, which in the latter is almost
wholly absent. In _Pteromys_ the tail is cylindrical and comparatively
thin, while in _Sciuropterus_ it is broad, flat, and laterally expanded,
and evidently compensates for the absence of the interfemoral membrane
by acting as a supplementary parachute. In appearance Flying Squirrels
resemble the other forms, although they are even more beautifully
coloured. Their habits, food, etc., are also very similar to those of the
true Squirrels, except that they are more decidedly nocturnal, and are
therefore less often seen by the traveller; their peculiar shrill cry
is, however, well known to all who have camped out in the regions which
they inhabit. Their mode of flight is precisely similar to that of the
Flying Phalangers of Australia. Of each of the two genera there are about
thirteen or fourteen species, all natives of the Oriental region, except
that one of _Sciuropterus_ is found in North America, and another in
Siberia and Eastern Europe.
_Eupetaurus._[300]—Externally as in _Pteromys_, except that the claws
are less sharp. Skull with a more produced muzzle than in the latter,
more distinct supraorbital notches, longer anterior palatal foramina,
and a shorter bony palate. Cheek-teeth differing from those of all
other _Sciuridæ_ in their hypsodont character. One large species (_E.
cinereus_), from Gilgit and adjacent districts on the extreme north-west
of Kashmir territory. This fine Flying Squirrel is chiefly known by one
entire specimen and some imperfect skins.
_Extinct Genera._—The genera _Pseudosciurus_ and _Sciuroides_, from the
Upper Eocene of Europe, have the molar teeth more elongated than in
_Sciurus_. _Gymnoptychus_ with _p_ ¹⁄₁, from the North American Miocene,
approximates in the structure of its molars to _Tamias_. _Meniscomys_
(_p_ ²⁄₁), from the latter deposits, together with _Sciurodon_ of the
French Phosphorites, are regarded as Squirrels showing signs of affinity
with the _Haplodontidæ_.
Subfamily =Arctomyinæ=.—Incisors not compressed; typically the form
stout, and the tail comparatively short. This subfamily comprises
burrowing forms which may be collectively known as Marmots; as already
mentioned, they are so intimately connected with the preceding subfamily
that the division into two groups is purely a matter of convenience. They
are confined to the Palæarctic and Nearctic regions.
_Arctomys._[301]—External form stout and heavy, ears short, tail short
and hairy, cheek-pouches rudimentary or absent. Fore feet with four
well-developed digits, and a rudimentary pollex provided with a flat
nail. Skull (Fig. 198) large and heavy, with the postorbital process
stout, and at right angles to the axis. Incisors broad and powerful.
First upper premolar nearly as large as the second. Molar series nearly
parallel, scarcely converging behind at all.
The various species of true Marmot, which exceed a dozen in number, are
all much alike in general appearance, ranging in size from about 15 to 25
inches in length, with tails from 3 to 12 inches long.
The Alpine Marmot (Fig. 201) is peculiar to Europe, being found in
the Alps, Pyrenees, and Carpathians; its remains occur in European
Pleistocene deposits. _A. bobac_ occurs in Eastern Europe and Siberia.
Several species (_e.g._ _A. monax_, Fig. 198) are found in the Nearctic
region, and many in Kashmir and Central Asia. The long-tailed Red Marmot
(_A. caudatus_) is a fine Himalayan species, which may be seen on the
mountain passes to the north of the valley of Kashmir, as soon as the
snow begins to disappear, sitting at the entrance to its burrow, which is
generally beneath a rhubarb plant.
[Illustration: FIG. 201.—Alpine Marmot (_Arctomys marmotta_). After
Brehm.]
The following account of the habits of the Alpine Marmot is given by
Professor Blasius: “Marmots live high up in the snowy regions of the
mountains, generally preferring exposed cliffs, whence they may have a
clear view of any approaching danger, for which, while quietly basking
in the sun or actively running about in search of food, a constant watch
is kept. When one of them raises the cry of warning, the loud piercing
whistle so well known to travellers in the Alps, they all instantly take
to flight and hide themselves in holes and crannies among the rocks,
often not reappearing at the entrance of their hiding-places until
several hours have elapsed, and then frequently standing motionless on
the look-out for a still longer period. Their food consists of the roots
and leaves of various Alpine plants, which, like squirrels, they lift to
their mouths with their fore paws. For their winter quarters they make a
large round burrow, with but one entrance, and ending in a sleeping-place
thickly lined with hay. Here often from ten to fifteen Marmots pass the
winter, all lying closely packed together fast asleep until the spring.”
_Cynomys._[302]—Size and form intermediate between _Arctomys_ and
_Spermophilus_. Ears and tail short. Cheek-pouches shallow. Fore feet
with five claws, that on the pollex as large as that on the fifth toe.
Skull (Fig. 202) heavily built, with the postorbital processes directed
outwards. Dentition (as shown in Fig. 202) remarkably heavy, the molar
teeth differing from those of _Arctomys_ and _Spermophilus_ by having
three instead of two transverse grooves on their crowns. First premolar
nearly as large as the second. Molar series strongly convergent behind.
Two species of Prairie Marmots, or, as they are often called,
“Prairie-Dogs,” are found in North America. They live together in large
communities, inhabiting burrows excavated at short distances apart, and
feeding on the buffalo-grass which covers the plains. The small burrowing
owl (_Athene cunicularia_) and the rattlesnake are often found inhabiting
their burrows; the former probably availing itself of the convenience of
a ready-made habitation, the latter coming there to feed on the young
Marmots.
[Illustration: FIG. 202.—Palatal aspect of the cranium of the Prairie
Marmot (_Cynomys ludovicianus_).]
_Spermophilus._[303]—Size much smaller than in either of the preceding
genera; form more slender and squirrel-like. Tail very variable, from 1
to 8 or 9 inches in length. Cheek-pouches always present. Fore feet with
four well-developed toes and a rudimentary pollex, of which the claw may
be either present or absent. Skull more lightly built than in the other
preceding genera, with the postorbital processes slender and directed
backwards. Molar series nearly parallel, as in _Arctomys_, but all these
teeth much smaller and lighter; first premolar simply rounded, never more
than about one-third of the size of the second.
The Pouched Marmots, or Sousliks, have nearly the same distribution as
_Tamias_, and are represented by a considerable number of species. They
present a far greater range of variation than is found among the true
Marmots, some of them, such as the European species, being scarcely
as large as a common squirrel, almost entirely without external ears,
and with the tail reduced to a mere stump, barely an inch long, while
others are more than three times this size, with large and often tufted
ears, and long bushy squirrel-like tails. Professor Blasius gives the
following details of the habits of the common European Souslik (_S.
citillus_): “It lives in dry treeless plains, especially on a sandy or
clayey soil, and is never found either in forests or on swampy ground.
It forms burrows, often 6 or 8 feet deep, in which food is stored up
and the winter sleep takes place. Each burrow has but one entrance,
which is closed up when winter approaches,—a second hole, however, being
previously formed from the sleeping-place to just below the surface of
the ground. The second hole is opened the next year, and used as the
ordinary entrance, so that the number of closed-up holes round a burrow
gives an indication of the length of time that it has been occupied.
Sousliks ordinarily feed on roots, seeds, berries, etc., but occasionally
also on animal food, preying readily on eggs, small birds, and mice,
the remains of these latter being often found in their burrows. They
bring forth in the spring from four to eight young ones, which, if taken
early, may be easily tamed. They are often eaten by the peasants, the
inhabitants of the Russian steppes considering their flesh an especial
delicacy.”
Remains of _Spermophilus_ are not uncommon in European Tertiary deposits,
some belonging to living and others to extinct species.
_Extinct Genera._—_Plesispermophilus_, from the Upper Eocene Phosphorites
of Central France, appears to be closely allied to the Sousliks.
_Plesiarctomys_ (_Sciuravus_ or _Paramys_), which is common to the Middle
Tertiaries of Europe and North America, appears to be a generalised form,
showing some resemblance both to _Arctomys_ and _Sciurus_, but with
tritubercular upper molars and no postorbital processes to the skull;
in the latter respect agreeing with the next family. In the size of the
preorbital vacuity the skull resembles the Hystricomorpha.
_Family_ HAPLODONTIDÆ.
Distinguished from the _Sciuridæ_ by the absence of postorbital processes
to the frontals, the depressed skull, and the rootless cheek-teeth.
Premolars ²⁄₁; the penultimate upper one small.
_Haplodon._[304]—_H. rufus_ and _H. major_, of North America, west of the
Rocky Mountains, are the only representatives of the family; their habits
are similar to those of _Cynomys_.
_Family_ CASTORIDÆ.
Skull massive, without postorbital processes, the angle of the mandible
rounded, and the cheek-teeth rootless, with re-entering enamel-folds.
Premolars ¹⁄₁. Habits natatorial.
_Castor._[305]—The upper molars are subequal, each with one internal
and two external enamel-folds; the stomach has a large glandular
mass situated to the right of the œsophageal orifice; the anal and
urethro-genital orifices open within a common cloaca; the tail is broad,
horizontally flattened, and naked; and the hind feet are webbed. One or
two species, Palæarctic and Nearctic.
Zoologists are not yet of accord as to whether the European and American
Beavers should be regarded as distinct species or as local races; the
general concensus of opinion being in favour of the latter view.
The European Beaver (_C. fiber_) was at one time an inhabitant of the
British Isles, having been found, according to Pennant, in certain Welsh
rivers so late as the twelfth century, while subfossil remains of it
occur in the peat-beds of many parts of the country. In Scandinavia
Beavers are still found in the neighbourhood of Arendal. Isolated pairs
are occasionally met with on the banks of the Rhone, Weser, and Elbe;
and a considerable number are kept in a park belonging to the Emperor
of Austria, on the banks of the Danube. They also occur sparingly in
Russia and Poland, in the streams of the Ural Mountains, and in those
which flow into the Caspian. They live in burrows on the banks of rivers,
like the Water-Rat, and show little of the architectural instinct so
conspicuous in the American form, but this may be owing to unfavourable
external conditions rather than to want of the faculty; for there is a
well-authenticated instance of a colony of Beavers, on a small stream
near Magdeburg, whose habitations and dam were exactly similar to those
found in America.
The American Beaver (_C. canadensis_) extends over that part of the
American continent included between the Arctic circle and the tropic of
Cancer; owing, however, to the gradual spread of population over part of
this area, and still more to the enormous quantity of skins that, towards
the end of last and the beginning of the present century, were exported
to Europe, numbering about 200,000 annually, this species is in imminent
danger of extirpation. It is distinguished from the European Beaver by
the shorter and somewhat wider nasals.
Remains of extinct species of _Castor_ occur in the Pliocene of Europe,
and in the North American Miocene; the one from the last-mentioned
deposits being of small size, and separated by some writers as _Eucastor_.
_Extinct Genera._—A very large Beaver known as _Trogontherium_
(_Diobroticus_), and distinguished by the nature of the enamel-folds
of the molars, occurs in the Upper Pliocene and Pleistocene of Europe.
_Chalicomys_ (_Steneofiber_) is a considerably smaller form from the
Miocene of Europe and the United States, distinguished from all existing
Rodents by the presence of an entepicondylar foramen in the humerus.
_Palæocastor_, of the North American Miocene, is allied.
_Section_ MYOMORPHA.
[Illustration: FIG. 203.—Side view of skull of _Fiber zibethicus_,
natural size.]
Skull (Fig. 203), with slender zygomatic arch, in which the jugal seldom
extends far forwards, being usually supported by the long zygomatic
process of the maxilla; no postorbital process; infraorbital vacuity
variable; angle of mandible, except in the _Bathyerginæ_, rising from
the inferior surface of the incisive alveolus. Clavicles well developed,
except in _Lophiomys_. Tibia and fibula united.
_Family_ MYOXIDÆ.
Small arboreal forms, with long hairy tails, large eyes and ears, and
short fore limbs. No cæcum in the intestine. Skull with narrow frontals,
a high and narrow infraorbital vacuity of moderate size, and a long and
slender coronoid process to the mandible. Premolars ¹⁄₁; molars rooted,
with transverse enamel-folds.
The Dormice form a natural family allied to the Squirrels in form and
habits, and confined to the Palæarctic and Ethiopian regions. The absence
of the cæcum distinguishes them from all other members of the order.
They are usually divided into the following five genera, but some of
these are of very doubtful value, and it might be preferable to retain
_Muscardinus_ and include all the others in _Myoxus_.[306]
_Myoxus._[307]—Represented by the European _M. glis_, and characterised
by the bushy distichous tail, simple stomach, and the large size and
complex enamel-folds of the molars, which have flat crowns.
_Eliomys._[308]—Tail tufted and distichous; stomach simple; and the
molars small, with concave crowns and indistinct enamel-folds. Some seven
species, Ethiopian and Palæarctic.
_Graphiurus._[309]—Tail short, cylindrical, and tufted at the end; molars
very small, with the enamel-folds almost absent. Some three Ethiopian
species.
_Claviglis._[310]—Represented by one West African species, said to be
distinguished from all other forms by the shorter tail, which is more
distinctly pencilled. The right to generic distinction is, however, very
problematical.
_Muscardinus._[311]—Includes the Common Dormouse (_M. avellanarius_)
of Europe, distinguished by the cylindrical bushy tail, and thickened
glandular walls of the cardiac extremity of the œsophagus; the molars
have flat crowns, with complex enamel folds.
_Fossil Dormice._—Using the generic term _Myoxus_ in a more extended
sense than the above, it has existed in Europe from the date of the Upper
Eocene. A species nearly as large as a Guinea-Pig, with very complex
molars, is common in the Pleistocene of Malta.
_Family_ LOPHIOMYIDÆ.
[Illustration: FIG. 204.—_Lophiomys imhausi_. From Milne-Edwards.]
The genus _Lophiomys_,[312] represented only by _L. imhausi_ (Fig.
204) of North-East Africa, differs from the typical _Muridæ_ in having
the temporal fossæ roofed over by a thin plate of bone, rudimentary
clavicles, and an opposable hallux. On these grounds it has been made
the type of a family, but since all the features are Murine—the dentition
being that of a typical Cricetine—it appears doubtful whether that
distinction is justifiable. The hair forms a crest along on the back, and
is of a peculiar structure. The habits of this Rodent are arboreal.
_Family_ MURIDÆ.
Skull (Fig. 203) with contracted frontals; a short and slender jugal,
generally reduced to a splint between the zygomatic processes of the
maxilla and squamosal; the lower root of the former process more or less
flattened into a perpendicular plate; typically, the infraorbital vacuity
tall, and wide above and narrow below. Lower incisors compressed; no
premolars;[313] molars rooted, or rootless, tuberculate, or with angular
enamel-folds. Pollex rudimental; tail generally nearly naked and scaly.
Habits various, but mostly terrestrial.
This large and cosmopolitan family, which includes more than a third of
the existing Rodents, is represented by about forty genera.
Subfamily =Hydromyinæ=.—Molars ²⁄₂ in number, rooted, and divided into
transverse lobes. Represented by two Australasian genera.
_Hydromys._[314]—External form modified for an aquatic life. Tip of
muzzle extensively haired, so that the nostrils can be closed. Skull with
the infraorbital vacuity crescentic, scarcely narrowed below, and its
external wall without the perpendicular zygomatic plate characteristic of
most of the family; incisive foramina very small.
Two species, with habits like those of the Water Voles, are known from
Australia, Tasmania, and New Guinea. In the typical _H. chrysogaster_ the
colour of the back is black, with an admixture of golden-coloured hairs;
the belly being of a dark golden hue.[315]
_Xeromys._[316]—External form Murine. Tip of muzzle as in _Mus_, not as
in _Hydromys_. Toes unwebbed. Tail scaly, very finely haired. Skull as
in _Mus_, with the exception of the rounding of the supraorbital edges.
Teeth as in _Hydromys_.
Represented by _X. myoides_, of Queensland; a species about twice the
size of the Common Mouse. This genus serves to connect _Hydromys_ with
the other Murines, although it is difficult to say to which group it
comes nearest.
Subfamily =Platacanthomyinæ=.—Molars rooted, with transverse laminæ.
Flattened spines mingled with the hair; tail thickly haired. Represented
by one genus.
_Platacanthomys._[317]—The one representative of this genus is _P.
lasiurus_, found in the clefts of rocks and hollow trees in Southern
India at elevations of about 3000 feet. This elegant little animal
closely resembles a Dormouse; the tail and body having a length of 6
inches.
Subfamily =Gerbillinæ=.—Incisors narrow; molars with transverse laminæ
(Fig. 205). Auditory bullæ very large in most cases. Hind limbs
elongated. Tail usually long and hairy. Ranges over the Palæarctic,
Oriental, and Ethiopian regions.
_Gerbillus._[318]—Upper incisors grooved; first molar with three laminæ,
second with two, and third with one. There are some sixty species, with
a range coextensive with that of the family. The Gerbils, with their
large and bright eyes and long tufted tails, are very graceful creatures,
inhabiting sandy plains, where they form extensive burrows. Remains of
existing species are found in cavern-deposits in Madras (Fig. 205).
[Illustration: FIG. 205.—The left ramus of the mandible of _Gerbillus
indicus_, with an enlarged view of the molars, from a cavern deposit in
Madras. (From the _Palæontologia Indica_.)]
_Pachyuromys._[319]—The African genus _Pachyuromys_ is distinguished by
the very large size of the auditory bulla, as well as by the short and
fleshy tail, which is club-shaped. The incisors are narrow and faintly
grooved.
_Mystromys_,[320] _Otomys_,[321] and _Dasymys_.[322]—These genera, also
from South Africa, differ from _Gerbillus_ in the form of the molars, and
are represented by a few species.
_Malacomys._[323]—The one known species of this genus is from the Gaboon,
and is in some respect intermediate between the true Gerbils and the
Rats. Thus the dentition and feet are those of the former, but the long
scaly tail resembles that of the latter.
Subfamily =Phlœomyinæ=.[324]—This subfamily is represented only by
_Phlœomys_[325] _cumingi_, of the Philippine Islands, in which the
incisors are very broad, the molars are divided into transverse laminæ,
and the claws are large. The muzzle is blunt; the ears are hairy
externally; the tail is moderate, and thickly haired; and the auditory
bullæ are very small. The first upper molar has three, and the others two
laminæ.
Subfamily =Dendromyinæ=.—Incisors convex in front; molars ³⁄₃, rooted and
tuberculated. Ears hairy; claws long. Confined to the Ethiopian region.
_Dendromys._[326]—A small Rodent, with the habits of a Dormouse,
characterised by its grooved incisors, slender form, and long, scaly
tail, which is sparsely haired. Two other Murines described as
_Steatomys_[327] and _Lophuromys_[328] are referred to this subfamily.
The first is of plump form, with a rather short and thickly haired tail,
and grooved incisors. The latter resembles _Steatomys_ in form, but has
fine flattened bristles instead of fur, and plain incisors.
Subfamily =Cricetinæ=.—Molars ²⁄₃, tuberculate and rooted, with the
tubercles of the upper ones arranged in two longitudinal rows (Fig. 206,
_B_). This subfamily has an almost cosmopolitan distribution, and appears
to include the most generalised members of the family, from which the
more specialised _Murinæ_ have been evolved.
_Cricetus._[329]—According to the arrangement proposed by Mr. O.
Thomas[330] this genus is taken to include both the Hamsters of the
Old World (_Cricetus_ proper) and the white-footed or Vesper Mice
(_Hesperomys_) of the New. Cheek-pouches are frequently present, and
may be very large. The first molar (Fig. 206, _B_) generally has six
tubercles. The tail may be very short.
[Illustration: FIG. 206.—Left upper molars of _Mus_ (_A_) and _Cricetus_
(_B_).]
This large and unwieldy genus may be divided into a number of groups or
subgenera. The typical group includes the Hamsters of the Old World,
characterised by the large size of their cheek-pouches, the walls of
which are connected with muscles arising from the lumbar vertebræ. The
tail is remarkable for its shortness. The best-known species is _C.
frumentarius_, inhabiting Europe and Northern Asia. The American forms,
which range over the whole of that continent, comprise a number of
subgenera, of which the following are the most important. _Rhipidomys_,
including Dormouse-like forms with long tails and a dentition like
that of the typical group; _Oryzomys_, represented by Murine species;
_Calomys_, with short tail and Hamster-like body; _Vesperimus_, with
only five tubercles on the first molar; _Onychomys_, in which the
tail is extremely short and Hamster-like, and the form is Arvicoline;
_Scapteromys_, of Murine form with a long and hairy tail; _Phyllotis_,
with a shorter tail; _Habrothrix_, an Arvicoline group, with a short
and thinly haired tail; and _Oxymycterus_, distinguished from the
preceding by having a nail instead of a claw on the pollex. With regard
to the distribution of these forms Mr. Thomas[331] remarks that in
South America as we proceed southwards there is a general tendency “to
a disappearance of the tropical and northern Mouse- and Dormouse-like
subgenera _Rhipidomys_, _Vesperimus_, and _Oryzomys_, with the appearance
and increase of the Vole- and Hamster-like _Habrothrix_ and _Calomys_—a
change that is curiously paralleled in the Old World by the gradual
supercession of _Mus_ and _Myoxus_ in favour of _Arvicola_ and _Cricetus_
as we go northwards from tropical to temperate and arctic regions.” One
species has spines in the fur.
Remains of _Cricetus_ are abundant in the Pleistocene cavern-deposits of
Brazil, where a number of the forms are referable to existing species;
the genus is also represented in the Miocene of North America and Europe,
the species from the former area having been described as _Eomys_, and
those from the latter as _Cricetodon_.
_Holochilus_[332] (_Nectomys_).—The Rats of this genus are allied to
the American forms of _Cricetus_, but have the third upper molars
proportionately larger and the skull more stoutly built. This genus is
confined to Brazil, and contains about six species, some of which are
the largest indigenous Rats of America. Two species are aquatic in their
habits, and have short webs between the toes of their hind feet.
_Sigmodon_[333] differs from _Cricetus_ in the pattern of the molar
teeth. It contains one species only, the Rice-Rat, _S. hispidus_, ranging
from the United States to Ecuador.
_Rhithrodon_,[334] and _Ochetodon_.[335]—These are more or less
like _Cricetus_, but with grooved upper incisors. The first, is a
South-American genus, and contains five Rat-like species, one from
Venezuela, another from Peru, and the other three from Patagonia. The
second consists of three North American mice, of about the size and
proportions of the English Wood-Mouse (_Mus sylvaticus_).
_Neotoma._[336]—A peculiar North American genus, in which the teeth
simulate the prismatic appearance of those of the _Arvicolinæ_. There
are four species known as Wood-Rats, all of about the size of _Mus
decumanus_; one of them (_N. cinerea_) having a tail almost as bushy as
a Squirrel’s while the other three have ordinary scaly Rat-like tails.
Fossil remains of _Neotoma_ from cavern-deposits in Pennsylvania are
not improbably referable to the existing Florida Rat (_N. floridana_).
_Paciculus_, from the Miocene of the United States, is regarded as an
allied extinct genus with enamel-folds to the molars.
_Hypogeomys._[337]—This and the following genera are confined to
Madagascar, where they are the sole representatives of the Rodentia.
_Hypogeomys_ is a very peculiar form of large size, with long ears, feet,
and tail. There is only one species, _H. antimena_, a fawn-coloured Rat
about 9 inches long.
_Nesomys._[338]—Contains two species of long-haired Rats, more or less
rufous in colour, about the size of the Brown Rat.
_Brachytarsomys._[339]—Represented only by _B. albicauda_, a pretty
velvety-haired fawn-coloured Rat, with short feet and a long tail.
_Hallomys._[340]—The only species (_H. audeberti_) is very like a
_Nesomys_, but has much longer hind feet.
_Eliurus._[341]—Represented by one small Dormouse-like species,
characterised by its nearly naked and short ears, and long tail, of which
the proximal third is scaly, and the remainder covered with long hair.
The pollex is rudimental, but the hallux well developed.
Subfamily =Arvicolinæ=.—Molars usually imperfectly rooted or rootless,
and composed of two longitudinal rows of triangular prisms placed
alternately (Fig. 207). Tail moderate or short. Common to the Palæarctic
and Nearctic regions.
[Illustration: FIG. 207.—Upper (_A_) and lower (_B_) molars of the
Water-Vole (_Arvicola amphibius_).]
The Voles, as the members of this group are commonly termed, are so
closely connected with the Cricetines that they may be regarded merely as
a branch of that subfamily which has attained a peculiarly specialised
type of molar dentition. The Voles are externally distinguished, as a
rule, from true Rats and Mice by their more clumsy and heavy build and
less graceful movements; by the small size of their eyes, the bluntness
of the muzzle, the small ears, and the shorter limbs and tail.
_Phenacomys._[342]—A North American genus distinguished by its rooted
molars, and thus connecting the typical forms with Cricetines like
_Neotoma_. Several species have been described by Dr. C. H. Merriam.
_Arvicola._[343]—The type genus _Arvicola_ has rootless molars, and naked
soles to the feet. It includes over forty species inhabiting Europe,
North America, and Asia, a few species entering into the northern limits
of the Oriental region in India. Three species of the genus are found
in the British Isles, of which the following account is given by Mr. O.
Thomas:—
The common Water-Vole (_A. amphibius_) is as large as the Brown Rat.
Its fur is long, soft, and thick, of a uniform grizzled brown all over,
except when, as is not uncommon, it is wholly black. The tail is about
half the length of its head and body, and the hind feet are unusually
long and powerful, although not webbed, and have five rounded pads
on their lower surfaces. Its molar teeth (see Fig. 207) present the
following number of prismatic spaces:—in the upper jaw the first, or
anterior, has 5, the second 4, and the third 4, of which the last is very
irregular in shape, and is sometimes itself divided into two, making 5
in all; in the lower jaw the first has 7 spaces, of which the 3 anterior
are generally not fully separated from one another, the second has 5,
and the third 3. These numbers for the different teeth are taken as the
characters of the subgenus _Paludicola_ of Dr. Blasius, by whom this
method of subdividing the genus was first introduced. The Water-Vole
is one of the commonest English mammals, and is perhaps the most
often actually seen of all, owing to its diurnal habits. It frequents
rivers and streams, burrowing deeply into their banks, and in this way
often causing considerable damage. Its food consists almost wholly of
water-weeds, rushes, and other vegetable substances, but, like so many
other Rodents, it will also occasionally eat animal food, in the shape
of insects, mice, or young birds. The female during the warm season of
the year has three or four litters, each of from two to seven young.
The range of the Water-Vole extends over the whole of Europe and North
Asia, from England to China, but it is not found in Ireland. The common
Field-Vole, or short-tailed Field-Mouse (_A. agrestis_), representing
the subgenus _Agricola_, is about the size of a House-Mouse, but with
a short stumpy body, and a tail only about one third the length of the
head and body combined. Its hind feet have six pads on their inferior
surfaces. The colour is dull grizzled brown above, and grayish-white
below. Its molar teeth have respectively 5, 5, and 6 prismatic spaces
above, and 9, 5, and 3 below. The Field-Vole is one of the commonest of
our smaller mammals, and frequents fields, woods, and gardens in enormous
numbers, often doing very considerable damage in the latter, owing to its
fondness for garden produce of all kinds. It is spread over the whole
of Great Britain from the Hebrides southwards. Abroad its range extends
from Finland to North Italy and from France and Spain to Russia. The
Bank-Vole (_A. glareolus_) resembles in size and general appearance the
common Field-Vole, but may be distinguished by its more or less rusty or
rufous-coloured back, its larger ears, and the relatively longer tail,
which attains to about half the length of the head and body. Its molar
teeth present characters so different from those of all other Voles as
to have caused it to be regarded as belonging to an entirely distinct
genus, for which the name of _Evotomys_ has been used. Their chief
distinction lies in the fact that, unlike those of all other Voles, their
pulp-cavities close up in adult life, and they form distinct roots, more
resembling those of the ordinary Rats and Mice. The enamel-spaces of
these teeth number respectively 5, 4, and 5 above, and 7, 3, and 3 below.
The habits of this species are in every way similar to those of the
Field-Vole. Its range in Great Britain extends northwards to Morayshire,
beyond which it has not yet been observed. It is also found all along
the north temperate zone from France to China, and is replaced in North
America by a closely allied animal known as _A. gapperi_. It is probable,
however, that both _A. gapperi_ and _A. glareolus_ are only southern
climatic offshoots of a still more northern species, the _A. rutilus_ of
Northern Europe, Siberia, and Arctic America.
Fossil remains of _Arvicola_ are common in European Pleistocene deposits,
and they have also been obtained from the Upper Pliocene of the Norwich
Crag.
_Synaptomys._[344]—Represented by one North American species, having
grooved upper incisors, skull and molars like those of _Myodes_, with the
external characters of _Arvicola_.
_Myodes._[345]—Distinguished from _Arvicola_ by the more clumsy build,
convex obtuse head, extremely short and Rabbit-like tail, short ears,
small feet, the soles of which are furred, elongated claws, and thick
fur, as well as by the breadth and massiveness of the skull, in which the
zygomatic arch has a laminar expansion and the palate a peculiar contour;
while the root of the lower incisor does not extend behind the last
molar, the upper incisors are bevelled, and not grooved, and the molars
have a characteristic pattern, which cannot be well explained without a
figure.
[Illustration: FIG. 208.—The Lemming (_Myodes lemmus_).]
The Lemmings, as the members of the genus are commonly called, are
represented by the Norwegian Lemming (_M. lemmus_, Fig. 208), and the
North American _M. obensis_. Different individuals of the Norwegian
Lemming vary considerably both in size and colour, but its usual length
is about 5 inches, and its soft fur yellowish brown, marked with spots
of dark brown and black. It has a short, rounded head, obtuse muzzle,
small bead-like eyes, and short rounded ears, nearly concealed by the
fur. The tail is very short. The feet are small, each with five claws,
those of the fore feet strongest, and fitted for scratching and digging.
The usual dwelling place of the Lemmings is in the highlands or fells of
the great central mountain chain of Norway and Sweden, from the southern
branches of the Langfjeldene in Christiansand-stift to the North Cape and
the Varangerfjord. South of the Arctic circle they are, under ordinary
circumstances, exclusively confined to the plateaus covered with dwarf
birch and juniper above the conifer region, though in Tromsö-amt and in
Finmarken they occur in all suitable localities down to the level of the
sea. The nest is formed under a tussock of grass or a stone, constructed
of short dry straws, and usually lined with hair. The number of young
in each nest is generally five, sometimes only three, but occasionally
seven or eight, and at least two broods are produced annually. Their
food is entirely vegetable, especially grass-roots and stalks, shoots of
the dwarf birch, reindeer-lichens, and mosses, in search of which they
form, in winter, long galleries through the turf or under the snow. They
are restless, courageous, and pugnacious little animals. When suddenly
disturbed, instead of trying to escape they will sit upright, with their
back against a stone or other coign of vantage, hissing and showing fight
in a very determined manner (Fig. 208).
The circumstance which has given more popular interest to the Lemming
than to a host of other species of the same order of animals is that
certain districts of the cultivated lands of Norway and Sweden, where
in ordinary circumstances they are quite unknown, are occasionally and
at very uncertain intervals, varying from five to twenty or more years,
literally overrun by an army of these little creatures, which steadily
and slowly advance, always in the same direction, and regardless of
all obstacles, swimming across streams and even lakes of several miles
in breadth, and committing considerable devastation on their line of
march by the quantity of food they consume. In their turn they are
pursued and harassed by crowds of beasts and birds of prey, as bears,
wolves, foxes, dogs, wild cats, stoats, weasels, eagles, hawks, and
owls, and never spared by man; even the domestic animals not usually
predaceous, as cattle, goats, and reindeer, are said to join in the
destruction, stamping them to the ground with their feet, and even eating
their bodies. Numbers also die from diseases apparently produced from
overcrowding. None ever return by the course by which they came, and the
onward march of the survivors never ceases until they reach the sea,
into which they plunge, and swimming onwards in the same direction as
before perish in the waves. These extraordinary and sudden appearances
of vast bodies of Lemmings, and their singular habit of persistently
pursuing the same onward course of migration, have given rise to various
speculations, from the ancient belief of the Norwegian peasants, shared
in by Olaus Magnus, that they fall down from the clouds, to the almost
equally untenable hypothesis, ingeniously maintained by the late Mr. W.
D. Crotch, that they are acting in these migrations in obedience to an
instinct inherited from vastly ancient times, and are still seeking the
congenial home in a supposed submerged Atlantis, to which their ancestors
of the Miocene period were wont to resort when driven from their ordinary
dwelling-places by crowding or scarcity of food. The principal really
ascertained facts regarding these migrations seem to be as follows.
When any combination of circumstances has occasioned an increase in the
numbers of the Lemmings in their ordinary dwelling-places, impelled by
the restless or migratory instinct possessed in a less developed degree
by so many of their congeners, a movement takes place at the edge of the
elevated plateau, and a migration towards the lower-lying land begins.
The whole body moves forward slowly, always advancing in the same general
direction in which they originally started, but following more or less
the course of the great valleys. They only travel by night; and, staying
in congenial places for considerable periods, with unaccustomed abundance
of provender, notwithstanding all the destructive influences to which
they are exposed, they multiply excessively during their journey, having
families still more numerous and more frequently than in their usual
homes. The progress may last from one to three years, according to the
route taken, and the distance to be traversed until the sea-coast is
reached, which in a country so surrounded by water as the Scandinavian
peninsula must be the ultimate goal of such a journey. This may be either
the Atlantic or the Gulf of Bothnia, according as the migration has
commenced from the west or the east side of the central elevated plateau.
Those that finally perish in the sea, committing what appears to be a
voluntary suicide, are only acting under the same blind impulse which has
led them previously to cross smaller pieces of water with safety.
_Cuniculus._[346]—Cranial and incisive characters those of _Myodes_, in
the main, but the molars more of an Arvicoline type, the first upper one
differing from that of all other members of the family in having seven
prisms. Externally of the general shape of _Myodes_, but distinguished
by the absence of external ears, the shortness and dense furring of the
feet, the obsolete pollex with rudimentary nail, and the great length of
the two middle claws of the manus. Represented by one species, the Banded
Lemming (_C. torquatus_), of the Arctic region.
Remains of both _C. torquatus_ and _Myodes lemmus_ occur in British
Pleistocene deposits.
_Fiber._[347]—Closely allied to _Arvicola_, both externally and in
cranial and dental characters, but with the tail nearly as long as the
body (apart from the head), compressed, nearly naked, and reticulate.
Feet incompletely webbed, and the whole body adapted for a thoroughly
aquatic life.
The Musk-Rat or Musquash (_F. zibethicus_, Fig. 209) is the only
representative of this genus, and the largest member of the subfamily,
the head and body being about 12 inches in length. It is rather a heavily
built animal, with a broad head, no distinct neck, and short limbs; the
eyes are small, and the ears project very little beyond the fur. The fore
limbs have four toes and a rudimentary thumb, all with claws; the hind
limbs are larger, with five distinct toes, united by short webs at their
bases. The tail is laterally compressed, nearly naked, and scaly. The
hair much resembles that of a beaver, but is shorter; it consists of a
thick soft under-fur interspersed with longer stiff, glistening hairs,
which overlie and conceal the former on the upper surface and sides of
the body. The general colour is dark umber-brown, almost black on the
back and gray below. The tail and naked parts of the feet are black. The
musky odour from which it derives its name is due to the secretion of a
large gland situated in the inguinal region, and present in both sexes.
[Illustration: FIG. 209.—The Musk-Rat (_Fiber zibethicus_.)]
The Musk-Rat is peculiar to America, being extensively distributed in
suitable localities in the northern part of the continent, extending
from the Atlantic to the Pacific, and from the Rio Grande to the barren
grounds bordering the Arctic Seas. It is aquatic in its habits, living on
the shores of lakes and rivers, swimming and diving with great facility,
feeding on the roots, stems, and leaves of water-plants, or on fruits
and vegetables which grow near the margin of the streams it inhabits.
Musk-Rats are most active at night, spending the greater part of the day
concealed in their burrows dug out of the bank, consisting of a chamber
with numerous passages, all of which open under the surface of the
water. For winter quarters they build more elaborate houses of conical
or dome-like form, composed of sedges, grasses, and similar materials
plastered together with mud. As their fur is an important article of
commerce, large numbers are annually killed, being either trapped or
speared at the mouths of their holes.
The skull of the Musk-Rat is shown in Fig. 203 (p. 459); its structure
is essentially Arvicoline, but the squamosals are greatly expanded,
with a corresponding reduction of the parietal and interparietal, and
the interorbital constriction of the frontals attains its greatest
development. Fossil remains of _Fiber_ occur in the North American
Pleistocene.
_Neofiber._[348]—This genus, while agreeing with _Fiber_ in the
characters of the skull and teeth, differs by the cylindrical tail, and
the normal form of the feet, in which the toes are not bent laterally
at an angle with the sole. The single species _N. alleni_, commonly
known as the Round-tailed Musk-Rat, is found in Florida, and is much
less completely aquatic in its habits than _Fiber_. Its colour is brown
above, and silvery-white mixed with rufous below, the sides of the body
gradually shading from brown to rufous, the forehead and the tip of the
nose are black, while the tail is rufous mingled with black.
Subfamily =Siphneinæ=.—Includes two genera of Mole-like Rodents with
an _Arvicoline_ dentition, but with the body thoroughly adapted for a
subterranean life, the limbs and tail being very short, and the external
ears rudimentary. Both are Palæarctic.
_Ellobius._[349]—The Russian _E. talpinus_, the typical representative of
the genus, has short claws, and comes nearest to the _Arvicolinæ_. _E.
fuscocapillus_ is from Afghanistan.
[Illustration: FIG. 210.—_Siphneus armandi._ (From Milne-Edwards.)]
_Siphneus._[350]—This genus (Fig. 210) includes species inhabiting
Northern and Central Asia, and is characterised by the great length of
the claws of the manus. Remains of an existing species occur in the
Pleistocene of the Altai, while an extinct one has been described from
the Pliocene of North China.
Subfamily =Deomyinæ=.—Represented only by the under-mentioned genus,
in which the bituberculate anterior and tricuspidate middle ridge of
the first upper molar presents a condition intermediate between that
obtaining in the _Cricetinæ_ and that of the _Murinæ_.
_Deomys._[351]—Externally as in _Mus_. Pollex with a narrow nail; hind
feet elongate. Infraorbital vacuity of skull triangular, not narrowed
below. Upper incisors with a pair of minute grooves. First upper molar
with seven distinct tubercles, of which three are placed on the middle
ridge, and two on each of the others. One species, _D. ferrugineus_, from
the Lower Congo, an animal about the size of the Common Mouse.
Subfamily =Murinæ=.—Molars rooted and tuberculated; those of the upper
jaw with three longitudinal rows of tubercles (Fig. 206, _A_).
This group includes the true Rats and Mice, and may be regarded as more
specialised than the _Cricetinæ_. All the members of the group closely
resemble one another, and are light and active, with large ears, bright
eyes, and long and scaly tails. Their coloration, in conformity with the
fossorial and nocturnal habits of most of the forms, is sombre, and their
movements are remarkably agile and graceful.
[Illustration: FIG. 211.—The Australian Brown-footed Rat (_Mus
fuscipes_). After Gould.]
_Mus._[352]—Incisors narrow, without grooves. Structure of molars as
in Fig. 206, _A_ (p. 463). Incisive foramina of skull long; coronoid
process of mandible well developed. Ears and eyes large; muzzle naked at
the extremity. Fur soft, in some cases intermingled with spines. Pollex
with a short nail in place of a claw. No cheek-pouches. Tail long, nearly
naked, with rings of overlapping scales. Vertebræ: C 7, D 13, L 6, S 4, C
26-32.
This genus is the largest in the whole mammalian class, comprising not
less than 130 species, ranging over the whole of the Old World, with
the noteworthy exception of Madagascar. On the whole, the species are
more numerous in tropical than in temperate regions, and very few occur
in cold countries. Many of the species living in warm climates have
flattened spines mingled with the fur; these spines being shed in winter,
when a warmer covering is necessary, and replaced by hair. Five species
occur in England, which are briefly noticed below; and it may be observed
that none of the species are much larger than _M. decumanus_ or smaller
than _M. minutus_. As a rule the habits of the species are similar to
those of the English forms, but a few are arboreal, while others again,
like the one represented in Fig. 211, are aquatic. The earliest known
representatives of the genus (excluding _Acanthomys gaudryi_ of the Lower
Pliocene Pikermi beds of Attica) occur in the Pleistocene of Europe.
[Illustration: FIG. 212.—_A_, Head of Brown Rat (_M. decumanus_). _B_,
Head of Black Rat (_Mus rattus_).]
The Brown or Norway Rat (_M. decumanus_) is a heavily built animal,
growing to 8 or 9 inches in length, with a bluff rounded head, small ears
(Fig. 212, _A_), and a comparatively short tail, which is always shorter
than the head and body combined, and generally not longer than the body
alone. The colour is a uniform grayish-brown above and white below,
the ears, feet, and tail being flesh coloured. Black varieties, which
are often mistaken for true Black Rats, are by no means rare, but the
differences in size and proportions form a ready means of distinguishing
the two. The Brown Rat is believed to be a native of Western China,
where a race (_M. humiliatus_) has been discovered so like it as to be
practically indistinguishable. Both this, and the next species agree in
their predaceous habits, omnivorous diet, and great fecundity. They bear
four or five times in the year from four to ten blind and naked young,
which are in their turn able to breed at an age of about six months; the
time of gestation being about twenty days.
The Black Rat (_M. rattus_) is a smaller and more lightly built species,
generally not more than 7 inches in length, with a slender head (Fig.
212, _B_), large ears, and a thin tail of about 8 or 9 inches in length.
The colour is usually a glossy bluish-black, somewhat lighter below; but
in the tropical variety described as _M. alexandrinus_ the general colour
is gray or rufous, and the belly white. The disposition of the Black Rat
is milder than that of _M. decumanus_, and the white and pied rats kept
as pets mostly belong to this species. In many localities where it was
formerly abundant it has been entirely superseded by _M. decumanus_, but
it is said that in some parts of Germany it has been lately reasserting
itself.
_M. musculus_, the Common House-Mouse, is, like the Brown Rat, originally
a native of Asia, whence it has spread to all the inhabited parts of
the globe. Its habits and appearance are too well known to need any
description.
_M. sylvaticus_, the Wood or Long-tailed Field-Mouse, is very common in
many parts of England, often taking to barns and outhouses for shelter
during the winter. It is of about the same size and proportions as _M.
musculus_, but of a bright reddish-gray colour, with a pure white belly.
_M. minutus_, the Harvest-Mouse, is the smallest of the European Mice,
seldom exceeding 2½ or 3 inches in length. It is of a yellowish-red
colour, with comparatively short ears and tail. It lives entirely away
from human habitations, generally dwelling in grass or corn-fields, where
it builds a globular nest of dried grass of the size of a cricket-ball,
in which the young are nurtured.
_Nesocia._[353]—General characters those of _Mus_, but the incisors and
molars very much wider, and the tubercles of the latter more connected by
transverse ridges, thus producing a laminated type of structure.
This genus has been placed by some writers in a distinct subfamily with
_Phlœomys_, but Mr. O. Thomas regards it as so closely allied to _Mus_
that even its generic separation may be open to question. It comprises
several species, mostly spread over Southern Asia, ranging from Palestine
to Formosa, and from Kashmir to Ceylon, but _N. scullyi_ is found in
Turkestan. The great Indian Bandicoot-Rat (_N. bandicota_) is the largest
representative of the subfamily, often exceeding a foot in length. _N.
bengalensis_ is remarkable for possessing no less than eighteen mammæ.
Fossil remains of _Nesocia_ occur in the Pleistocene of Madras and in the
Pliocene of Northern India; those from the first-named deposits being
referable to existing species.
_Golunda._[354]—Like _Mus_, but with a distinct groove down the front of
the upper incisors. There are only three species, one from Western India,
one from West Africa, and the other from Eastern Africa.
_Uromys._[355]—Differs from _Mus_ in having the scales of the tail not
overlapping, but set edge to edge, so as to form a sort of mosaic work.
There are about six species of _Uromys_, spread over the northern part of
the Australian region from the Aru Islands to Queensland.
_Chiruromys._[356]—Externally like _Mus_, but with the terminal portion
of the tail without scales above, quite naked, transversely wrinkled,
and prehensile. Scales of remainder of tail more or less pentagonal,
and arranged in oblique diagonal series. Supraorbital vacuity of skull
without projecting plate in external wall. Incisive foramina short
and narrow; auditory bulla small. Upper molars very complex, with the
tubercles (of which there are eleven in the first tooth) low, and
distinctly arranged in transverse rows. Known only by _C. forbesi_, from
mountains in New Guinea, which must be regarded as a specialised form
very similar in outward appearance to _Uromys cervinipes_.
_Hapalotis._[357]—Hind limbs elongated. Incisive foramina very large. No
coronoid process to the mandible. This genus is confined to Australia,
where there are about fifteen species known. They are pretty little
animals, with long ears and tail, and in many respects resemble the
Jerboas, whose place they seem to take in the sandy Australian deserts.
Remains of _H. albipes_ occur in the Pleistocene of New South Wales.
_Mastacomys._[358]—Like _Mus_, but with the molars remarkably broadened,
and with only four mammæ. The single species of the genus is as yet only
known from Tasmania, though it has been found fossil in New South Wales;
it is somewhat similar in size and general appearance to the English
Water-Vole, but has much longer and softer fur.
_Acanthomys._[359]—Fur almost entirely composed of flattened spines.
Teeth and skull as in _Mus_, but the coronoid process of mandible
very small. There are six species of Spiny-Mice known, all of about
the size of the Common Mouse. They are found in Syria, Palestine, and
Eastern Africa as far south as Mozambique. _A. dimidiatus_ presents the
appearance of a little Hedgehog when its spines are erected; it inhabits
the stony deserts of Arabia Petræa and Palestine, and feeds on bulbs. A
fossil Mouse (_A. gaudryi_) referred to this genus occurs in the Lower
Pliocene of Attica.
_Echinothrix._[360]—A very remarkable rat with an extremely elongated
muzzle, all the bones of the face being much produced. The incisors are
faintly grooved. The only species is _E. leucura_, an animal of about
the size of the Brown Rat, with its fur thickly mixed with spines. It is
found in Celebes.
_Typhlomys._[361]—This genus is represented by a single species from
China, which resembles a House-Mouse in size and general appearance, but
has smaller ears, while the eyes are so reduced in size as to be totally
concealed by the long eyelashes.
_Cricetomys_[362] and _Saccostomus_.[363]—These two African genera
have been—from the presence of cheek-pouches—usually placed in the
neighbourhood of _Cricetus_, but their molars are of the Murine type.
_Cricetomys_ is said to have grooved upper incisors, and is represented
only by _C. gambianus_. There are two species of _Saccostomus_.
_Pithechirus._—A small Rodent from Sumatra and Java described under this
name is a true Mouse, having nothing to do with _Chiropodomys_, to which
it has been compared.
_Family_ SPALACIDÆ.
Mole-like forms, with very small or rudimentary eyes and ear-conchs,
large claws, and short or rudimentary tail. Form cylindrical. Incisors
large; premolars present or absent; molars rooted, with re-entering
enamel-folds; palate narrow.
Subfamily =Spalacinæ=.—Angular part of the mandible arising from the
lower edge of the socket of the lower incisor. No premolars.
_Spalax._[364]—Represented by the great Mole-Rat (_S. typhlus_) of
South-Eastern Europe, in which the eyes are completely covered by the
skin.
_Rhizomys._[365]—Eyes uncovered, although very minute; small naked
ear-conchs; and a short partially hairy tail. Includes several species
from Northern India, Tibet, China, Burma, Malaya, and Eastern Africa. A
fossil species occurs in the Pliocene Siwaliks of Northern India.
Subfamily =Bathyerginæ=.—Angular part of the mandible arising from the
side of the socket of the lower incisor. Premolars absent or present.
Confined to the Ethiopian region.
_Bathyergus._[366]—Upper incisors strongly grooved; _p_ ¹⁄₁, _m_ ³⁄₃; no
ear-conchs; very powerful claws. One species (_B. maritimus_), from South
Africa, attaining a length of about 10 inches.
_Georychus_[367] and _Myoscalops_.[368]—Upper incisors without grooves.
_Georychus_, with some half dozen species, generally has _p_ ¹⁄₁;
_Myoscalops_, with one species, usually has _p_ ³⁄₃, and the second toe
of the foot is the longest. In _Georychus_ the premolar may be wanting,
and some examples of _Myoscalops_ have only two teeth of this series.
_Heterocephalus._[369]—Small and nearly naked forms, with small head,
small eyes, no ear-conchs, moderately long tail, and powerful fore feet
provided with a pair of large pads; _p_ ⁰⁄₀, _m_ ²⁻³⁄₂₋₃. Two species.
These very remarkable little Rodents are regarded by Mr. O. Thomas as
very closely allied to _Georychus_, but specialised, and, so to speak,
somewhat degraded for a purely subterranean life, for which their
hairless body is peculiarly adapted. They are found in Somali-land, where
they burrow in the sandy soil.
_Family_ GEOMYIDÆ.[370]
Terrestrial or fossorial forms, with large cheek-pouches opening on
the cheeks outside the mouth. Squamosal much expanded, and the jugal
extending forwards to the lachrymal. _P_ ¹⁄₁; molars rooted or rootless,
with transverse laminæ. Nearctic and Neotropical regions.
Subfamily =Geomyinæ=.—Incisors broad; mastoid not appearing on the top
of the skull; eyes small; ear-conch rudimentary; limbs short, subequal.
Habits fossorial.
_Geomys._[371]—Upper incisors deeply grooved. The common North American
Pouched-Rat or “Pocket-Gopher” (_G. bursarius_) inhabits the plains
of the Mississippi and lives in burrows. Several other species are
recognised from the Southern United States, Mexico, and Central America.
The genus is represented in the Pleistocene and Pliocene of the United
States.
_Thomomys._[372]—Upper incisors plain. Represented by two species, with
numerous varieties found all over Canada and North America west of the
Rocky Mountains. Remains referred to an existing species occur in the
Pliocene of Oregon. _Entoptychus_, from the Miocene of the United States,
is an allied genus, with broad incisors and rootless molars.
Subfamily =Heteromyinæ=.—Incisors narrow; mastoid appearing largely on
the top of the skull; eyes and ears moderate or large; hind limbs and
tail elongated. Habits terrestrial.
_Dipodomys._[373]—This genus is characterised by the rootless molars. It
is best known by _D. phillipsi_, the Kangaroo-Rat of the desert regions
east of the Rocky Mountains, having habits like those of the Jerboas. The
typical forms have four toes in the pes; but in others, which it has been
proposed to separate as _Dipodops_, there are five: _D. ordi_ and _D.
agilis_ belong to the latter group.
_Perognathus_[374] and _Heteromys_.[375]—In both these genera, which are
represented by species of very small size, the molars are rooted; the
latter being distinguished by the presence of flattened spines mingled
with the fur, and having species ranging into South America. According to
Dr. C. H. Merriam the forms described as _Cricetodipus_ are not separable
from _Perognathus_; while Dr. Coues considers that _Saccomys_ was founded
upon a species of _Heteromys_. _Pleurolichus_, from the Miocene of the
United States, is regarded as an extinct genus allied to _Heteromys_.
_Family_ DIPODIDÆ.
Terrestrial forms usually with four upper cheek-teeth, and typically with
the following characters. Incisors compressed; molars with transverse
enamel-folds; infraorbital vacuity of skull (Fig. 7, p. 37) large and
rounded; jugal ascending in front to the lachrymal; and the mastoid part
of the auditory bulla usually very large.
Subfamily =Sminthinæ=.—Molars rooted; _p_ ¹⁄₀, _m_ ³⁄₃. Skull with the
infraorbital vacuity widest below, and the incisive palatal foramina
long. Limbs short. Palæarctic.
_Sminthus._[376]—Represented by the Rat-like _S. vagans_ from Northern
Europe and Asia, in which the ears are rather long and pointed, the tail
is covered with short hairs and nearly as long as the body, while the
molars present a somewhat complicated pattern. This genus has generally
been regarded as an aberrant member of the _Muridæ_, but was transferred
in 1887 to the present family by Dr. H. Winge.
Subfamily =Zapodinæ=.—Molars rooted; _p_ ¹⁄₁, _m_ ³⁄₃; cervical vertebræ
free; hind limbs elongated; metatarsals separate; hind feet with five
digits. Nearctic region.
_Zapus._[377]—The American Jumping-Mouse (_Z. hudsonianus_) extends over
almost the whole North-American continent from Labrador to Mexico.
Subfamily =Dipodinæ=.—Molars rooted; _p_ ⁰⁻¹⁄₀₋₁, _m_ ³⁄₃; cervical
vertebræ more or less ankylosed; hind limbs elongated; metatarsals
united; hind feet with only three functional digits. Palæarctic and
Ethiopian regions.
This subfamily includes the true Jerboas, and contains three
genera: _Dipus_[378] with three toes, and _Alactaga_[379] and
_Platycercomys_[380] with five, the outer two not reaching to the ground.
The latter is distinguished by the absence of premolars, and comprises
many species extending from Siberia to Nubia.
Remains of the existing _Alactaga decumana_[381] occur in the Pleistocene
of Germany, and those of _Zapus hudsonianus_ in the corresponding
strata of the United States. _Platycercomys_ has been recorded from the
Pleistocene of Northern Asia.
Subfamily =Pedetinæ=.—Molars rootless; cervical vertebræ free; hind limbs
elongated; metatarsals separate; hind feet with four digits. Vertebræ: C
7, D 12, L 7, S 3, C 30. Ethiopian region.
_Pedetes_,[382] the Cape Jumping-Hare (_P. caffer_), by far the largest
species of the family, extends from Mozambique and Angola to the Cape of
Good Hope.
_Section_ HYSTRICOMORPHA.
Skull (Fig. 213) with a stout zygomatic arch; jugal not supported below
by a continuation of the maxillary zygomatic process; infraorbital
vacuity large; mandible with the angular part arising from the outer side
of the bony socket of the lower incisor. Clavicles perfect or imperfect;
fibula distinct. One premolar in each jaw.
_Family_ OCTODONTIDÆ.
Clavicles complete. Skull with long incisive foramina extending into the
maxillæ; and usually an inferior angle to the jugal. Molars with external
and internal enamel-folds; _p_ ¹⁄₁, except in _Ctenodactylus_. Mammæ
placed high up on the sides of the body. Confined to the Ethiopian and
Neotropical regions, with the exception of one species of _Echinomys_
which ranges into Central America. Habits mostly terrestrial, but
occasionally fossorial or natatorial.
Subfamily =Ctenodactylinæ=.—Molars semi-rooted; jugal as in _Dipodidæ_;
the two inner toes of the hind feet with a horny comb and rigid bristles.
Ethiopian region.
_Ctenodactylus._[383]—Represented only by _C. gundi_ from North Africa,
on the borders of the Sahara. Has no premolars; each foot has four
digits; the hind limbs are rather longer than the fore; the ears small;
and the tail reduced to a stump. This animal is about the size of the
Water-Vole, and dwells on rocky ground, its habits being diurnal. The
peculiar comb-like inner toes are employed for dressing the fur.
[Illustration: FIG. 213.—Skull of _Hydrochœrus capybara_ (reduced).]
_Pectinator._[384]—Closely allied to the preceding, but with a minute
premolar in each jaw; and a moderately long and bushy tail. One species
(_P. spekei_), from Somali-land.
Subfamily =Octodontinæ=.—Molars semi-rooted or rootless, with simple
enamel-folds; fur soft. There are some six existing genera, including
Rat-like species, all of which are South American, except _Petromys_,
which is Ethiopian.
_Octodon._[385]—Upper and lower molars alike; ears moderate; tail of
medium length and tufted. Vertebræ: C 7, D 12, L 7, S 4, C 25. Typically
represented by _C. cumingi_ of Chili and Peru, with other species from
Chili and Bolivia. They live in large communities.
_Habrocoma._[386]—Lower molars more complex than the upper; ears large;
and fur extremely soft. Two Bolivian species.
_Schizodon._[387]—One species, inhabiting elevated spots in the Southern
Andes, and characterised by the enamel-folds of the upper molars meeting
in the middle line. The external characters are much the same as in
_Ctenomys_, but the ears are larger and the claws shorter.
_Ctenomys._[388]—Incisors broad; molars rootless, with kidney-shaped
crowns; last molar small and cylindrical; eyes and ears very small; claws
larger than the toes. Some four species. Fossil remains are common in the
Pleistocene of Buenos Ayres and the cavern-deposits of Brazil. Habits
fossorial.
_Spalacopus._[389]—Represented by two Chilian species, distinguished
from the preceding genus by the rudimentary ears. These rodents store up
magazines of food in their burrows.
_Petromys._[390]—The South African _P. typicus_ is closely allied to
_Spalacopus_, but differs by its harsh fur, the shortness of the pollex,
and the somewhat bushy tail. The teeth are semi-rooted, with single inner
and outer enamel-folds, nearly meeting in the middle.
Subfamily =Echinomyinæ=.—Molars semi-rooted or rootless, with deep and
curved enamel-folds; fur more or less harsh, frequently mixed with
spines; tail generally long. One Ethiopian genus, and the remaining nine
or so Neotropical. Many of the species are of large size, some being
arboreal and others aquatic.
_Myopotamus._[391]—Incisors very large; molars with two internal and two
external enamel-folds in the upper, and three internal and one external
in the lower jaw, last molar the largest; ears moderate; tail about
two-thirds the length of the head and body, scaly, and sparsely haired;
hind feet webbed; five digits. Vertebræ: C 7, D 13, L 6, S 4, C 25. The
well-known Coypu (_M. coypu_), the only existing representative of this
genus, is one of the largest living members of the order, and attains a
length of about 2 feet. It is common in South America, living in burrows
near water, and feeding on aquatic plants. Fossil remains of the genus
occur in the caverns of Brazil, as well as in the Tertiaries of Argentina.
_Capromys._[392]—This genus comprises arboreal forms from the West
Indies allied to the Coypu, but, according to Dr. G. E. Dobson, showing
signs of affinity with the _Hystricidæ_. The incisors are smaller than
in the Coypu, and the upper molars have one internal and two external
enamel-folds; the ears are comparatively small; the tail usually of
considerable length, and the general form somewhat Rat-like. The typical
_C. pilorides_ is somewhat smaller than the Coypu, and is confined to
Cuba; it is remarkable for the subdivision of the lobes of the liver
into a number of lobules. _C. brachyurus_ and _C. prehensilis_ are also
confined to Cuba. In Jamaica the genus is represented by _C. melanurus_,
which is somewhat smaller than a Rabbit, and has no secondary lobulation
of the liver.[393]
_Aulacodus._[394]—Upper incisors with three deep grooves; molars as
in _Capromys_. Fur very harsh; tail moderate, sparsely haired; manus
with rudimentary pollex, and small fifth digit; pes with no hallux, and
rudimental fifth digit. One species (_A. swinderianus_), from Western and
Southern Africa, which attains a length of nearly 2 feet, and dwells in
burrows.
_Plagiodon._[395]—Allied to _Capromys_, but with the enamel-folds of the
molars very complex, and forming a kind of zig-zag pattern in those of
the upper jaw. Represented only by _P. ædium_ of Hayti and Jamaica.
_Loncheres_[396] and _Echinomys_.[397]—These genera include small South
American species, in most of which flattened lanceolate spikes are
mingled with the fur. The majority of the species occur in Guiana and
Brazil, but one species of _Echinomys_ has been recorded from Central
America. Fossil remains of both genera occur in the cavern-deposits of
Brazil.
_Mesomys._[398]—This genus resembles _Loncheres_ externally, but the
pollex has a short curved claw, and there are no spines in the fur.
_Dactylomys._[399]—A Brazilian genus presenting the following distinctive
features. Ears short; tail long and scaly; pollex minute; third and
fourth digits of manus elongated, with short convex nails. Incisors flat;
molars divided into two lobes, each of which has a single enamel-fold.
Represented by two species, _D. typus_ and _D. amblyonyx_, both of which
seem to be rare and but little known. In the elongation of some of the
digits _Dactylomys_ recalls _Chiromys_ among the Primates.
_Cercomys._[400]—This South American genus is usually placed near
_Carterodon_, from which it is readily distinguished by the pointed
muzzle and the plain incisors.
_Carterodon._[401]—This genus, which was originally described upon the
evidence of skulls from the Brazil caves, but subsequently found living,
is readily distinguished by the broad and grooved incisors. The upper
molars have one inner and two outer enamel-folds; those of the lower jaw
being the reverse of this.
_Fossil Forms._—Remains of the existing genus _Loncheres_ occur in the
Brazilian cave-deposits, which also yield the extinct _Dicolpomys_. A
large number of fossil _Octodontidæ_ from the Tertiaries of South America
have been described under many generic names, but it will be sufficient
to mention that _Phloramys_ and _Pithanotomys_ are considered to be
allied to _Ctenomys_; while _Morenia_, _Orthomys_, and _Trilodon_ show
affinity to _Myopotamus_. _Pellegrinia_, from the Pleistocene of Sicily,
may be allied both to _Ctenodactylus_ and _Octodon_.
_Family_ THERIDOMYIDÆ.
This extinct family, which is represented in the Tertiaries of Europe
and the United States, comprises several genera of comparatively small
Rodents, which are regarded by Dr. Schlosser as nearly related to the
_Octodontidæ_, although connected by _Archæomys_ with the _Chinchillidæ_.
The dental formula is the same as in the _Octodontidæ_. In the typical
genus _Theridomys_, from the Lower Miocene and Upper Eocene of Europe,
the molars are rooted, and have three or four re-entering enamel-folds,
which form isolated discs on the worn crowns. _Syllophodus_, from the
Miocene of the United States, is closely allied. _Protechinomys_ and
_Trechomys_ are genera from the Phosphorites of Central France with
rooted molars; while in _Archæomys_ of the same deposits the molars are
rootless, with the enamel-folds dividing their crowns into laminæ, as in
the Chinchillas.
_Family_ HYSTRICIDÆ.
Build stout. Limbs subequal. A number of long and stout spines in
the integument. Facial portion of skull short and broad, and the
jugal without an inferior angle. Molars with external and internal
enamel-folds; completely or partly rooted.
Subfamily =Synetherinæ=.—Molars rooted; clavicles complete; upper lip
not cleft; soles tuberculated; pollex absent; four mammæ; tail generally
prehensile; spines mixed with long hairs. This group is confined to
America, all the forms except one being arboreal, and their habits less
strictly nocturnal than in the next subfamily. There are three genera.
_Erethizon._[402]—Represented by the common Canadian Porcupine (_E.
dorsatus_), a stout heavily-built animal, with long hairs almost or quite
hiding the spines; four anterior and five posterior toes; and a short
stumpy tail. It is a native of the greater part of Canada and the United
States where there is any remnant of the original forest left. Remains of
_Erethizon_ occur in cavern-deposits in Pennsylvania.
[Illustration: FIG. 214.—The Tree Porcupine (_Synetheres prehensilis_).]
_Synetheres._[403]—This genus contains some eight or ten species, known
as Tree Porcupines (Fig. 214), found throughout the tropical parts of
South America, and one of them extending northwards into Mexico. They
are of a lighter build than the Ground Porcupines, are covered with
short, close, many-coloured spines, often mixed with hairs, and their
tails are always prehensile. Their hind feet have only four toes, owing
to the suppression of the hallux; but they have a peculiar fleshy pad on
the inner side of the foot, between which and the toes boughs and other
objects can be firmly grasped as with a hand. Vertebræ: C 7, D 17, L 5,
S 3, C 36. An extinct species of this genus has been described from the
cavern-deposits of Brazil.
_Chætomys._[404]—Distinguished by the shape of its skull and the greater
complexity of its teeth. It contains only one species (_C. subspinosus_),
a native of the hottest parts of Brazil.
Subfamily =Hystricinæ=.—Molars semi-rooted; clavicles incomplete; soles
smooth; a rudimentary pollex: six mammæ; tail not prehensile. Now
confined to the Old World, where they occur in Southern Europe, Africa,
India, and the Malay Archipelago as far eastwards as Borneo. Habits
terrestrial and nocturnal. Three genera.
[Illustration: FIG. 215.—The Common Porcupine (_Hystrix cristata_).]
_Hystrix._[405]—This genus is readily characterised by the inflated
skull, in which the nasal chamber is often considerably larger than the
brain-case, and by the short tail, tipped with numerous slender stalked
open quills, which make a loud rattling noise when the animal moves.
Vertebræ: C 7, D 15, L 4, S 4, C 12. The best-known member is the Common
Porcupine (_H. cristata_, Fig. 215), which occurs throughout Southern
Europe and North and West Africa, but is replaced in South Africa by
_H. africæ-australis_, and in India by the Hairy-nosed Porcupine (_H.
leucura_).
The following account of the habits of the last-named species is from Dr.
Jerdon: “_Hystrix leucura_ is found over a great part of India, from the
lower ranges of the Himalayas to the extreme south, but does not occur
in lower Bengal, where it is replaced by _H. bengalensis_. It forms
extensive burrows, often in societies, in the sides of hills, banks of
rivers and nullas, and very often in the dams of tanks, and in old mud
walls, etc. In some parts of the country they are very destructive to
various crops, potatoes, carrots, and other vegetables. They never issue
forth till after dark, but now and then one will be found returning
to his lair in daylight. Dogs take up the scent of the Porcupine very
keenly, and on the Nilghiris I have killed many by the aid of dogs,
tracking them to their dens. They charge backwards at their foes,
erecting their spines at the same time, and dogs generally get seriously
injured by their strong spines, which are sometimes driven deeply into
the assailant. The Porcupine is not bad eating,—the meat, which is white,
tasting something between pork and veal.”
Besides these three large crested species of _Hystrix_, there are four or
five smaller species without nuchal crests occurring in North-East India
and in the Malay region, from Nipal to Borneo.
Fossil species of _Hystrix_ occur in the Pleistocene and Pliocene of
India, and in Europe from the Upper Pliocene to the Middle Miocene,
being perhaps also represented in the French Phosphorites. Remains from
the Pliocene and Miocene of the United States have been referred to
this genus, and if rightly determined are of especial interest from a
distributional point of view.
_Atherura._[406]—The Brush-tailed Porcupines are much smaller animals
than the last, characterised by their long tails tipped with bundles of
peculiar flattened spines. Of the three species two are found in the
Malay region and one in West Africa. A fossil species occurs in the
cavern-deposits of Madras.
_Trichys._[407]—This genus contains but one Bornean species (_T.
guentheri_), externally very like an _Atherura_, but differing from the
members of that genus in many important cranial characters.
_Family_ CHINCHILLIDÆ.
Terrestrial forms, with elongated hind limbs, bushy tails, very soft fur,
and complete clavicles. Jugal without an inferior angle, and extending
forwards to the lachrymal; palate contracted in front and deeply
emarginate behind; incisors short, and the molars divided by continuous
enamel-folds into transverse laminæ. Neotropical region. This family
includes only three existing species, divided into as many genera.
_Chinchilla._[408]—In this genus the fore feet have five and the hind
four digits, the tail is long and bushy, and the auditory bullæ are
enormous, appearing on the top of the skull. The one species (_C.
lanigera_) is restricted to the alpine zones of the Andes from the north
of Peru to the south of Chili. It is a Squirrel-like Rodent, about 10
inches in length, the tail somewhat exceeding 5 inches, and the ears very
large. Its fur is greatly valued on account of its extreme softness and
delicate gray colour.
_Lagidium_[409] and _Lagostomus_.[410]—_Lagidium_ has four digits in
both fore and hind feet, and _Lagostomus_ three only in the hind feet,
and the auditory bullæ are much smaller than in the preceding genus.
_Lagidium_ has the same distribution as _Chinchilla_; while _Lagostomus_,
as represented by the Viscacha (_L. trichodactylus_), is found in the
Pampas from the Uruguay River to the Rio Negro. The Viscachas live in
burrows, generally in large numbers, and are nocturnal in their habits.
Remains referable to the existing species, as well as others which appear
to belong to extinct forms, occur in the Pleistocene deposits of South
America.
_Extinct Genera._—Several Rodents from the South American Tertiaries
more or less closely allied to _Lagostomus_ have been described by Dr.
Ameghino under the names of _Prolagostomus_, _Pliolagostomus_, etc.
The huge _Megamys_ (_Potamarchus_), from the infra-Pampean deposits of
Parana and Patagonia, is referred to this family, and has dimensions
approximating to those of an Ox. Other fossil genera have received the
names of _Epiblema_ and _Tetrastylus_.
_Family_ CASTOROIDIDÆ.
_Castoroides._[411]—The large Beaver-like Rodent with the dimensions of
a Bear from the Pleistocene of the United States described under this
name is regarded by Dr. Coues as the type of a family. Its dentition
is nearest to that of _Chinchilla_ and _Hydrochœrus_, but some of
the cranial characters are like those of the _Castoridæ_. The genera
_Amblyrhiza_ and _Loxomylus_, from the Pleistocene of the Antilles,
appear to be allied types.
_Family_ DASYPROCTIDÆ.
Terrestrial forms with subequal limbs, hoof-like claws, short or obsolete
tail, and rudimentary clavicles. Mandibular masseteric ridge obsolete;
palate broad; incisors long; molars semi-rooted, with external and
internal enamel-folds. Neotropical region.
_Dasyprocta._[412]—Includes several slender-limbed species, with three
hind toes, commonly called Agoutis, inhabiting Central and South America,
one (_D. cristata_) extending into the West-Indian Islands. Numerous
fossil remains of this genus occur in the cavern-deposits of Brazil.
_Cælogenys._[413]—This genus is readily characterised by the presence
of five hind toes, and the extraordinary development of its zygomatic
arches, which are enormously expanded vertically, forming great convex
bony capsules on the sides of the face, enclosing on each side a large
cavity lined with mucous membrane, and communicating by a small opening
with the mouth. The Paca (_C. paca_) is about 2 feet long, and, like
the species of _Dasyprocta_, lives generally in the forests or along
the banks of rivers. This species appears to date from the epoch of the
Pleistocene deposits of the Brazilian caves. A smaller species from
Ecuador, living at elevations of from 6000 to 10,000 feet, has been
described as _C. taczanowskii_.
_Family_ DINOMYIDÆ.
Distinguished from the _Dasyproctidæ_ by the cleft upper lip, rather
long and bushy tail, the presence of four digits in both fore and hind
feet, and the complete clavicles. The manubrium is broad; the optic
foramina are confluent; the incisors broad; and the molars rootless, with
enamel-folds dividing them into transverse laminæ.
_Dinomys._[414]—The sole representative of this family is the Rodent
known as _D. branicki_, of which hitherto only a single specimen
has been obtained. This was captured in Peru, where it was found at
daybreak walking about a courtyard; the inhabitants of the district were
previously unacquainted with the species, from which its extreme rarity
may be inferred. Externally it resembles much the Paca, having similar
S-like nostrils; but in the laminated molars, and many features of the
skeleton, it differs from all the other Rodents with hoof-like nails. It
is regarded by its describer, the late Professor Peters, as a connecting
link between the _Octodontidæ_, _Chinchillidæ_, _Dasyproctidæ_, and
_Caviidæ_.
_Family_ CAVIIDÆ.
Terrestrial or natatorial forms, with short incisors, strong mandibular
masseteric ridges, long and curved paroccipitals, and palate contracted
in front. Fore feet with four digits, hind feet with three. Clavicles
imperfect. Molars divided by enamel-folds into transverse laminæ;
milk-teeth shed before birth. Other characters as in _Dasyproctidæ_.
Neotropical region.
_Cavia._[415]—Limbs and ears short, subequal; tail none. Vertebræ: C 7, D
13, L 6, S 4, C 7. This genus includes several species widely distributed
throughout South America, extending even to the Straits of Magellan. The
Restless Cavy (_C. porcellus_), which is found throughout Uruguay and
Brazil, has been very generally regarded as the ancestral form of the
domesticated Guinea-Pig. It is about 10 inches long, and weighs a little
over a pound; its fur is long and of a nearly uniform grayish-brown
colour. This species is rarely found in dry sandy localities, preferring
marshes covered with aquatic plants, among which it lies concealed,
feeding in the early morning and after sunset in the evening; but when
the soil is dry it forms burrows. It lives in societies of from six to
eighteen individuals, breeding but once a year, with one, or at most
only two, young at a birth. The Guinea-Pig (probably a misnomer of
Guiana-Pig) is larger than _C. porcellus_, and is regarded by Dr. Nehring
as descended from another species, _C. cutleri_. It is white in colour,
with irregular patches of reddish-brown and black. The Bolivian Cavy (_C.
boliviensis_), found throughout the higher regions of Bolivia, usually at
an elevation of 10,000 or 12,000 feet, is exceedingly shy, and lives in
burrows, which in some districts are so numerous as to have completely
undermined the soil. The Rock-Cavy (_C. rupestris_), distinguished by its
short, blunt nails, is found in rocky situations throughout Brazil, and
is much sought after for its flesh. The Southern Cavy (_C. australis_),
common along the coast of Patagonia, forms deep burrows, with several
outlets, in sandy declivities. Remains of existing species of _Cavia_ are
found in the cavern-deposits of Lagoa Santa, Brazil.
_Dolichotis._[416]—Characterised by the great length of the ears and the
short tail. The palate is so much contracted in front that the premolars
of opposite sides touch by their antero-internal edges. Vertebræ: C 7, D
12, L 8, S 3, C 10.
The Patagonian Cavy (_D. patachonica_)—the only living representative of
the genus—is rather larger than a Hare, which it somewhat resembles in
external appearance. It inhabits the dry sterile districts of Patagonia
and La Plata, disappearing wherever the country becomes more humid. This
animal burrows in the earth, although in districts where the Viscacha is
found it is said to avail itself of the works of the latter. Unlike other
cavies, its eyes are protected from the glare of the sun by prominent
eyelashes. The body is covered with a long dense fur of a rusty colour.
Two young are produced at a birth. Three species of _Dolichotis_ have
been described from the Brazilian cave-deposits, one of which is probably
not really separable from the existing form.
_Hydrochœrus._[417]—A large aquatic form with all the feet fully webbed;
the skull (Fig. 213, p. 481) large, with enormous paroccipital processes;
and the molars very complex, the third upper one having some twelve
transverse laminæ. Upper incisors grooved. Vertebræ: C 7, D 14, L 6, S 3,
C 8.
The Capybara (_H. capybara_) is the largest existing Rodent, and the
only living representative of the genus. It is a bulky and stoutly built
animal, and attains a length of about 4 feet. The body is covered with
long and coarse hair, reddish-brown above and brownish-yellow beneath.
Capybaras are found over the whole of the eastern part of South America,
and to the westward range into Bolivia and Peru. They frequent the
borders of rivers and lakes, concealing themselves among reeds and other
water plants. Remains of _Hydrochœrus_ are found in the cavern-deposits
of Brazil, which are probably referable to the existing species; one
extinct species from the Pleistocene of Buenos Ayres is estimated to
have attained a length of 5 feet, while _H. magnus_ of the same deposits
was of still larger dimensions. The genus is also represented in the
Pleistocene of South Carolina and the infra-Pampean beds of Parana.
_Extinct Genera._—A number of South American fossil Rodents have been
referred to extinct genera of _Caviidæ_. Thus _Plexochœrus_, from the
Tertiary of Argentina, differs from _Hydrochœrus_ in having only nine
laminæ in the last upper molar; _Cardiomys_, _Cardiatherium_, etc., from
the infra-Pampeans are also stated to be allied to _Hydrochœrus_, while
_Contracavia_, of the same deposits, is related to _Cavia_, but of larger
size. _Microcavia_, again, from the Pleistocene of Argentina, is regarded
as connecting _Cavia_ with _Dolichotis_. The Tertiary European genera
_Issiodoromys_ and _Nesocerodon_ are apparently referable to the present
family.
_Suborder_ DUPLICIDENTATA.
Two pairs of incisors in the upper jaw (the second very small, and placed
directly behind the large first pair), the enamel of which extends
round to their posterior surfaces. At birth there are three pairs of
these incisors, but the outer one on each side is soon lost. Incisive
foramina large; and usually confluent; bony palate very narrow from
before backwards; no true alisphenoid canal; fibula ankylosed to the
tibia, and articulating with the calcaneum. Testes permanently external.
This suborder includes the Picas, Hares, and Rabbits, all of which are
strictly terrestrial.
_Family_ LAGOMYIDÆ.
Complete clavicles, subequal limbs, no external tail, and short ears.
Skull depressed, frontals contracted and without postorbital processes;
_p_ ¹⁄₁ or ²⁄₂; molars rootless, with transverse enamel-folds. Palæarctic
and Nearctic.
_Lagomys._[418]—Represented by about a dozen species of small
Guinea-Pig-like animals, inhabiting chiefly the mountainous parts of
Northern Asia (from 11,000 to 14,000 feet), one species only being known
from South-East Europe, and another from the Rocky Mountains.
The Picas, or Tailless Hares, live in holes among the rocks of their
native mountains, and are agile and shy little creatures. The genus is
well represented through the upper and middle Tertiaries. It has been
proposed to separate those fossil forms with _p_ ²⁄₁ as _Myolagus_, and
those with _p_ ¹⁄₁ as _Titanomys_, but this seems scarcely advisable.
_Family_ LEPORIDÆ.
Imperfect clavicles, elongated hind limbs, short recurved tail, and
long ears. Skull (Fig. 216) compressed, frontals with large wing-shaped
postorbital processes _p_ ³⁄₂; molars as in the _Lagomyidæ_. Cosmopolitan
(except Australasia). Vertebræ: C 7, D 12, L 7, S 4, C 13-15.
[Illustration: FIG. 216.—Skull of Hare (_Lepus timidus_).]
_Lepus._[419]—The single genus _Lepus_ includes about twenty species,
all of which resemble one another in general external characters. In all
the fore limbs have five and the hind only four digits, and the soles of
the feet are densely clothed with hairs similar to those covering the
legs; the inner surface of the cheeks is also hairy. Although the family
has such a wide distribution, the greater number of the species are
restricted to the Palæarctic and Nearctic regions, only a single species
(_L. brasiliensis_) extending into South America, where it has existed
since the date of the Pleistocene deposits of the Brazilian caves.
The Common Hare (_L. timidus_[420]) may be taken as a typical example of
the genus, and is characterised by the great length of the ears and hind
limbs. It is found in all parts of Europe except the north of Russia,
the Scandinavian peninsula, and Ireland. Its fur is usually of a tawny
gray colour above and white beneath, with the upper surface of the short
tail and the tips of the ears black. The colour of the fur differs,
however, considerably in different latitudes and at different seasons of
the year; showing a tendency to become white during winter in northern
countries, while assuming a reddish-yellow hue in the more genial climate
of southern Europe. The Hare is a nocturnal animal, remaining during the
day on its “form,” as the slight depression is called which it makes in
the open field, usually among grass.
[Illustration: FIG. 217.—The Common Hare (_Lepus timidus_).]
The Mountain Hare (_L. variabilis_) is found throughout the northern part
of the Palæarctic region, ranging from Ireland in the west to Japan in
the east, and also occurring in several of the more southerly mountain
ranges, such as the Pyrenees, the Alps, and the Caucasus. It is smaller
than the common species, with a smaller and more rounded head, and
shorter ears, tail, and hind limbs. In cold climates the colour of the
whole animal changes in the winter to a pure white (as in Fig. 218), with
the exception of the tips of the ears, which remain black. In Ireland no
winter change of colour takes place.
[Illustration: FIG. 218.—The Mountain Hare (_Lepus variabilis_).]
The Rabbit (_L. cuniculus_), speaking of the wild race only, is
distinguished from the Hare externally by its smaller size, shorter ears
and feet, the absence or reduction of the black patch at the tip of
the ears so characteristic of the Hare, and by its grayer colour. The
skull is smaller and lighter, with a slenderer muzzle and a longer and
narrower palate. Besides these characters, however, the Rabbit is sharply
separated from the Hare by the fact that it brings forth its young naked,
blind, and helpless; to compensate for this, it digs a deep burrow in
the earth in which they are born and reared, while the young of the Hare
are born fully clothed with fur, and able to take care of themselves in
the “form” in which they are born. The weight of the Rabbit is from 2½
to 3 lbs., although individuals perfectly wild have been recorded up to
more than 5 lbs. Its general habits are too well known to need a detailed
description here. It breeds from four to eight times a year, bringing
forth each time from three to eight young. Its period of gestation is
about thirty days, and it begins to breed when six months old. It attains
to an age of about seven or eight years.
[Illustration: FIG. 219.—The Rabbit (_Lepus cuniculus_).]
The geographical distribution of the Rabbit presents many most
interesting peculiarities. It is believed to be originally a native of
the western half of the Mediterranean basin only, and still abounds in
Spain, Sardinia, Southern Italy, Sicily, Greece, Tunis, and Algeria; and
many of the Islands adjoining these countries are quite overrun with
it. Thence it has spread, partly by man’s agency, northwards throughout
temperate Western Europe, increasing rapidly wherever it gains a footing;
and this extension is still going on, as is shown by the case of
Scotland, in which sixty years ago Rabbits were little known, while they
are now found in all suitable localities up to the extreme north. It has
also gained admittance into Ireland, and now abounds there as much as in
England. Out of Europe the same extension of range has been going on. In
New Zealand and Australia Rabbits, introduced either for profit or sport,
have increased to such an extent as to form one of the most serious
pests that the farmers have to contend against, as the climate and soil
seem to suit them perfectly, and their natural enemies are too few and
too lowly organised to keep their numbers within reasonable bounds. In
other cases Rabbits introduced into islands have become or remained
more or less distinct from their parent stock; thus the Rabbits both of
the Falkland Islands and of Jamaica still show traces of their descent
from domesticated varieties, and have never reverted to the ordinary
brownish-gray type. And again, as was pointed out by Mr. Darwin,[421]
the Rabbits in the island of Porto Santo, near Madeira, whose ancestors
were introduced from Spain in 1418 or 1419, have formed quite a distinct
diminutive race, barely half the bulk or weight of English Rabbits, and
differing in certain slight details of colour and habits.
_Bibliography of Rodentia._—G. R. Waterhouse, “Observations
of the Rodentia,” _Mag. Nat. Hist._ iii. (1839); Id. _Ann.
Nat. Hist._ viii. and x. (1839-42); Id. “On the Geographical
Distribution of the Rodentia,” _Proc. Zool. Soc._ 1839, pp.
162-174; Id. _Natural History of the Mammalia_, vol. ii.
“Rodentia” (1848); Gervais, _Dic. Univ. d’Hist. Nat._ xi. p.
202 (1848); Brandt, “Untersuchungen über die craniologischen
Entwickelungsstufen und Classification der Nager der Jetzwelt,”
_Mém. de l’Acad. Impér. de St. Pétersbourg_ (1855); Lilljeborg,
_Systematisk Œfversight af de Gnagnde Däggdjuren_, Upsala,
1866; Alston, “On the Classification of the Order _Glires_,”
_Proc. Zool. Soc._ 1876, pp. 61-98; Trouessart, “Catal. de
Rongeurs, Vivants et Fossiles,” _Bullet. Soc. d’Études Scient.
d’Angers_, 1880-1881; Coues and Allen, “Monographs of North
American Rodentia,” _United States Geol. Surv. of Territories_,
vol. xi. (1877); Winge, “Rodentia pa Lagos Santa, Brazil.”
_Mus. Lund._ vol. iii. (1887); various papers by Peters in
_Monatsber. Ak. Berlin_, and by Alston, Anderson, Blanford,
Dobson, Milne-Edwards, Thomas, and others, in _Proc. Zool.
Soc._, _Journ. Asiat. Soc. Beng._, _Ann. Mag. Nat. Hist._, etc.
CHAPTER XI
THE ORDER CARNIVORA
Though the existing Carnivora as at present restricted[422] form a very
natural and well-defined order among the Mammalia, it is difficult to
find any important common diagnostic characters by which they can be
absolutely separated; so that, as in the case of so many other natural
groups, it is by the possession of a combination of various characters
that they must be distinguished. Thus they are all unguiculate, and never
have less than four well-developed toes on each foot, with nails more
or less pointed, rarely rudimentary or absent. The pollex and hallux
are never opposable to the other digits. They are regularly diphyodont
and heterodont, and their teeth are always rooted.[423] Their dentition
consists of small pointed incisors, usually three in number, on either
side of each jaw, of which the first is always the smallest and the third
the largest, the difference being most marked in the upper jaw; strong
conical, pointed, recurved canines; cheek-teeth variable, but generally,
especially in the anterior part of the series, more or less compressed,
pointed, and trenchant; if the crowns are flat and tuberculated they
are never complex or divided into lobes by deep inflexions of enamel.
The condyle of the lower jaw is a transversely placed half-cylinder
working in a deep glenoid fossa of corresponding form. The brain varies
much in relative size and form, but the hemispheres are never destitute
of well-marked convolutions (Fig. 23, p. 71). The stomach (Fig. 234)
is always simple and pyriform. The cæcum is either absent or short
and simple (Fig. 235), and the colon is not sacculated, or greatly
wider than the small intestine. Vesiculæ seminales are never present.
Cowper’s glands are present in some, absent in other groups. The uterus
is bicornuate. The mammæ are abdominal, and very variable in number.
The placenta is deciduate, and almost always zonary. The clavicle is
often entirely absent, and when present is never complete. The humerus
often has an entepicondylar foramen. The radius and ulna are distinct.
The scaphoid and lunar bones are united into one, and there is never
a distinct os centrale in the adult. The fibula is always a distinct
slender bone.
Several of these characters are, however, not applicable to all the
members of the extinct group of Carnivores for which the name Creodonta
has been proposed, as will be noticed in the sequel.
The large majority of the species composing this order subsist chiefly
upon some variety of animal food, though many are omnivorous, and some
few chiefly, though not entirely, vegetable eaters. The more typical
forms live altogether on recently killed warm-blooded animals, and their
whole organisation is thoroughly adapted to a predaceous mode of life.
In conformity with this manner of obtaining their subsistence they are
generally bold and savage in disposition, though some species are capable
of being domesticated, and when placed under favourable circumstances
for the development of such qualities exhibit a very high degree of
intelligence and fidelity. The existing representatives of the order
are naturally divided into two suborders, the members of the one being
the more typical, and mainly terrestrial in their mode of life; while
those of the other are aberrant, having the whole of their organisation
specially modified for living habitually in water. These are called
respectively the True, or Fissiped, and the Pinniped Carnivora.
_Suborder_ CARNIVORA VERA.
[Illustration: FIG. 220.—Left upper carnassial teeth of Carnivora. I,
_Felis_; II, _Canis_; III, _Ursus_. 1, Anterior, 2, middle (paracone),
and 3, posterior (metacone) cusp of blade; 4, inner tubercle (protocone)
supported on distinct root; 5, inner cusp posterior in position, and
without distinct root, characteristic of the _Ursidæ_.]
Generally adapted for terrestrial progression and mode of life, though
some may be partially aquatic in their habits. The fore limbs never have
the first digit, or the hind limbs the first and fifth digits, longer
than the others. Incisors ³⁄₃ on each side, with very rare exceptions.
Cerebral hemispheres more or less elongated; always with three or four
gyri on the outer surface forming arches above each other, the lowest
surrounding the Sylvian fissure. The molar series of teeth have not
the uniform characters of those of the Pinnipedia. There is always one
tooth in each jaw which is specially modified, and to which the name of
“sectorial” or “carnassial” tooth has been applied. The teeth in front of
this are more or less sharp pointed and compressed; while those behind
it are broad and tuberculated. The characters of the carnassial teeth
deserve special attention, as, though fundamentally the same throughout
the suborder, they are greatly modified in different genera. The upper
carnassial is the most posterior of the teeth which have predecessors,
and is therefore reckoned as the last premolar (_p_ ⁴⁄ of the typical
dentition). It consists essentially of a more or less compressed blade
supported on two roots and an inner tubercle supported by a distinct
root (see Fig. 220). The blade when fully developed has three cusps
or lobes (1, 2, and 3), but the anterior is always small, and often
absent. The middle lobe is conical, high, and pointed; the posterior
lobe has a compressed straight knife-like edge. The inner tubercle (4)
varies very much in extent, but is generally placed near the anterior
end of the blade, though sometimes it is median in position. In the
_Ursidæ_ alone both the inner tubercle and root are wanting, and there
is often a small internal and posterior cusp (5) without root. In this
aberrant family also the carnassial is relatively to the other teeth much
smaller than in the rest of the Carnivora. The lower carnassial (see
Fig. 221) is the most anterior of the teeth without predecessors in the
milk-series; it is therefore reckoned the first true molar (_m_ ¹⁄). It
has two roots supporting a crown, consisting when fully developed of a
compressed bilobed blade (1 and 2), a heel, or talon (4), and an inner
cusp (3). The lobes of the blade, of which the hinder (2) is the larger,
are separated by a notch, generally prolonged into a linear fissure. In
the most specialised Carnivora, as the _Felidæ_ (I), the blade alone
is developed, both talon and inner cusp being absent or rudimentary. In
others, as _Meles_ (V) and _Ursus_ (VI), the heel is greatly developed,
broad, and tuberculated. The blade in these cases is generally placed
obliquely, its flat or convex (outer) side looking forwards, so that the
two lobes are almost side by side, instead of anterior and posterior. The
inner cusp (3) is generally conical, pointed, and placed to the inner
side of the hinder lobe of the blade. The special characters of these
teeth are more disguised in the Sea Otter (_Latax_) than in any other
form, but even in it they can be traced.
[Illustration: FIG. 221.—Left lower carnassial teeth of Carnivora. I,
_Felis_; II, _Canis_; III, _Herpestes_; IV, _Lutra_; V, _Meles_; VI,
_Ursus_. 1, Anterior lobe (paraconid) of blade; 2, posterior (protoconid)
lobe of blade; 3, inner cusp (metaconid); 4, talon (hypoconid). It will
be seen that the relative size of the two roots varies according to
the development of the portion of the crown they have respectively to
support.]
The homology of the various parts of the Carnivorous carnassial with the
primitive tritubercular type (p. 30) is indicated in the figures. It may
be observed, however, that the anterior lobe of the three-lobed upper
carnassial is an element added on to the more primitive two-lobed type.
When the talon of the lower carnassial, as in _Canis_, consists of a
large outer and small inner cusp, the latter (not seen in the figure) is
the entoconid.
The toes are nearly always armed with large, strong, curved, and
tolerably sharp claws, ensheathing the ungual phalanges, and held more
firmly in their places by broad laminæ of bone reflected over their
attached ends from the bases of the phalanges. In some forms, most
notably the _Felidæ_, these claws are retractile; that is to say, the
ungual phalanx, with the claw attached, folds back in the fore foot into
a sheath by the outer or ulnar side of the middle phalanx of the digit,
being retained in this position when the animal is at rest by a strong
elastic ligament. In the hind foot the ungual phalanx is retracted on
to the top, and not the side of the middle phalanx. By the action of
the deep flexor muscles, the ungual phalanges are straightened out, the
claws protruded from their sheath, and the soft “velvety” paw becomes
suddenly converted into a most formidable weapon of offence. The habitual
retraction of the claws preserves their points from wear in ordinary
progression.
The skeleton of the Lion represented in Fig. 15 (p. 45) illustrates the
digitigrade mode of progression of the _Felidæ_, as well as the essential
characters of the bony framework of a typical Carnivore.
The Fissipedal Carnivora were divided by Cuvier into two groups,
according to the position of the feet in walking,—the Plantigrada,
or those that place the whole of the soles to the ground, and the
Digitigrada, or those that walk only on the toes; and the difference
between these groups was considered of equal importance to that which
separated the Pinnigrada or Seals from both of them. The distinction is,
however, quite an artificial one, since every intermediate condition
exists between the extreme typical plantigrade gait of the Bears and the
truly digitigrade walk of the Cats and Dogs; in fact, the greater number
of the Carnivora belong to neither one form nor the other, but may be
called “subplantigrade”; often when at rest applying the whole of the
sole to the ground, but keeping the heel raised to a greater or less
extent when walking.
An amended classification of the existing forms is into three distinct
sections, of which the Cats, the Dogs, and the Bears may be respectively
taken as representatives, and which are hence called Æluroidea, Cynoidea,
and Arctoidea. This division is founded mainly on characters exhibited
by the base of the skull, but is corroborated by the structure of other
parts.[424] The presence or absence of a bridge of bone, covering the
external carotid artery in a part of its course by the side of the
alisphenoid bone, and enclosing the “alisphenoid canal” (see Fig. 8, p.
38), a character to which the late Mr. H. N. Turner first drew attention,
might seem unimportant at first sight, but it is curiously constant
in certain groups, which we have other reasons, derived often from a
combination of less easily definable characters, to regard as natural. It
is therefore generally mentioned in the following family definitions.
It must, however, be stated that while the arrangement is a convenient
one as regards the existing Carnivores, it will not hold good when the
fossil forms are included. Thus there is ample evidence to show that
the Dogs and Bears were formerly so intimately connected that in a
palæontological classification the _Canidæ_ cannot be satisfactorily
separated from the _Ursidæ_; while in another direction the _Canidæ_ were
closely allied to the ancestral _Viverridæ_. The most important objection
against this classification is, however, the apparent intimate connection
exhibited by fossil forms between the _Viverridæ_ and the _Mustelidæ_,
which, so far as the present evidence goes, tends to show that the latter
are derived from the former. If this be eventually fully proved, it would
seem to indicate that the Arctoidea are not a natural group; and that the
resemblances between the _Ursidæ_ and _Mustelidæ_ have been independently
acquired, in the course of the descent of the one family from a Canoid,
and of the other from a Viverroid stock.
_Section_ ÆLUROIDEA.
[Illustration: FIG. 222.—Left side of the palatal aspect of the cranium
and mandible of the Suricate (_Suricata tetradactyla_). _c_, Carotid
foramen; _f_, fissure in floor of auditory meatus. From Mivart, _Proc.
Zool. Soc._ 1882, p. 184.]
The Æluroidea or Cat-like Carnivores include the _Felidæ_, _Viverridæ_,
_Proteleidæ_, and _Hyænidæ_. The existing representatives of this section
present the following common features. Auditory bulla (Fig. 222) much
dilated, rounded smooth, thin-walled, and (except in the _Hyænidæ_)
divided into two chambers, by a septum. Bony auditory meatus short.
Paroccipital process applied to, and spread over the hinder part of the
bulla (Fig. 222). Mastoid process never very salient, and often obsolete.
Carotid canal (Fig. 8, p. 38, _car_) small, sometimes very inconspicuous.
Condyloid and glenoid foramina concealed or wanting. Cæcum small, rarely
absent. Os penis generally small and irregular (large in _Cryptoprocta_).
Cowper’s glands present; prostate distinctly lobed. Some details of the
anatomy of the soft parts will be found under the head of _Genetta_.
_Family_ FELIDÆ.
In all the forms, both recent and fossil, which can be included in this
family the canines are strongly developed, there are never more than
one upper and two lower molars, and the three lower incisors are placed
in the same horizontal line. With one exception, the humerus has an
entepicondylar foramen.
The following characters are common to all the existing members. True
molars reduced to one above and below, that of the upper jaw very small
and transversely extended. Only two inferior premolars. Upper carnassial
with three lobes to the blade; lower without talon or inner cusp.
Auditory bulla not externally constricted. No alisphenoid canal. Carotid
canal very minute. Digits 5-4. Dorsal vertebræ 13.
[Illustration: FIG. 223.—Front view of skull of Lion (_Felis leo_).]
_Felis._[425]—The whole structure of the animals of this genus exhibits
the Carnivorous type in its fullest perfection. Dentition: _i_ ³⁄₃, _c_
¹⁄₁, _p_ ³⁄₂, _m_ ¹⁄₁; total 30. A distinctly cusped inner tubercle to
the upper carnassial. Claws completely retractile. The upper anterior
premolar (_p._ 2), always small, and may be absent without any other
modification in the dental or other structures. Such a variation should
not therefore be considered as of generic importance. Incisors very
small. Canines large, strong, slightly recurved, with trenchant edges and
sharp points, and placed wide apart (Fig. 223). Premolars compressed and
sharp pointed. The most posterior in the upper jaw (the carnassial), a
very large tooth, consisting of a subcompressed blade, divided into three
unequal lobes supported by two roots, with a very small inner tubercle
placed near the front end of the tooth and supported by a distinct root
(Fig. 220). The upper true molar a very small tubercular tooth placed
more or less transversely at the inner side of the hinder end of the
last. In the lower jaw the true molar (carnassial) reduced to the blade
alone, which is very large, trenchant, and much compressed, divided
into two subequal lobes. Occasionally it has a rudimentary talon, but
never an inner cusp. The skull is generally short and rounded, though
proportionally more elongated in the larger forms. The facial portion
is especially short and broad, and the zygomatic arches are very
wide and strong. The auditory bullæ are large, rounded, and smooth.
Vertebræ: C 7, D 13, L 7, S 3, C 13-29. Clavicles better developed
than in other Carnivora, but not articulating with either the scapulæ
or sternum. Limbs digitigrade. Anterior feet with five toes, the third
and fourth nearly equal and longest, the second slightly and the fifth
considerably shorter; the pollex still shorter, not reaching as far as
the metacarpo-phalangeal articulation of the second. Hind feet with
only four toes. The third and fourth the longest, the second and fifth
somewhat shorter and nearly equal; the hallux represented only by the
rudimentary metatarsal bone. The claws all very large, strongly curved,
compressed, very sharp, and exhibiting the retractile condition in the
highest degree. The tail varies greatly in length, being in some a mere
stump, in others nearly as long as the body. Ears of moderate size, more
or less triangular and pointed. Eyes rather large. Iris very mobile, and
with a pupillary aperture which contracts under the influence of light
in some species to a narrow vertical slit, in others to an oval, and in
some to a circular aperture. Tongue thickly covered with sharp-pointed,
recurved horny papillæ. Cæcum small and simple.
As in structure so in habits, the Cats may be considered the most
specialised of all the Carnivora. All the known members of the genus
feed, in the natural state, almost exclusively on warm-blooded animals
which they have themselves killed. One Indian species (_F. viverrina_)
preys on fish and even (it is said) on freshwater molluscs. Unlike the
Dogs, they never associate in packs, and rarely hunt their prey in open
ground, but from some place of concealment wait until the unsuspecting
victim comes within reach, or with noiseless and stealthy tread,
crouching close to the ground for concealment, approach near enough to
make the fatal spring. In this manner they frequently attack and kill
animals considerably exceeding their own size. They are mostly nocturnal,
and the greater number, especially the smaller species, more or less
arboreal. None are aquatic, and all take to the water with reluctance,
though some may habitually haunt the banks of rivers or pools, because
they more easily obtain their prey in such situations.
The numerous species of the genus are very widely diffused over the
greater part of the habitable world, though most abundant in the warm
latitudes of both hemispheres. No species are, however, found in the
Australian region, or in Madagascar. Although the Old-World and New-World
Cats (except perhaps the Northern Lynx) are all specifically distinct,
no common structural character has been pointed out by which the former
can be separated from the latter. On the contrary, most of the minor
groups into which the genus has been divided have representatives in both
hemispheres.
Notwithstanding the considerable diversity in external appearance and
size between different members of this extensive genus, the structural
differences are but slight, and so variously combined in different
species that the numerous attempts hitherto made to subdivide it are all
unsatisfactory and artificial. The principal differences are to be found
in the form of the cranium, especially of the nasal and adjoining bones,
the completeness of the bony orbit posteriorly, the development of the
first upper premolar and of the inner tubercle of the upper carnassial,
the length of the tail, the form of the pupil, and the condition and
coloration of the fur, especially the presence or absence of tufts
or pencils of hair on the external ears. Writing in 1881 Professor
Mivart[426] gave the number of existing species of _Felis_ as 48, but
by Mr. Blanford’s reduction of the number of Indian species[427] the
list may now be diminished to some 41. The following account is chiefly
devoted to some of the more important and better known species.
A. _Old World Species._—The Lion (_F. leo_, Fig. 224) has been well known
to man from the earliest historic times. Its geographical habitat made it
familiar to all the races among whom human civilisation took its origin,
and its strongly marked physical and moral characteristics have rendered
it proverbial, perhaps to an exaggerated degree, and have in all ages
afforded favourite types for poetry, art, and heraldry. The literature
of the ancient Hebrews abounds in allusions to the Lion; and the almost
incredible numbers that are stated to have been provided for exhibition
and destruction in the Roman amphitheatres (as many as six hundred on a
single occasion by Pompey, for example) show how abundant these animals
must have been within accessible distance of the capital of the world.
The geographical range of the Lion was once far more extensive than at
present, even within the historic period covering the whole of Africa,
the south of Asia, including Syria, Arabia, Asia Minor, Persia, and the
greater part of Northern and Central India, and also the south-eastern
portion of Europe, as shown by the well-known story told by Herodotus of
the attacks by Lions on the Camels which carried the baggage of the army
of Xerxes on its march through the country of the Pæonians in Macedonia.
The very circumstantial account of that historian shows that the animal
in his time ranged through the country south of the Balkans, through
Roumania to the west of the River Carasu, and through Thessaly as far
south as the Gulf of Lepanto and the Isthmus of Corinth, having as its
western boundary the River Potamo and the Pindus mountains. The whole
of the evidence relating to the existence of Lions in Europe, and to
their retreat from that continent shortly before the commencement of the
Christian era, has been collected in the article on “_Felis spelæa_” in
Boyd Dawkins and Sandford’s _British Pleistocene Mammalia_ (1868). Fossil
remains attest a still wider range, as it is shown in the same work that
there is absolutely no osteological or dental character by which the
well-known Cave Lion (_F. spelæa_), so abundantly found in cave-deposits
of the Pleistocene age in Western Europe, can be distinguished from the
existing _F. leo_.
[Illustration: FIG. 224.—Lion and Lioness, after a drawing by Wolf in
Elliot’s Monograph of the _Felidæ_.]
At the present day the Lion is found in localities suitable to its
habits, and where not exterminated (as it probably was in Europe) by the
encroachments of man, throughout Africa from Algeria to the Cape Colony,
and in Mesopotamia, Persia, and some parts of the north-west of India.
According to Blanford,[428] Lions are still very numerous in the reedy
swamps bordering the Tigris and Euphrates, and also occur on the west
flanks of the Zagros mountains and the oak-clad ranges near Shiraz, to
which they are attracted by the immense herds of swine which feed on the
acorns. The Lion nowhere exists in the table-land of Persia, nor is it
found in Baluchistan. In India, where it is verging on extinction, it
appears now to be confined to parts of Kattywar and Rajputana, though
within the present century its range extended through the north-west part
of India, from Bahawalpur and Sind to at least the Jumna (about Delhi),
southward as far as Khandesh, and in Central India through the Saugor
and Narbada territories, Bundelkund, and as far east as Palamau. It was
extirpated in Harriana about 1824. One was killed at Rhyli, in the Dumaoh
district, Saugor and Narbada territories, so late as in the cold season
of 1847-48; and one was shot in 1810 near Kot-Deji, Sind.[429]
The great variations in external characters which different Lions
present, especially in the colour and the amount of mane, has given rise
to the idea that there are several species, or at all events distinct
varieties peculiar to different localities. It was at one time supposed,
on the authority of Captain Walter Smee,[430] that the Lion of Gujerat
differed essentially from that of Africa in the absence of a mane, but
subsequent evidence has not supported this view, which was probably
founded upon young specimens having been mistaken for adults. Lions from
that district as well as from Babylonia, which have lived in the gardens
of the London Zoological Society, have had as fully developed manes as
any other of the species. Mr. F. C. Selous[431] has shown that in South
Africa the so-called Black-maned Lion and others with yellow scanty manes
are found, not only in the same locality, but even among individuals of
the same parentage.
The Lion belongs to a well-defined group, containing the largest members
of the genus, and differing from the others in the well-marked character
that the anterior cornu of the hyoid arch is but little ossified, so that
this arch is connected with the cranium by a long ligament, instead of by
a continuous chain of bones, and by the less important one that the pupil
of the eye, when contracted, is a circular hole, instead of a vertical
slit as in the cat. The Lion agrees with the Tiger and the Leopard in
these respects, but differs from them in its uniform style of colouring,
and from all the other _Felidæ_ in the arrangement of its hairy covering;
thus the hair of the top of the head, chin, and neck, as far back as the
shoulder, is not only very much longer, but also differently disposed
from the hair elsewhere, being erect or directed forwards, and so
constituting the characteristic ornament called the mane. There is also a
tuft of elongated hairs at the end of the tail, one upon each elbow, and
in most lions a copious fringe along the middle line of the under surface
of the body, wanting, however, in some examples.[432] It must, however,
be observed that these characters are peculiar to the adults of the male
sex only, and that young lions show indications of the darker stripes and
mottlings so characteristic of the greater number of the members of the
genus.
The usual colour of the adult is yellowish-brown, but it may vary from a
deep red or chestnut brown to an almost silver gray. The mane, as well as
the long hair of the other parts of the body, sometimes scarcely differs
from the general colour, but it is usually darker and not unfrequently
nearly black. The mane begins to grow when the animal is about three
years old, and is fully developed at five or six.
In size the Lion is only equalled or exceeded by the Tiger among the
existing _Felidæ_; though both species present great variations, the
largest specimens of the latter appear to surpass the largest Lions. A
full-sized South African Lion, according to Selous, measures slightly
less than 10 feet from nose to tip of tail, following the curves of
the body. Harris gives 10 feet 6 inches, of which the tail occupies 3
feet. The Lioness is about a foot less. The tongue, like that of the
other species of the genus, is long and flat, and remarkable for the
development of the papillæ of the anterior part of the dorsal surface,
which (except near the edge) are modified so as to resemble long,
compressed, recurved, horny spines or claws; these, near the middle line,
attaining the length of one-fifth of an inch. They give the part of the
tongue on which they occur the appearance and feel of a coarse rasp, and
serve the purpose of such an instrument in cleaning the flesh from the
bones of the animals on which the Lions feed.
The habits of the Lion in a state of nature are fairly well known from
the united observations of numerous travellers and sportsmen who have
explored those districts of the African continent in which it is still
common. It lives chiefly in sandy plains and rocky places interspersed
with dense thorn-thickets, or frequents the low bushes and tall rank
grass and reeds that grow along the sides of streams and near the
springs where it lies in wait for the larger herbivorous animals on
which it feeds. Although it is occasionally seen abroad during the
day, especially in wild and desolate regions, where it is subject to
but little molestation, the night is, as in the case of so many other
predaceous animals, the period of its greatest activity. It is then that
its characteristic roar is chiefly heard, as thus graphically described
by Gordon Cumming:—
“One of the most striking things connected with the Lion is his voice,
which is extremely grand and peculiarly striking. It consists at
times of a low, deep moaning, repeated five or six times, ending in
faintly audible sighs; at other times he startles the forest with loud,
deep-toned, solemn roars, repeated in quick succession, each increasing
in loudness to the third or fourth, when his voice dies away in five
or six low muffled sounds very much resembling distant thunder. At
times, and not unfrequently, a troop may be heard roaring in concert,
one assuming the lead, and two, three, or four more regularly taking
up their parts, like persons singing a catch. Like our Scottish stags
at the rutting season, they roar loudest in cold frosty nights; but on
no occasions are their voices to be heard in such perfection, or so
intensely powerful, as when two or three troops of strange Lions approach
a fountain to drink at the same time. When this occurs, every member
of each troop sounds a bold roar of defiance at the opposite parties;
and when one roars, all roar together, and each seems to vie with his
comrades in the intensity and power of his voice. The power and grandeur
of these nocturnal concerts are inconceivably striking and pleasing to
the hunter’s ear.”
“The usual pace of a Lion,” C. J. Andersson[433] says, “is a walk, and,
though apparently rather slow, yet, from the great length of his body, he
is able to get over a good deal of ground in a short time. Occasionally
he trots, when his speed is not inconsiderable. His gallop—or rather
succession of bounds—is, for a short distance, very fast—nearly or quite
equal to that of a horse. Indeed, unless the steed has somewhat the start
when the beast charges, it will be puzzled to escape. Many instances
are on record of horsemen who have incautiously approached too near to
the Lion, prior to firing, who have been pulled down by him before they
could get out of harm’s way. Happily, however, the beast soon tires of
the exertion of galloping, and unless his first rush succeeds he, for
the most part, soon halts and beats a retreat.” “The Lion, as with other
members of the feline family,” the same writer tells us, “seldom attacks
his prey openly, unless compelled by extreme hunger. For the most part he
steals upon it in the manner of a cat, or ambushes himself near to the
water or a pathway frequented by game. At such times he lies crouched
upon his belly in a thicket until the animal approaches sufficiently
near, when, with one prodigious bound, he pounces upon it. In most cases
he is successful, but should his intended victim escape, as at times
happens, from his having miscalculated the distance, he may make a second
or even a third bound, which, however, usually prove fruitless, or he
returns disconcerted to his hiding-place, there to wait for another
opportunity.” His food consists of all the larger herbivorous animals of
the country in which he resides—buffaloes, antelopes, zebras, giraffes,
or even young elephants or rhinoceroses, though the adults of these
latter he dare not attack. In cultivated districts the cattle, sheep,
and even human inhabitants are never safe from his nocturnal ravages.
He appears, however, as a general rule, only to kill when hungry or
attacked, and not for the mere pleasure of killing, as with some other
carnivorous animals. Moreover, he by no means limits himself to animals
of his own killing, but, according to Selous, often prefers eating game
that has been killed by man, even when not very fresh, to taking the
trouble to catch an animal himself. All books of African travel and sport
abound with stories, many of which are apparently well authenticated, of
the lion’s prodigious strength, as, exemplified by his being able to drag
off a whole ox in his mouth to a long distance, even leaping fences and
dykes with it.
The Lion appears to be monogamous, a single male and female continuing
attached to each other irrespectively of the pairing season. At all
events the Lion remains with the Lioness while the cubs are young and
helpless, and assists in providing her and them with food, and in
educating them in the art of providing for themselves. The number of cubs
at a birth is from two to four, usually three. They are said to remain
with their parents till they are about three years old. The following
account by an eye-witness gives a good idea of Lion family life[434]:—
“I once had the pleasure of, unobserved myself, watching a lion family
feeding. I was encamped on the Black Umfolosi in Zululand, and towards
evening, walking out, about half a mile from camp, I saw a herd of zebra
galloping across me, and when they were nearly 200 yards off, I saw a
yellow body flash towards the leader, and saw him fall beneath the lion’s
weight. There was a tall tree about 60 yards from the place, and anxious
to see what went on, I stalked up to it, while the lion was still too
much occupied to look about him, and climbed up. He had by this time
quite killed the beautifully striped animal, but instead of proceeding
to eat it, he got up and roared vigorously, until there was an answer,
and in a few minutes a lioness, accompanied by four whelps, came trotting
up from the same direction as the zebra, which no doubt she had been to
drive towards her husband. They formed a fine picture as they all stood
round the carcase, the whelps tearing it and biting it, but unable to get
through the tough skin. Then the lion lay down, and the lioness driving
her offspring before her did the same four or five yards off, upon
which he got up, and, commencing to eat, had soon finished a hind leg,
retiring a few yards on one side as soon as he had done so. The lioness
came up next and tore the carcase to shreds, bolting huge mouthfuls, but
not objecting to the whelps eating us much as they could find. There was
a good deal of snarling and quarrelling among these young lions, and
occasionally a stand-up fight for a minute, but their mother did not take
any notice of them, except to give them a smart blow with her paw if
they got in her way.... There was now little left of the zebra but a few
bones, which hundreds of vultures were circling round waiting to pick,
while almost an equal number hopped awkwardly about on the ground within
50 or 60 yards of it, and the whole lion family walked quietly away, the
lioness leading, and the lion, often turning his head to see that they
were not followed, bringing up the rear.”
Though not strictly gregarious, Lions appear to be sociable towards their
own species, and often are found in small troops, sometimes consisting of
a pair of old Lions, with their nearly full-grown cubs, but occasionally
of adults of the same sex; and there seems to be good evidence that
several Lions will associate together for the purpose of hunting upon
a preconcerted plan. As might be supposed, their natural ferocity and
powerful armature are sometimes turned upon one another; combats, often
mortal, occur among male Lions under the influence of jealousy; and
Andersson relates an instance of a quarrel between a hungry Lion and
Lioness over the carcase of an Antelope which they had just killed, and
which did not seem sufficient for the appetite of both, ending in the
Lion not only killing, but even devouring his mate. Old Lions, whose
teeth have become injured with constant wear, often become “man-eaters,”
finding their easiest means of obtaining a subsistence in lurking in
the neighbourhood of villages, and dashing into the tents at night and
carrying off one of the sleeping inmates. Lions differ from most of the
smaller _Felidæ_ in never climbing trees; indeed, as mentioned before,
they are rarely found in forests.
With regard to the character of the Lion, those who have had
opportunities of observing it in its native haunts differ greatly. The
exaggerated accounts of early writers as to its courage, nobility, and
magnanimity have led to a reaction, which causes some modern authors
to speak of it in language quite the reverse, and to accuse it of
positive cowardice and all kinds of meanness. Livingstone goes so far
as to say, “Nothing that I ever learned of the lion could lead me to
attribute to it either the ferocious or noble character ascribed to
it elsewhere,” and he adds that its roar is not distinguishable from
that of the ostrich. Of course these different estimates depend to
a great extent upon the particular standard of the writer, and also
upon the circumstance that Lions, like other animals, undoubtedly show
considerable individual differences in character, and behave differently
under varying circumstances. They are certainly not so reckless as to be
entirely devoid of the instinct of self-preservation, and if one, perhaps
satiated with a good meal the night before, unexpectedly disturbed in the
daytime, will occasionally retreat when confronted, even by an unarmed
man, that is scarcely a reason for assigning cowardice as one of the
characteristics of the species. The latest authority, Selous, while never
denying the daring courage of the Lion when hungry or provoked, and
vindicating the awe-inspiring character of the roar of several Lions in
unison, when heard at close quarters, as the grandest sound in nature,
says with regard to its outward aspect:—
“It has always appeared to me that the word ‘majestic’ is singularly
inapplicable to the lion in its wild state, as when seen by daylight
he always has a stealthy furtive look that entirely does away with the
idea of majesty. To look majestic a lion should hold his head high. This
he seldom does. When walking he holds it low, lower than the line of
his back, and it is only when he first becomes aware of the presence of
man that he sometimes raises his head and takes a look at the intruder,
usually lowering it immediately, and trotting away with a growl. When
at bay, standing with open mouth and glaring eyes, holding his head
low between his shoulders, and keeping up a continuous low growling,
twitching his tail the while from side to side, no animal can look more
unpleasant than a lion; but there is then nothing majestic or noble in
his appearance.”
Notwithstanding this evidently truthful description of the animal when
seen under what may be called unfavourable circumstances, no one with an
eye for beauty can contemplate the form of a fine specimen of a Lion,
at all events in a state of repose, even though in the confinement of a
menagerie, without being impressed with the feeling that it is a grand
and noble-looking animal.
The Tiger (_F. tigris_) is so closely related to the Lion that it is
chiefly by external characters that the two species are distinguished.
There are, however, slight distinctions in the proportionate size of the
lower teeth, the general form of the cranium, and the relative length of
the nasal bones and ascending processes of the maxillaries by which the
skull of the Lion and Tiger can be easily discriminated by the practised
observer.
Although examples of both species present considerable variations in
size, and reliance cannot always be placed upon alleged dimensions,
especially when taken from skins stripped from the body, it seems well
ascertained that the length of the largest-sized Bengal Tiger may exceed
that of any Lion. According to Mr. W. T. Blanford,[435] adult males
measure from 5½ to 6½ feet from the nose to the root of the tail; the
tail itself measuring some 3 feet in length. Measured along the curves
of the head and back to the tip of the tail, males usually give a length
of from 9 to 10 feet, but some specimens reach to 12 feet. The female
is somewhat smaller, and has a lighter and narrower head. The Tiger
has no mane, but in old males the hair of the cheeks is rather long
and spreading. The ground colour of the upper and outer parts of the
head, body, limbs, and tail is a bright rufous fawn, and these parts
are beautifully marked with transverse stripes of a dark, almost black
colour. The markings vary much in different individuals, and even on the
two sides of the same individual. The under parts of the body, the inside
of the limbs, the cheeks, and a large spot over each eye are nearly
white. The Tigers which inhabit hotter regions, as Bengal and the south
Asiatic islands, have shorter and smoother hair, and are more richly
coloured and distinctly striped than those of Northern China and Siberia,
in which the fur is longer, softer, and lighter coloured.
[Illustration: FIG. 225.—The Tiger (_Felis tigris_).]
The Tiger is exclusively Asiatic, but has a very wide range in that
continent, having been found in almost all suitable localities south of
a line drawn from the river Euphrates, passing along the southern shores
of the Caspian and Sea of Aral by Lake Baikal to the Sea of Okhotsk.
Its most northern range is the territory of the Amur, its most southern
the islands of Sumatra, Java, and Bali. Westward it reaches to Turkish
Georgia and eastward to the island of Saghalin. It is absent, however,
from the great elevated plateau of Central Asia, nor does it inhabit
Ceylon, Borneo, or the other islands of the Indo-Malayan Archipelago,
except those above mentioned. Its absence from Ceylon leads Mr. Blanford
to conclude that the Tiger has only recently migrated into Southern India.
The principal food of the Tiger in India is cattle, deer, wild hog, and
pea-fowl, and occasionally human beings. The regular “man-eater” is
generally an old Tiger whose vigour is passed, and whose teeth are worn
and defective; it takes up its abode in the neighbourhood of a village,
the population of which it finds an easier prey than the larger or
wilder animals named above. Though chiefly affecting grassy plains or
swamps, it is also found in forests, and seems to be fond of haunting the
neighbourhood of old ruins. As a rule, Tigers do not climb trees; but
when pressed by fear, as during an inundation, they have been known to
do so. They take to the water readily and are good swimmers. The Tigers
of the Sundarbans (Ganges delta) continually swim from one island to the
other to change their hunting-grounds for deer. The following extract on
the habits of the Tiger is taken from Sir J. Fayrer’s _Royal Tiger of
Bengal_ (1875):—
“The tigress gives birth to from two to five, even six cubs; but three is
a frequent number. She is a most affectionate and attached mother, and
generally guards and trains her young with the most watchful solicitude.
They remain with her until nearly full grown, or about the second year,
when they are able to kill for themselves and begin life on their own
account. Whilst they remain with her she is peculiarly vicious and
aggressive, defending them with the greatest courage and energy, and
when robbed of them is terrible in her rage; but she has been known to
desert them when pressed, and even to eat them when starved. As soon
as they begin to require other food than her milk, she kills for them,
teaching them to do so for themselves by practising on small animals,
such as deer and young calves or pigs. At these times she is wanton and
extravagant in her cruelty, killing apparently for the gratification
of her ferocious and bloodthirsty nature, and perhaps to excite and
instruct the young ones, and it is not until they are thoroughly capable
of killing their own food that she separates from them. The young tigers
are far more destructive than the old. They will kill three or four
cows at a time, whilst the older and more experienced rarely kill more
than one, and this at intervals of from three or four days to a week.
For this purpose the tiger will leave its retreat in the dense jungle,
proceed to the neighbourhood of a village or gowrie, where cattle feed,
and during the night will steal on and strike down a bullock, drag it
into a secluded place, and then remain near the ‘marrie,’ or ‘kill,’ for
several days, until it has eaten it, when it will proceed in search of a
further supply, and, having found good hunting ground in the vicinity of
a village or gowrie, continue its ravages, destroying one or two cows or
buffaloes a week. It is very fond of the ordinary domestic cattle, which
in the plains of India are generally weak, half-starved, under-sized
creatures. One of these is easily struck down and carried or dragged off.
The smaller buffaloes are also easily disposed of; but the buffalo bulls,
and especially the wild ones, are formidable antagonists, and have often
been known to beat the Tiger off, and even to wound him seriously.”
In many districts of India the number of Tigers has been very
considerably diminished of late years. In some other countries they
appear, however, to be on the increase; thus according to one of the
administration reports of Java laid before the Dutch Chambers, portions
of that island are being depopulated through Tigers. In 1882 the
population of a village in the south-west of the Bantam province was
removed and transferred to an island off the coast in consequence of the
trouble caused to the people by Tigers. These animals have now become
an intolerable pest in parts of the same province. The total population
is about 600,000, and, in 1887, sixty-one were killed by Tigers, and in
consequence of the dread existing among the people, it has been proposed
to deport the inhabitants of the villages most threatened to other parts
of the country where Tigers are not so common, and where they can pursue
their agricultural occupations with a greater degree of security. At
present they fear to go anywhere near the borders of the forest. The
people seem disinclined, or they lack the means and courage, to attack
and destroy their enemy, although considerable rewards are offered by
Government for the destruction of beasts of prey. In 1888 the reward for
killing a Royal Tiger was raised to two hundred florins. It appears also
that the immunity of the Tiger is in part due to superstition, for it is
considered wrong to kill one unless he attacks first or otherwise does
injury.
The Leopard (_F. pardus_, Fig. 226), although belonging to the same
restricted group as the two preceding species, is distinguished from both
by its inferior size, and its coloration. The animal now commonly known
as the Leopard was called Pard (πάρδος and πάρδαλις) or Panther (πάνθηρ)
by the ancients. Leopard (_leo-pardus_) is a later term, originally
applied, it is believed, to the Cheeta or Hunting Leopard, upon the
supposition that it was a creature intermediate between the Lion and the
true Pard. If so it has been completely transferred to the more common
species, and though in this sense a perfectly unnecessary and unmeaning
term, has gradually superseded those by which this was originally known.
Pard, so commonly used by Elizabethan authors, is now nearly obsolete
in the English language, and Panther has either become synonymous with
Leopard, or is used vaguely for any similar large feline animal, even the
Puma of America.
[Illustration: FIG. 226.—The Leopard (_Felis pardus_).]
Owing to their extensive geographical range, and the great variations,
both in size, form, and coloration to which Leopards are subject,
zoologists have scarcely decided whether all the forms popularly referred
to this animal should be regarded as specifically alike, or whether they
should constitute several distinct species, but the prevailing opinion
is in favour of the former view. The attempts to separate a larger and
more robust variety, under the name of Panther, from a smaller and more
graceful form, to which the term Leopard might properly be restricted,
have failed, owing to the existence of intermediate conditions which
cannot be assigned definitely to either one or the other form.[436] The
most marked anatomical difference yet noted in different varieties of
leopard is in the length of the tail as compared with that of the body,
even the number of the caudal vertebræ showing variation, though within
what limits, and whether correlated with other characters, has not yet
been clearly ascertained. The fur of those specimens which inhabit the
most northern confines of its range of distribution, as North China, is
longer and softer, and the markings are consequently less distinct than
on those from more congenial climates, and the well-marked variation thus
produced has given rise to the idea of specific distinction.
The size of different individuals, as before said, varies greatly, the
head and body usually measuring from 3½ to 4½ feet in length, and the
tail from 2½ to 3 feet, but specimens have been met with which fall short
of or exceed these limits. The ground colour of the fur varies from a
pale fawn to a rufous buff, graduating into a pure white on the under
parts and inside of the limbs. This is spotted over with dark brown or
black; the spots on the back and sides being arranged in rosettes or
broken rings, which vary greatly in size and distinctness in different
individuals, but are without the central spot seen in those of the
Jaguar. The spots on the under parts and limbs are simple and blacker
than those on the other parts of the body. The bases of the ears behind
are black, the tips buff. The upper side of the tail is buff, spotted
with broken rings like the back, its under surface white with simple
spots. The hair of the cubs is longer than that of the adults, its
ground colour less bright, and its spots less distinct. Perfectly black
Leopards, which, however, in certain lights show the characteristic
markings on the fur, are not uncommon. These appear to be examples of
melanism, occurring as individual variations, sometimes in one cub out
of a litter of which the rest are normally coloured, and therefore not
indicating a distinct race, much less a species. These are met with
chiefly in Southern Asia. We are not aware of any recorded case from
Africa, though there seems no reason why they should not occur.
In habits the Leopard resembles the other large Cat-like animals,
yielding to none in the ferocity and bloodthirstiness of its disposition.
It is exceedingly quick and active in its movements, but seizes its
prey by waiting in ambush or stealthily approaching to within springing
distance, when it suddenly rushes upon it and tears it to the ground with
its powerful claws and teeth. It preys upon almost any animal it can
overcome, such as antelopes, deer, sheep, goats, monkeys, peafowls, and
is said to have a special liking for dogs. It not unfrequently attacks
human beings in India, chiefly children and old women, but instances have
been known of a Leopard becoming a regular “man-eater.” When favourable
opportunities occur, it often kills many more victims than it can devour
at once, apparently to gratify its propensity for killing, or only for
the sake of their fresh blood. It generally inhabits woody districts,
and can climb high trees with facility if necessary for its safety when
hunted, but usually lives on or near the ground, among rocks, bushes, and
roots and low branches of large trees.
The present geographical range of the Leopard is very extensive, as it is
met with in various suitable localities, where not too much interfered
with by human cultivation, throughout the greater part of Africa from
Algeria to the Cape Colony, and through the whole of the South of Asia
from Palestine to China, including all India south of the Himalaya,
and the islands of Ceylon, Java, Sumatra, and Borneo. Fossil bones and
teeth, indistinguishable from those of existing Leopards, have been
found in cave-deposits of Pleistocene age in Spain, France, Germany, and
England. The evidence of the former existence of the Leopard in England
is described at length by Boyd Dawkins and Sanford in their _British
Pleistocene Mammalia_.[437]
The Ounce, or Snow Leopard (_F. uncia_), inhabits the highlands of
Central Asia, from the lofty mountains of Tibet to the southern parts
of Siberia, at altitudes of from 9000 to 18,000 feet above the sea.
It is about the size of the common Leopard, but lighter in colour,
with longer fur, less distinct spots, and a long thick tail. Its skull
differs in shape from that of all the other _Felidæ_; the facial portion
being very broad, the nasal bones especially being wide and depressed,
and the zygomatic arches very strong and deep. The Clouded Tiger (_F.
nebulosa_[438]) is a beautifully marked species, with elongated head
and body, long tail, and rather short limbs. The canine teeth are
proportionally longer than in any existing member of the genus. It is
thoroughly arboreal, and is found in the forests of South-East Asia and
the islands of Sumatra, Java, Borneo, and Formosa. _F. serval_, the
Serval, from South Africa, is yellow with black spots, and has a short
tail and large ears. Numerous smaller species called Tiger Cats and Wild
Cats, of which the Oriental _F. marmorata_ (Fig. 227) is a good example,
are found throughout the warmer parts of Asia and Africa. The Wild Cat of
Europe, _F. catus_, still inhabits the mountainous and wooded parts of
Great Britain.
[Illustration: FIG. 227.—The Marbled Cat (_Felis marmorata_). From
Blanford, _Mammalia of British India_, p. 74, after Elliot.]
The Caffre Cat (_F. caffra_[439]), of Africa and Southern Asia, was the
species held in veneration by the ancient Egyptians, and immense numbers
of its mummified remains have recently been found in Egypt, whence they
have been imported in large quantities to this country for manure. This
species is generally regarded as the main ancestral stock from which the
European Domestic Cat has been derived; one of the arguments in support
of this opinion being that the whole of the sole of the hind foot of
_F. caffra_ is black, and that the same feature obtains in the darker
varieties of the Domestic Cat; while in _F. catus_ there are only spots
of black upon this portion of the limb. Remains of the Caffre Cat occur
in the Pleistocene cave-deposits at Gibraltar. The Indian _F. rubiginosa_
is the smallest species of Cat.
The Caracal or Persian Lynx (_F. caracal_) is an animal about the size
of a fox, of slender build, with a moderately long tail, reaching down
to the heels. It is of a uniform vinous or bright fulvous brown colour
above, and is paler, sometimes almost white, beneath. It is quite or
almost entirely unspotted. The tail has a black tip, and the ears are
black externally, long, upright, pointed, and surmounted by a pencil
of fine black hairs. It inhabits Central and North-West India, Persia,
Arabia, Syria, and the greater part of Africa.
The true Lynxes comprise various species or varieties found in the
northern and temperate regions of both the Old and New World, all larger
than the true Wild Cats, with long limbs, short stumpy tail, ears tufted
at the tip, and pupil of the eye linear when contracted. Their fur is
generally long and soft, varying, however, according to season and
locality, and always longish upon the cheeks. Their colour is always
light brown or gray, and generally more or less spotted with a darker
shade. The naked pads of the feet are more or less covered by the hair
that grows between them. The skull and skeleton do not differ markedly
from those of the other cats, but the small anterior upper premolar tooth
found in many other species is usually wanting; and the lower carnassial
has a rudimental talon. Their habits are exactly those of the other Wild
Cats, and they are exceeded by none in the untameable savageness of their
disposition. They capture their prey in the same manner, either lying in
wait, or noiselessly stealing within reach, and then making a sudden rush
or spring upon it. Their food consists of any mammals or birds which they
can overpower. In inhabited countries they commit extensive ravages upon
sheep, lambs, and poultry. Lynxes generally frequent rocky places and
forests, being active climbers, and passing much of their time among the
branches of the trees. Their skins are of considerable commercial value.
Zoologists are by no means agreed at present as to the specific
distinctions, if any really exist, between the various modifications
of this group. As many as eight species are sometimes recognised, four
belonging to the Old and four to the New World. The former are _F.
lynx_, of Scandinavia, Russia, Northern Asia, and till lately the forest
regions of Central Europe; though not an inhabitant of Britain during
the historic period, its remains have been found in cave-deposits of
Pleistocene age; _F. cervaria_, Siberia; _F. pardina_, Turkey, Greece,
Sicily, Sardinia, and Spain; and _F. isabellina_, Tibet. The American
varieties are _F. canadensis_, the most northern species, and _F.
rufa_, the American Wild Cat or Bay Lynx, extensively distributed from
the Atlantic to the Pacific throughout nearly the whole latitude of
the United States, but replaced in Texas and southern California by
_F. maculata_, and in northern Oregon and Washington territory by _F.
fasciata_.
[Illustration: FIG. 228.—European Lynx (_Felis lynx_). From a drawing by
Wolf in Elliot’s _Monograph of the Felidæ_.]
In both cases, as might be supposed, specimens obtained from the more
southern climates are shorter in their fur, more brightly coloured,
and more distinctly spotted than those from colder regions. When only
a few individuals of each most markedly different form are examined
the distinctions are sufficiently evident. The occurrence, however,
of transitional or intermediate forms makes it extremely difficult to
draw the line between the different varieties or species, or to assign
definite characters by which they can be separated. Wherefore it is best
at present to accept the so-called species as only provisional, and wait
until more abundant materials, with fuller knowledge of the localities
from which they are derived, and of the variations due to age, sex,
season, and climate, have been more carefully studied. We shall then
probably come to the conclusion that all or nearly all the existing forms
of northern Lynxes, whether American or Eurasian, belong to what may
fairly be called a species, which is becoming by degrees differentiated
into several more or less strongly marked local varieties. Mr. W. T.
Blanford has indeed shown that the Tibetan Lynx (_F. isabellina_) is
inseparable from _F. lynx_; the specimens from Gilgit being intermediate
in colour between the typical forms of the two races. On the other hand,
from the evidence of cranial characters, Professor Mivart is disposed to
regard _F. pardina_ as a valid species.
[Illustration: FIG. 229.—The Puma (_Felis concolor_).]
B. _New World Species._—The Puma or Couguar (_F. concolor_, Fig. 229),
commonly called “Panther” in the United States, is about the size of a
Leopard, but of an uniform brown colour. It usually measures from nose
to root of tail about 40 inches, the tail being rather more than half
that length. The head is rather small compared with that of other Cats
and has no mane. The ears are large and rounded. The tail is cylindrical,
with some bushy elongation of the hairs near the end, but not forming a
distinct tuft as in the Lion. The general colour of all the upper parts
and sides of the adult is a tawny yellowish-brown, sometimes having a
gray or silvery shade, but in some individuals dark or inclining to
red. The lower parts of the body, inner surface of the limbs, the
throat, chin, and upper lip are dirty white; the outside of the ears,
particularly at their base, and a patch on each side of the muzzle black;
the end of the tail dusky. The young are, when born, spotted with dusky
brown and the tail ringed; these markings gradually fading, and quite
disappearing before the animal becomes full-grown.
The Puma has an exceedingly wide range of geographical distribution,
extending over a hundred degrees of latitude, from Canada in the north
to Patagonia in the south, and was formerly pretty generally diffused
in suitable localities from the Atlantic to the Pacific Ocean, but the
advances of civilisation have in recent years considerably curtailed
the extent of the districts which it inhabits. In Central America it is
still common in the dense forests which clothe the mountain ranges as
high as 8000 or 9000 feet above the sea-level, where the hideous sound
of its howling is said to be almost continuously heard at night during
the breeding season. Though an expert climber, it is by no means confined
to wooded districts, being frequently found in scrub and reeds along the
banks of rivers, and even in the open pampas and prairies. Its habits
much resemble those of the rest of the group to which it belongs; and,
like the Leopard, when it happens to come within reach of an abundant
and easy prey, as the sheep or calves of an outlying farming station, it
kills far more than it can eat, either for the sake of the blood only
or to gratify its propensity for destruction. It rarely attacks man,
and, when pursued, escapes if possible by ascending lofty trees. Several
instances have occurred of Pumas becoming tame in captivity. Edmund Kean,
the celebrated actor, had one which followed him about like a dog. When
caressed they express their pleasure by purring like a domestic cat.
_F. onca_, the Jaguar, is a larger and more powerful animal than the
last, and more resembles the Leopard in its colours. It also is found in
both North and South America, but with less extensive range, reaching
northwards only as far as Texas, and southwards nearly to Patagonia.
It climbs as well as the Puma, and preys to a great extent upon
monkeys. Several allied smaller elegantly spotted forms inhabiting the
intratropical regions of America are commonly included under the name
of Ocelot or Tiger Cat, though zoologists are still undecided whether
under this designation several distinct species have not been confused,
or whether all the Ocelots are to be referred to a single species (_F.
pardalis_) showing great individual or racial variation. Their fur has
always a tawny yellow or reddish-gray ground colour, and is marked with
black spots, aggregated in streaks and blotches, or in elongated rings
enclosing an area which is rather darker than the general ground colour.
They range through the wooded parts of tropical America, from Arkansas
in the north as far south as Paraguay, and in their habits resemble
the other smaller members of the Cat tribe, being ready climbers and
exceedingly bloodthirsty.
_F. yaguarundi_, rather larger than the Domestic Cat, with an elongated
head and body, and of a uniform brownish-gray colour, ranges from
Matamoras to Paraguay. _F. eyra_ is a small Cat, very Musteline in form,
having an elongated head, body, and tail, and short limbs, and is also
of a uniform light reddish-brown colour. It is a native of South America
and Mexico. _F. pajeros_ is the Pampas Cat. The American Lynxes have been
already noticed with those of the Old World.
[Illustration: FIG. 230.—The Ocelot (_Felis pardalis_).]
C. _Fossil Species._—It has been already incidentally mentioned that
several of the existing species of _Felis_, such as the Lion, Leopard
and Caffre Cat, are met with in a fossil condition in the European
Pleistocene deposits, and it may be added that the Pardine Lynx has left
its remains in the cavern-deposits of Gibraltar. The caves of Brazil have
yielded remains of the Jaguar and Ocelot; while the Puma is found in the
Pleistocene of the United States. Existing species now inhabiting India
are met with in cavern-deposits in Madras. In the Pliocene Siwaliks of
Northern India the huge extinct _F. cristata_ shows characters connecting
it both with the Tiger and the Jaguar; and the same deposit also
contains the remains of a small species of the size of _F. bengalensis_.
In Europe numerous species occur in the Upper and Lower Pliocene, some
of which were as large as a Leopard. _F. atrox_ and _F. augusta_, of the
Pliocene of the United States, were of the dimensions of the Lion.
_Cynælurus._[440]—The Cheeta or Hunting Leopard (_C. jubatus_) is
distinguished from the other _Felidæ_ by the inner tubercle of the upper
carnassial, though supported by a distinct root, having no salient cusp
upon it; by the tubercular molar being more in a line with the other
teeth; and by the claws being smaller, less curved, and less completely
retractile, owing to the feebler development of the elastic ligaments.
The skull is short and high, with the frontal region broad and elevated
in consequence of the large development of the frontal air-sinuses. The
head is small and round, the body light, the limbs and tail long. Its
colour is pale yellowish-brown with small black spots. The Cheeta is
less savage and more easily tamed than most of the Cats. In Asia it has
been trained for the chase of the Antelope. It has rather an extensive
geographical range from the Cape of Good Hope, throughout Africa and the
south-western parts of Asia, as far as Southern India.
_Extinct Genera._—A number of forms are gradually becoming known,
especially through the researches of American palæontologists, which,
though evidently animals of the same general type, and therefore to be
placed in or near the family _Felidæ_, depart so much in various details
of structure that they must be referred to different genera. As one of
the points in which _Felis_ manifests its specialisation is the reduction
of the number of the molar series of teeth, with concomitant shortening
of the jaws, it might be supposed that in the earlier and perhaps
ancestral forms these teeth would be more numerous and approach more
nearly to the primitive or typical number of the heterodont mammals, viz.
seven on each side. This is actually the case. Similarly we find that
many of these forms exhibit a less specialised structure of the teeth
themselves, as is shown by the absence of the anterior lobe of the upper
carnassial, and the retention of the hind talon in the corresponding
lower tooth. Again, some of them have an alisphenoid canal in the skull;
while the femur may have a third trochanter, and the claws be very
imperfectly retractile.
An extremely generalised form is the small _Proælurus_, from the Upper
Eocene and Lower Miocene, with _p_ ⁴⁄₄, _m_ ¹⁄₂, an alisphenoid canal,
and a third trochanter to the femur. _Dinictis_, of the North American
Miocene, is a larger allied form, with _p_ ³⁄₃, _m_ ¹⁄₂; the upper
carnassial having no anterior lobe, and the ungual phalanges being devoid
of bony sheaths. The characters of the base of the skull, and the form
and relations of the astragalus, differ very considerably from _Felis_.
_Pseudælurus_, from the French Miocene, is another very generalised
Feline, in which there may be either three or four premolars, and the
lower carnassial may retain its inner cusp. _Ælurictis_, of the French
Phosphorites, with _p_ ³⁄₃₋₄, _m_ ¹⁄₁₋₂, together with several American
Miocene genera, such as _Nimravus_ (_p_ ³⁄₂, _m_ ¹⁄₂), _Archælurus_ (_p_
³⁄₃₋₄, _m_ ¹⁄₂), _Pogonodon_ (_p_ ³⁄₃, _m_ ¹⁄₁), and _Hoplophoneus_ (_p_
²⁻³⁄₂, _m_ ¹⁄₁), approach more closely to the modern Cats, although many
or all of them retain the alisphenoid canal, and have not yet developed
the anterior lobe to the upper carnassial, or lost the talon to the lower
one. _Hoplophoneus_ has a descending flange to the mandible; and its
scapholunar bone has a line indicating its dual origin; while the femur
still retains the third trochanter, of which all traces are lost in the
modern Cats.
On the other hand, some of the extinct _Felidæ_ show a most remarkable
tendency towards a specialisation not occurring in any of the surviving
members of the family, viz. an enormous development of the upper canines,
with which is usually associated an expansion downwards and flattening
of the anterior part of the ramus of the lower jaw, on the outer side
of which the canine lies, when the mouth is closed. In _Machærodus
næogeus_, the Sabre-toothed Tiger, from the caves of Brazil and also
from Pleistocene deposits near Buenos Ayres, an animal about the size
of a Tiger, these teeth are 7 inches in length, greatly compressed, and
finely serrated on the trenchant anterior edges. Similar serrations are
seen on a much fainter scale in the unworn teeth of modern Tigers. Many
modifications of this commonly-called “machærodont” type have been met
with both in the Old and New World. In _M. cultridens_, of the Upper
Pliocene of Italy and France, the upper canine is long and narrow, with
smooth cutting edges; the smaller form described as _M. meganthereon_
being apparently the female of this species. _M. crenatidens_, of
the same deposits, is distinguished by the shorter and broader upper
canine, in which both edges are strongly serrated; the same feature
occurring in the closely allied or identical _M. latidens_ of the English
cavern-deposits. The Italian Pliocene form described as _M. nestianus_
has serrations only on the hinder edge of the upper canine, and the third
lower premolar is separated by a long interval from the fourth. _M.
necator_, of the Pleistocene of South America, is remarkable as being
the only member of the family in which the humerus has no entepicondylar
foramen. A very remarkable form, _Eusmilus_, from the Upper Eocene
Phosphorites of Central France, differs from all other known Felines in
having only two pairs of incisors in the lower jaw, and a small canine
separated by a very long diastema from the cheek-teeth, which consist
only of one premolar and one sectorial true molar. The lower jaw is
enormously expanded towards the symphysis to protect the large upper
canines. This animal then, although of Eocene age, appears to form the
culminating development of the sabre-toothed or machærodont dentition,
the most specially carnivorous type of structure known.
Other species of _Machærodus_ are found in the Pliocene deposits of
Europe and Asia. The accompanying woodcut exhibits the last two upper
teeth of the Indian _M. sivalensis_, from which it will be seen that the
inner tubercle of the carnassial is much reduced in size, while the molar
is very minute.
_Family_ VIVERRIDÆ.
[Illustration: FIG. 231.—Oral surface of the left upper carnassial and
molar of _Machærodus sivalensis_.]
Premolars ³⁄₃ or ⁴⁄₄. Molars ¹⁄₁ or ²⁄₂. Upper carnassial usually without
an anterior lobe, and the lower one with a well-developed talon; second
lower incisor (as in all the following families) raised above the level
of the first and third. Auditory bulla externally constricted, and
divided by a septum. An alisphenoid canal (with very rare exceptions).
Carotid canal distinct as a groove on the side of the bulla. Humerus
usually with an entepicondylar foramen. Digits usually 5-5, but sometimes
the pollex or hallux or both may be wanting. Dorsal vertebræ 13 or 14.
Limited in distribution to the Old World.
The subfamily =Cryptoproctinæ= contains the single genus
_Cryptoprocta_.[441] Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ¹⁄₁; total
36. The teeth generally closely resemble those of the _Felidæ_. The first
premolar of both jaws is very minute and early deciduous. The upper
carnassial has a very small inner tubercle, quite at the anterior part
of the tooth. The true molar is very small and placed transversely. The
lower carnassial has a large trenchant bilobed blade, and a very minute
talon, but no inner cusp. Skull generally like that of _Felis_, but
proportionately longer and narrower. Orbit widely open behind. Vertebræ:
C 7, D 13, L 7, S 3, C 29. Body elongated. Limbs moderate in size. Feet
subplantigrade; five well-developed toes on each, with sharp, compressed,
retractile claws. Ears moderate. Tail long and cylindrical.
The only known species, _C. ferox_, the “Foussa” of the Malagasy, is
peculiar to Madagascar, being the largest carnivorous animal in the
island. It is about twice the size of the common Cat (5 feet from nose
to end of tail), with short close fur of nearly uniform pale brown.
Little is as yet known of its habits, except that it is nocturnal,
frequently attacks and carries off goats, and especially kids, and shows
great ferocity when wounded, on which account it is much dreaded by the
natives.
The remaining numerous specific and generic modifications found in the
existing animals belonging to this family seem to arrange themselves
mainly into two tolerably distinct groups, distinguishable by the
characters of the auditory bulla and neighbouring parts of the base of
the skull, and by the structure of the feet. The one form has the genus
_Viverra_ or Civet Cats for its most typical representative, and the
other _Herpestes_ or the Ichneumons.
Subfamily =Viverrinæ=.—Auditory bulla oval, or rather conical, broad
and truncated and not everted behind, narrow in front and more or less
compressed at the sides. The outer or anterior chamber very small and
flat. The meatus with scarcely any inferior lip, its orifice being
close to the tympanic ring. Paroccipital process triangular, its apex
projecting slightly beyond the bulla. Claws strongly curved and more or
less retractile. Perineal scent-glands generally present.
This subfamily includes both Ethiopian and Oriental forms, but the former
are the more numerous.
The typical section, which includes five genera, has the following
characters. Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ²⁄₂ (¹⁄₂ in
_Prionodon_); total 40. Skull elongated; facial portion small and
compressed. Orbits well-defined but incomplete behind. Teeth always
sectorial, never very small. Vertebræ: C 7, D 13, L 7 (or D 14, L 6), S
3, C 22-30. Body elongated and compressed. Head pointed in front; ears
rather small. Extremities short. Feet small and rounded. Toes short, five
on each foot. First toe both on fore and hind feet much shorter than the
others. Palms and soles covered with hair, except the pads of the feet
and toes, and in some species a narrow central line on the under side
of the sole, extending backwards nearly to the heel. Tail moderate or
long; usually marked with dark and light rings. A pair of large glandular
follicles situated on the perineum (in both sexes), and secreting in most
species an oily substance of a peculiarly penetrating odour.
The numerous species of this section form a large series, the two
extremes of which differ considerably, but the several genera into which
they may be divided blend so into one another that it is difficult to
differentiate them sharply.
All the animals of this section are, for their size, extremely active,
fierce, and rapacious. They feed chiefly on small mammals and birds.
_Viverra._[442]—This includes the largest species. The teeth (Fig. 232)
are stouter and less compressed than in the other genera; the second
upper molar being especially larger. The auditory bulla smaller and more
pointed in front. Body shorter and stouter; limbs longer; tail shorter,
tapering. Under side of tarsus completely covered with hair. Claws
longer and less retractile. Fur rather long and loose, and in the middle
line of the neck and back usually elongated so as to form a sort of
crest or mane; neck with a black gorget. Pupil circular when contracted.
Perineal glands greatly developed. These characters apply especially
to _V. civetta_, the African Civet, or “Civet-Cat” as it is commonly
called, an animal rather larger than a common Fox, and an inhabitant of
intratropical Africa. _V. zibetha_, the Indian Civet, of about equal
size, inhabits Bengal, China, the Malay Peninsula, and adjoining islands.
_V. tangalunga_, from Java, Sumatra, Borneo, and the Philippines, and _V.
megaspila_, from Burma, are smaller but nearly allied animals; the latter
being more distinctly spotted than either of the others. From these
species and the next the civet of commerce, once so much admired as a
perfume in England, and still largely used in the East, is obtained. The
animals are kept in cages, and the odoriferous secretion collected from
the interior of the perineal follicles with a spoon or spatula.
[Illustration: FIG. 232.—The left upper dentition of the Indian Civet
(_Viverra zibetha_). From the _Palæontologia Indica_.]
The Rasse or Lesser Indian Civet (_V. malaccensis_) may be regarded as
the representative of a distinct group of _Viverra_, although often
referred to a separate genus (_Viverricula_). The size of this animal
is smaller than in the typical group, the build is slighter, the muzzle
finer, the claws sharper and more curved, and there is no erectile mane
along the back. Generally there is an alisphenoid canal in the skull; and
the anterior chamber of the auditory bulla is much more inflated than the
hinder one, so that the apparent length of the whole bulla is increased.
This species is found over the greater part of India, and extends to the
Malay Peninsula and Southern China.
Large species of _Viverra_ occur in the Pleistocene and Pliocene of
India, and also in the Pliocene of France, which approximate in some
characters of the dentition to the extinct genus _Ictitherium_, mentioned
at the end of the family. Species of this genus have also been described
from the Miocene and Upper Eocene of Europe. The Lower Miocene _V.
antiqua_ has an alisphenoid canal, and all the other cranial characters
of the typical forms.
_Fossa._[443]—The Fossa of Madagascar comes so close to the Rasse that
its right to generic distinction seems doubtful. There is, however, no
scent-pouch. The limbs are slender; and there are two small bare spots
on the sole of the hind foot, above the plantar pads. There is no dark
line along the back; the throat gorget of _Viverra_ is absent; and in the
tail the spots only tend to form rings, which are not complete. The skull
has an alisphenoid canal, and a large bulla as in the typical group of
_Viverra_.
[Illustration: FIG. 233.—The Common Genet (_Genetta vulgaris_).]
_Genetta._[444]—The Genettes are smaller animals, with more elongated
and slender bodies, and shorter limbs than the Civets. Skull elongated
and narrow. Auditory bulla large, elongated, rounded at both ends. Teeth
compressed and sharp pointed. The inner side of the third upper premolar
has a tubercle not present in the previous genus, and the talon of the
lower carnassial is larger. Pupil contracting to a linear aperture. Tail
long, slender. Fur short and soft, spotted or cloudy. Under side of the
tarso-metatarsus with a narrow longitudinal bald streak. No pouch for
storing the secretion of the scent-gland. _G. vulgaris_, the common
Genet (Fig. 233), is found in France south of the river Loire, Spain,
South-Western Asia, and Africa from Barbary to the Cape. _G. felina_,
_senegalensis_, _tigrina_, and _pardalis_ are other named species, all
African in habitat.
[Illustration: FIG. 234.—Stomach of Genet cut open. _œ_, Œsophagus; _pv_,
pyloric valve; _x_, sudden bend where the internal folds are interrupted.
(From Mivart, _Proc. Zool. Soc._ 1882, p. 505.)]
[Illustration: FIG. 235.—Cæcum of Genet. (After Mivart, _loc. cit._ p.
508.)]
A few details (taken from Professor Mivart’s memoirs on the Æluroidea) of
the anatomy of the soft parts of the Genet may be given as illustration
of these parts in the Carnivora generally, and of this family and genus
in particular. The salivary glands are shown in Fig. 19 (p. 56), and
these conform to the general type prevalent in the Æluroidea. Thus
there is a distinct zygomatic gland; the parotid with its (Steno’s)
duct is well developed; and there is a small submaxillary gland. The
stomach (Fig. 234), while conforming to the simple type characteristic
of the Carnivora, is much larger than in the Cat; it is characterised
by the presence of some strongly marked internal folds near the pyloric
extremity, which stop suddenly at a point where the stomach makes an
abrupt constriction and flexure. Beyond this point there are three other
longitudinal folds; and the pyloric valve is small. The allied genera
present modifications from this form of stomach. The cæcum (Fig. 235) is
short, thick, and pointed. The liver (Fig. 236) much resembles that of
the Cat, but differs in that the left lateral lobe is undivided, although
having a small groove on its posterior or abdominal aspect, while the
cystic fissure is less deep, and situated more to the right. The caudate
lobe is relatively longer, has a deep concavity, and runs uninterruptedly
into the Spigelian; the latter being relatively somewhat larger than in
the Cat, with a deep groove dividing the proximal third from the distal
two-thirds. In _Viverra_ the right lateral and right central lobes are
nearly equal in size. The variations in the form of the liver of the
allied genera are detailed in Professor Mivart’s memoir. The brain of the
Genet is shown in Fig. 23 (p. 71); the small depression _d_ placed on
the superior lateral gyrus appears to be the sole representative of the
distinct crucial sulcus which distinguishes the brains of the _Felidæ_
from those of all other members of the Æluroidea.
[Illustration: FIG. 236.—Abdominal aspect of the liver of the Genet. _c_,
Caudal lobe; _gb_, gall-bladder; _ha_, hepatic artery; _hd_, hepatic
duct; _LC_, left central lobe; _LL_, left lateral lobe; _pv_, portal
vein; _RC_, right central lobe; _RL_, right lateral lobe; _Sp_, Spigelian
lobe; _vc_, vena cava. (From Mivart, _Proc. Zool. Soc._ 1882, p. 510.)]
[Illustration: FIG. 237.—Cæcum of _Prionodon_. (From Mivart, _Proc. Zool.
Soc._ 1882, p. 508.)]
_Prionodon._[445]—This and the following genus comprise the beautiful
Linsangs (Fig. 238), which are distinguished from the preceding genera
by the loss of the second upper molar, which is, however, very small in
some of the Genets. In the present genus the ground colour is whitish
or yellowish with brown or black markings, which may either form broad
continuous patches across the hinder part of the body, or may be broken
up into spots. The tail is very long, the limbs comparatively short, and
the fur very short and close. The pollex and hallux are well developed;
the claws are almost completely retractile; and the tarsus and metatarsus
are completely haired. The pupil is round. The cæcum (Fig. 237) is
remarkably small. This genus is exclusively Oriental, and comprises _P.
gracilis_ from Borneo, Java, and (?) Sumatra, _P. pardicolor_ from Nipal,
and _P. maculosus_ from Tenasserim; the head and body of the latter
measuring from 18 to 20 inches in length. Speaking of _P. pardicolor_,
Mr. Hodgson observes that it is “equally at home on trees and on the
ground; it dwells and breeds in the hollows of decayed trees. It is not
gregarious at all, and preys chiefly upon small birds, which it is wont
to pounce upon from the cover of the grass. The times of breeding are
said to be February and August, and the litter to consist of two young,
there being two litters each year.”
_Poiana._[446]—This African genus, represented solely by one species,
_P. poënsis_ (Fig. 238), from Fernando Po, is very closely allied to
the preceding, but the spots are smaller, and show no tendency to run
into transverse bands or stripes, except in the region of the head and
shoulder; while the sole of the foot has a narrow bald band running up
towards the tarsus, as in _Genetta_. The length of the head and body is
38 inches, and that of the tail about 40 inches. It is probable that this
animal should really be regarded as a slightly aberrant species of the
genus _Prionodon_.
[Illustration: FIG. 238.—The African Linsang (_Poiana poënsis_). From
Mivart, _Proc. Zool. Soc._ 1882, p. 160.]
The five following genera differ in several important respects from all
the preceding, and collectively constitute the _Paradoxurine_ section
of Professor Mivart. With the exception of one African form, they are
mainly Oriental. In this section the auditory bulla is frequently in two
portions, the posterior moiety in one case being unossified, and it is
always much narrowed in front (Fig. 239). The palate (as in the figure)
may be much produced behind the molars; and the teeth are often but
slightly sectorial, and may be very small. The long tail is in most cases
not ringed.
_Paradoxurus._[447]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ²⁄₂; total
40. The blunt and rounded form of the cusps of the hinder premolar and
the molar teeth distinguishes this genus from most of the members of the
family. Vertebræ: C 7, D 13, L 7, S 3, C 29-36. Head pointed in front.
Ears small, rounded. Body long. Limbs moderate. Palms and soles almost
entirely naked, and joining the foot-pads without the intervention of
any hairy space. Claws completely retractile. Pupil vertical. Tail long,
non-prehensile; in the Indian species without rings. The Paradoxures
or Palm-Civets are less strictly carnivorous than the other members of
the family. They are mostly about the size of the common Cat, or rather
larger, and are partly arboreal in their habits. The species are rather
numerous, and present considerable variations in the details of the
form and size of their molar teeth; in only a few does the bony palate
extend behind the molars. They are restricted geographically to Southern
Asia and the Indo-Malayan archipelago. The best known species[448] are
_P. niger_, _P. hermaphroditus_, _P. jerdoni_, _P. aureus_, _P. grayi_
from India and Burma, _P. philippinensis_ of the Philippines, _P.
larvatus_ of Southern China and Formosa, _P. leucomystax_ of the Malay
Peninsula, Sumatra, and Borneo, and _P. musschenbroeki_ of Celebes. The
name _Paradoxurus_ was applied from the mistaken notion that the tail
was prehensile. Mr. Blanford[449] gives the following account of the
habits of _P. niger_: “The common Palm-Civet, Tree-Cat, or Toddy-Cat,
is a familiar animal in most parts of India, though, being thoroughly
nocturnal in its habits, it is but rarely seen in the daytime. It is
arboreal, passing the day generally in trees, either coiled up in the
branches, or in a hole in the trunk, and in places where cocoa-nut
palms are common it frequently selects one of them for a residence.
Mango groves are also a favourite resort. It not unfrequently takes up
its abode in the thatched roofs of houses; Jerdon found a large colony
established in the rafters of his own house in Tellicheri. It even
occurs in large towns; I have known of one being caught in the middle of
Calcutta.”
[Illustration: FIG. 239.—Palatal aspect of the left side of the
cranium and mandible of _Arctogale leucotis_. _a_, Anterior opening of
alisphenoid canal; _o_, foramen ovale; _c_, carotid canal ¹⁄₁. (From
Mivart, _Proc. Zool Soc._ 1882, p. 165.)]
_Arctogale._[450]—This genus—represented only by _A. trivirgata_ of Java,
and _A. leucotis_ of Burma, Tenasserim, Sumatra, Java, etc.—is chiefly
distinguished from _Paradoxurus_ by the extremely small size of the
cheek-teeth (Fig. 239), which are often not in contact with one another;
the upper carnassial being almost triangular in shape. Palate frequently
convex longitudinally between the carnassials, and greatly produced
behind the last molar, with a very narrow bony aperture of the posterior
nares. The soles of the feet are still more naked than in _Paradoxurus_;
and the pollex and hallux are more divergent. In _A. leucotis_ the length
of the head and body is 26·5 inches, and the tail 27 inches. In many
specimens the three dorsal stripes are much less distinctly marked than
in others, and tend to break up into spots; while the general coloration
is considerably lighter.
_Hemigale_,[451] another modification of the Paradoxure type, contains
one species, _H. hardwickei_, from Borneo and Malacca, an elegant-looking
animal, smaller and more slender than the Paradoxures, of light gray
colour, with transverse broad dark bands across the back and loins;
the proximal portion of the tail being ringed. The tarsus is hairy. The
general cranial characters are those of _Paradoxurus_, but the auditory
bulla is ankylosed into a single piece.
_Arctictis._[452]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ²⁄₂; total
40. The posterior upper molar and the first lower premolar very often
absent. Cheek-teeth generally small and rounded, with a distinct
interval between them, but formed generally on the same pattern as
_Paradoxurus_. Vertebræ: C 7, D 14, L 5, S 3, C 34. Body elongated. Head
broad behind, with a small pointed face. Whiskers long and numerous. Ears
small, rounded, but clothed with a pencil of long hairs. Eyes small.
Limbs short. Soles and palms broad, entirely naked. Tail very long and
prehensile; thickly covered with long hair. Fur long and harsh. Cæcum
extremely small. But one species is known, _A. binturong_, the Binturong,
an inhabitant of Southern Asia from Nipal through the Malay Peninsula to
the islands of Sumatra and Java. Although structurally agreeing closely
with the Paradoxures, its tufted ears, long, coarse, and dark hair, and
prehensile tail give it a very different external appearance. It may
be regarded as a very aberrant Paradoxure, connected, so far as dental
characters are concerned, with _Paradoxurus_ by means of _Arctogale_. The
bony palate also extends considerably behind the last molar, as in the
latter. The Binturong is slow and cautious in its movements, chiefly if
not entirely arboreal, and appears to feed on vegetable as well as animal
substances.
_Nandinia_[453] contains one species, _N. binotata_, a somewhat aberrant
Paradoxure, from West Africa. It is rather smaller than the true
Paradoxures, with smaller and more pointed molar teeth, and no cæcum. The
wall of the hinder chamber of the auditory bulla remains through life
unossified.
The dentition appears to be of a more decidedly carnivorous type than in
the other members of the section.
_Cynogale._[454]—This remarkable genus is regarded by Professor Mivart as
representing a third section of the _Viverrinæ_; it contains one species,
_C. bennetti_ (described by S. Müller under the name of _Potamophilus
barbatus_), from Borneo, Sumatra, and the Malay Peninsula. This is a
curious Otter-like modification of the Viverrine type, having semiaquatic
habits, both swimming in the water and climbing trees, living upon fish,
crustacea, small mammals, birds, and fruit. The number and general
arrangement of its teeth are as in _Paradoxurus_, but the premolars are
peculiarly elongated, compressed, pointed and recurved, somewhat as in
the Seals, though the molars are tuberculated. The head is elongated, the
muzzle broad and depressed. Whiskers very long and abundant. Ears small
and rounded. Toes short and slightly webbed at the base. Tail short,
cylindrical, covered with short hair. Fur very dense and soft, of a dark
brown colour, mixed with black and gray. Humerus without entepicondylar
foramen.
Subfamily =Herpestinæ=.—Auditory bulla very prominent, and somewhat
pear-shaped, the posterior chamber being large, rounded, and generally
with its greatest prominence to the outer side. The anterior chamber
considerably dilated, and produced into a short inferior wall to the
auditory meatus, in which is a depression or vacuity just below the
centre of the opening of the meatus. Sometimes this vacuity is continued
into the meatus, forming a narrow fissure. The paroccipital process
does not project beyond the bulla, but is spread out and lost (in adult
animals) on its posterior surface. Toes straight; claws lengthened,
exserted, non-retractile. No perineal glands. The dentition is always of
a markedly sectorial type; and the orbit may be surrounded by bone. Very
generally the anus opens into a sac-like depression. The majority of the
genera are Ethiopian; the type genus alone extending into the Oriental
and Palæarctic regions.
_Herpestes._[455]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, sometimes ³⁄₃,
_m_ ²⁄₂; total 40 or 36. Teeth of molar series generally with strongly
developed, sharply-pointed cusps. Skull elongated, constricted behind
the orbits. Face short and compressed. Frontal region broad and arched.
Postorbital processes of frontal and jugal bones well developed,
generally meeting so as to complete the circle of the orbit behind.
Vertebræ: C 7, D 13, L 7, S 3, C 21-26. Head pointed in front. Ears short
and rounded. Body very long and slender. Extremities short. Five toes on
each foot, the first, especially that on the hind foot, very short. Toes
free, or but slightly palmated. Palms generally naked. Distal portion of
soles naked, under surface of tarsus and metatarsus usually clothed with
hair, but considerable specific variation in this respect. Tail long or
moderate, generally thick at the base, and sometimes covered with more or
less elongated hair. The longer hairs covering the body and tail almost
always annulated. This genus contains a very large number of animals
commonly called Ichneumons, or in India Mungooses, varying in size from
that of a large Cat down to a Weasel. They are widely distributed over
the African continent and the southern parts of Asia, especially India
and the Indo-Malayan archipelago, one species occurring also in Spain.
They are mostly terrestrial in their habits, feeding on small mammals
and birds, reptiles, especially snakes, eggs of birds and reptiles, and
also insects. Some species are partially domesticated, being used to
keep houses clear of rats, mice, and snakes. _H. ichneumon_ was a sacred
animal to the ancient Egyptians. They vary considerably in appearance,
some, as _H. galera_ and _H. urva_ (Fig. 240), are larger and heavier,
with stouter body, longer limbs, and stronger teeth. The common Indian
Mungoose (_H. mungo_) is considerably smaller than the Egyptian form;
its fur is of a pale gray colour, the hairs being largely white ringed,
while the cheeks and throat are more or less reddish. Like the Egyptian
species, it is frequently domesticated, and put to a similar use. It is
especially serviceable in India as a serpent-killer, destroying not only
the eggs and young of these creatures, but attacking without hesitation
and killing the most venomous adult snakes. The fact that it invariably
survives those encounters has led to the belief that it either enjoys
immunity from the effects of snake-poison, or that after being bitten
it has recourse, as the natives maintain, to the root of a plant as an
antidote. Neither of these suppositions has stood the test of scientific
examination, for it has been found that when actually bitten it falls
a victim to the poison as rapidly as other mammals, while there is no
trustworthy evidence of its seeking a vegetable antidote. The truth
seems to be that the Mungoose, by its exceeding agility and quickness
of eye, avoids the fangs of the snake while fixing its own teeth in
the back of the reptile’s neck. One large species, believed to be from
Africa, recently described as _H. grandis_, is remarkable for the extreme
complexity of the cusps on the molars, and also for the absence of an
entepicondylar foramen to the humerus; the latter feature also occurring
in the allied _H. albicaudatus_. The Oriental _H. urva_ (Fig. 246) is
stated to be somewhat aquatic in habits, and to feed on frogs and crabs.
[Illustration: FIG. 240.—The Crab-eating Mungoose (_Herpestes urva_).
From Blanford, _Mammalia of British India_, p. 130.]
Remains of the small _H. nipalensis_ occur in the cavern-deposits of
Madras. Viverroids from the Miocene and Upper Eocene of Europe, which
agree with _Herpestes_ in the presence of an inner tubercle to the
third upper premolar and of a hinder cusp to the fourth lower premolar,
have been referred to the existing genus. The species which have been
separated generically under the three following names are very closely
allied to _Herpestes_.
_Helogale_,[456] premolars ³⁄₃, without diastema between first and
second; soles of feet completely naked. Contains two small South-African
species, _H. parvula_ and _H. undulata_.
_Bdeogale_[457] contains also two small Ichneumon-like animals, _B.
crassicauda_ and _puisa_, differing from _Herpestes_ proper in having
only four toes on each foot, both pollex and hallux being absent. The
orbit is nearly complete, the tail of moderate length and rather bushy.
_Cynictis._[458]—Pollex present, but hallux absent. Skull shorter and
broader than in _Herpestes_, rather contracted behind the orbits, which
are large and complete behind. Face short. Anterior chamber of the
auditory bulla very large. Front claws elongated. _C. penicillata_, from
South Africa. The cæcum (Fig. 241) of this genus is longer than in any
other member of the family.
All the foregoing Herpestines have the nose short, with its under surface
flat, bald, and with a median longitudinal groove. The remaining forms
have the nose more or less produced, with its under side convex, and a
space between the nostrils and the upper lip covered with close adpressed
hairs, and without any median groove.
[Illustration: FIG. 241.—Cæcum of _Cynictis penicillata_. (From Mivart,
_Proc. Zool. Soc._ 1882, p. 508.)]
_Rhinogale._[459]—Toes 5-5. Claws of fore feet short, compressed, acute.
Under surface of tarsus hairy. Palate flat. Founded on a single specimen
from East Africa, _R. melleri_.
_Crossarchus._[460]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ²⁄₂; total
36. Snout elongated. Toes 5-5. Claws on fore feet long and curved.
Hallux very short. Under surface of tarsus naked. Tail shorter than the
body, tapering. Palate flat. Fur harsh. Species: _C. obscurus_, the
Kusimanse, a small burrowing animal from West Africa, of uniform dark
brown colour; _C. fasciatus_; _C. zebra_; and _C. gambianus_.
_Suricata._[461]—A more distinct genus than any of the above. The dental
formula as in the last, but the teeth of the cheek-series remarkably
short in the antero-posterior direction, corresponding with the shortness
of the skull generally (Fig. 222). Orbits complete behind. Vertebræ: C
7, D 15, L 6, S 3, C 20. Though the head is short and broad, the nose is
pointed and rather produced and movable. Ears very short. Body shorter
and limbs longer than in _Herpestes_. Toes 4-4, the pollex and hallux
being absent. Claws on fore feet very long and narrow, arched, pointed,
and subequal. Hind feet with much shorter claws, soles hairy. Tail rather
shorter than the body. One species only is known, the Suricate, _S.
tetradactyla_, a small gray-brown animal, with dark transverse stripes on
the hinder part of the back, from South Africa. The cæcum is short.
[Illustration: FIG. 242.—Cæcum of _Galidea elegans_. (From Mivart, _Proc.
Zool. Soc._ 1882, p. 508.)]
_Galidictis_,[462] _Galidea_,[463] and _Hemigalidea_[464] are names
of three slight generic modifications of the Viverrine type, allied
to the _Herpestinæ_, but placed by Mivart in a distinct subfamily,
_Galidictiinæ_. They are all characterised by the absence of the
alisphenoid canal in the skull, as well as of the entepicondylar foramen
to the humerus; and are inhabitants of Madagascar. The best known,
_Galidea elegans_, is a lively Squirrel-like little animal with soft fur
and a long bushy tail, which climbs and jumps with agility. It is of a
chestnut-brown colour, the tail being annulated with darker brown. The
cæcum (Fig. 242) is remarkable for its comparative length and pointed
termination. _Hemigalidea_ is distinguished by the absence of rings on
the tail. _Galidictis vittata_ and _striata_ chiefly differ from the
Ichneumons in their coloration, being gray with parallel longitudinal
stripes of dark brown.
_Eupleres_[465] is another form, also from Madagascar, which has been
placed in a subfamily apart. It differs remarkably from all the other
_Viverridæ_ in the weak development of the jaws and the small size of the
teeth (Fig. 243), in consequence of which it was, when first discovered,
placed in the order Insectivora. Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄,
_m_ ²⁄₂; total 40. Vertebræ: C 7, D 13, L 7, S 3, C 20. No alisphenoid
canal; an entepicondylar foramen to the humerus. But one species is
known, _E. goudoti_.
[Illustration: FIG. 243.—Skull of _Eupleres goudoti_. ⅘ natural size.
Mus. Roy. Coll. Surgeons.]
_Extinct Genera._—The Tertiaries of the Old World have yielded
several genera allied to the existing Viverroids, some of which show
decided signs of affinity with other families. Of these the Lower
Miocene _Amphictis_ appears to be nearly related to _Viverra_, but is
distinguished by the form of the second lower molar, which is longer and
has two distinct roots. _Palæoprionodon_, of the French Phosphorites, has
a dentition very like that of _Prionodon_, the molars being reduced to
¹⁄₂; the skull has an alisphenoid canal and the general basal characters
of the _Viverridæ_, but resembles the _Mustelidæ_ in the presence of
a glenoid foramen and in the position of the condylar foramen. In
_Stenoplesictis_, of the same deposits, the dental formula is _i_ ³⁄₃,
_c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ²⁄₂; and although the skull has a complete septum
in the bulla, yet some of the cranial and dental features approximate
so decidedly towards those of the extinct _Mustelidæ_, as to lead
some authorities to refer the genus to that family. The most probable
explanation of this resemblance is that the Musteloids have originated
from generalised Viverroids allied to _Stenoplesictis_. The Lower
Pliocene _Ictitherium_ differs from all other Viverroids in the presence
of three distinct lobes to the upper carnassial, and thereby connects
the other members of the family so closely with the _Hyænidæ_ that it is
practically impossible to draw up a definition which will distinguish the
two families.
The North American Eocene genera _Miacis_ and _Didymictis_ are generally
regarded as representing a separate family—_Miacidæ_—with affinities both
to the _Viverridæ_ and _Canidæ_.
_Family_ PROTELEIDÆ.
Skull with no alisphenoid canal; and the auditory bulla divided into two
distinct chambers. Dorsal vertebræ 15. Molars ¹⁄₁. Premolar and molar
teeth very small and simple in character.
_Proteles._[466]—This genus contains but a single species, _P.
cristatus_, the Aard-Wolf or Earth-Wolf of the Dutch colonists of the
Cape, an animal nearly allied to the Hyænas, but remarkably modified
in its dentition, the molar teeth being very small, placed far apart,
and almost rudimentary in character (Fig. 244). The canines are long
and rather slender. The dental formula is _i_ ³⁄₃, _c_ ¹⁄₁, _p_ and _m_
⁴⁄₃₋₄; total 30 or 32. Vertebræ: C 7, D 15, L 5, S 2, C 24. The fore feet
with five toes; the pollex though short, with a distinct claw. The hind
feet with four subequal toes. Claws all strong, blunt, subcompressed, and
non-retractile. The general external appearance is very like that of a
small Striped Hyæna, but the muzzle is more pointed and the ears larger.
It has a copious mane of long hair, capable of being erected when the
animal is excited, along the middle line of the neck and back. It is a
native of South Africa, and is a burrowing nocturnal animal, feeding on
decomposing animal substances, larvæ, and termites. Observations upon
specimens in captivity indicate that it has neither inclination nor power
to attack or feed upon living vertebrated animals.
[Illustration: FIG. 244.—Skull and Dentition of the Aard-Wolf (_Proteles
cristatus_). ½ natural size.]
Some writers regard _Proteles_ as representing a subfamily of the
_Hyænidæ_.[467]
_Family_ HYÆNIDÆ.
Skull with no alisphenoid canal; and the auditory bulla not divided by a
septum into two chambers. Dorsal vertebræ 15. Molars usually ¹⁄₁, but in
some fossil forms ¹⁄₂, or ²⁄₂, the second lower molar being very small;
upper carnassial with three distinct lobes; lower carnassial with a
large blade and small talon. No entepicondylar foramen to the humerus.
This family is confined to the Old World, where it is now represented
by a single genus, which, although evidently nearly related to the
_Viverridæ_, is sufficiently distinct to be regarded as not referable to
that family. The extinct _Ictitherium_, however, as already mentioned,
connects the more generalised members of the _Hyænidæ_ very closely with
the _Viverridæ_.
_Hyæna._[468]—Dentition in existing forms usually _i_ ³⁄₃, _c_ ¹⁄₁,
_p_ ⁴⁄₃, _m_ ¹⁄₁; total 34. Teeth, especially canines and premolars,
very large, strong, and conical. Upper carnassial (Fig. 245) with a
very large, distinctly trilobed blade and a moderately developed inner
tubercle placed at the anterior extremity of the blade. Molar very
small, and placed transversely close to the hinder edge of the last, as
in the _Felidæ_. Lower carnassial consisting of little more than the
bilobed blade. Zygomatic arches of cranium very wide and strong. Sagittal
crest high, giving attachment to very powerful biting muscles. Orbits
incomplete behind. Vertebræ: C 7, D 15, L 5, S 4, C 19. Limbs rather
long, especially the anterior pair, digitigrade, four subequal toes on
each, with stout non-retractile claws. Pollex and hallux only represented
by rudimentary metacarpal and metatarsal bones. Tail rather short. A
large post-anal median glandular pouch, into which the largely developed
anal scent glands pour their secretion.
[Illustration: FIG. 245.—Outer (_A_) and palatal (_B_) aspects of the
right upper carnassial tooth of the Striped Hyæna (_Hyæna striata_). From
the _Quart. Journ. Geol. Soc._]
The three existing species of Hyæna are divisible into two sections, to
which some zoologists assign generic rank, but fossil forms show such
a transition between these two types as to render any such division
impracticable.
The typical or _Euhyænine_ group presents the following distinctive
features. Upper molar moderately developed and three-rooted. An inner
cusp and hind talon more or less developed on the lower molar. Ears
large, pointed. Hair long, forming a mane on the back and shoulders. _H.
striata_, the Striped Hyæna (Fig. 246) of Northern Africa and Southern
Asia. _H. brunnea_, of South Africa, in some respects intermediate
between this and the next group.
The Striped Hyæna is dirty gray in colour, with narrow transverse
tawny or blackish stripes on the body and legs; the length of the
head and body is 3½ feet, and that of the tail, with its hair, 1½
feet. It occurs throughout peninsular India, where it is most common
in open hilly districts, and in North Africa. Mr. Blanford[469] gives
the following account of its habits: “It is a nocturnal animal, and
although an occasional individual may be met with returning to its den
in the early morning, its rambles are usually commenced after sunset
and ended before sunrise. During the night it roams far and wide, and
no tracks of wild animals are more common in the countries where it is
found than its unmistakable footprints, very like a dog’s in shape, but
with the marks of the hind feet conspicuously smaller than those of the
fore feet. Unlike the Spotted Hyæna, the Striped species appears to
be solitary in its habits, and it is rare to meet with more than two
together. The principal food of the Hyæna consists of the carcases of
animals that have died of disease or been killed by beasts of prey, and
very often it carries off portions of the body to its den. I once shot
one that was carrying away the hind leg of a Nilghai. The powerful jaws
and large teeth are admirably adapted for crushing bones, which are
consumed by Hyænas, after the flesh has been picked off by vultures and
jackals. Occasionally sheep or goats, and more often dogs, are carried
off by Hyænas, and the latter at all events are often taken alive to the
animal’s den.” The Striped Hyæna is essentially a cowardly animal, and
one that is much more silent than _H. crocuta_. Remains of _H. striata_
are found in the cavern-deposits of the south of France, and also in the
Upper Pliocene of the Val d’Arno in Tuscany, and in the English Red Crag.
[Illustration: FIG. 246.—The Striped Hyæna (_Hyæna striata_).]
The _Crocutine_ group presents the following characters. Upper molar
extremely small, two- or one-rooted, often deciduous. Lower molar
without trace of inner cusp, and with an extremely small talon. Ears
moderate, rounded. Hair not elongated to form a mane. _H. crocuta_, the
Spotted Hyæna (Fig. 247), from Africa south of the Sahara. In dental
characters as well as in its visceral anatomy, especially as regards the
reproductive organs of the female,[470] this species may be considered
as by far the more specialised form. The Spotted Hyæna is a larger and
bolder animal than the Striped species, hunting in packs, and uttering
very frequently its unearthly cry. The coloration consists of dark brown
spots on a yellowish ground. It was formerly very common at the Cape.
Remains of a large race of this species are exceedingly common in the
cavern-deposits of Europe, where they were first described under the
name of _Hyæna spelæa_; teeth have also been met with in the Norfolk
Forest-bed, and in cavern-deposits in Madras—the latter locality being
exceedingly interesting from a distributional point of view.
[Illustration: FIG. 247.—The Spotted Hyæna (_Hyæna crocuta_).]
In addition to the remains of existing species, to which reference has
been already made, there were numerous extinct forms of _Hyæna_ in the
upper Tertiaries of Europe, from the horizon of the Lower Pliocene
Pikermi beds of Greece upwards. In the Crocutine group _H. colvini_ of
the Pliocene of India (Fig. 248), and _H. robusta_ of that of Italy,
appear to have been ancestral forms allied to _H. crocuta_; the former
being distinguished by the loss of the first upper premolar. _H. eximia_,
of the Pikermi beds, is a more generalised form, in which the first lower
premolar (lost in existing forms) is retained. In the typical group, _H.
arvernensis_ and _H. perrieri_, of the Upper Pliocene of the Continent,
approximate to _H. brunnea_; although _H. perrieri_ makes a farther step
towards the Crocutine group by the loss of the inner cusp in the lower
carnassial. The extinct _Hyænictine_ group, as represented by the Indian
_H. sivalensis_ and the Grecian _H. græca_, connects _H. striata_ with
_Palhyæna_. Both are characterised by the presence of a small second
lower molar behind the carnassial; while _H. græca_ also has four lower
premolars. Still more generalised is the _Lychyænine_ group; comprising
_H. macrostoma_ of India and _H. chæretis_ of the Pikermi beds; in these
forms the muzzle was longer, and the premolars much more compressed than
in the existing species, thus making a very decided approach to the
_Viverridæ_. There were four lower premolars; the lower carnassial had
an inner cusp, and it is probable that there was a second lower molar;
while the first upper molar was placed partially behind the carnassial.
The Lower Pliocene _Palhyæna hipparionum_, in which the dental formula
is _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ²⁄₂, is a smaller form with long jaws
and compressed premolars which approaches so closely to the Viverroid
genus _Ictitherium_ as to show pretty clearly how the Hyænas have been
gradually modified from that stock.
[Illustration: FIG. 248.—Outer view of part of the right ramus of the
mandible of _Hyæna colvini_, showing the third and fourth premolars and
the carnassial. (From the _Palæontologia Indica_.)]
_Section_ CYNOIDEA.
_Family_ CANIDÆ.
This section contains the single family of the _Canidæ_, or Dog-like
animals, which appear to hold an intermediate position between the other
two sections, retaining also many of the more generalised characters of
the ancient members of the order. The structure of the auditory bulla and
adjacent parts of the bones of the skull is intermediate between that
of the Æluroid and Arctoid forms. In the number and arrangement of the
teeth they more nearly approach the primitive heterodont type than any
other existing Carnivora. A cæcum is always present, sometimes short and
simple, but when long it is folded upon itself in a characteristic manner.
[Illustration: FIG. 249.—Right lateral aspect of the skull of the Dog
(_Canis familiaris_).]
The characters of the base of the cranium are shown in Fig. 8 (p. 38),
where it will be seen that the auditory bulla is inflated, although
it has only a rudimental internal septum; the paroccipital process,
although in contact with the bulla, is prominent, and there is a large
glenoid foramen. In all the existing forms the humerus has lost the
entepicondylar foramen; the crowns of the upper molars are triangular in
shape (Fig. 251), and the blade of the upper carnassial consists of two
lobes.
[Illustration: FIG. 250.—Cæcum of the Arctic Fox (_Canis lagopus_). _i_,
Ileum; _c_, colon. In the natural position the colon is uppermost.]
In the alimentary canal the cæcum (Fig. 250) is extremely characteristic.
It is a simple appendage of nearly uniform width (about equal to that of
the ileum) attached to the side of the canal, just beyond the ileo-cæcal
valve, and with a rounded termination. In a Dog of average size it is 5
or 6 inches long if uncoiled, but it is normally folded by its mesenteric
attachments backwards and forwards several times on itself by the side of
the ileum, after the manner shown in the figure.
The existing Dogs form a very compact group, with numerous species
closely resembling each other in essential characters, though differing
considerably externally. The most marked differences are slight
variations in the number of the true molar teeth, which exceed the usual
number in the Cape Long-eared Fox (_Otocyon_), and fall short of it in
some other less aberrant forms to which the names of _Icticyon_ and
_Cyon_ have been given, and a diminution in the number of toes in the
Cape Hunting Dog (_Lycaon_), which has 4-4, instead of 5-4 as in the
remainder of the family. After taking these away, there remain a great
number of animals called Dogs, Wolves, Jackals, and Foxes, varying from
one another only in the characters of the tail, ears, fur, form of the
pupil, and some trifling peculiarities of skull and teeth, upon which
some authors have divided them into many genera. These divisions are,
however, extremely difficult, if not impossible, to define, on account of
the numerous gradual transitions from one form to the other.
[Illustration: FIG. 251.—The last four left upper teeth of an extinct
Wolf (_Canis cautleyi_). From the _Palæontologia Indica_.]
_Canis._[471]—It appears on the whole convenient to retain all the
species, with the exception of _Otocyon_, _Icticyon_, and _Lycaon_, in
the old genus _Canis_, the most prominent characters of which are the
following. Teeth, usually _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ²⁄₃; total
42. The absence of the last upper molar (_m_ ³⁄), alone distinguishes
this from the generalised dentition of heterodonts, and this tooth is
occasionally present in one species (_C. cancrivorus_). In certain
Asiatic species (_C. primævus_ and its allies), which on this account
have been separated to form the genus _Cyon_ of Hodgson, the last lower
molar ⁄_m₃_ appears to be constantly absent. The milk-dentition is _di_
³⁄₃, _dc_ ¹⁄₁, _dm_ ³⁄₃; total 28,—the first permanent premolar having no
predecessor. The teeth of both permanent and milk or temporary series are
figured on p. 26, Fig. 3, from the outer aspect, while the woodcut 251
shows the palatal aspect of the hinder upper teeth. The upper carnassial
(_p_ ⁴⁄) consists of a stout blade, of which the anterior lobe is almost
obsolete, the middle lobe large, conical, and pointed backwards, and the
posterior lobe in the form of a compressed ridge; the inner tubercle is
very small, and placed quite at the fore part of the tooth. The first
molar is more than half the antero-posterior length of the carnassial,
and considerably wider than it is long; its crown consists of two
prominent conical cusps, of which the anterior is the larger, and a low
broad inward prolongation, supporting two more or less distinct cusps and
a raised inner border. The second molar resembles the first in general
form, but is considerably smaller. The lower carnassial ⁄_m₁_ is a very
large tooth, with a strong compressed bilobed blade, the hinder lobe
being considerably the larger and more pointed, a small but distinct
inner cusp placed at the hinder margin of the posterior lobe of the
blade, and a broad, low, tuberculated talon, or heel, occupying about
one-third of the whole length of the tooth. The second molar is less than
half the length of the first, with a pair of cusps placed side by side
anteriorly, and a less distinct posterior pair. The third is an extremely
small and simple tooth, with a subcircular tuberculated crown and single
root.
The cranium (Fig. 249) is more or less elongated, the facial portion
tapering forwards and compressed. The jaws are elongated, and the
zygomata moderately strong. The postorbital processes of the frontal
short, leaving the orbit widely open posteriorly. Vertebræ: C 7, D 13,
L 7, S 3, C 17-22. Clavicles present, but very rudimentary. Limbs of
moderate proportions, digitigrade. Feet short; five toes on the fore
foot, the pollex much shorter than the others, and not reaching to the
ground. Four toes on the hind foot, the hallux being represented by a
rudiment of the metatarsal.[472] All the toes are provided with exserted,
non-retractile, slightly curved, and blunt claws, which, being exposed,
become worn at the tips. Tail moderate, or rather long, generally
somewhat bushy. The pupil of the eye, when contracted, is in some species
round, in others elliptical and vertical.
This extensive genus may be considered as truly cosmopolitan. One or more
species occur in every part of the American continent from Greenland
to Patagonia and the Falkland Isles; and similarly, in the Old World,
Europe, Africa, and Asia, with most of the large islands adjacent, and
even Australia, have their wild Dogs, though in the last case they may
belong to a feral race, introduced originally by man. They are generally
sociable animals, hunting their prey in packs. Many species burrow in
the ground; none habitually climb trees. Though mostly carnivorous,
feeding chiefly on animals they have chased and killed themselves, many,
especially among the smaller species, eat garbage, carrion, insects, and
also fruit, berries, and other vegetable substances. The species are
very numerous, and, as in most other large genera, very ill-defined,
few zoologists agreeing as to which of the many slightly different
modifications should be considered as local varieties and which true
species. Perhaps the best cranial character by which the different
members of the genus can be distinguished is that pointed out by
Burmeister, viz. that in the animals generally called Dogs, Wolves, and
Jackals the postorbital process of the frontal bone is regularly smooth
and convex above, with its extremity bent downwards, whereas in Foxes
this process is hollowed above, with its outer margin (particularly of
the anterior border) somewhat raised. This modification coincides in the
main with that upon which Professor Huxley[473] has based his division
of the group into two parallel series, the Thooids or Lupine forms and
Alopecoids or Vulpine forms, which he characterises by the presence of
frontal air-sinuses in the former, which not only affect the external
contour but to a still greater degree the shape of the anterior part of
the cranial cavity, and the absence of such sinuses in the latter. The
pupil of the eye when contracted is round in most members of the first
group, and vertically elliptical in the others, but more observations are
required before this character can be absolutely relied upon. The form
and length of the tail is often used for the purposes of classification,
but its characters do not coincide with those of the cranium, since many
of the South American _Canidæ_ have the long bushy tails of Foxes and
the skulls of Wolves. Taking into account various combinations of these
and other minor characters, the species may be arranged in the following
groups, which some authors have considered as of generic importance.
A. _Thooid or Lupine Series._—The typical group, or _Canis_ proper,
contains the largest members of the genus, the true Wolves of the
northern parts of both Old and New Worlds (_C. lupus_, etc.), the
Jackals of Southern Asia and Africa (_C. aureus_, _mesomelas_, etc.),
and the various breeds of the domestic Dog (_C. familiaris_). The true
Wolves are (excluding some varieties of the domestic Dog) the largest
members of the genus, and have a wide geographical range, extending over
nearly the whole of Europe and Asia, and North America from Greenland
to Mexico, but they are not found in South America or Africa, being
replaced in both of these continents by various species of Jackals and
Foxes. As might be expected from this extensive range, and the varied
character of the climatic conditions of the countries they inhabit, they
present great diversities of size, length and thickness of fur, and
coloration, although resembling each other in all important structural
characters. These differences have given rise to a supposed multiplicity
of species, expressed by the names of _C. lupus_, _C. lycaon_ (Central
Europe), _C. laniger_ and _C. niger_ (Tibet), _C. pallipes_ (India), _C.
occidentalis_, _C. nubilis_, _C. mexicanus_, etc., of North America, but
it is very doubtful whether some of these ought to be distinguished as
other than local varieties. Mr. W. T. Blanford, in his recent work on the
mammals of India, regards the two forms from Tibet mentioned above as
inseparable from _C. lupus_. In North America there is a very distinct
smaller species, called the Coyote or Prairie Wolf (_C. latrans_);
and perhaps the Japanese Wolf (_C. hodophylax_) may also be distinct,
although, except for its smaller size and shorter legs, it is scarcely
distinguishable from the common species. Though generally distributed
throughout the Indian peninsula, the Indian Wolf (_C. pallipes_), which
is rather smaller and slighter than _C. lupus_, is not found in Ceylon,
nor in Burma and Siam. The ordinary colour of the Common Wolf is a
yellowish or fulvous gray, but specimens have been met with almost pure
white and others entirely black. In northern countries the fur is longer
and thicker, and the animal generally larger and more powerful than in
the southern portion of its range; this being especially the case with
the Tibetan races. The habits of the Wolf are similar everywhere, and it
is still, and has been from time immemorial, especially known to man in
all the countries it inhabits as the devastator of his flocks of sheep.
They do not catch their prey by lying in ambush, or stealing up close to
it and making a sudden spring as the Cat tribe do, but by fairly running
it down in open chase, which their speed and remarkable endurance enable
them to do; and usually, except during summer, when the young families of
cubs are being separately provided for by their parents, they assemble in
troops or packs, and by their combined and persevering efforts are able
to overpower and kill even such great animals as the American Bison. It
is singular that such closely allied species as the Domestic Dog and the
Arctic Fox are among the favourite prey of Wolves, and, as is well known,
children and even full-grown people are not unfrequently the objects
of their attack when pressed by hunger. Notwithstanding the proverbial
ferocity of the Wolf in a wild state, many instances are recorded of
animals taken when quite young becoming perfectly tame and attached to
the person who has brought them up, when they exhibit many of the ways of
a Dog. They can, however, rarely be trusted by strangers.
The history of the Wolf in the British Isles and its gradual extirpation
has been thoroughly investigated by Mr. J. E. Harting in his work on
_Extinct British Animals_, from which the following account is abridged:
To judge by the osteological remains which the researches of geologists
have brought to light, there was perhaps scarcely a county in England
or Wales in which, at one time or another, wolves did not abound, while
in Scotland and Ireland they must have been still more numerous. The
fossil remains which have been discovered in Britain are not larger
than, nor in any way to be distinguished from, those of European wolves
of the present day. Wolf-hunting was a favourite pursuit of the ancient
Britons as well as of the Anglo-Saxons. In Athelstan’s reign these
animals abounded to such an extent in Yorkshire that a retreat was
built by one Acehorn, at Flixton, near Filey, wherein travellers might
seek refuge if attacked by them. As is well known, great efforts were
made by King Edgar to reduce the number of wolves in the country, but,
notwithstanding the annual tribute of 300 skins paid to him during
several years by the king of Wales, he was not altogether so successful
as has been commonly imagined. In the reign of Henry III the number of
wolves in some parts of the country was sufficient to induce the king to
make grants of land to various individuals upon the express condition of
their taking measures to destroy these animals wherever they could be
found. In Edward II’s time the king’s forest of the Peak, in Derbyshire,
is especially mentioned as infested with wolves, and it was not until the
reign of Henry VII (1485-1509) that wolves appear to have become finally
extinct in England. This, however, is rather a matter of inference from
the cessation of all mention of them in local records than from any
definite evidence of their extirpation. Their last retreat was probably
in the desolate wolds of Yorkshire. In Scotland, as might be supposed
from the nature of the country, the wolf maintained its hold for a much
longer period. There is a well-known story of the last of the race being
killed by Sir Ewen Cameron of Lochiel in 1680, but there is evidence
of wolves having survived in Sutherlandshire and other parts into the
following century (perhaps as late as 1743), though the date of their
final extinction cannot be accurately fixed. In Ireland, in Cromwell’s
time, wolves were particularly troublesome, and said to be increasing in
numbers, so that special measures were taken for their destruction, such
as the offering of large rewards for their heads, and the prohibition
(in 1652) of the exportation of “wolf-dogs,” the large dogs used for
hunting the wolves. The active measures taken then and later reduced
their numbers greatly, so that towards the end of the century they became
scarce, but, as in the case of the sister island, the date of their final
disappearance cannot now be ascertained. It has been placed, upon the
evidence of somewhat doubtful traditions, as late as 1766.
Remains of _C. lupus_ are common in the European Pleistocene; while the
Indian Pliocene _C. cautleyi_, of which the upper teeth are shown in Fig.
251, was probably the ancestor of _C. pallipes_. _C. neschersensis_, of
the Upper Pliocene of France, was a smaller extinct Wolf. A lower jaw
from the French Pleistocene, described under the name of _Lycorus_, has
only three premolars, but evidently belongs to the Wolf.
The Jackals are smaller than the Wolves, with the bushy tail about
one-third the length of the head and body, and the carnassials relatively
shorter as compared with the tubercular molars. The Common Jackal
(_C. aureus_, Fig. 252) has a very wide distribution, ranging from
South-Eastern Europe through South-Western Asia to India and Burma, and
also occurring in Northern Africa; being replaced in the Ethiopian region
by closely allied species. Remains indistinguishable from _C. aureus_
occur in the Pliocene Siwaliks of Northern India. Jackals hunt at night
in packs, uttering the piercing cries so well known to all who have
resided in countries where these animals are found.
The origin of the Domestic Dog, with its numerous breeds, has been
the subject of much controversy. Some naturalists believe it to be a
distinct species, descended from one that no longer exists in a wild
state; others have sought to find its progenitors in some one of the wild
or feral races, either of true Dogs, Wolves, or Jackals; while others
again believe that it is derived from the mingling of two or more wild
species or races. It was probably the earliest animal domesticated by
man, and few if any other species have undergone such an extraordinary
amount of variation in size, form, and proportion of limbs, ears, and
tail—variations which have been perpetuated and increased by careful
selective breeding. The Dingo or Australian Dog is met with wild, and
also as the domestic companion of the aboriginal people. Dogs were also
in the possession of the natives of New Zealand and other islands of the
Pacific, where no placental mammals exist naturally, on their discovery
by Europeans in the last century.
[Illustration: FIG. 252.—The Jackal (_Canis aureus_).]
The second group includes the wild Dogs of the south-east of Asia,
described as _Cyon_, and distinguished by slight modifications as _C.
rutilans_, _C. dukhunensis_, and _C. javanicus_, and differing from the
above in wanting the small last lower tubercular molar. This difference
reduces the number of the teeth to the same as in _Viverra_, and
is precisely paralleled by some of the species of the extinct genus
_Cynodictis_ mentioned below. The muzzle is shorter than in other
species, and the facial profile is slightly convex instead of concave.
The mammæ are also 12 or 14 instead of the normal 10; while there is
long hair between the foot-pads. Wild Dogs inhabit not only the whole
of the Oriental region, but extend into Central Asia as far north as
the Altai and Amurland (_C. alpinus_). _C. dukhunensis_ ranges from the
forest regions of peninsular India to Gilgit and Western Tibet, where it
must inhabit open country. In their general form, and more especially
the shortness of the legs, these animals come nearer to the Jackals than
to the Wolves. They hunt their prey in packs. Remains of species of
this group occur in the cavern-deposits of the Continent, and have been
described under the name of _C. europæus_.
A group for which the name _Lycalopex_ has been proposed comprises
certain South American _Canidæ_, distinguished from _Canis_ proper
by their longer tails and Fox-like aspect:—_C. cancrivorus_, _C.
brasiliensis_, _C. melampus_, _C. vetulus_, _C. fulvicaudus_, _C.
azaræ_, _C. magellanicus_, _C. griseus_. The last three have been
further separated (under the name of _Pseudalopex_) on account of slight
differences in the relative size of the molar teeth, and of their pupil
being elliptical when contracted. _Nyctereutes_ (one species, _C.
procyonides_, from Japan and North-East Asia) has no claims to generic
distinction but such as are founded upon its long loose fur, short ears,
and short bushy tail, which give it some superficial resemblance to a
Raccoon.
B. _Alopecoid or Vulpine Series._—The _Vulpine_ group (_Vulpes_) includes
the true Foxes, of which there are numerous varieties and species, spread
over North America, Eurasia, and Africa, which have been described under
the names of _C. vulpes_ (_Vulpes alopex_), the common Fox of Europe;
_C. niloticus_, _adustus_, and _variegatus_, Africa; _C. flavescens_,
_montanus_, _bengalensis_, _japonicus_, _corsac_, Asia; _C. fulvus_,
_macrurus_, _velox_, North America. Mr. Blanford[474] concludes, however,
that the Asiatic _C. flavescens_ and _C. montanus_, and very probably
the North American Cross-Fox (_C. fulvus_) are merely local races of
_C. vulpes_, distinguished by certain peculiarities of coloration. The
English Fox measures about 2 feet in length exclusive of the tail, which
is about a foot long. Its fur is of a reddish-brown colour above, and
more or less white beneath; the back of the ears and the fore part of
the limbs are black, and the tip of its bushy tail is white. Its long,
sharp muzzle, erect pointed ears, and sharp eye, give it the well-known
appearance of sagacity and cunning. The Fox is a solitary animal,
inhabiting a burrow, which it either excavates for itself, or obtains by
ejecting the badger or the rabbit. So averse, indeed, is the Fox to dig
for itself, that when foiled in its attempts to dispossess the badger,
it has been known to take up its quarters with the latter, and it can be
induced to make its home in artificial burrows constructed of stone and
earth for the purpose of facilitating the operation of digging out the
cubs. The Fox also occurs in woods, and even in the open country without
burrows, lying in its “cover” by day and stealing forth at night in
search of its prey. Remains of the Common Fox occur not unfrequently in
the Pleistocene deposits of Europe. The Indian _C. bengalensis_ is a very
much smaller and well-marked species.
The tail of the above forms is clothed with soft fur and long hair,
uniformly mixed; from them Baird distinguishes, under the name of
_Urocyon_, other species which have a concealed erect mane of stiff hairs
along the upper line of the tail. These have also a shorter muzzle and a
wide space between the temporal crests; they are _C. virginianus_ and _C.
littoralis_, both from North America. The Arctic Fox (_C. lagopus_, genus
_Leucocyon_, Gray) has the tail very full and bushy and the soles of the
feet densely furred below. Its colour changes according to season from
bluish-gray to pure white.
Certain small elegant African Foxes (_C. zerda_, _famelicus_, and
_chama_), with very large ears and corresponding large auditory bullæ,
have been separated under the name of _Fennecus_, and are commonly known
as Fennecs.
The earliest undoubted occurrence of the genus _Canis_ seems to be in the
Upper Miocene of Switzerland, where it is represented by the Fox-like _C.
œningensis_. In the Upper Pliocene of France _C. megamastoides_ is said
to be allied to the Foxes and Jackals, but with some signs of affinity to
the extinct _Cynodictis_. In the Pliocene Siwaliks of India there occurs
_C. curvipalatus_, of the size of a small Fox, which appears to have
certain resemblances to _Otocyon_.
_Lycaon._[475]—This genus resembles in most of its characters the Dogs
of the Lupine series, but the teeth are rather more massive and rounded,
the skull is shorter and broader, and there are but four toes on each
limb, as in _Hyæna_. The one species, _L. pictus_, the Cape Hunting
Dog (Fig. 253) from South and East Africa, is very distinct externally
from all the other _Canidæ_. It is nearly as large as a Mastiff, with
large, broadly ovate erect ears, and singularly coloured, being not only
variable in different individuals, but unsymmetrically marked with large
spots of white, yellow, and black. It presents some curious superficial
resemblances to _Hyæna crocuta_, perhaps a case of mimetic analogy.
It hunts its prey in large packs. A lower jaw from a cave-deposit in
Glamorganshire, which agrees with that of the existing form in the
presence of an anterior cusp to the last lower premolar, has been made
the type of a distinct species (_L. anglicus_).
_Icticyon._[476]—The Bush-Dog (_I. venaticus_), from Guiana and Brazil,
is a species about the size of a Fox, with close hair, and short legs and
tail, distinguished from all other Dogs by the reduction of the molar
teeth to ¹⁄₂, and their comparatively small size. The lower carnassial
is also characterised by the loss of the inner cusp of the blade, and
the secant form of its hind talon; both these features indicating a
specialised type. Remains of the Bush-Dog are found in the Pleistocene
cavern-deposits of Brazil, and were originally described under the name
of _Speothos_.
[Illustration: FIG. 253.—The Cape Hunting Dog (_Lycaon pictus_).]
_Otocyon._[477]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁻⁴⁄₄; total 46
or 48. The molar teeth are thus in excess of any other living heterodont
mammal. They have the same general characters as in _Canis_, with
very pointed cusps. The lower carnassial shows little of its typical
characters, having five cusps on the surface; these can, however, be
identified as the inner cusp, the two greatly reduced and obliquely
placed lobes of the blade, and two cusps on the talon. The skull
generally resembles that of the smaller Foxes, particularly the Fennecs.
The auditory bullæ are very large. The hinder edge of the mandible has
a very peculiar form, owing to the great development of an expanded,
compressed, and somewhat inverted subangular process. Vertebræ: C 7, D
13, L 7, S 3, C 22. Ears very large. Limbs rather long. Toes 5-4. One
species, _O. megalotis_, from South Africa, rather smaller than a common
Fox.
Professor Huxley looks upon this as the least differentiated or most
primitive existing form of the family, regarding the presence of the
four molar teeth as a survival of a condition of the dentition exhibited
by the common ancestors of the existing _Canidæ_ and the existing
carnivorous Marsupials. There is, however, at present no palæontological
proof of this, as none of the numerous fossil forms of _Canidæ_ yet
discovered have more than the normal number of molars.
_Extinct Genera._—A large number of fossil Carnivora have been described
from various Tertiary deposits which are more or less closely allied to
the existing _Canidæ_, although, as already mentioned, connecting the
latter so closely on the one hand with the _Viverridæ_ and on the other
hand with the _Ursidæ_, that it is almost, if not quite impossible to
say where one family begins and the other ends. A few only of the more
important of these annectant types will be mentioned here. _Temnocyon_,
of the Miocene of the United States, is a true Dog, which agrees with
_Icticyon_ in having a secant hind talon to the lower carnassial, but
preserves a generalised character in having an entepicondylar foramen
to the humerus. An extremely interesting form is _Cynodictis_, of
the Middle Tertiaries of Europe and the United States, which (as now
restricted by Dr. Schlosser) includes a number of species mostly not
larger than Foxes. The dental formula is generally the same as in
_Canis_, but (as in that genus) the last lower molar may be absent. The
teeth are very like those of _Viverridæ_, the lower carnassial never
being greatly elongated antero-posteriorly, and its inner cusp being
situated immediately on the inner side of the hinder lobe of the blade,
instead of somewhat behind it, as is the case in most Dogs. In the
skull the auditory bulla is inflated, but is said to have no distinct
septum; while the humerus invariably has an entepicondylar foramen. It
is suggested that _Cynodictis_ is not far removed from the ancestral
type of many of the Viverroids and Canoids, and may itself have been
derived from the under-mentioned genus _Amphicyon_. M. Boule considers,
indeed, that from the resemblance of the Pliocene _Canis megamastoides_
(p. 553) to _Cynodictis_ we ought to regard the Foxes and Jackals as the
descendants of _Cynodictis_, while the Wolves have been derived directly
from _Amphicyon_. The last named genus, which includes some species
as large as a Bear, is found in the Upper Eocene and Lower Miocene of
Europe, and is represented in the Miocene of the United States by the
allied _Daphœnus_. It is characterised by the presence of three upper
molars—thus bringing up the dental formula to the full Eutherian number;
by the five digits on all the feet, which were plantigrade; and by
the presence of a third trochanter to the femur and an entepicondylar
foramen to the humerus. The teeth are essentially those of a dog, and
the base of the skull is also dog-like, although it is highly probable
that the auditory bulla had no trace of a septum. According, however, to
Dr. Filhol[478] the minute foramina described by Professor Cope[479] in
the postparietal and mastoid which occur in _Ursus_, but are said to be
absent in _Canis_, are present in _Amphicyon_. So far, however, as we
can see, the presence or absence of those foramina cannot be regarded
as diagnostic of _Ursus_ and _Canis_, although they are generally more
strongly developed in the former. _Amphicyon_ may, indeed, be considered
as a very generalised Dog, with affinities to the Bears in the structure
of its limbs. _Dinocyon_ is a still larger form, from the Middle Miocene
of France, which, so far as its teeth are concerned, connects _Amphicyon_
with the Ursoid genus _Hyænarctus_ so closely as to render it absolutely
impossible to indicate any characters of family importance by which they
can be distinguished. The upper carnassial of _Dinocyon_ is unknown. For
other genera, see p. 562.
_Section_ ARCTOIDEA.
[Illustration: FIG. 254.—Right half of the palatal aspect of the cranium
of the Raccoon (_Procyon lotor_). Letters as in Fig. 8, p. 38. (From the
_Proc. Zool. Soc._ 1869, p. 10.)]
This section includes a considerable number of forms which agree in the
essential characteristics of the structures of the base of the cranium
and reproductive organs, and in the absence of a cæcum to the intestinal
canal. They have no Cowper’s glands, but there is a rudimentary prostate
and a large cylindrical penial bone; while all the members of the group
have five completely developed toes on each foot. Considerable diversity
is found in the characters of the base of the skull in the various forms,
but the following features are common to all. The cavity of the auditory
bulla is simple, and has no trace of a dividing septum; the inferior lip
of the auditory meatus (_am_, Fig. 254) is considerably prolonged; the
paroccipital process (_p_) of the exoccipital is more or less triangular,
directed backwards, outwards, and downwards, and standing quite apart
from the bulla; the mastoid process (_m_) of the periotic is always
widely separated from the paroccipital, and generally very prominent;
the carotid foramen (_car_) is large, and placed on the inner margin of
the bulla, usually near the middle, but occasionally more posteriorly;
the condyloid foramen is distinct and exposed, and never sunk into a
common opening with the foramen lacerum posticum; and the glenoid foramen
is always present, and usually conspicuous. The alisphenoid canal is
absent except in _Ursus_, _Melursus_, and _Ælurus_.
It has been already observed (p. 501) that the evidence of fossil forms,
so far as it goes, is not in favour of the Arctoidea being a natural
group; so that its retention must be regarded as a somewhat provisional
measure, largely based on its convenience. The group may be divided into
the three families, _Ursidæ_, _Procyonidæ_, and _Mustelidæ_.[480]
_Family_ URSIDÆ.
In existing forms the true molars ²⁄₃, with broad, flat tuberculated
crowns. Typically the three anterior premolars of both jaws rudimentary
and often deciduous. Fourth upper premolar (carnassial) with no third or
inner root. An alisphenoid canal (except in _Æluropus_). Skull with the
auditory bulla depressed, and scarcely at all inflated. Feet plantigrade.
No entepicondylar foramen to the humerus. Kidneys conglomerate.
Geographical distribution extensive.
_Ursus._[481]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ²⁄₃; total 42.
The three anterior premolars above and below one-rooted, rudimentary, and
frequently wanting. Usually the first (placed close to the canine) is
present, and after a considerable interval the third, which is situated
close to the other teeth of the molar series. The second is very rarely
present in the adult state. The fourth (upper carnassial) differs
essentially from the corresponding tooth of other Carnivores in wanting
the inner tubercle supported by a distinct root. Its sectorial characters
are very slightly marked, and it is much smaller than the first molar.
The crowns of both the true molars are longer than broad, with flattened,
tuberculated, grinding surfaces. The second has a large backward
prolongation or heel. The lower carnassial has a small and indistinct
blade and greatly developed tubercular heel. The second molar is of
about the same length, but with a broader and more flattened tubercular
crown. The third is smaller. The milk-teeth are comparatively small, and
shed at an early age. Skull more or less elongated. Orbits small and
incomplete behind. Palate prolonged considerably behind the last molar
tooth. Vertebræ: C 7, D 14, L 6, S 5, C 8-10. Body heavy. Feet broad,
completely plantigrade; the five toes on each foot all well developed,
and armed with long compressed and moderately curved non-retractile
claws. Palms and soles naked. Tail very short. Ears moderate, erect,
rounded, hairy. Fur generally long, soft, and shaggy.
[Illustration: FIG. 255.—Head of the Brown Bear (_Ursus arctos_). From
Sclater, _Proc. Zool. Soc._ 1867, p. 817.]
The Bears are all animals of considerable bulk, and include among them
the largest members of the order. Though the species are not numerous,
they are widely spread over the earth’s surface (but absent from the
Ethiopian and Australian regions, and only represented by one species in
the Neotropical region), and differ much among themselves in their food
and manner of life. They are mostly omnivorous or vegetable feeders, and
even the Polar Bear, usually purely carnivorous or piscivorous, devours
grass with avidity in summer. The various species maybe arranged in the
following groups:—
_Thalassarctine Group._—Head comparatively small, molar teeth small and
narrow. Soles more covered with hair than in the others. This group is
represented only by the well-known Polar or White Bear (_U. maritimus_)
of the Arctic regions, which is one of the few mammals which are
completely white at all seasons of the year.
The typical, or _Ursine_, group includes a number of species, of which
the Common Brown Bear (_U. arctos_) is the best known example. This
species is an exceedingly variable one, and has a very wide range in
the Palæarctic region; the Syrian form described as _U. syriacus_, as
well as the Hairy-eared Bear (_U. piscator_, Fig. 255) of North-Eastern
Asia, and the Snow-Bear (_U. isabellinus_) of Kashmir and Nipal, not
being specifically separable. The Brown Bear hibernates in cold regions,
and in the Himalaya keeps to comparatively high regions, emerging
from its winter lair in March, April, or May, according to the season
and elevation, to feed on the numerous bulbous plants which abound in
the regions it inhabits. Both the Syrian and Himalayan varieties are
generally of lighter colour and smaller size than the typical European
form. Bears were at one time found in the British Isles, from which,
however, they have been long since exterminated. They are still found in
the Pyrenees, and are comparatively abundant in parts of Norway, Hungary,
and Russia. In the Kashmir Himalaya they were very abundant in some
districts a few years ago, one of the present writers having in 1874 seen
no less than seven examples at one time from the top of a mountain ridge;
of late years their numbers have, however, been greatly diminished. The
Brown Bear, although with strong powers of smelling, is very slow of
sight and hearing, and in the Himalaya it is easy to approach so near
that they may be shot with a smooth-bore gun. The Grizzly Bear (_U.
horribilis_) of North America is so closely allied to the Brown Bear
that some writers think it should only rank as a very well-marked local
variety. The Black Bears of the Himalaya (_U. torquatus_), Japan (_U.
japonicus_), and North America (_U. americanus_) belong to this group.
The Himalayan species ranges from Persia to Assam, and thence to China
and Formosa. In the greater part of this area it is essentially a forest
animal, and may be found in autumn in the forests of the Kashmir valley
feeding upon chestnuts and other fruits. It is also exceedingly fond
of maize, mulberries, and walnuts; and a few years ago it was no very
uncommon sight to see three or even five of these bears up a single
mulberry or walnut tree in Kashmir. The Spectacled Bear (_U. ornatus_) of
the Peruvian Andes is another member of this group.
The _Helarctine_ group is represented only by the Malay Bear or Sun Bear
(_U. malayanus_), in which the head is short and broad; the molar teeth
are comparatively broad (but the length still exceeding the breadth),
the tongue is very long and extensile, and the fur short and smooth.
This small species inhabits the Malay Peninsula, Sumatra, Java, Borneo,
Tenasserim, Arakan, Chittagong, and the Garo hills of India; it inhabits
forest districts, and is an expert climber.
The earliest known occurrence of the genus is in the Lower Pliocene of
the Indian Siwalik Hills; where it is represented by _U. theobaldi_,
which was probably the ancestor of the existing _Melursus_. The genus is
represented in the Upper Pliocene of Europe by the small _U. etruscus_;
and in the Pleistocene by the existing _U. arctos_, as well as by the
great extinct Cave-Bear (_U. spelæus_), distinguished by the complexity
of the crowns of the molars and the total loss of the three anterior
premolars in the adult condition. Remains of Bears are also found in
cavern-deposits in the north of Africa. The small _U. namadicus_, from
the Pleistocene of the Narbada valley, India, may have been allied to _U.
malayanus_.
_Melursus._[482]—This differs from the true Bears in the first upper
incisor being absent or shed at a very early age, in the very small
size of the other teeth, in the very large extensile lips, the deep
concavity of the palate, and other minor characters. The one species,
_M. labiatus_, the well-known Sloth-Bear of India, feeds chiefly on
black ants, termites, beetles, fruit, honey, etc. This species inhabits
peninsular India, from near the Himalaya to Cape Comorin and Ceylon, and
its remains are found in the cavern-deposits of Madras. The black hair
is very long and coarse; there is a light horse-shoe-shaped mark on the
chest (as in _Ursus torquatus_), and the extremity of the muzzle is of an
ashy gray.
[Illustration: FIG. 256.—_Æluropus melanoleucus._ (From Milne-Edwards.)]
_Æluropus._[483]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₃, _m_ ²⁄₃; total 40.
Premolars large, increasing in size from first to last, and two-rooted
except the first. First upper molar with quadrate crown, broader than
long; second larger than the first. Cranium with zygomatic arches and
sagittal crest immensely developed, and ascending ramus of mandible
very high, giving greater spaces for attachments of temporal muscle
than in any other existing member of the order. Facial portion short.
Bony palate not extending behind the last molar tooth. No alisphenoid
canal. Feet bear-like, but soles more hairy, and perhaps less completely
plantigrade. Fur long and thick. Tail very short. One extremely rare
species, _A. melanoleucus_ (Fig. 256), discovered by Père David in 1869,
in the most inaccessible mountains of Moupin in Eastern Tibet. Said to
feed principally on roots, bamboos, and other vegetables. It is of the
size of a small Brown Bear, of a white colour, with ears, spots round the
eyes, shoulders and limbs black. In the large size and complex crowns of
the upper premolars this genus differs very markedly from the true Bears.
The fourth upper premolar (carnassial) makes no approach to the markedly
sectorial type presented by the corresponding tooth of _Hyænarctus_, its
structure being, on the whole, more like that of _Ælurus_.
[Illustration: FIG. 257.—Palate of _Arctotherium bonariense_,
Pleistocene, South America—¼ natural size. (From the _Palæontologia
Indica_.)]
_Extinct Genera._—The genus _Arctotherium_ includes some very large
Bear-like animals from the Pleistocene of South America and California,
in which the dentition departs less widely from a normal carnivorous
type than in the true Bears. Thus the upper carnassial (Fig. 257) is
relatively larger than in _Ursus_; while the crowns of the upper molars
are broader and shorter. The humerus is said to have an entepicondylar
foramen. _Hyænarctus_, of the Miocene and Pliocene of Europe and Southern
Asia, has the crowns of the upper molars either square or triangular;
the upper carnassial having three distinct lobes to the blade, while
the lower carnassial is practically indistinguishable from that of the
Dog-like _Dinocyon_ (p. 556). The proximal extremity of the ulna differs
from that of _Ursus_ in having a long olecranon, and thereby resembles
the corresponding bone of the Dogs. Indeed all the characters at present
available tend to show a complete passage from the Tertiary Dog-like
animals, through _Dinocyon_, _Hyænarctus_, and _Arctotherium_, to the
true Bears. Most of the species of _Hyænarctus_ were of very large
dimensions, but smaller forms occur in the Miocene. _Cephalogale_, of
the Continental Tertiaries, is a genus represented by several species
of medium size showing evident signs of affinity with _Hyænarctus_. The
upper molars have subtriangular crowns, while the carnassial is short,
and has two comparatively low lobes. Here also may be mentioned several
other genera, apparently more or less closely allied to the present
group, some of which are regarded by Dr. Schlosser as showing marked
signs of affinity to the _Procyonidæ_. Among these are _Simocyon_ from
the Pliocene of Europe, with _p_ ²⁄₂₋₄, _m_ ²⁄₂; and _Enhydrocyon_ of
the North American Miocene, with _p_ ³⁄₃, _m_ ²⁄₂, a secant talon to
the lower carnassial, and a very short skull. The Miocene _Ælurodon_
comprises several large North American forms, having a trilobed upper
carnassial like that of _Hyænarctus_, and a dental formula similar to
that of the latter and _Canis Prohyæna_ is founded upon a much-worn jaw
of _Ælurodon_. _Hyænocyon_, of the Miocene of the United States, with _p_
³⁄₃, _m_ ¹⁄₂, appears to be an allied form, also having a trilobed upper
carnassial.
_Family_ PROCYONIDÆ.
True molars ²⁄₂, tuberculated or multicuspid; upper carnassial short and
broad. Alisphenoid canal absent, except in _Ælurus_. Feet plantigrade.
Tail generally annulated. In some cases an entepicondylar foramen to
the humerus. Typically American, but with the outlying Oriental genus
_Ælurus_.
_Ælurus._[484]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₄, _m_ ²⁄₂; total
38. First lower premolar very minute and deciduous. Molars (Fig. 259)
remarkable for their great transverse breadth and the numerous cusps of
their crowns. Vertebræ: C 7, D 14, L 6, S 3, C 18. Skull (Fig. 259) high
and compressed, very convex, with the facial portion short, the palate
convex antero-posteriorly, and the ascending ramus of mandible extremely
high. Head round. Face short and broad. Ears large, erect, pointed.
Limbs stout, with large sharp semiretractile claws. Tail nearly as long
as body, cylindrical, annulated, and clothed with long hairs. Fur long
and thick. One existing species, _Æ. fulgens_, the Panda (Fig. 258),
an animal rather larger than a Cat, found in the South-East Himalaya,
at heights of from 7,000 to 12,000 feet above the sea, among rocks and
trees, and chiefly feeding on fruits and other vegetable substances. Its
fur is of a remarkably rich reddish-brown colour, darker below.
The genus _Ælurus_ has been made the type of a distinct family, but its
relationship to the Raccoons is regarded by Mr. W. T. Blanford[485] as
sufficiently close to admit of its being included in the same family.
According to this zoölogist the Panda often sleeps coiled up like a Cat,
with the bushy tail over its head, but at other times resting on its legs
with the head tucked under the chest and between the fore legs, after a
manner said to be common with the Raccoons. Although by no means strictly
nocturnal, these animals sleep much during the day, and roam out in
search of food in the morning and evening. The young are born in a very
helpless condition, and remain for a long period concealed in the holes
of trees or rocks.
[Illustration: FIG. 258.—The Panda (_Ælurus fulgens_). The dark nasal
stripe shown in this figure is generally absent. (From Sclater, _Proc.
Zool. Soc._ 1869, p. 408.)]
Fossil remains of a species of _Ælurus_ (_Æ. anglicus_) have been
obtained from the English Pliocene Crag deposits which indicate an animal
of about one and half times the size of _Æ. fulgens_. The first evidence
of this fossil species was afforded by part of the mandible with the
last molar in place, and the subsequent discovery of an entire first
upper molar renders full confirmation of the generic determination. This
distribution of _Ælurus_ is very important, as showing how its area
may have once approximated to that of the ancestors of the American
representatives of the family. It is probable that the genus existed in
India during the Siwalik period.
The whole of the under-mentioned genera are American, and are
characterised by the absence of an alisphenoid canal in the skull.
[Illustration: FIG. 259.—Lateral view of skull and right half of palate
of _Ælurus fulgens_. (From Blanford, _Mammalia of British India_, p.
190.)]
_Procyon._[486]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ²⁄₂; total 40.
The molar teeth broad and tuberculated (Fig. 259). The upper carnassial
with three cusps along the outer margin, and a very broad bicuspid
inner tubercle, giving an almost quadrate form to the crown. First
molar with a large tuberculated crown, rather broader than long; second
considerably smaller, with transversely oblong crown. Lower carnassial
with an extremely small and ill-defined blade, placed transversely in
front, and a large inner cusp and hind talon. Second molar as long as the
first, but narrower behind, with five obtuse cusps. Vertebræ: C 7, D
14, L 6, S 3, C 16-20. Body stout. Head broad behind, but with a pointed
muzzle. Limbs plantigrade, but in walking the entire sole is not applied
to the ground as it is when the animal is standing. Toes, especially of
the fore foot, very free, and capable of being spread wide apart. Claws
compressed, curved, pointed, and non-retractile. Tail moderately long,
cylindrical, thickly covered with hair, annulated, non-prehensile. Fur
long, thick, and soft. The well-known Raccoon[487] (_Procyon lotor_,
Fig. 260) of North America is the type of this genus. It is a clumsy
thickly-built animal about the size of a Badger, with a coat of long
coarse grayish-brown hairs, short ears, and a bushy black and white
ringed tail. Its range extends over the whole of the United States, and
stretches on the west northwards to Alaska and southwards into Central
America, where it attains its maximum size. The following notes on the
habits of the Raccoon are taken from Dr. C. H. Merriam’s _Mammals of the
Adirondack Region_:—
[Illustration: FIG. 260.—The Raccoon (_Procyon lotor_).]
“Raccoons are omnivorous beasts, and feed upon mice, small birds, birds’
eggs, turtles and their eggs, frogs, fish, crayfish, molluscs, insects,
nuts, fruits, maize, and sometimes poultry. Excepting the bats and flying
squirrels, they are the most strictly nocturnal of all our mammals, and
yet I have several times seen them abroad on cloudy days. They haunt the
banks of ponds and streams, and find much of their food in these places,
such as crayfish, mussels, and fish, although they are unable to dive and
pursue the latter under water, like the otter and mink. They are good
swimmers, and do not hesitate to cross rivers that lie in their path....
The Raccoon hibernates during the severest part of the winter, retiring
to its nest rather early, and appearing again in February or March,
according to the earliness or lateness of the season. It makes its home
high up in the hollow of some large tree, preferring a dead limb to the
trunk itself. It does little in the way of constructing a nest, and from
four to six young are commonly born at a time, generally early in April
in this region. The young remain with the mother about a year.”
The South-American _P. cancrivorus_, the Crab-eating Raccoon, is very
similar to _P. lotor_, but differs by its much shorter fur, larger size,
proportionally more powerful teeth, and other minor characters. It
extends over the whole of South America, as far south as the Rio Negro,
and is very common in all suitable localities. Its habits are similar to
those of the North-American species. Fossil remains of _Procyon_ have
been described from the Pleistocene deposits of the United States.
_Bassaris._[488]—A form closely allied to _Procyon_, but of more slender
and elegant proportions, with a sharper nose, longer tail, and more
digitigrade feet, and with teeth otherwise like, but smaller, and more
sharply denticulated. It was formerly, but erroneously, placed among the
_Viverridæ_. Two species:—_B. astuta_, from the southern parts of the
United States and Mexico, and _B. sumichrasti_, from Central America.
_Bassaricyon._[489]—This name has been given to a distinct modification
of the Procyonine type of which at present only two examples are known,
one from Costa Rica and the other from Ecuador, which, appearing to be
different species, have been named _B. gabbi_ and _B. alleni_. They much
resemble the Kinkajou (_Cercoleptes_) in external appearance, but the
skull and teeth are more like those of _Procyon_ and _Nasua_.
_Nasua._[490]—Dentition as in _Procyon_, but the upper canines are
larger and more strongly compressed, and the molars smaller. The facial
portion of the skull is more elongated and narrow. Vertebræ: C 7, D 14,
L 6, S 3, C 22-23. Body elongated and rather compressed. Nose prolonged
into a somewhat upturned, obliquely truncated, mobile snout. Tail long,
non-prehensile, tapering, annulated. These animals, commonly called
Coatis or Coati-Mundis, live in small troops of eight to twenty, are
chiefly arboreal, and feed on fruits, young birds, eggs, insects, etc.
Recent researches have reduced the number of supposed species to two, _N.
narica_ of Mexico and Central America, and _N. rufa_ of South America
from Surinam to Paraguay. Remains of this genus, mostly referable to the
existing species, occur in the cavern-deposits of Brazil.
_Cercoleptes._[491]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ²⁄₂; total
36. Molars with low flat crowns, very obscurely tuberculated. Skull short
and rounded, with flat upper surface. Vertebræ: C 7, D 14, L 6, S 3,
C 26-29. Clavicles present, but in a very rudimentary condition. Head
broad and round. Ears short. Body long and musteline. Limbs short. Tail
long, tapering, and prehensile. Fur short and soft. Tongue long and very
extensile. But one species of this somewhat aberrant genus is known, _C.
caudivolvulus_, the Kinkajou, found in the forests of the warmer parts of
South and Central America. It is about the size of a Cat, of a uniform,
pale, yellowish-brown colour, nocturnal and arboreal in its habits,
feeding on fruit, honey, eggs, and small birds and mammals, and is of a
tolerably gentle disposition and easily tamed.
_Family_ MUSTELIDÆ.
True molars ¹⁄₂ (or ¹⁄₁ in _Mellivora_[492]). No alisphenoid canal. In
the upper molar the inner tubercular portion is always longer in the
antero-posterior direction than the secant external portion; the degree
of inflation of the auditory bulla is but slight; and the palate is
generally much produced behind the last molars, as is the case with the
members of the preceding family. The post-glenoid process of the cranium
is generally considerably curved over the glenoid fossa, so as to hold
very tightly the condyle of the mandible. The humerus may or may not have
an entepicondylar foramen. Except in the Otters, the kidneys resemble
those of the _Procyonidæ_ in being of simple structure.
This family is a large and widely distributed one, especially in the
northern temperate regions of the earth. The different genera, which are
very difficult to arrange in any natural order, are rather artificially
divided, chiefly according to the characters of their feet and claws,
into the Otter-like (Lutrine), Badger-like (Meline), and Weasel-like
(Musteline) forms.
Subfamily =Lutrinæ=.—Feet short, rounded (except the hind feet of
_Latax_). Toes webbed. Claws small, curved, blunt. Head broad and
much depressed. Upper molar large and quadrate, with its inner
tubercular portion much expanded antero-posteriorly (Fig. 261). Kidneys
conglomerate. Habits aquatic.
_Lutra._[493]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₃, _m_ ¹⁄₂; total 36.
Upper carnassial with a trenchant tricuspid blade, and a very large
inner lobe, hollowed on the free surface, with a raised sharp edge, and
extending along two-thirds or more of the length of the blade. True molar
large, with a quadricuspidate crown, broader than long. First upper
premolar very small, and in some cases absent (Fig. 261). Skull broad and
depressed, contracted immediately behind the orbits. Facial portion very
short; brain case large. Vertebræ: C 7, D 14-15, L 6-5, S 3, C 20-26.
Body very long. Ears short and rounded. Limbs short. Feet more or less
completely webbed; claws usually well developed on all the toes, although
they may be rudimentary or absent. Tail long, thick at the base and
tapering, rather depressed. Fur short and close. The humerus may or may
not have an entepicondylar foramen. In conformity with the shape of the
skull, the posterior part of the brain is expanded laterally.
[Illustration: FIG. 261.—Palate of _Lutra cinerea_. (From the
_Palæontologia Indica_.)]
The Common British Otter (_L. vulgaris_), as the type of the genus, may
be described somewhat fully. It has an elongated, low body, short limbs,
short broad feet, with five toes on each, connected together by webs, and
all with short, moderately strong, compressed, curved, pointed claws.
Head rather small, broad, and flat; muzzle very broad; whiskers thick
and strong; eyes small and black; ears short and rounded. Tail a little
more than half the length of the body and head together, very broad and
strong at the base, and gradually tapering to the end, somewhat flattened
horizontally. The fur is of very fine quality, consisting of a short soft
under fur of a whitish-gray colour, brown at the tips, interspersed with
longer, stiffer, and thicker hairs, very shining, grayish at the base,
bright rich brown at the points, especially on the upper parts and outer
surface of the legs; the throat, cheeks, under parts and inner surface of
the legs brownish-gray throughout. Individual Otters vary much in size;
but the total length from the nose to the end of the tail averages about
3½ feet, of which the tail occupies 1 foot 3 or 4 inches. The weight of a
full-sized male is from 18 to 24 lbs., that of a female about 4 lbs. less.
As the Otter lives almost exclusively on fish, it is rarely met with far
from water, and usually frequents the shores of brooks, rivers, lakes,
and, in some localities, the sea itself. It is a most expert swimmer and
diver, easily overtaking and seizing fish in the water, but when it has
captured its prey it brings it to shore to devour it. When lying upon the
bank it holds the fish between its forepaws, commences at the head, and
then eats gradually towards the tail, which it is said always to leave.
The female produces three to five young ones at a time, in the month of
March or April, and brings them up in a nest formed of grass or other
herbage, usually placed in a hollow place in the bank of a river, or
under the shelter of the roots of some overhanging tree. The Common Otter
is found in localities suitable to its habits throughout Great Britain
and Ireland, though far less abundantly than formerly, for, being very
destructive to fish, and thus coming into keen competition with those
who pursue the occupation of fishing either for sport or for gain, it
is rarely allowed to live in peace when once its haunts are discovered.
Otter-hunting with packs of hounds of a special breed, and trained for
the purpose, was formerly a common pastime in the country. When hunted
down and brought to bay by the dogs, the Otter is finally despatched by
long spears carried for the purpose by the huntsmen.
The Common Otter ranges throughout the greater part of Europe and Asia,
the Indian _L. nair_ not being distinct. A closely allied but larger
species, _L. canadensis_, is extensively distributed throughout North
America, where it is systematically pursued by professional trappers
for the value of its fur. The Common Otter is regularly trained by the
natives of some parts of Bengal to assist them in fishing, by driving the
fish into the nets. In China Otters are taught to catch fish, being let
into the water for the purpose attached to a long cord.
Otters are widely distributed over the earth, and, as they are much
alike in size and coloration, their specific distinctions are by no
means well defined.[494] Besides those mentioned above, the following
may be noticed. In the Oriental region there are _L. ellioti_[495] of
India, _L. sumatrana_ of the Malay countries, and _L. cinerea_ ranging
over the greater part of the region. The latter species (often known
as _L. leptonyx_) is of small size, with a short head, and rudimentary
claws, which may be absent; it was at one time regarded as generically
distinct, under the name of _Aonyx_. The upper true molar (Fig. 261) is
characterised by the great development of its inner tubercular portion,
and the first upper premolar is absent. In the Ethiopian region there
are two species, _L. capensis_ and _L. maculicollis_. Of the Neotropical
forms it will suffice to mention the small _L. felina_ and the large _L.
brasiliensis_. The latter is by far the largest of the existing forms,
and is characterised by the presence of a prominent flange-like ridge
along each lateral margin of the tail, on which account it was referred
by Dr. Gray to a distinct genus, with the name of _Pteronura sambachi_.
It should be observed that all Otters have a very distinct inner cusp to
the blade of the lower carnassial, but that the relative size of this
cusp varies in the different species.
_Extinct Otters._—Several species of fossil Otters have been
described. Thus in the Indian Siwaliks we have _L. palæindica_, which
is closely allied to _L. sumatrana_, and a larger form described
as _L. bathygnathus_. The Pliocene of Hessen-Darmstadt yields _L.
hessica_; while _L. dubia_, of the Middle Miocene of France, is a
species characterised by the small size of the inner cusp of the lower
carnassial—a character in which it resembles those Tertiary forms
described as _Trochictis_, which are believed to connect _Lutra_ with the
_Mustelinæ_. Two very large Otters, respectively from the Indian Siwaliks
and the Italian Miocene, named _L. sivalensis_ and _L. campanii_, may
be regarded either as representing a very distinct _Enhydriodont_ group
of _Lutra_ or as referable to a separate genus _Enhydriodon_. They are
characterised by certain peculiarities in the structure of the teeth,
and the second upper premolar may be absent in the Indian form. Lastly,
the genus _Potamotherium_ contains a small Otter (_P. valetoni_) from
the Lower Miocene of the Continent, which differs from all other known
_Mustelidæ_ in having a minute second upper true molar. This species is
evidently a very generalised form approximating to the _Viverridæ_ in
its dental formula, and also in the characters of the teeth themselves.
The brain, as recently described by Dr. Filhol, differs from that
of _Lutra_ and other Mustelines in the great relative width of the
anterior extremity of the hemispheres and olfactory lobes, and also in
the disposition of the sulci, in both of which respects it more nearly
resembles the _Viverridæ_.
_Latax._[496]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ¹⁄₂; total 32.
Differs from all other existing Carnivora in having but two incisors on
each side of the lower jaw, the one corresponding to the first (very
small in the true Otters) being constantly absent. Though the molar teeth
generally resemble those of _Lutra_ in their proportions, they differ
very much in the exceeding roundness and massiveness of their crowns
and bluntness of their cusps. Feet webbed. Fore feet small, with five
subequal toes, furnished with short compressed claws; palms naked. Hind
feet very large, depressed, and fin-like. The phalanges flattened as in
the Seals. The fifth toe the longest and stoutest, the rest gradually
diminishing in size to the first, all with moderate claws. Tail
moderate, cylindrical, and obtuse; about one-fourth the length of the
head and body.
The Sea-Otter (_L. lutris_, Fig. 262) is the sole representative of
this genus. The entire length of the animal from nose to end of tail
is about 4 feet, so that the body is considerably larger and more
massive than that of the English Otter. The skin is peculiarly loose,
and stretches when removed from the animal so as to give the idea of
a still larger creature than it really is. The pellage is remarkable
for the preponderance of the beautifully soft woolly under fur, the
longer stiffer hairs being very scanty. The general colour is a deep
liver brown, everywhere silvered or frosted with the hoary tips of the
longer hairs. These are, however, removed when the skin is dressed for
commercial purposes.
[Illustration: FIG. 262.—The Sea-Otter (_Latax lutris_). From Wolf,
_Proc. Zool. Soc._ 1865, pl, vii.]
Sea-Otters are only found upon the rocky shores of certain parts of
the North Pacific Ocean, especially the Aleutian Islands and Alaska,
extending as far south on the American coast as Oregon; but, owing to the
unremitting persecution to which they are subjected for the sake of their
skins, which rank among the most valuable known to the furrier, their
numbers are greatly diminishing, and, unless some restriction can be
placed upon their destruction, such as that which protects the Fur-Seals
of the Pribyloff Islands, the species is threatened with extermination,
or, at all events, excessive scarcity. When this occurs, the occupation
of five thousand of the half-civilised natives of Alaska, who are
dependent upon Sea-Otter hunting as a means for obtaining their living,
will be gone. The principal hunting grounds at present are the little
rocky islets and reefs around the island of Saanach and the Chernobours,
where they are captured by spearing, clubbing, or nets, and recently
by the more destructive rifle bullet. They do not feed on fish, like
the true Otters, but on clams, mussels, sea-urchins, and crabs, for the
mastication of which the blunt cusps of their teeth are admirably suited.
The female brings forth but a single young one at a time, apparently
at any season of the year. They are excessively shy and wary, and all
attempts to rear the young ones in captivity have hitherto failed.
Subfamily =Melinæ=.—Feet elongated. Toes straight. Claws non-retractile,
slightly curved, subcompressed, blunt; those of the fore foot especially
large. Upper molar variable. Kidneys simple. Habits mostly terrestrial
and fossorial.
_Mephitis._[497]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ¹⁄₂; total
34. Upper molar larger than the carnassial, subquadrate, rather broader
than long. Lower carnassial with talon less than half the length of
the whole tooth. Bony palate terminating posteriorly opposite the
hinder border of the last molar tooth. Facial portion of skull short
and somewhat truncated in front. Vertebræ: C 7, D 16, L 6, S 2, C 21.
Head small. Body elongated. Limbs moderate, subplantigrade. Ears short
and rounded. Tail long, abundantly clothed with very long fine hair.
Anal glands largely developed. The secretion of these glands, which can
be discharged at the will of the animal, has an intolerably offensive
odour, which circumstance has rendered the Skunks, as they are commonly
called, proverbial. They are strictly nocturnal animals, terrestrial and
burrowing, feeding chiefly on small mammals, birds, reptiles, insects,
worms, roots, and berries. All the known species have a prevalent black
colour, varied by white strips or spots on the upper part (Fig. 263).
They generally carry the body, much arched, and the tail erect, the long
loose hair of which waves like a plume over the back. There are three
species, all inhabitants of the American continent, over which they have
an extensive range.
[Illustration: FIG. 263.—The Common Skunk (_Mephitis mephitica_).]
The Common Skunk (_M. mephitica_, Fig. 263) is an animal of about
the size of a small Cat, ranging from Hudson’s Bay to Guatemala. The
following account of its habits is given by Dr. C. H. Merriam in his
_Mammals of the Adirondack Region_:—
“The skunk preys upon mice, salamanders, frogs, and the eggs of birds
that nest on or within reach from the ground. At times he eats carrion,
and if he chances to stumble upon a hen’s nest the eggs are liable to
suffer; and once in a while he acquires the evil habit of robbing the
hen-roost, but as a rule skunks are not addicted to this vice. Of all
our native mammals perhaps no one is so universally abused and has so
many unpleasant things said about it as the innocent subject of the
present biography; and yet no other species is so valuable to the farmer.
Pre-eminently an insect-eater, he destroys more beetles, grasshoppers,
and the like than all our other mammals together, and in addition to
these he devours vast numbers of mice. He does not evince that dread of
man that is so manifest in the great majority of our mammals, and when
met during any of his circumambulations rarely thinks of running away. He
is slow in movement and deliberate in action, and does not often hurry
himself in whatever he does. His ordinary gait is a measured walk, but
when pressed for time he breaks into a low shuffling gallop. It is hard
to intimidate a skunk, but when once really frightened he manages to get
over the ground at a very fair pace. Skunks remain active throughout the
greater part of the year in this region, and hibernate only during the
severest portion of the winter. They differ from most of our hibernating
mammals in that the inactive period is apparently dependent solely on the
temperature, while the mere amount of snow has no influence whatever upon
their movements. Skunks, particularly when young, make very pretty pets,
being attractive in appearance, gentle in disposition, interesting in
manners, and cleanly in habits—rare qualities indeed! They are playful,
sometimes mischievous, and manifest considerable affection for those who
have the care of them. Their flesh is white, tender, and sweet, and is
delicious eating. Skunks have large families, from six to ten young being
commonly raised each season; and as a rule they all live in the same hole
until the following spring.”
The two ducts leading from the anal glands open at the tips of two small
conical papillæ placed in such a position that the animal can protrude
them externally, and can thus guide the direction of the jet of nauseous
fluid, which can be propelled by the powerful muscles surrounding the
glands to a distance of from 8 to 12 feet.
The Long-tailed Skunk (_M. macrura_), from Central and Southern Mexico,
has two lateral stripes, and a longer and more bushy tail than the
common species. _M. putorius_, of the Southern United States and thence
southwards to Yucatan and Guatemala, is of a much smaller size, with four
interrupted white lateral stripes, and a skull differing considerably in
form from that of the type species. It is regarded by some writers as
representing a distinct genus, _Spilogale_; and has been recently divided
by Dr. C. H. Merriam into several nominal species.
_Conepatus._[498]—The Skunk of tropical America (_C. mapacito_), ranging
from Texas to Chili and Patagonia, differs considerably from the true
Skunks, although in colour it is almost precisely similar to the common
species, with which it also agrees in the variation of the relative
development of the black and white. Its build is heavier than that of
_Mephitis_; the snout and head are more Pig-like; and the nostrils open
downwards and forwards instead of laterally on the sides of the muzzle.
The skull also has many special characters, and the teeth are different
in shape and, as, a rule, in number also, the first minute premolar of
_Mephitis_ being almost invariably absent, so that the dental formula is
_i_ ³⁄₃, _c_ ¹⁄₁, _p_ ²⁄₃, _m_ ¹⁄₂; total 32.
Remains of _Conepatus_, which have been referred to three species, are
found in the cavern-deposits of Brazil.
_Arctonyx._[499]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ¹⁄₂; total
38. Incisor line curved, the outer teeth being placed posteriorly to the
others. Lower incisors proclivous. First premolars often rudimentary
or absent. Upper molar much larger than the carnassial, longer in the
antero-posterior direction than broad; lower carnassial with a very
large, low, tuberculated talon. Cranium elongated and depressed; face
long, narrow, and concave above. Bony palate extending as far backwards
as the level of the glenoid fossa; palatal bones dilated; suborbital
foramina very large. Vertebræ: C 7, D 16, L 4, S 4, C 20. Snout long,
naked, mobile, and truncated, with large terminal nostrils, much like
that of a Pig. Eyes small. Ears very small and rounded. Body compressed
rather than depressed. Limbs of moderate length and digitigrade in
walking. Tail moderate, tapering. A full soft under fur, with longer,
bristly hairs interspersed. The best-known species is _A. collaris_,
the Sand-Badger, or _Bhálu-soor_[500] (_i.e._ Bear-pig) of the natives,
found in the mountains of the north-east of India and Assam. It is rather
larger than the English Badger, higher on its legs, and very Pig-like
in general aspect, of a light gray colour, with flesh-coloured snout
and feet; and is nocturnal and omnivorous in habits. The imperfectly
known _A. taxoides_ from Assam and Arakan, and perhaps China, is a much
smaller species. A third form probably exists in Eastern Tibet. Professor
Mivart remarks that the brain-case of _Arctonyx_ is narrower than in any
other Arctoid; while the palate is relatively longer than in any other
Carnivore except _Procyon_; and the metatarsus is relatively shorter than
in any other member of the order.
_Mydaus._[501]—Dentition as in the last genus, but the cusps of the
teeth more acutely pointed. Cranium elongated, face narrow and produced.
Suborbital foramen small, and the palate, as in all the succeeding genera
of this group, produced backwards about midway between the last molar
tooth and the glenoid fossa. Vertebræ: C 7, D 14-15, L 6-5, S 3, C 12.
Head pointed in front; snout produced, mobile, obliquely truncated, the
nostrils being inferior. Limbs rather short and stout. Tail extremely
short, but clothed with rather long bushy hair. Anal glands largely
developed, and emitting an odour like that of the American Skunks. One
species, _M. meliceps_, the Teledu, a small burrowing Badger, found
in the mountains of Java at an elevation of 7000 or more feet above
sea-level.
_Meles._[502]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ¹⁄₂; total 38.
The first premolar in both jaws extremely minute and often deciduous.
Upper molar very much larger than the carnassial, subquadrate, as broad
as long. Lower carnassial with a broad, low, tuberculated talon, more
than half the length of the whole tooth. The post-glenoid processes of
the skull are so strongly developed, and the glenoid fossa is so deep,
that the condyle of the lower jaw is firmly held in its place even after
all the surrounding soft parts are removed. Vertebræ: C 7, D 15, L 5, S
3, C 18. Muzzle pointed. Ears very short. Body stout, broad. Limbs short,
strong, subplantigrade. Tail short. The best-known species is the common
Badger (_M. taxus_) of Europe and Northern Asia, still found in many
parts of England, where it lives in woods, is nocturnal, burrowing, and
very omnivorous, feeding on mice, reptiles, insects, fruit, acorns, and
roots. Other nearly allied species, _M. leucurus_ and _M. chinensis_, are
found in continental Asia, _M. canescens_ in Persia, and _M. anakuma_ in
Japan.
The appearance of the common Badger is too well known to need
description, but, it may be mentioned that a full-grown individual stands
about a foot in height at the shoulder, and measures from 2½ to 3 feet
in length. The young are born in a naked and blind condition, usually in
litters of three or four. It appears that the usual period of gestation
is about eleven and a half months, but instances are recorded where the
period has been protracted to upwards of fifteen months.
Fossil remains of the common Badger are found in the Pleistocene deposits
of Europe, while extinct species have been described from the Lower
Pliocene beds of Maragha, in Persia.
_Taxidea._[503]—Dental formula as in _Meles_, except that the rudimentary
anterior premolar appears to be always wanting in the upper jaw. The
upper carnassial much larger in proportion to the other teeth. Upper
molar about the same size as the carnassial, triangular, with the apex
turned backwards. Talon of lower carnassial less than half the length
of the tooth. Skull very wide in the occipital region; the lambdoidal
crest very greatly developed, and the sagittal but slightly, contrary to
what obtains in _Meles_. Vertebræ: C 7, D 15, L 5, S 3, C 16. Body very
stoutly built and depressed. Tail short. The animals of this genus are
peculiar to North America, where they represent the Badgers of the Old
World, resembling them much in appearance and habits. _T. americana_ is
the common American Badger of the United States; _T. berlandieri_, the
Mexican Badger, is perhaps only a local variety.
_Mellivora._[504]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ¹⁄₁; total
32. Upper carnassial large, with its inner tubercle quite at the anterior
end of the blade, as in the following genera; molar much smaller and
transversely extended, having a very small outer and a larger rounded
inner lobe. Talon of lower carnassial very small, scarcely one-fourth of
the whole length of the tooth, and with but one cusp; lower tubercular
molar absent. Vertebræ: C 7, D 14, L 4, S 4, C 15. Body stout, depressed.
Limbs short, strong. Head depressed, nose rather pointed. External ears
rudimentary. Tail short. The animals of this genus are commonly called
Ratels. _M. indica_ from India, and, _M. ratel_ (Fig. 264) from South
and West Africa, have nearly the same general appearance and size, being
rather larger than a common Badger. Their coloration is peculiar, all
the upper surface of the body, head, and tail being ashy gray, while the
lower parts, separated by a distinct longitudinal boundary line, are
black. The two species may be distinguished by the circumstance that the
African one has a distinct white line round the body at the junction of
the gray of the upper side with the black of the lower, while in the
Indian form this line is absent; the teeth also of the former are, on the
whole, larger, rounder, and heavier than those of the latter. In spite of
these differences the two are, however, so nearly allied that they might
almost be considered as local races of a single widely spread species.
[Illustration: FIG. 264.—The African Ratel (_Mellivora ratel_).]
The following account of the Indian species is extracted from Dr.
Jerdon’s _Mammals of India_: “The Indian badger is found throughout the
whole of India, from the extreme south to the foot of the Himalayas,
chiefly in hilly districts, where it has greater facilities for
constructing the holes and dens in which it lives; but also in the north
of India in alluvial plains, where the banks of large rivers afford
equally suitable localities wherein to make its lair. It is stated to
live usually in pairs, and to eat rats, birds, frogs, white ants, and
various insects, and in the north of India it is accused of digging out
dead bodies, and is popularly known as the grave-digger. It doubtless
also, like its Cape congener, occasionally partakes of honey. It is often
very destructive to poultry, and I have known of several having been
trapped and killed whilst committing such depredations in Central India
and in the northern Circars. In confinement the Indian badger is quiet
and will partake of vegetable food, fruits, rice, etc.”
A fossil species of _Millivora_, apparently closely allied to the
existing forms, occurs in the Pliocene Siwaliks of India. The same
deposits have also yielded remains of an extinct genus described as
_Mellivorodon_.
[Illustration: FIG. 265.—_Helictis personata._ (From Blanford, _Mammalia
of British India_, p. 175.)]
_Helictis._[505]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ¹⁄₂; total
38. Upper carnassial with a large bicuspid inner tubercle; upper molar
smaller, wider transversely than in the antero-posterior direction.
Lower carnassial with talon about one-third the length of the tooth.
Skull elongated, rather narrow and depressed. Facial portion especially
narrow. Infraorbital foramen very large. Head rather small and produced
in front, with an elongated, obliquely truncated, naked snout. Ears
small. Body elongated. Limbs short. Tail short or moderate, bushy.
Several species are described (_H. orientalis_, _personata_ [Fig. 265],
_moschata_, _subaurantiaca_), all from Eastern Asia; they are all small
animals compared with the other members of the subfamily, climbing trees
with agility and living much on fruit and berries as well as on small
mammals and birds. The two first named species occur in British India,
_H. orientalis_ also ranging into Java; the Chinese _H. subaurantiaca_ is
brilliantly coloured in the region of the throat.[506]
[Illustration: FIG. 266.—Left lateral and superior aspect of the brain of
_Helictis subaurantiaca_. (From Garrod, _Proc. Zool. Soc._ 1879, p. 307.)]
The brain of _Helictis_, represented in the accompanying figure, shows
the general type of cerebral structure characteristic of the _Mustelidæ_.
The brain of this genus differs, however, from that of every other
Carnivore in that the hippocampal gyrus rises to the surface on either
side of the great longitudinal fissure, in consequence of which there is
no crucial fissure, and the so-called “Ursine lozenge,” so characteristic
of the Arctoidea, is incomplete behind. The superior gyrus, as in
_Ictonyx_ and _Mustela_, ceases at the superior posterior angle of the
hemisphere.
_Ictonyx._[507]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ¹⁄₂; total
34. In general characters the teeth much resemble those of the Polecats
(_Mustela_), being more delicately cut and sharply cusped than in most
of the foregoing. Upper molar smaller than the carnassial, narrow from
before backwards. Lower carnassial with a small narrow talon and distinct
inner cusp. General form of body Musteline. Limbs short. Fore feet large
and broad, with five stout, nearly straight, blunt, and non-retractile
claws, of which the first and fifth are considerably shorter than the
others. Tail moderate, with longer hairs towards the end, giving it a
bushy appearance. Hairs generally long and loose. The best known species
of this genus, _I. zorilla_, the Cape Polecat, was placed by Cuvier in
the genus _Mustela_, and by Lichtenstein in _Mephitis_; and in many
characters it forms a transition between these genera. It is about the
size of an English Polecat, but conspicuous by its coloration, having
broad, longitudinal bands of dark brown, alternating with white. Its
odour is said to be as offensive as that of the American Skunks. From the
Cape of Good Hope it ranges as far north as Senegal. Another species, _I.
frenata_, from Sennaar and Egypt, has been described.
Subfamily =Mustelinæ=.—Toes short, partially webbed; claws short,
compressed, acute, curved, often semiretractile. Upper molar of moderate
size, wide transversely. Kidneys simple. Terrestrial and arboreal in
habits.
_Galictis._[508]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ¹⁄₂; total 34.
Molars small but stout. Upper carnassial with the inner tubercle near
the middle of the inner border of the tooth. Lower carnassial with talon
small, and inner cusp small or absent. Body long. Limbs short; claws
non-retractile. Palms and soles naked. Head broad and depressed. Tail
of moderate length. The best-known species are _G. vittata_, the Grison
(genus _Grisonia_, Gray), and _G. barbara_, the Tayra (genus _Galera_,
Gray), both South American; _G. allamandi_ is an intermediate form.
Remains of _Galictis_ occur in the Pleistocene cavern-deposits of Brazil,
and also in the Pleistocene of North America.
_Mustela._[509]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁻⁴⁄₃₋₄, _m_ ¹⁄₂; total
34 or 38. Upper carnassial with inner tubercle close to the anterior edge
of the tooth. Molar nearly as large as carnassial. Lower carnassial with
small or no inner cusp. Vertebræ: C 7, D 14, L 6, S 3, C 18-23. Body long
and slender. Limbs short, digitigrade. Feet rounded; toes short, with
compressed, acute, semiretractile claws. Tail moderate or long, more or
less bushy.
The genus _Mustela_, as restricted by Cuvier (_Règne Animal_, 1817),
contains a very natural assemblage of animals commonly called Martens,
Sables, Polecats, Stoats, Ermines, and Weasels, all closely allied in
structure and habits. A structural division, however, occurs between the
two first-named and all the others, especially shown in the presence
of an additional small premolar tooth on each side of the jaw; and,
availing himself of this and some other minor characters, Cuvier divided
the genus into two subgenera, for the first of which he retained the
name of _Mustela_, and to the second assigned that of _Putorius_. Three
years later Nilsson (_Skand. Fauna_, 1820) definitely constituted the
two groups into genera, applying to the first the name of _Martes_, by
which the animals composing it had been generally designated by the Latin
writing zoologists of the preceding century, and keeping _Mustela_ for
the more typical Weasels and their immediate allies. Later zoologists
have been divided between the nomenclature of Cuvier, which has the
priority, and that of Nilsson, which on other grounds is preferable.
Those who adopt the latter affirm that Cuvier’s names, being only used
by him in a subgeneric sense, and not binominally, need not be applied
generically, but this is contrary to the practice usually followed in
such cases; and therefore, if the original genus be divided, the name
_Mustela_ should be retained for the Martens, and _Putorius_ for the
Polecats and Weasels. Here, however, the genus will be employed in its
wider sense, and divided into two groups.
The typical group of the Martens[510] presents the following distinctive
features. Body long, slender, and very flexible, though less so than in
the true Weasels. Head somewhat triangular; muzzle pointed, the nose
extending a little beyond the lips; eyes large and prominent; ears
conspicuous, broad, somewhat triangular, rounded at the ends, furred
outside and in. Limbs short; feet rounded; toes short, five on each
foot, all with short, compressed, curved, sharp-pointed claws; soles
densely furred between the naked pads. Tail moderately long, more or
less bushy. Outer fur long, strong, and glossy; a very abundant soft
under fur. Skull elongated and depressed. Facial portion moderate and
rather compressed. Zygomata arched and wide, but slender. Postorbital
processes small. Auditory bullæ large, but not very globose. Mandible
with a strong triangular vertical coronoid process and a well-developed
angular process. Premolars ⁴⁄₄. Upper incisors in a straight transverse
line, rather long and compressed; first and second subequal, third
considerably larger. Lower incisors very small, especially the first, and
crowded together, the second placed rather behind the others. Canines
long and sharp-pointed. Upper premolars: first very small, with simple
crown and one root; second and third nearly equal in size and two-rooted,
with simple compressed sharp-pointed crowns, with very slightly developed
accessory cusps; fourth (the carnassial) with blade consisting chiefly of
the central and posterior lobes, the anterior being rudimentary, inner
tubercle small and confined to the anterior part of the tooth. True molar
tubercular, about twice as wide transversely as in the antero-posterior
direction, having an outer, more elevated, but smaller portion, bearing
three blunt tubercles; to the inner side of this the crown is contracted,
and its surface deeply hollowed; it then expands again into a broad low
lobe, with the central part elevated, and a raised, even, semicircular,
slightly crenated internal border. Lower premolars: first very small,
simple, and one-rooted; second, third, and fourth increasing slightly in
size, with high compressed pointed crowns and posterior accessory cusps,
best marked in the third. First molar (carnassial) with well-marked
bilobed blade, talon scarcely more than one-third of the length of the
tooth, and a very small inner cusp. Second molar small, single-rooted,
with a low, flattened, subcircular or oval tubercular crown.
In geographical distribution the Martens are limited to the northern
hemisphere, ranging throughout the greater part of the temperate regions
of both Old and New Worlds, as far north as conditions of existence
suited to their habits are met with, and southwards in America to 35° N.
lat., while in Asia one species is met with as far in this direction as
the island of Java.
The various species appear to be very similar in their habits. They
live in woods and rocky places, and are thoroughly arboreal, spending
most of their time in trees, although descending to the ground in quest
of prey. They climb with great facility, and are agile and graceful in
their movements. Some species are said occasionally to resort to berries
and other fruit for food, but as a rule they are strictly carnivorous,
feeding chiefly on birds and their eggs, small mammals, as squirrels,
hares, rabbits, and moles, but chiefly mice of various kinds, of which
they destroy great numbers, and occasionally snakes, lizards, and frogs.
In proportion to their size they are among the most bloodthirsty of
animals, though less so than the true Weasels. The female usually makes
her nest of moss, dried leaves, and grass in the hollow of a tree, but
sometimes in a hole among rocks or ruined buildings, and produces several
young at a birth, usually from four to six. Though wild and untameable
to a great degree if captured when fully grown, when taken young they
are very docile, and have frequently been made pets of, not having the
strong unpleasant odour of the smaller _Mustelidæ_. The common European
Marten appears to have been partially domesticated by the Greeks and
Romans, and to have been used to keep houses clear from rats and mice
before cats were introduced.[511] In the same way, according to Hodgson,
the Yellow-bellied Weasel (_M. cathia_) “is exceedingly prized by the
Nipalese for its service in ridding houses of rats. It is easily tamed;
and such is the dread of it common to all Murine animals that not one
will approach a house where it is domiciled.” It is, however, to the
great value attached to the pelts of these animals that their importance
to man is chiefly due. Though all yield fur of serviceable quality, the
commercial value varies immensely, not only according to the particular
species from which it is obtained, but according to individual variation,
depending upon age, sex, season, and other trifling circumstances. The
skins from northern regions are more full and of a finer colour and gloss
than those from more temperate climates, as are those of animals killed
in winter compared with the same individuals in the summer season. The
caprices of fashion have, moreover, set wholly factitious values upon
slight shades of colour, recognised and named by experienced furriers,
but not indicating any specific or other distinctions of which zoologists
have any cognisance. Enormous numbers of animals are annually caught,
chiefly in traps, to supply the demand of the fur trade, Siberia and
North America being the principal localities from which they are obtained.
With the exception of the Pekan (_M. pennanti_) all the Martens are so
much alike in size, general colouring, and cranial and dental characters
that the discrimination of the species, and assignment of the proper
geographical distribution to each, has been a subject which has sorely
perplexed the ingenuity and patience of zoologists. The following
description by Dr. Elliott Coues of the external characters of the
American Pine Marten (_M. americana_) will apply almost equally well
to most of the others: “It is almost impossible to describe the colour
of the Pine Marten, except in general terms, without going into the
details of the endless diversities occasioned by age, sex, season, or
other incidents. The animal is ‘brown,’ of various shades from orange or
tawny to quite blackish; the tail and feet are ordinarily the darkest,
the head lightest, often quite whitish; the ears are usually rimmed
with whitish; on the throat there is usually a large tawny-yellowish or
orange-brown patch, from the chin to the fore legs, sometimes entire,
sometimes broken into a number of smaller, irregular blotches, sometimes
wanting, sometimes prolonged on the whole under surface, when the animal
is bicolor like a Stoat in summer. The general ‘brown’ has a grayish
cast, as far as the under fur is concerned, and is overlaid with rich
lustrous blackish-brown in places where the long bristly hairs prevail.
The claws are whitish; the naked nose pad and whiskers are black. The
tail occasionally shows interspersed white hairs, or a white tip.”
The species generally recognised as distinct are the following, the first
five belonging to the Old and the last two to the New World:—
_M. foina_, the Beech Marten, Stone Marten, or White-breasted
Marten.—Distinguished from the following by the greater breadth of the
skull, and some minute but constant dental characters, by the dull
grayish-brown colour of the fur of the upper parts, and the pure white
of the throat and breast. It inhabits the greater part of the continent
of Europe, but is more southern than the next in its distribution, not
being found in Sweden or Norway, nor, according to the investigations of
Mr. Alston, in the British Isles, although included in their fauna by
all earlier writers; to the eastward it ranges into Afghanistan and the
Himalaya.
[Illustration: FIG. 267.—The Pine Marten (_Mustela martes_).]
_M. martes_, the Pine Marten (Fig. 267).—Outer fur rich dark brown; under
fur reddish-gray, with clear yellow tips; breast spot usually yellow,
varying from bright orange to pale cream-colour or yellowish-white.
Length of head and body 16 to 18 inches; of tail (including the hair) 9
to 12 inches. This species is extensively distributed throughout northern
Europe and Asia, and was formerly common in most parts of Great Britain
and Ireland. Though commonly called “Pine Marten,” it does not appear to
have any special preference for coniferous trees, except that, inasmuch
as they constitute the greater proportion of the forests of the countries
which it inhabits, it is more often met with in them than in any other.
With regard to its recent occurrence in the British Isles, Mr. Alston
writes in the _Proc. Zool. Soc._ 1879:—
“Although greatly reduced in numbers by persecution, it still maintains
its ground in the wilder districts of Scotland, the north of England,
Wales, and Ireland; and occasionally specimens are killed in counties
where the species was thought to have been long extinct. In Scotland it
is still found, though comparatively rarely, in the Lews and in most of
the Highland mainland counties, being perhaps most abundant in Sutherland
and Ross-shire, especially in the deer forests. In the Lowlands a Marten
is now a very great rarity; but a fine example was killed in Ayrshire
in the winter of 1875-76. In the north of England Mr. W. A. Durnford
says the species is still plentiful in the wilder parts of Cumberland,
Westmoreland, and Lancashire, and in Lincolnshire several have been
recorded, the latest killed in 1865, by Mr. Cordeaux. In Norfolk one
was shot last year; and I have myself examined a fine example which was
shot in Hertfordshire, within 20 miles of London, in December 1872. In
Dorsetshire the last is said to have been killed in 1804; but a specimen
occurred in Hampshire about forty years ago, and another in Surrey in
1847. In Ireland the following counties were enumerated by Thompson as
habitats of this species: Donegal, Londonderry, Antrim, Down, Armagh,
Fermanagh, Longford, Galway, Tipperary, Cork, and Kerry. The _Cat-crann_
is probably now a rarer animal in Ireland than it was when Thompson
wrote; but it still exists in various districts, especially in County
Kerry, whence the society has received several living examples; and
Professor A. Leith Adams states that it has been seen of late years even
in county Dublin.”
_M. zibellina_, the Sable (German, _Zobel_ and _Zebel_; Swedish, _sabel_;
Russian, _sobel_, a word probably of Turanian origin).—Closely resembling
the last, if indeed differing from it except in the quality of the fur,
which is the most highly valued of that of all the group. Found chiefly
in Eastern Siberia.
_M. flavigula_, the Indian Marten.—Inhabits the southern slopes of the
Himalaya, the Nilgiri Hills, the interior of Ceylon, the Malay Peninsula,
and Java. The coloration of this species is very striking, the upper
parts being blackish-brown, and the throat and breast yellow or orange,
in the bright coloured variety. It differs from the other species in
having the soles of the feet more or less naked.
_M. melampus._—Japan.
_M. americana_, the North-American Sable or Marten.—A species so closely
allied to the European Pine Marten and Asiatic Sable that it is very
difficult to assign constant distinguishing characters between them. The
importance of the fur of this animal as an article of commerce may be
judged of from the fact that 15,000 skins were sold in one year by the
Hudson’s Bay Company as long ago as 1743, and the more recent annual
imports into Great Britain have exceeded 100,000. It is ordinarily caught
in wooden traps of very simple construction, being little enclosures of
stakes or brush in which the bait is placed upon a trigger, with a short
upright stick supporting a log of wood, which falls upon its victim on
the slightest disturbance. A line of such traps, several to a mile, often
extends many miles. The bait is any kind of meat, a mouse, squirrel,
piece of fish, or bird’s head. It is principally trapped during the
colder months, from October to April, when the fur is in good condition,
as it is nearly valueless during the shedding in summer. Dr. Coues tells
us that, notwithstanding the persistent and uninterrupted destruction to
which the American Sable is subjected, it does not appear to diminish
materially in numbers in unsettled parts of the country. It holds its own
partly in consequence of its shyness, which keeps it away from the abodes
of men, and partly because it is so prolific, bringing forth six to eight
young at a litter. Its home is sometimes a den under ground or beneath
rocks, but oftener the hollow of a tree, and it is said frequently to
take forcible possession of a squirrel’s nest, driving off or devouring
the rightful proprietor.
_M. pennanti_, the Pekan or Pennant’s Marten, also called Fisher
Marten, though there appears to be nothing in its habits to justify the
appellation.—This is the largest species of the group, the head and
body measuring from 24 to 30 inches, and the tail 14 to 18 inches. It
is also more robust in form than the others, its general aspect being
more that of a Fox than a Weasel; in fact, its usual name among the
American hunters is “Black Fox.” Its general colour is blackish, lighter
by mixture of brown or gray on the head and upper fore part of the body,
with no light patch on the throat, and unlike the other Martens generally
darker below than above. It was generally distributed in wooded districts
throughout the greater part of North America, as far north as Great Slave
Lake, 63° N. lat., and Alaska, and extending south to the parallel of
35°; but at the present time it is almost exterminated in the settled
parts of the United States east of the Mississippi.
Fossil remains of a Marten from the Pliocene Siwaliks of India indicate a
species which cannot be distinguished from those now inhabiting the same
region; while remains of _M. martes_ occur in European cavern-deposits,
and in the fens of Cambridgeshire.
With the _Putoriine_ group (genus _Putorius_) we come to those smaller
forms distinguished by having only three premolars in each jaw, by the
absence of an inner cusp to the blade of the lower carnassial, as well as
by certain external characters. This group contains a few species known
as Minks, differing from the rest by slight structural modifications,
and especially by their semiaquatic habits. They are distinguished
from the Polecats, Stoats, and Weasels, which constitute the remainder
of the group, by the facial part of the skull being narrower and
more approaching in form that of the Martens, by the premolar teeth
(especially the anterior one in the upper jaw) being larger, by the toes
being partially webbed, and by the absence of hair in the intervals
between the naked pads of the soles of the feet. The two best-known
species, so much alike in size, form, colour, and habits that although
they are widely separated geographically some zoologists question their
specific distinction, are _M. lutreola_, the _Nörz_ or _Sumpfotter_
(Marsh-Otter) of Eastern Europe, and _M. vison_, the Mink of North
America. The former inhabits Finland, Poland, and the greater part of
Russia, though not found east of the Ural Mountains. Formerly it extended
westward into Central Germany, but is now very rare, if not extinct,
in that country. The latter is found in places which suit its habits
throughout the whole of North America. Another form, _M. sibirica_, from
Eastern Asia, of which much less is known, appears to connect the true
Minks with the Polecats.
For the following description, chiefly taken from the American form
(though almost equally applicable to that of Europe), we are mainly
indebted to Dr. Coues’s _Fur-bearing Animals of North America_. In size
it much resembles the English Polecat,—the length of the head and body
being usually from 15 to 18 inches, that of the tail to the end of the
hair about 9 inches. The female is considerably smaller than the male.
The tail is bushy, but tapering at the end. The ears are small, low,
rounded, and scarcely project beyond the adjacent fur. The pellage
consists of a dense, soft, matted under fur, mixed with long, stiff,
lustrous hairs on all parts of the body and tail. The gloss is greatest
on the upper parts; on the tail the bristly hairs predominate. Northern
specimens have the finest and most glistening pellage; in those from
southern regions there is less difference between the under and over
fur, and the whole pellage is coarser and harsher. In colour different
specimens present a considerable range of variation, but the animal is
ordinarily of a rich dark brown, scarcely or not paler below than on the
general upper parts; but the back is usually the darkest, and the tail is
nearly black. The under jaw, from the chin about as far back as the angle
of the mouth, is generally white. In the European Mink the upper lip is
also white, but as this occasionally occurs in American specimens it
fails as an absolutely distinguishing character. Besides the white on the
chin, there are often other irregular white patches on the under parts of
the body. In very rare instances the tail is tipped with white. The fur,
like that of most of the animals of the group to which it belongs, is an
important article of commerce.
The principal characteristic of the Mink in comparison with its congeners
is its amphibious mode of life. It is to the water what the other Weasels
are to the land, or Martens to the trees, being as essentially aquatic
in its habits as the Otter, Beaver, or Musk-Rat, and spending perhaps
more of its time in the water than it does on land. It swims with most of
the body submerged, and dives with perfect ease, remaining long without
coming to the surface to breathe. It makes its nest in burrows in the
banks of streams, breeding once a year about the month of April, and
producing five or six young at a birth. Its food consists of frogs, fish,
freshwater molluscs and crustaceans, as well as mice, rats, musk-rats,
rabbits, and small birds. In common with the other animals of the genus,
it has a very peculiar and disagreeable effluvium, which, according to
Coues, is more powerful, penetrating, and lasting than that of any animal
of the country except the Skunk. It also possesses the courage, ferocity,
and tenacity of life of its allies. When taken young, however, it can be
readily tamed, and lately Minks have been extensively bred in captivity
in America, both for the sake of their fur and for the purpose of using
them in like manner as Ferrets in England, to clear buildings of rats.
[Illustration: FIG. 268.—The Common Polecat (_Mustela putorius_).]
The Polecats include four species confined to the northern hemisphere,
the best known of which is the Common Polecat (_M. putorius_, Fig.
268). The Ferret is a domesticated variety of this species, generally of
a yellowish-white colour; whereas the Wild Polecat is dark brown above
and black beneath, the face being variegated with dark brown and white
markings.
The skull is rough, strongly ridged, and of a far more powerful type than
that of the Stoats, Weasels, or Martens; being in the female much smaller
and lighter than in the male. The fur, which is long, coarse, and of
comparatively small value, changes its colour very little, if at all, at
the different seasons of the year.
The distribution and habits of this species have been described by
Blasius, the following being an abstract of his account. The Polecat
ranges over the greater part of Europe, reaching northwards into Southern
Sweden, and in Russia to the region of the White Sea. It does not occur
in the extreme South, but is common everywhere throughout Central Europe.
In the Alps it ranges far above the tree-line during the summer, but
retreats in winter to lower ground. In fine weather it lives either in
the open air, in holes, fox-earths, rabbit-warrens, under rocks, or
in wood-stacks, while in winter it seeks the protection of deserted
buildings. During the day it sleeps in its hiding-place, sallying forth
at night to plunder dovecots and hen-houses. It climbs but little, and
shows far less activity than the Marten. It feeds ordinarily on small
mammals, such as rabbits, hamsters, rats, and mice, on such birds as it
can catch, especially poultry and pigeons, and also on snakes, lizards,
frogs, fish, and eggs. Its prey is devoured only in its lair, but,
even though it can carry away but a single victim, it commonly kills
everything that comes in its way, often destroying all the inhabitants of
a hen-house in order to gratify its passion for slaughter. The pairing
time is towards the end of the winter, and the young, from three to
eight in number, are born in April or May, after a period of gestation
of about two months. The young, if taken early, may be easily trained,
like Ferrets, for rabbit catching. The Polecat is very tenacious of life,
and will bear many severe wounds before succumbing; it is also said to
receive with impunity the bite of the adder. Its fetid smell has become
proverbial.
Four other species of Polecats are known, viz.—The Siberian Polecat
(_M. eversmanni_) of Western and Northern Asia is nearly allied to the
European species, but the head and back are almost white, and the skull
is stouter and more constricted behind the orbits. The Tibetan _M.
larvata_ is distinguished from the last by the presence of a process
connecting the pterygoid with the auditory bulla, and by a difference
in the shape of the upper molar. The American Polecat (_M. nigripes_),
inhabiting the central plateau of the United States, and extending
southwards into Texas, is another closely allied species, although some
zoologists have made it the type of the genus _Cynomyonax_. Finally,
the Mottled Polecat (_M. sarmatica_) is a species sparsely distributed
in Eastern Europe and parts of Western Asia, but common in Southern
Afghanistan. Its skull, although smaller, resembles that of the common
species; but the coloration is very different, all the upper parts being
mottled with large irregular reddish spots on a white ground, and the
under side, limbs, and tail deep shining black. The tail is long.
The Common Polecat occurs in a fossil condition in the cave-deposits of
Europe.
[Illustration: FIG. 269.—The Common Weasel (_Mustela vulgaris_).]
The remaining members of the genus comprise the true Weasels and Stoats,
which are of almost cosmopolitan distribution. In the Common Weasel (_M.
vulgaris_, Fig. 269) the upper parts, outside of limbs and tail, are a
uniform reddish-brown, the under parts pure white. In very cold regions,
both in Europe and America, it turns completely white in winter, but less
regularly and at a lower temperature than the Stoat, from which it is
easily distinguished by its smaller size, and by its wanting the black
end of the tail. The length of the head and body of the male is usually
about 8 inches, that of the tail 2½ inches; the female is smaller.
This species is pretty generally distributed throughout Europe, Northern
and Central Asia, British North America, and the northern portions of the
United States. It possesses in a full degree all the active, courageous,
and bloodthirsty disposition of the rest of the genus, but its diminutive
size prevents it attacking and destroying any but the smaller mammals
and birds. Mice, rats, voles, moles, and frogs constitute its principal
food. It is generally found on or near the surface of the ground, but it
can not only pursue its prey through very small holes and crevices of
rocks and under dense tangled herbage, but follow it up the stems and
branches of trees, or even into the water, swimming with perfect ease. It
constructs a nest of dried leaves and herbage, placed in a hole in the
ground or a bank or hollow tree, in which it brings up its litter of four
to six (usually five) young ones. The mother will defend her young with
the utmost desperation against any assailant, having been often known to
sacrifice her own life rather than desert them.
The Stoat or Ermine (_M. erminea_) has nearly the same distribution as
the Weasel, but in Asia it is said to extend into parts of the Kashmir
Himalaya. Its size, as already mentioned, considerably exceeds that
of the Weasel; and its most distinctive feature is the black tip at
the end of the tail, which remains when the rest of the pellage turns
white. The white winter skins from the northern regions of its habitat,
where the fur is thick and close, form the well-known and valuable
ermine of commerce. Remains of the Stoat are found in the Pleistocene
cavern-deposits of Europe. The other species of Weasels are very numerous
and widely distributed.
_Extinct Mustelines._—A number of European Miocene Carnivores may be
referred to the genus _Mustela_ in its wider sense, and serve to confirm
the propriety of this use of the term. Thus _M. sectoria_ is a species
of somewhat larger size than the Stoat, with _p_ ⁴⁄₄, while in _M.
angustifrons_ the number of premolars is ³⁄₄, and in _M. mustelina_
⁴⁄₃; the latter species agreeing very closely in size with the Stoat.
The extinct _Plesictis_, in which there are _p_ ⁴⁄₄ and the lower
carnassial has a large inner cusp, is distinguished from _Mustela_ by the
circumstance that the temporal ridges of the skull never unite to form
a sagittal crest. Moreover, the inner tubercular portion of the upper
molar (as in some of the Miocene species of _Mustela_) is shorter in an
antero-posterior direction than the secant outer moiety; and the auditory
bulla is more inflated than in _Mustela_, although it has no septum.
Both these features indicate a decided approximation to the Viverroid
genus _Stenoplesiotis_ (p. 539); and since there are no well-marked
characters of family value by which these two genera can be distinguished
the available evidence points to a transition from the Viverroid to the
Musteloid type. _Mustela larteti_, of the Middle Miocene of France,
should perhaps be referred to _Ictonyx_.
_Pœcilogale._[512]—This genus has been made for the reception of the
South African _Mustela albinucha_, in which the coloration is similar
to that of _Ictonyx_, but the number of cheek-teeth is usually reduced
to _p_ ²⁄₂, _m_ ¹⁄₁, although there may be a second lower molar. The
auditory bulla is quite flat.
_Lyncodon._[513]—This name has been proposed for a small Musteline from
Patagonia, with _p_ ²⁄₂, _m_ ¹⁄₁, which Mr. O. Thomas suggests may be
nothing more than an aberrant southern form of _Mustela_ (_Putorius_)
_brasiliensis_. The auditory bulla is more inflated than in the typical
Weasels. This animal is somewhat larger than the Stoat.
[Illustration: FIG. 270.—The Wolverene (_Gulo luscus_).]
_Gulo._[514]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ¹⁄₂; total 38.
Crowns of the teeth very stout. Upper molar very much smaller than the
carnassial. Lower carnassial large, with very small talon and no inner
cusp. Third upper incisor unusually large, almost like a canine. The
dentition, though really but a modification of that of the Weasels,
presents a great general resemblance to that of the Hyæna. Palate
prolonged somewhat behind the last molar. Humerus with an entepicondylar
foramen. Vertebræ: C 7, D 15, L 5, S 3, C 15. Body and limbs stoutly
made. Feet large and powerful, subplantigrade, with large, compressed,
much curved, and sharp-pointed claws. Soles of the feet (except the
pads of the toes) covered with thick bristly hairs. Ears very small,
nearly concealed by the fur. Eyes small. Tail short, thick, and bushy.
Fur full, long, and rather coarse. The one species, the Wolverene or
Glutton (_G. luscus_, Fig. 270), an inhabitant of the forest regions
of Northern Europe, Asia, and America, much resembles a small Bear in
appearance. It is a very powerful animal for its size, climbs trees, and
lives on grouse, squirrels, hares, foxes, beavers, reindeer, and is said
to attack even horses and cows. The Wolverene has a curious habit of
stealing and secreting articles of which it can make no possible use, as
is exemplified in the following instance related by Dr. Coues: “A hunter
and his family, having left their lodge unguarded during their absence,
on their return found it completely gutted—the walls were there, but
nothing else. Blankets, guns, kettles, axes, cans, knives, and all the
other paraphernalia of a trapper’s tent had vanished, and the tracks left
by the beast showed who had been the thief. The family set to work, and,
by carefully following up all his paths, recovered, with some trifling
exceptions, the whole of the lost property.” The pairing season occurs in
March, and the female, secure in her burrow, produces her young, four or
five at a birth, in June or July. In defence of these she is exceedingly
bold, and the Indians, according to Coues, “have been heard to say that
they would sooner encounter a she-bear with her cubs than a carcajou (the
Indian name of the glutton) under the same circumstances.”
Fossil remains of the Wolverene are found in cavern and other Pleistocene
deposits in various parts of Europe.
_Suborder_ PINNIPEDIA.
The Eared-Seals, Walruses, and Seals differ from the rest of the
Carnivora mainly in the structure of their limbs, which are modified
for aquatic progression,—the two proximal segments being very short
and partially enveloped in the general integument of the body; while
the third segment, especially in the hinder extremities, is elongated,
expanded, and webbed. There are always five well-developed digits on
each limb. In the hind limb the two marginal digits (first and fifth)
are stouter and generally longer than the others. The teeth also differ
from those of the more typical Carnivora. The incisors are always fewer
than ³⁄₃. The cheek series consists generally of four premolars and one
molar of very uniform characters, with never more than two roots, and
with conical, more or less compressed, pointed crowns, which may have
accessory cusps, placed before or behind the principal one, but are never
broad and tuberculated; and there is no differentiated carnassial tooth.
The milk-teeth are very small and simple, and are shed or absorbed at a
very early age, usually either before or within a few days after birth.
The brain is relatively large; the cerebral hemispheres being broad in
proportion to their length, with numerous and complex convolutions. There
is a very short cæcum. The kidneys are divided into numerous distinct
lobules. There are no Cowper’s glands. The mammæ are either two or four,
and abdominal in position. No clavicles. Tail always very short. Eyes
very large and exposed, with flat cornea.
The animals of this group are all aquatic in their mode of life, spending
the greater part of their time in the water, swimming and diving with
great facility, feeding mainly on fish, crustaceans, and other marine
animals, and progressing on land with difficulty. They always come on
shore, however, for the purpose of bringing forth their young. They
are generally marine, but they occasionally ascend large rivers, and
some inhabit inland seas and lakes, as the Caspian and Baikal. Though
not numerous in species, they are widely distributed over the world,
but occur most abundantly on the coasts of lands situated in cold and
temperate zones. The suborder is divisible into three well-marked
families: the _Otariidæ_, Fur-Seals or Sea-Bears, which form a transition
from the Fissiped Carnivora to the Seals; the _Trichechidæ_, containing
the Walrus; and the _Phocidæ_ or typical Seals.
The resemblances between the skull and other parts of the body of the
Fur Seals and the Ursoid true Carnivora is suggestive of some genetic
relationship between the two groups, and Professor Mivart[515] expresses
the opinion that the one group is the direct descendant of the other. The
same writer goes on to suggest that if the Eared-Seals have been derived
from Bear-like Carnivores this need not necessarily hold good with the
true Seals, which may have had another, and possibly Lutrine, origin.
The presence of an alisphenoid canal in _Ursus_ and the _Otariidæ_,
and its absence in _Lutra_ and the _Phocidæ_, together with other
osteological features, are cited in support of this view; but although
these resemblances and differences are certainly remarkable, yet much
more evidence is required before the hypothesis can be accepted as even
a probable one. It must, moreover, be borne in mind that the true Bears
are a very modern group; and there is a possibility that the Pinnipeds
may prove to have been independently derived from the extinct Carnivora
noticed below under the name of Creodonta.
_Family_ OTARIIDÆ.
When on land the hind feet are turned forwards under the body, and aid
in supporting and moving the trunk as in ordinary mammals. A small
external ear. Testes suspended in a distinct external scrotum. Skull
with postorbital processes, and an alisphenoid canal. Angle of mandible
inflected. Palms and soles of feet naked.
_Otaria._[516]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ¹⁻²⁄₁; total
34 or 36. First and second upper incisors small, with the summits of
the crowns divided by a deep transverse groove into an anterior and a
posterior cusp of nearly equal height; the third large and canine-like.
Canines large, conical, pointed, recurved. Molars and premolars usually
⁵⁄₅, of which the second, third, and fourth are preceded by milk-teeth
shed a few days after birth; sometimes (as in Fig. 271) a sixth upper
molar (occasionally developed on one side and not the other); all with
similar characters, generally uniradicular; crown moderate, compressed,
pointed, with a single principal cusp, and sometimes a cingulum, and more
or less developed anterior and posterior accessory cusps. Vertebræ: C 7,
D 15, L 5, S 4, C 9-14. Head rounded. Eyes large. Pinna of ear small,
narrow, and pointed. Neck long. Skin of all the feet extended far beyond
the nails and ends of the digits, with a deeply-lobed margin. The nails
small and often quite rudimentary, especially those of the first and
fifth toes of both feet, the best developed and most constant being the
three middle claws of the hind foot, which are elongated, compressed, and
curved.
[Illustration: FIG. 271.—Skull of _Otaria forsteri_. (From Gray, _Proc.
Zool. Soc._ 1872, p. 660.)]
The Eared-Seals, commonly called Sea-Bears or Sea-Lions, are widely
distributed, especially in the temperate regions of both hemispheres,
though absent from the coasts of the North Atlantic. As might be
inferred from their power of walking on all fours, they spend more of
their time on shore, and range inland to greater distances, than the
true Seals, especially at the breeding time, though they are obliged
always to return to the water to seek their food. They are gregarious
and polygamous, and the males are usually much larger than the females,
a circumstance which has given rise to some of the confusion existing
in the specific determination of the various members of the genus. Some
of the species possess, in addition to the stiff, close, hairy covering
common to all the group, an exceedingly fine, dense, woolly under fur.
The skins of these, when dressed and deprived of the longer harsh outer
hairs, constitute the “seal-skin” of commerce, so much valued for
wearing apparel, which is not the product of any of the true Seals.
The best-known species are _O. stelleri_, the Northern Sea Lion, the
largest of the genus, from the North Pacific, about 10 feet in length;
_O. jubata_, the Patagonian or Southern Sea Lion (Fig. 272), from the
Falkland Islands and Patagonia; _O. californiana_, from California,
frequently exhibited alive in menageries in Europe; _O. ursina_, the
common Sea-Bear or Fur-Seal of the North Pacific, the skins of which are
imported in immense numbers from the Prybiloff Islands; _O. pusilla_,
from the Cape of Good Hope; _O. forsteri_ and others, from the coasts of
Australia and various islands scattered over the southern hemisphere.
These have been grouped by some zoologists into many genera, founded upon
very trivial modifications of teeth and skull. In a recent memoir Mr.
Beddard[517] concludes that if the genus be split up at all, it should
be divided into _Otaria_, containing only _O. jubata_ (with its numerous
synonyms), and _Arctocephalus_, comprising all the other species. The
latter group is distinguished by the more narrow and pointed nose, the
longer ears, the palate not excavated nor truncated posteriorly, the
presence of a hook-like process to the pterygoids, and by the posterior
border of the nasals extending behind the zygoma.
[Illustration: FIG. 272.—The Patagonian Sea-Lion (_Otaria jubata_). From
Sclater, _Proc. Zool. Soc._ 1866, p. 80.]
The following account of _O. ursina_ in the Prybiloff Islands is taken,
with slight verbal alteration, from Nordenskiöld’s _Voyage of the Vega_:
“The Sea-Bears are found year after year during summer at certain parts
of the coast, known as ‘rookeries,’ where, collected in hundreds of
thousands, they pass several months without the least food. The males
or ‘bulls’ come first to the place, most of them in the month of May
or in the beginning of June. The most violent conflicts, often with a
deadly issue for one of the parties, now arise regarding the space of
about a hundred square feet which each bull-seal considers necessary for
his home. The strongest and most successful in fight retain the best
places near the shore; the weaker have to crawl farther up on land,
where the chances of getting a sufficient number of spouses are not
particularly great. The fighting goes on with many feigned attacks and
parades. At first the contest concerns only the proprietorship of the
soil. The attacked, therefore, never follows his opponent beyond the area
he has once taken up, but haughtily lays itself down, when the enemy
has retired, in order to collect strength for a new combat. The animal
in such a case grunts with satisfaction, throws himself on his back,
scratches himself with his fore feet, attends to his toilet, or cools
himself by slowly fanning with one of his hind feet; but he is always on
the alert and ready for a new fight, until he is tired out and meets his
match and is driven farther up from the beach. In the middle of June the
females come up from the sea. At the water’s edge they are received in
a very gallant way by some strong bulls that have succeeded in securing
for themselves places next the shore, and now are bent by fair means or
foul on annexing the females for their harem. But scarcely is the female
that has come up out of the water established with male No. 1 than he
rushes towards a new female on the surface of the water. Male No. 2 now
stretches out his neck and without ceremony lays hold of the female of
No. 1, to be afterwards exposed to a similar trick by No. 3. In such
cases the females are quite passive, never fall out with each other, and
bear with patience the severe wounds they often get when they are pulled
about by the combatants, now in one direction, now in another. All the
females are finally distributed in this way after furious combats among
the males, those of the latter who are nearest the beach getting from
12 to 15 consorts to their share. Soon after landing the females bring
forth their young, which are treated with great indifference, and are
protected by their adopted father only within the limits of the harem.
Next comes the pairing season, and when it has passed there is an end
to the arrangement and distribution into families at first so strictly
maintained. The males, rendered lean by three months’ absolute fasting,
by degrees leave the rookery, which is left in possession of the Walruses
and the young Sea Bears, including a number of young males that have not
ventured to the place before. In the middle of September, when the young
have learned to swim, the place is quite abandoned, with the exception of
single animals that have for some reason remained behind.”
_Family_ TRICHECHIDÆ.
In many characters the single genus representing this family is
intermediate between the _Otariidæ_ and _Phocidæ_, but it has a
completely aberrant dentition. It has no external ears, as in the
_Phocidæ_; but when on land the hind feet are turned forwards and used
in progression, though less completely than in the _Otariidæ_. The upper
canines are developed into immense tusks, which descend a long distance
below the lower jaw. All the other teeth (Fig. 273), including the lower
canines, are much alike, small, simple, and one-rooted, the molars
with flat crowns. The skull is without postorbital process, but has an
alisphenoid canal.
[Illustration: FIG. 273.—Diagram of the dentition of the Walrus
(_Trichechus rosmarus_). The denticles placed apart from the others are
milk-teeth, and disappear soon after birth. The small teeth in connection
with the jaws frequently persist throughout life.]
_Trichechus._[518]—Dentition of young: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ and _m_ ⁵⁄₄.
Many of these teeth are, however, lost early or remain through life in
a rudimentary state concealed by the gums. The teeth which are usually
developed functionally are _i_ ¹⁄₀, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ⁰⁄₀; total
18. Vertebræ: C 7, D 14, L 6, S 4, C 12. Head round. Eyes rather small.
Muzzle short and broad, with on each side a group of long, very stiff,
bristly whiskers. The remainder of the hair-covering very short and
adpressed. Tail very rudimentary. Fore feet with subequal toes, carrying
five minute flattened nails. Hind feet with subequal toes, the fifth
slightly the largest, having cutaneous lobes projecting beyond the ends
as in _Otaria_; first and fifth with minute flattened nails; second,
third, and fourth with large, elongated, subcompressed pointed nails.
_Trichechus_ is the almost universally accepted generic name by which
the Walrus or Morse[519] is known to zoologists, but some confusion has
been introduced into literature by the revival of the nearly obsolete
terms _Rosmarus_ by some authors and _Odobænus_ by others. _T. rosmarus_
is the name of the species met with in the Arctic seas; that of the
North Pacific, if distinct, is _T. obesus_. The preceding and following
descriptions will apply equally to both. A full-grown male Walrus
measures from 10 to 11 feet from the nose to the end of the very short
tail, and is a heavy, bulky animal, especially thick about the shoulders.
The soles of both fore and hind feet are bare, rough, and warty. The
surface of the skin generally is covered with short, adpressed hair of
a light, yellowish-brown colour, which, on the under parts of the body
and base of the flippers, passes into dark reddish-brown or chestnut.
In old animals the hair becomes more scanty, sometimes almost entirely
disappearing, and the skin shows ample evidence of the rough life and
pugnacious habits of the animal in the innumerable scars with which it is
usually covered. It is everywhere more or less wrinkled, but especially
over the shoulders, where it is thrown into deep and heavy folds.
[Illustration: FIG. 274.—The Walrus (_Trichechus rosmarus_).]
The tusks are formidable weapons of defence, but their principal use
seems to be scraping and digging among the sand and shingle for the
molluscs and crustaceans on which the Walrus feeds. They are said also
to aid in climbing up the slippery rocks and ledges of ice on which
so much of the animal’s life is passed. Although this function of the
tusks is affirmed by numerous authors, some of whom appear to have had
opportunities of actual observation, it is explicitly denied by Malmgren.
Walruses are more or less gregarious in their habits, being met with
generally in companies or herds of various sizes. They are only found
near the coast or on large masses of floating ice, and rarely far out in
the open sea; and, though often moving from one part of their feeding
ground to another, they have no regular seasonal migrations. Their young
are born between the months of April and June, usually but one at a
time, never more than two. Their strong affection for their young, and
their sympathy for each other in times of danger, have been particularly
noticed by all who have had the opportunity of observing them in their
native haunts. When one of their number is wounded, the whole herd
usually join in a concerted and intelligent defence. Although harmless
and inoffensive when not molested, they exhibit considerable fierceness
when attacked, using their great tusks with tremendous effect either on
human enemies who come into too close quarters or on Polar Bears, the
only other adversaries they can meet with in their own natural territory.
Their voice is a loud roaring, and can be heard at a great distance; it
is described by Dr. Kane as “something between the mooing of a cow and
the deepest baying of a mastiff, very round and full, with its bark or
detached notes repeated rather quickly seven or nine times in succession.”
The principal food of the Walrus consists of bivalved molluscs,
especially _Mya truncata_ and _Saxicava rugosa_, two species very
abundant in the Arctic regions, which it digs up from the mud and sand
in which they lie buried at the bottom of the sea by means of its tusks.
It crushes and removes the shells by the aid of its grinding teeth and
tongue, swallowing only the soft part of the animal. It also feeds on
other molluscs, sand-worms, star-fishes, and shrimps. Portions of various
kinds of algæ or sea-weeds have been found in its stomach, but whether
swallowed intentionally or not is still doubtful.
The commercial products of the Walrus are its oil, hide (used to
manufacture harness and sole-leather and twisted into tiller ropes), and
tusks. The ivory of the latter is, however, inferior in quality to that
of the Elephant. Its flesh forms an important article of food to the
Eskimo and Tchuktchis. Of the coast tribes of the last-named people the
Walrus forms the chief means of support. “The flesh supplies them with
food, the ivory tusks are made into implements used in the chase and for
other domestic purposes, as well as a affording a valuable article of
barter, and the skin furnishes the material for covering their summer
habitations, harness for their dog-teams, and lines for their fishing
gear” (Scammon).
Geographically the Walrus is confined to the northern circumpolar
regions of the globe, extending apparently as far north as explorers
have penetrated, but its southern range has been much restricted of late
in consequence of the persecutions of man. On the Atlantic coast of
America it was met with in the sixteenth century as low as the southern
coast of Nova Scotia, and in the last century it was common in the Gulf
of St. Lawrence and on the shores of Labrador. It still inhabits the
coast round Hudson’s Bay, Davis Straits, and Greenland, where, however,
its numbers are daily decreasing. It is not found on the Arctic coast
of America between the 97th and 158th meridians. In Europe occasional
stragglers have reached the British Isles, and it was formerly abundant
on the coasts of Finmark. It is rare in Iceland, but Spitzbergen, Nova
Zembla, and the western part of the north coast of Siberia are still
constant places of resort, in all of which a regular war of extermination
is carried on. The North Pacific, including both sides of Behring’s
Strait, northern Kamschatka, Alaska, and the Pribyloff Islands, are also
the haunts of numerous Walruses, which are isolated from those of the
North Atlantic by the long stretches of coast, both of Siberia and North
America, where they do not occur. The Pacific Walrus appears to be as
large as, if not larger than, that of the Atlantic; its tusks are longer
and more slender, and curved inwards; the whiskers are smaller, and the
muzzle (of the skull) relatively deeper and broader. These and certain
other minor differences have induced some naturalists to consider it
specifically distinct under the name of _Trichechus obesus_. Its habits
appear to be quite similar to those of the Atlantic form. Though formerly
found in immense herds, it is rapidly becoming scarce, as the methods of
destruction used by the American whalers, who have systematically entered
upon its pursuit, are far more certain and deadly than those of the
native Tchuktchis, to whom, as mentioned before, the Walrus long afforded
the principal means of subsistence.
Fossil remains of Walruses and closely allied animals have been found in
the United States, and in England, Belgium, and France, in deposits of
Pliocene age.
_Family_ PHOCIDÆ.
The true Seals are the most completely adapted for aquatic life of all
the Pinnipeds. When on land the hind limbs are extended behind them and
take no part in progression, which is effected by a series of jumping
movements produced by the muscles of the trunk, in some species aided by
the fore limbs only. The palms and soles of the feet are hairy. There
is no pinna to the ear, and no scrotum, the testes being abdominal. The
upper incisors have simple, pointed crowns, and vary in number in the
different groups. All the forms have well-developed canines and ⁵⁄₅ teeth
of the cheek-series. In those species of which the milk-dentition is
known, there are three milk molars (Fig. 275), which precede the second,
third, and fourth permanent molars; the dentition is therefore _p_ ⁴⁄₄,
_m_ ¹⁄₁, the first premolar having as usual no milk-predecessor. The
skull has no postorbital process and no alisphenoid canal; and the angle
of the mandible is not inflected. The fur is stiff and adpressed, without
woolly under fur.
Subfamily =Phocinæ=.—Incisors ³⁄₂. All the feet with five well-developed
claws. The toes on the hind feet subequal, the first and fifth not
greatly exceeding the others in length, and with the interdigital
membrane not extending beyond the toes.
_Halichœrus._[520]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ¹⁄₁;
total 34. Crowns of molars large, simple, conical, recurved, slightly
compressed, with sharp anterior and posterior edges, but without
accessory cusps, except sometimes in the two hinder ones of the lower
jaw. With the exception of the last one or two in the upper jaw and the
last in the lower jaw they are all uniradicular. Vertebræ: C 7, D 15, L
5, S 4, C 14.
One species, _H. grypus_, the Gray Seal of the coasts of Scandinavia and
the British Isles (see page 604.)
[Illustration: FIG. 275.—Upper permanent and deciduous dentition of the
Greenland Seal (_Phoca grœnlandica_). The first and second deciduous
incisors are already absorbed.]
_Phoca._[521]—Dental formula as the last. Teeth smaller and more pointed.
Molars (Figs. 275 and 276) with two roots (except the first in each jaw);
and their crowns with accessory cusps. Vertebræ: C 7, D 15, L 5, S 4,
C 12-15. Head round and short. Fore feet short, with five very strong,
subcompressed, slightly curved, rather sharp claws, subequal in length.
On the hind feet the claws much narrower and less curved. The species of
this genus are widely distributed throughout the northern hemisphere, and
include _P. barbata_, the Bearded Seal; _P. grœnlandica_, the Greenland
Seal; _P. vitulina_, the Common Seal (Fig. 277); and _P. hispida_, the
Ringed Seal of the North Atlantic; _P. caspica_, from the Caspian and
Aral Seas; and _P. sibirica_, from Lake Baikal.
[Illustration: FIG. 276.—Skull of Common Seal, showing form of teeth.]
Although the members of this subfamily swim and dive with the greatest
ease, often remaining as much as a quarter of an hour or more below the
surface, and are dependent for their sustenance entirely on living prey
captured in the water, yet they frequently resort to sandy beaches,
rocks, or ice-floes, either to sleep or to bask in the sun, and
especially for the purpose of bringing forth their young. The latter
appears to be the universal habit, and, strange as it may seem, the
young seals—of some species at least—take to the water at first very
reluctantly, and have actually to be taught to swim by their parents. The
number of young produced is usually one annually, though occasionally
two. They are at first covered with a coat of very thick, soft, nearly
white fur, and until it falls off they do not usually enter the water.
This occurs in the Greenland and Gray Seal when from two to three weeks
old, but in the Common Seal apparently much earlier. One of this species
born in the London Zoological Gardens had shed its infantile woolly
coat and was swimming and diving about in its pond within three hours
after its birth. The movements of the true Seals upon the ground or ice
are very different from those of the Eared-Seals. Thus the hinder limbs
(by which mainly they propel themselves through the water) are on land
always perfectly passive, stretched backwards, with the soles of the
feet applied to each other, and often raised to avoid contact with the
ground. Sometimes the fore limbs are equally passive, being placed close
to the sides of the body, and motion is then effected by a shuffling or
wriggling action produced by the muscles of the trunk. When, however,
there is any necessity for a more rapid mode of progression the animals
use the fore paws, either alternately or simultaneously, pressing the
palmar surface on the ground and lifting and dragging the body forwards
in a succession of short jumps. In this way they manage to move so fast
that a man has to step out beyond a walk to keep up with them; but such
rapid action costs considerable effort, and they very soon become heated
and exhausted. These various modes of progression appear to be common to
all species so far as has been observed.
Most kinds of Seals are gregarious and congregate, especially at the
breeding season, in immense herds. Such is the habit of the Greenland
Seal (_Phoca grœnlandica_), which resorts in the spring to the ice-floes
of the North Sea, around Jan Mayen Island, where about 200,000 are
killed annually by the crews of the Scotch, Dutch, and Norwegian sealing
vessels. Others, like the Common Seal of the British islands (_P.
vitulina_), though having a wide geographical range, are never met with
in such large numbers or far away from land. This species is stationary
all the year round, but some have a regular season of migration, moving
south in winter and north in summer. They are usually harmless, timid,
inoffensive animals, though, being polygamous, the old males often fight
desperately with each other, their skins being frequently found covered
with wounds and scars. They are greatly attached to their young, and
remarkably docile and easily trained when in captivity; indeed, although
there would seem little in the structure or habits of the Seal to fit
it by nature to be a companion of man, yet there is perhaps no wild
animal which attaches itself so readily to the person who takes care
of and feeds it. Seals appear to have much curiosity, and it is a very
old and apparently well-attested observation that they are strongly
attracted by musical sounds. Their sense of smell is very acute, and
their voice varies from a harsh bark or grunt to a plaintive bleat.
Seals feed chiefly on fish, of which they consume enormous quantities;
some, however, subsist largely on crustaceans, especially species
of _Gammarus_, which swarm in the northern seas, also on molluscs,
echinoderms, and even occasionally sea-birds, which they seize when
swimming or floating on the water.
[Illustration: FIG. 277.—The Common Seal (_Phoca vitulina_).]
Although the true Seals do not possess the beautiful under fur
(“seal-skin” of the furriers) which makes the skin of the Sea-Bears so
precious, yet their hides are still sufficiently valuable as articles of
commerce, together with the oil yielded by their fat, to subject them to
a devastating persecution, by which their numbers are being continually
diminished.
Two species of seals only are met with regularly on the British
coasts, the Common Seal and the Gray Seal. The former (Fig. 277) is
a constant resident in all suitable localities round the Scottish,
Irish, and English coasts, from which it has not been driven away by
the molestations of man. Although, naturally, the most secluded and
out-of-the-way spots are selected as their habitual dwelling-places,
there are few localities where they may not be occasionally met with.
Within the writers’ knowledge one was seen not many years ago lying on
the shingly beach at so populous a place as Brighton, and another was
caught in the river Welland, near Stamford, 30 miles from the sea. They
frequent bays, inlets, and estuaries, and are often seen on sandbanks
or mudflats left dry at low tide, and, unlike some of their congeners,
are not found on the ice-floes of the open sea, nor, though gregarious,
are very large numbers ever seen in one spot. The young are produced
at the end of May or beginning of June. They feed chiefly on fish, and
the destruction they occasion among salmon is well known to Scottish
fishermen. The Common Seal is widely distributed, being found not only on
the European and American coasts bordering the Atlantic Ocean, but also
in the North Pacific. It is from 4 to 5 feet in length, and variable in
colour, though usually yellowish-gray, with irregular spots of dark brown
or black above and yellowish-white beneath. The Gray Seal (_Halichœrus
grypus_) is of considerably larger size, the males attaining when fully
adult a length of 8 feet from nose to end of hind feet. It is of a
yellowish-gray colour, lighter beneath, and with dark gray spots or
blotches, but, like most other Seals, is liable to great variations of
colour according to age. This species appears to be restricted to the
North Atlantic, having been rarely seen on the American coasts, but not
farther south than Nova Scotia; it is chiefly met with on the coasts of
Ireland, England, Scotland, Norway, and Sweden, including the Baltic
and Gulf of Bothnia, and Iceland, though it does not appear to range
farther north. It is apparently not migratory, and its favourite breeding
places are rocky islands; the young being born in the end of September or
beginning of October.
Subfamily =Monachinæ=.—Incisors ²⁄₂. Cheek-teeth two-rooted, except the
first. On the hind feet the first and fifth toes greatly exceeding the
others in length, with nails rudimentary or absent.
_Monachus._[522]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ¹⁄₁; total 32.
Crowns of molars strong, conical, compressed, hollowed on the inner side,
with a strongly marked lobed cingulum, especially on the inner side, and
slightly developed accessory cusps before and behind. The first and last
upper and the first lower molar considerably smaller than the others.
Vertebræ: C 7, D 15, L 5, S 2, C 11. All the nails of both fore and
hind feet very small and rudimentary. One species, _M. albiventer_, the
Monk-Seal of the Mediterranean and adjacent parts of the Atlantic.
The other genera[523] of this section have the same dental formula, but
are distinguished by the characters of the cheek-teeth and the feet. They
are all inhabitants of the shores of the southern hemisphere.
_Ogmorhinus._[524]—All the teeth of the cheek-series with three distinct
pointed cusps, deeply separated from each other; of these the middle or
principal cusp is largest and slightly recurved; the other two (anterior
and posterior) are nearly equal in size, and have their apices directed
towards the middle one. Skull much elongated. One species, _O. leptonyx_,
the Sea-Leopard, widely distributed in the Antarctic and southern
temperate seas.
_Lobodon._[525]—Cheek-teeth with much-compressed elongated crowns and a
principal recurved cusp, rounded and somewhat bulbous at the apex, and
one anterior, and one, two, or three posterior, very distinct accessory
cusps. One species, _L. carcinophaga_.
_Pœcilophoca._[526]—Cheek-teeth small, with simple, subcompressed,
conical crowns, having a broad cingulum, but no distinct accessory cusps.
One species, _P. weddelli_.
_Ommatophoca._[527]—All the teeth very small; those of the cheek-series
with pointed recurved crowns, and small posterior and still less
developed anterior accessory cusps. Orbits very large. Nails quite
rudimentary on front, and absent on hind feet. The skull bears a
considerable resemblance to that of the members of the next subfamily,
towards which it may form a transition. There is one species, _O. rossi_,
of which very little is known.
Subfamily =Cystophorinsæ=.—Incisors ²⁄₁. Teeth of cheek-series generally
one-rooted. Nose of males with an appendage capable of being inflated.
First and fifth toes of hind feet greatly exceeding the others in length,
with prolonged cutaneous lobes, and rudimentary or no nails.
_Cystophora._[528]—Dentition: _i_ ²⁄₁, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ¹⁄₁; total
30. The last molar has generally two distinct roots. Beneath the skin
over the face of the adult male, and connected with the nostrils, is a
sac which, when inflated, forms a kind of hood covering the upper part of
the head. Nails present, though small, on the hind feet. One species, _C.
cristata_, the Hooded or Bladder-Nose Seal of the Polar Seas.
_Macrorhinus._[529]—Dentition as the last, but cheek-teeth of simpler
character, and all one-rooted. All the teeth, except the canines, very
small relatively to the size of the animal. Hind feet without nails.
Vertebræ: C 7, D 15, L 5, S 3, C 11. Nose of adult male produced into a
short tubular proboscis, ordinarily flaccid, but capable of dilatation
and elongation under excitement. One species, _M. leoninus_, the
Elephant Seal, or Sea-Elephant of the whalers, the largest of the whole
family, attaining the length of nearly 20 feet. Formerly abundant in the
Antarctic Seas, and also found on the coast of California.
_Extinct Seals._—Remains of animals of this group have been found in late
Miocene and Pliocene strata in Europe and America, the most abundant and
best-preserved being those of the Pliocene Antwerp Crag, the subject of
an illustrated monograph by Van Beneden. Nothing has, however, yet been
discovered which throws any light upon the origin of the group, since
all the extinct forms at present known come within the definition of
the existing families; and, though annectant forms between these occur,
there are as yet no transitions to a more generalised type of mammal.
Indeed, all those of which the characters are best known belong to the
completely developed Phocine or Trichechine, and not to the Otariine,
type. The typical genus _Phoca_ occurs in the Antwerp Crag, while remains
of Seals provisionally referred to this genus are found in the Pliocene
of the Crimea and the Miocene of Malta and Virginia. Of the other
Antwerp forms _Callophoca_ is said to be allied to _Phoca grœnlandica_,
_Platyphoca_ to _Phoca barbata_, _Phocanella_ to _Phoca foetida_,
_Gryphoca_ to _Halichœrus_, _Palæophoca_ and _Monatherium_ to _Monachus_,
and _Mesotaria_ to _Cystophora_; while _Prophoca_ does not appear to
come very close to any existing form. It should be observed that it is
extremely doubtful whether all these fossil Seals are really entitled to
generic distinction.
_Bibliography of Pinnipedia._—J. A. Allen, _History of North
American Pinnipeds_, 1880; St. George Mivart, “Notes on the
Pinnipedia,” _Proc. Zool. Soc._ 1885, p. 484; P. J. Van
Beneden, _Ossements fossiles d’Anvers_, in the _Mém. Acad. Roy.
d. Belgique_.
_Suborder_ CREODONTA.
The discovery of fossil remains in Eocene and early Miocene formations
both in Europe and North America shows that numerous species of
terrestrial carnivorous animals existed upon the earth during those
periods which cannot be referred to either of the sections into which
the order has now become broken up. By some zoologists these have been
supposed to be Marsupials, or at least to show transitional characters
between the Metatherian and Eutherian subclasses. By others they are
looked upon as belonging altogether to the latter group, and as the
common ancestors of existing Carnivores and Insectivores, or perhaps
rather as descendants or relatives of such common ancestors, retaining
more of the generalised characters than any of the existing species. They
shade off almost insensibly into numerous other forms less distinctly
carnivorous, to the whole of which, including the modern Insectivora,
Cope (to whom we are indebted for much of our knowledge of the American
extinct species) gives the name of BUNOTHERIA, those more specially
related to the existing Carnivora forming the suborder Creodonta. These
are instances, however, in which the application of the principles of
classification adopted in the case of existing species, of which the
entire structure is known, and which have become divided into isolated
groups by the extinction of intermediate forms, is almost impossible.
If the generally accepted view of evolution is true, and the extreme
modifications pass insensibly into each other by minute gradations (a
view the palæontological proof of which becomes strengthened by every
fresh discovery), there must be many of these extinct forms which cannot
be assigned to definitely characterised groups. There are, however, some
which stand out prominently from the others as formed on distinct types,
having no exact representatives at present living on the earth.
[Illustration: FIG. 278.—Anterior portion of the skull of _Hyænodon
leptorhynchus_. (After Filhol.)]
The more typical Creodonts appear, however, to be so closely related to
the true Carnivora through the extinct _Miacidæ_ (p. 539), that it is on
the whole advisable to regard them as representing a distinct suborder
of Carnivora. In the strong development of the canines (Fig. 278) they
are distinguished from the modern Insectivora; and they also differ from
the latter and resemble the true Carnivores in the form of the incisors,
the second one in the lower jaw (when three are present) being thrust
up above the level of the other two in the manner obtaining in most of
the modern Carnivora. Some of the most generalised forms included in the
present group approximate so closely to the Condylarthrous Ungulates as
to indicate that both groups have probably had a common origin.
The Creodonta as a whole are characterised by the small size of the
brain, the absence of a single differentiated carnassial tooth, and the
triangular form or secant character of their upper molars. In the carpus
the scaphoid and lunar were usually distinct; the femur has a third
trochanter; the upper or tibial surface of the astragalus usually wants
the groove found in modern Carnivores: and the feet were plantigrade. The
curious resemblance of the molars of many of these forms to those of the
Marsupials may indicate a genetic relationship between the two groups;
but, on the other hand, the presence of a full set of milk-teeth and the
absence of palatal vacuities, or of an inflection of the angle of the
mandible, sharply distinguishes them from that order. Space permits of a
notice only of the more interesting forms.
_Hyænodontidæ._—This family is taken to include some of the more
specialised types, such as the European and American _Hyænodon_ and
_Oxhyæna_ and the European _Pterodon_. In _Hyænodon_ (Fig. 278) the
dental formula is _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ²⁄₃; the fourth premolar
above and the first true molar below being formed upon the “carnassial”
plan, but the teeth behind these, instead of being tuberculated as in all
existing Carnivora, repeat the characters of the carnassial, and also
increase in size, especially in the lower jaw, from before backwards.
The last lower molar differs from the two preceding teeth, and is very
like the carnassial of _Felis_. The scaphoid and lunar of the carpus
were fused together. Some species, as _H. leptorhynchus_, were as large
as a Wolf, while others did not exceed a Fox in size. _Pterodon_ is
readily distinguished by having _m_ ³⁄₃, by the larger size of the inner
tubercles of the upper molars, and the similarity in the form of the
three lower molars. In some species there were only two upper incisors,
and the first lower premolar may be wanting. _Oxhyæna_ is a specialised
form with _i_ ²⁻³⁄₀, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ²⁄₂, and a very long
mandibular symphysis.
_Proviverridæ._—The European and American genus _Proviverra_
(_Cynohyænodon_ or _Stypolophus_) may be regarded as representing a
second family. The dental formula in this genus is the typical _i_
³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃, the upper molars have a large inner
tubercle, while the lower molars are differentiated into a blade and
talon, the blade having a large inner cusp. The upper teeth closely
resemble the molars of _Dasyurus_, while the lower molars are like the
lower carnassial of _Cynodictis_ and _Viverra_; and thus indicate how the
Creodonts may have passed into the true Carnivores through the extinct
_Miacidæ_.
[Illustration: FIG. 279.—The three right upper molars of _Arctocyon
dueli_ (_a_), and the second of _A. gervaisi_ (_b_); from the lowest
Eocene of Rheims. _pr_, protocone; _pa_, paracone; _me_, metacone; _hy_,
hypocone; _ml_, metaconule; _pl_, paraconule. (From Osborn.)]
_Arctocyonidæ and Mesonychidæ._—The first of these families is
represented by _Arctocyon primævus_, one of the oldest known Tertiary
mammals, from the lowest Eocene beds of La Fère, department of Aisne,
France, and also by other species from corresponding beds at Rheims. The
dental formula is _i_ ³⁄₃, _c_ ¹⁄₁, _p_?⁄₃₋₄, _m_ ³⁄₃. The upper molars
(Fig. 279) are tritubercular, with an incipient postero-internal column
(hypocone); the lower are quadritubercular; and the premolars simple.
The typical species was of large size, but the two of which the teeth
are figured were considerably smaller. In the American _Mesonyx_ the
dental formula was the typical one, the jaws were comparatively short,
the mandibular symphysis was elongated, the cheek-teeth were of simple
structure, and resembled the premolars of many of the true Carnivora,
and the astragalus had a grooved tibial surface and distinct distal
facets for the cuboid and navicular, resembling in the latter respect the
corresponding bone of a Perissodactyle Ungulate. The terminal phalanges
had deeply fissured extremities, and are said to be more like those of
Rodents than true Carnivores. _Mesonyx ossifragus_ was larger than a
Grizzly Bear. _Amblyctonus_, of the same deposits, differs by the smooth
tibial face of the astragalus and the development of an anterior cusp to
the lower molars.
CHAPTER XII
THE ORDER INSECTIVORA
[Illustration: FIG. 280.—Right lateral aspect of the anterior portion of
the cranium of _Erinaceus collaris_. Enlarged. (From Dobson, _Proc. Zool.
Soc._ 1881, p. 403.)]
The Insectivora comprise a number of comparatively small mammals,
generally of terrestrial, although rarely of arboreal or aquatic habits,
and presenting the following common features. They are unguiculate, and
have plantigrade or subplantigrade, and generally pentadactylate feet, in
which the pollex and hallux are not opposable to the other digits. They
are diphyodont and heterodont, and the teeth are rooted. The molars are
studded with sharp cusps, the crowns of the upper molars being either
quadrangular or triangular; there are never less than two incisors in
either side of the mandible; and in many cases the incisors, canines, and
anterior premolars are not clearly differentiated from one another (Fig.
280); the canines being usually weak. Clavicles are present, except in
_Potamogale_. The body is clothed with fur or protected by an armature
of spines; the testes are inguinal or placed near the kidneys, and are
not received into a scrotum; the penis is pendent or suspended from the
wall of the abdomen; the uterus is two-horned and with or without a
distinct corpus uteri; the placenta is discoidal and deciduate; and the
smooth cerebral hemispheres do not extend backwards over the cerebellum
(Fig. 281). The projection of the muzzle far beyond the extremity
of the lower jaw is a very general feature. The humerus generally
has an entepicondylar foramen. Certain forms, such as _Talpa_ and
_Galeopithecus_, are unique among mammals in having ossified intercentra
in the dorso-lumbar region of the vertebral column.
Representatives of this order are found throughout the temperate and
tropical parts of both hemispheres (except South America and Australia),
and exhibit much variety both in organisation and in habits. With the
exception of the _Tupaiidæ_, all are nocturnal; the greater number
are cursorial, but some (_Talpa_, _Chrysochloris_, _Oryzorictes_) are
fossorial; some (_Potamogale_, _Nectogale_, _Myogale_) are natatorial,
and a few (_Tupaiidæ_) arboreal; while the species of the aberrant
genus _Galeopithecus_ glide through the air like the Flying Squirrels.
To the great majority the term insectivorous is strictly applicable,
_Galeopithecus_ alone being phytophagous; while _Potamogale_ is said to
feed on fish, and the different species of Moles live chiefly on worms.
The general organisation of the Insectivora indicates a very low type,
and were it not for the specialised character of their placentation and
the tendency to lose the differentiated characters of the anterior teeth
they might be regarded as closely allied to the ancestral type of many of
the heterodont mammals. The strongly marked distinction of the canines
from the incisors and anterior premolars in the Mesozoic and most of
the Tertiary mammals (excepting some of the Ungulates) points, however,
very decidedly to the conclusion that the want of definition between
these teeth in many of the modern Insectivora is an acquired feature.
Fossil forms apparently indicate a relationship on the one hand with the
Creodont Carnivora, and on the other with the Lemuroid Primates; indeed
it is in some instances impossible to say whether extinct genera are
really Insectivores or Lemuroids.
[Illustration: FIG. 281.—Upper surface of the brain of _Tupaia
ferruginea_. (From Garrod, _Proc. Zool. Soc._ 1879, p. 304.)]
In most Insectivora the cranial cavity is of small relative size, and
in none is the brain-case elevated to any considerable extent above the
facial line. The facial part of the skull is generally much produced,
and the premaxillary and nasal bones are well developed. The zygomatic
arch is usually slender or deficient, the latter being the case in most
of the species; and postorbital processes of the frontals are found only
in the _Galeopithecidæ_, _Tupaiidæ_, and _Macroscelididæ_. The number
of dorsal vertebræ varies from 13 in _Talpa_ to 19 in _Centetes_; that
of the lumbar from 3 in _Chrysochloris_ to 6 in _Talpa_ and _Sorex_;
and of the caudal from the rudimentary series of 8 in _Centetes_ to the
40 or more of _Microgale_. Not less variable are the characters of the
vertebræ themselves; the spinous processes often being very long in one
and short in another species of the same genus. In the _Soricidæ_ and
_Myogale_ the neural arches of the cervical vertebræ are very slender.
In the _Soricidæ_ and _Gymnura_ the four anterior vertebræ develop large
single hypapophyses. In _Galeopithecus_ the centrum of each vertebra
supports posteriorly a pair of intercentral ossifications; while in
_Erinaceus_, _Myogale_, and _Talpa_ small oval ossicles are found on
the inferior surfaces of the lumbar interspaces. In _Erinaceus_, owing
to the thickness of the neural cord in the cervical region and its
abrupt termination, the diameter of the neural canal in the cervical
and first two dorsal vertebræ greatly exceeds that of any of the
succeeding vertebræ. The sternum is variable, but generally narrow,
bilobate in front, and divided into segments. The pectoral girdle
presents some remarkable adaptive modifications, most fully expressed
in _Talpa_, having relation to the use of the fore limbs in burrowing;
but in the Golden Moles (_Chrysochloris_) the forearm and manus alone
become specially modified for this purpose. In _Galeopithecus_ and
_Macroscelides_ the bones of the forearm (radius and ulna) are distally
united. The manus has generally five digits, but in _Rhynchocyon_ and
in one species of _Oryzorictes_ the pollex is wanting, while in the
true Moles it is extremely modified. The femur has, in most species,
a prominent ridge below the greater trochanter representing a third
trochanter. In _Galeopithecus_, _Tupaia_, _Centetes_, _Hemicentetes_,
_Ericulus_, and _Solenodon_ the tibia and fibula are distinct, but in all
the other genera more or less united together. The pes usually possesses
five digits (rarely four by reduction of the hallux); and in some forms,
as in the leaping species (_Macroscelides_, _Rhynchocyon_), the tarsal
bones are greatly elongated. The form of the pelvis, and especially of
the symphysis pubis, varies within certain limits; and these differences
have been proposed by Leche as a basis for the classification of the
families. Thus in the _Galeopithecidæ_, _Tupaiidæ_, and _Macroscelididæ_
there is a long symphysis; in the _Erinaceidæ_, _Centetidæ_, and
_Potamogalidæ_ the symphysis is short; and in the _Soricidæ_, _Talpidæ_,
and _Chrysochloridæ_ there is none.
Space does not admit of attempting a sketch of the modifications of the
muscular system, which will be found fully described in Dr. Dobson’s
_Monograph_, referred to in the bibliography. As to the nervous system,
it has been already mentioned that the brain throughout the order
presents a low type of organisation; in none of the members do the
cerebral hemispheres present any trace of convolutions, nor do they
extend backwards so as to cover the cerebellum, while the olfactory
lobes are large and project in front, and the corpus callosum is short
and thin. In the Hedgehogs (_Erinaceus_) the spinal column ends abruptly
opposite the third or fourth dorsal vertebra in a slender filament,
and the dorsal and lumbar nerves, given off in front of this point,
are carried backwards in two compressed bundles occupying the suddenly
narrowed spinal canal as far as the sacrum.
Owing to the similarity in the character of the food, the truly
insectivorous species, forming more than nine-tenths of the order,
present little variety in the structure of their digestive organs. Except
in _Galeopithecus_ the stomach is a simple, thin-walled sac; but in some,
as in _Centetes_ and allied genera, the pyloric and œsophageal openings
are very close together. The intestinal canal has much the same calibre
throughout, and varies from three (in the Shrews) to twelve times (in
the Hedgehogs) the length of the head and body. In the arboreal genera,
_Galeopithecus_ and _Tupaia_, as well as in the _Macroscelididæ_, all of
which probably feed in part on vegetable substances, most of the species
possess a cæcum. The liver is deeply divided into lobes, the right and
left lateral being cut off by deep fissures; and both the caudate and
Spigelian lobes being generally well developed. The gall-bladder, which
is usually large and globular, is placed on the middle of the posterior
surface of the right central lobe.
In most of the members of the order (_Soricidæ_, _Centetidæ_,
_Chrysochloridæ_) the penis is capable of being more or less completely
retracted within the fold of integument surrounding the anus; in some
(_Galeopithecidæ_, _Talpidæ_) it is pendent in front of the anus; while
in others (_Macroscelididæ_, _Erinaceidæ_, _Solenodontidæ_) it is
carried forwards and suspended from the abdominal wall. In the subfamily
_Centetinæ_ and _Chrysochloris_ the testes lie immediately behind the
kidneys, but in others more or less within the pelvis. During the rutting
season they become greatly enlarged, forming protrusions in the inguinal
region. Except in _Rhynchocyon_ the uterine cornua are long and open
into a short corpus uteri, which in many species (_Soricidæ_, _Talpidæ_,
_Centetidæ_, _Chrysochloridæ_) is not separated from the vagina by a
distinct os uteri. With the exception of _Galeopithecus_ all Insectivora
appear to be multiparous, the number of young at a birth varying from two
to eight in _Erinaceus_, and from twelve to twenty in _Centetes_. The
position of the mammary glands and the number of the teats vary greatly.
Thus in _Galeopithecus_ there are two pairs of axillary teats, and in
_Solenodon_ a single post-inguinal pair; but in most species they range
from the thorax to the abdomen, varying from two pairs in _Gymnura_ to
twelve in _Centetes_. In _Chrysochloris_ the thoracic and inguinal teats
are lodged in deep cup-shaped depressions.
Odoriferous glands exist in many species. In most Shrews these glands
occur on the sides of the body at a short distance behind the axilla,
and their exudation is probably protective, since few carnivorous
animals will eat the dead bodies of these creatures. In both species of
_Gymnura_ and in _Potamogale_ large pouches are situated on either side
of the rectum and discharge their secretions by ducts, opening in the
first-named genus in front of, and in the latter within the margin of the
anus. In _Centetes_ the ducts of similarly situated racemose glands open
by pores at the bottom of deep pits placed at either side of the anus.
The integument is thin, but in many species is lined by a muscular coat,
which is probably more developed in the Hedgehogs (_Erinaceidæ_) than in
any other mammal. In this family and the _Centetidæ_ most of the species
are protected by spines implanted in the panniculus carnosus muscle, and
more or less replacing the fur of the upper surface of the body.
The order is usually divided into two suborders, but the very aberrant
genus which constitutes the first might well be raised to ordinal rank.
It has little in common with the true Insectivora, but as it certainly
belongs to no other of the recognised mammalian orders it is retained
among them chiefly to avoid the inconvenience of increasing the number of
ordinal divisions for the sake of a single isolated form.
_Suborder_ DERMOPTERA.
Upper and lower incisors compressed, multicuspidate, the lower deeply
pectinated; fore and hind limbs connected by a broad integumentary
expansion forming a parachute.
_Family_ GALEOPITHECIDÆ.
In addition to the characters given under the head of the suborder it may
be mentioned that the orbit is nearly surrounded by bone, the zygomatic
arches are well developed, the tympanic forms a bulla, the ulna is
distally united with the radius, the tibia and fibula are distinct, the
pubic symphysis is long, the penis is pendent, the testes are received
into inguinal pouches, the mammæ are axillary, the uterus is two-horned,
and there is a large cæcum.
_Galeopithecus._[530]—Dentition: _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ²⁄₂, _m_ ³⁄₃;
total 34. Second upper incisor and canine with two roots. Two species—_G.
volans_ and _G. philippinensis_. The former, which is distinguished
from the latter by the form of the upper incisors, has a total length
of nearly 2 feet. The long and slender limbs are connected by a broad
integumentary expansion extending outwards from the sides of the neck
and body, and forming also a web between the fingers and toes as far as
the base of the claws (Fig. 282); the hind limbs are further connected by
a similar expansion passing outwards along the back of the feet to the
base of the claws, and, inwardly, involving the long tail to the tip,
forming a true interfemoral membrane, as in the Bats.
The two species of Flying Lemurs, as the representatives of this genus
are commonly but erroneously called, live in the forests of the Malay
Peninsula, Sumatra, Borneo, and the Philippine Islands, where they feed
chiefly on the leaves and fruits of trees. Their habits are nocturnal,
and during the daytime they cling to the trunks or limbs of trees, head
downwards, in a state of repose. With the approach of night their season
of activity commences, when they may be seen gliding from tree to tree
supported on their cutaneous parachute, and they have been observed to
traverse in this way a space of 70 yards with a descent of only about one
in five.
[Illustration: FIG. 282.—Feet of _Galeopithecus philippinensis_.]
_Galeopithecus_ was referred by some of the older zoologists and
anatomists to the Bats, and by others to the Lemurs, but Professor
Peters’s view, that it belongs to neither of these orders, and should be
considered an aberrant Insectivore, has been very generally accepted,
although, as mentioned above, the association is by no means a close one.
Besides differing from the Bats in the form of the anterior limbs and of
the double-rooted outer incisor and canine, it also contrasts strongly
with them in the presence of a large sacculated cæcum, and in the great
length of the colon, which is so remarkably short in all the Chiroptera.
From the Lemurs, on the other hand, the form of the brain, the characters
of the teeth, the structure of the skull, and the deciduate discoidal
placenta completely separate it. In a recent elaborate memoir on the
myology and affinities of _Galeopithecus_ Dr. Leche[531] considers that
we have in this genus an indication of the mode in which the Insectivora
were modified into the Chiroptera, although it is completely off the
direct line of descent. The deeply pectinated crowns of the lower
incisors of _Galeopithecus_ are quite unique in the class, and the only
approach to the double-rooted canine, except in _Erinaceus_ and _Talpa_,
is found among the Marsupials in _Perameles_, where the root of the
canine is grooved.
_Suborder_ INSECTIVORA VERA.
Upper and lower incisors conical, unicuspidate or with basal cusps only,
the lower not pectinated; limbs free, formed for terrestrial progression.
The following table gives a key to the distinctive characters of the
existing families:—
I. Upper molars broad, multicuspidate, with more or less
well-defined W-shaped crowns.
A. Symphysis pubis long; generally a cæcum; cerebral cavity
comparatively large.
_a._ Orbit encircled by bone; metatarsus moderate; arboreal.
_Tupaiidæ_.
_b._ Orbit not encircled by bone; metatarsus greatly elongated;
terrestrial. _Macroscelididæ._
B. Symphysis pubis short or none; no cæcum; cerebral cavity
small; skull without postorbital processes.
_a._ First and second upper molars with a central fifth cusp.
_a′._ Tympanic annular, not forming a bulla. _Erinaceidæ._
_b._ No central fifth cusp to upper molars.
_a′._ Tympanic annular, not forming a bulla; no zygomatic
arch. _Soricidæ._
_b′._ Tympanic forming a bulla; zygomatic arch developed.
_Talpidæ._
II. Upper molars narrow, with V-shaped crowns.
_a′._ Tympanic annular, not forming a bulla; zygomatic
arch imperfect.
_a″._ No clavicles. _Potamogalidæ._
_b″._ Clavicles well developed.
_a‴._ Skull constricted between the orbits;
penis suspended. _Solenodontidæ._
_b‴._ Skull not constricted; penis pendent,
retractile. _Centetidæ._
_b′._ Tympanic forming a bulla; zygomatic arch well
developed. _Chrysochloridæ._
The second section, in which the molars are of the primitive
tritubercular type, should probably be regarded as containing the most
generalised representatives of the order; and it is noteworthy that the
whole of them are confined to Africa, Madagascar, and the West Indies,
whereas most of the first section are widely distributed over the
Palæarctic and Oriental regions. None of the existing families of the
second section are known in a fossil condition, although it is suggested
that the extinct _Leptictidæ_ includes allied types.
_Family_ TUPAIIDÆ.
Skull with comparatively large brain-case, orbit surrounded by bone,
well-developed zygomatic arch, perforated jugal, and a tympanic bulla.
Upper molar broad, with cusps arranged in a W. Pubic symphysis long;
radius and ulna, and tibia and fibula separate; metatarsus only slightly
longer than tarsus. Usually a short cæcum. Habits arboreal and diurnal.
Confined to the Oriental region.
[Illustration: FIG. 283.—The Pentailed Tree-Shrew (_Ptilocercus lowi_).
From Gray, _Proc. Zool. Soc._ 1848. ½ natural size.]
_Tupaia._[532]—Dentition: _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total
38. Feet naked beneath, the sole furnished with projecting pads; claws
moderate, curved, and sharp; head pointed; ears rounded; tail bushy,
distichous, with short hair below. The Tree-Shrews, of which there are
some nine species, are found in India, Burma, the Malay Peninsula,
the Nicobars, Sumatra, Java, and Borneo. The species closely resemble
one another, differing chiefly in size and in the colour and length of
the fur. Their general appearance is very Squirrel-like. Their food
consists of insects and fruit, which they usually seek in the trees, but
also occasionally on the ground. When feeding they often sit on their
haunches, holding the food, after the manner of Squirrels, between their
forepaws.
_Ptilocercus._[533]—Represented only by the Pentailed Tree-Shrew (_P.
lowi_, Fig. 283) of Borneo, in which the tail is of extraordinary length,
with the proximal two-thirds naked, and the remaining third furnished
with a bilateral fringe of long hairs, from which the genus takes its
name.
_Extinct Genera._—An Insectivore from the Middle Miocene of France,
described as _Lantanotherium_, is said to be nearly allied to _Tupaia_.
The genus _Parasorex_, from strata of similar age, has the dental formula
_i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃, and is regarded as connecting the
present with the following family.
_Family_ MACROSCELIDIDÆ.
Skull with comparatively large brain-case, strong zygomatic arch, a
tympanic bulla, orbit surrounded by bone, imperforate jugal, and usually
no postorbital process. Molars broad, with four cusps arranged in a W.
Pubic symphysis long; proximal end of tibia and fibula united; radius
and ulna united or separate; metatarsus much longer than tarsus. A large
cæcum. Habits terrestrial, saltatorial, and nocturnal. The family is
confined to Africa.
_Macroscelides._[534]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ²⁄₂₋₃;
total 40 or 42. Distal extremity of radius and ulna united. Five digits
in manus, and five or four in pes. This genus, which is taken to include
_Petrodromus_, comprises ten species widely distributed throughout the
African continent. All are closely related, resembling one another
in general form, and even in the colour of the fur. They fall into
two groups, distinguished by the presence or absence of a small third
lower molar.[535] _M. tetradactylus_ (Fig. 284), the type of the genus
_Petrodromus_, differs from all the other species in the absence of the
hallux, and of the third lower molar. These animals are commonly known
as Jumping Shrews, and, like the following genus, have the muzzle much
produced.
_Rhynchocyon._[536]—Dentition: _i_ ¹⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ²⁄₂;
total 36. Upper incisor frequently shed in the adult. Radius and ulna
distinct; hind limbs relatively shorter, and proboscis longer than in the
type genus; four digits in each foot. Four closely allied species have
been described from East Africa. The head and body of the type species
measures about 8 inches in length; and the long tail is covered with a
ringed skin, sparsely haired. Its habits are fossorial.
[Illustration: FIG. 284.—_Macroscelides tetradactylus._ × ½. (From
Peters, _Reise nach Mossambique._)]
_Family_ ERINACEIDÆ.
Skull with a small brain-case; no postorbital process; slender and
occasionally imperfect zygomatic arch, and an annular tympanic, which
does not form a bulla. Upper molars with four principal cusps and a small
central median cusp. Acromion of scapula bifid; pubic symphysis short;
radius and ulna free, but tibia and fibula united proximally. No cæcum;
penis carried forward and suspended from the wall of the abdomen. Habits
terrestrial. Found in the Palæarctic, Ethiopian, and Oriental regions.
Subfamily =Gymnurinæ=.—Palate completely ossified; pelvis very narrow;
fur without spines.
_Gymnura._[537]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃; total 44.
This genus, if _Hylomys_ is rightly included, is represented by the two
species, _G. rafflesi_ and _G. suilla_, from the Malay Peninsula and
Indian Archipelago. The former has the appearance of a large Rat with
a long tail and head and projecting mobile snout; the latter, which is
much smaller, with a short tail and small third upper premolar, has long
been known under the name of _Hylomys suillus_, and classed with the
_Tupaiidæ_. Both species present a very generalised type of dentition,
in this respect occupying an almost central position in the order.
_G. suilla_ is represented in Mount Kina-Balu, Borneo, by a variety
characterised by the presence of a dark dorsal streak. Many zoologists
prefer to retain _Hylomys_ as a distinct genus.
Subfamily =Erinaceinæ=.—Palate imperfectly ossified; pelvis wide; fur
with spines.
_Erinaceus._[538]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₁, _p_ ³⁄₂, _m_ ³⁄₃; total
36. The first pair of upper incisors (Fig. 285) are considerably larger
than the others, and are widely separated from one another in the middle
line; the canine is very similar to the third incisor; and, except
in _E. europæus_ (Fig. 285), each of these teeth is inserted by two
distinct roots (Fig. 280, p. 610). The first lower incisor is large and
proclivous. The number of vertebræ is C 7, D 15, L 6, S 3, C 11.
[Illustration: FIG. 285.—Right lateral aspect of the anterior portion of
the skull of the Hedgehog (_Erinaceus europæus_). Enlarged. (From Dobson,
_Proc. Zool. Soc._ 1881, p. 403.)]
The Hedgehogs comprise nearly twenty species, distributed throughout
Europe, Africa, and the greater part of Asia, but not found in
Madagascar, Ceylon, Burma, Siam, the Malay Peninsula, or Australia. All
the species resemble one another in the armature of spines investing the
upper surface and sides of the body; and all possess the power of rolling
themselves up into the form of a ball, protected on all sides by the
strong spines; the dorsal integument being brought downwards and inwards
over the head and tail, so as to include the limbs also, by the action of
special muscles. The common Hedgehog (_E. europæus_) is the most aberrant
species, differing from all the rest in the peculiarly shaped and
single-rooted third upper incisor and canine (Fig. 285), and in its very
coarse, harsh fur. The dentition of the long-eared North Indian form,
_E. collaris_ (Fig. 280), may be considered characteristic of all the
other species, the only important differences being found in the variable
size and position of the second upper premolar, which is very small,
external, and deciduous in the Indian _E. micropus_ and _pictus_. The
former species, limited to South India, is further distinguished by the
absence of the jugal bone. Of the African species, _E. diadematus_, with
long frontal spines, is probably the commonest; while _E. albiventris_
has been made the type of a separate genus on account of the total
absence of the hallux.
The well-known European species feeds on insects, worms, slugs, mice,
rats, lizards, snakes, etc., as well as on eggs, fruit, and roots. It
hibernates during the winter. The young are usually produced in July
or August in litters of not more than four, but there may be a second
litter in October; and the period of gestation is believed not to exceed
a month. The Indian, and probably also the African species, do not
hibernate.
The existing _E. europæus_ dates from the Pleistocene period, and extinct
species of the genus are found in the Upper and Middle Miocene of the
Continent.
_Extinct Genera._—The French Lower Miocene genus, _Palæoerinaceus_,
appears to be allied to _Erinaceus_, but is distinguished by the
wider and completely ossified palate. In the Upper Eocene of Central
France there are two genera, which appear to be most nearly allied to
_Gymnura_, although connected by _Palæoerinaceus_ with _Erinaceus_. Of
these _Necrogymnurus_,[539] with which _Cayluxotherium_ is apparently
identical, has teeth like _Gymnura_, but an imperfectly ossified palate
like _Erinaceus_; and the skull is remarkable for the peculiar rugose
structure of the parietal and temporal regions. _Comphotherium_ is
distinguished by the presence of a cingulum to the lower molars, like
that found in _Gymnura_.
_Family_ SORICIDÆ.
Skull (Fig. 286) long and narrow, with no zygomatic arch or postorbital
process, and the tympanic ring-like and not forming a bulla. Upper molars
with the cusps arranged in a distinct W. No pubic symphysis. The tibia
and fibula united. No cæcum. Habits usually terrestrial, rarely aquatic.
Distribution extensive.
The Shrews are Rat-like or Mouse-like insectivores, with the body covered
with hair, and the muzzle long and pointed. Their dentition (Fig. 286)
is peculiar and characteristic. Thus the first upper incisor is large
and hook-like, with a more or less developed basal cusp on the posterior
border. Between this and the last premolar there are a variable number
of small teeth, representing the other incisors, the canine, and the
anterior premolars; although, owing to the early obliteration of the
maxillo-premaxillary suture, their homology is exceedingly difficult to
determine. Three molars are invariably present, of which the third is
much the smallest. In the mandible there are always six teeth, but in one
species of _Myosorex_ there may be a seventh. The first lower incisor
is usually directed horizontally forwards; the second incisor (formerly
reckoned as the canine) is the smallest tooth of the series, the fourth
premolar being slightly larger.
This family, which includes considerably more than half the
representatives of the order, has a distribution coextensive with the
latter. Many classifications of this difficult group have been attempted,
but according to the latest proposal of Dr. Dobson,[540] the genera may
be divided into two subfamilies, distinguished by the apparently trivial
character of the colour of the teeth.
[Illustration: FIG. 286.—Left lateral view of the cranium and mandible
of _Sorex veræpacis_. In the cranium—_i_, first incisor; _c_, fourth
incisor; _p_, canine; _m_, fourth premolar: in the mandible—_i_, first
incisor; _c_, second incisor; _p_, fourth premolar; _m_, first molar.
(From Alston, _Proc. Zool. Soc._ 1877.)]
Subfamily =Soricinæ=.—Summits of the teeth coloured red.
_Sorex._[541]—Dentition: _i_ ⁴⁄₂, _c_ ¹⁄₀, _p_ ²⁄₁, _m_ ³⁄₃; total 32.
Openings of male and female generative organs separated from the anal
orifice; penis cylindrical or tapering; ear well developed; tail long,
covered with equal or subequal hairs.
It has been shown by Brandt that the position of the premaxillo-maxillary
sutures in the type of the genus is between the fourth and fifth tooth,
so that it appears that we must regard this genus as differing from all
other Eutherian mammals in having four upper incisors. Dr. Dobson, in
his paper quoted, classes the tooth here reckoned as the upper canine
with the premolar series in all the Shrews. Habits terrestrial. Species
numerous, inhabiting the Palæarctic and Nearctic regions.
Of the two species found in the British Isles the Common Shrew (_S.
vulgaris_, Fig. 287) is by far the most common in England, and is about
the size of the House Mouse, to which it approximates in general form.
The body is clothed with close long fur, very soft and dense, and varying
in colour from light reddish to dark brown above, rarely speckled or
banded with white. The under surface of both the body and the tail is
grayish. The basal four-fifths of all the hairs above and beneath are
dark bluish-gray; the hairs of the tail are less densely set and coarser.
On each side of the body, at a point about one-third of the distance
between the elbow and the knee, may be found, especially in the rutting
season, a gland covered by two rows of coarse hairs. This secretes a
peculiar fluid, on which the odour of the animal depends; this odour
being evidently protective, and rendering the creature secure against the
attacks of many predaceous animals.
The geographical range of the Common Shrew is exceedingly wide, extending
eastwards through Europe and Asia (north of the Himalayas) to North
America.
[Illustration: FIG. 287.—The Common Shrew (_Sorex vulgaris_).]
The Lesser Shrew (_S. pygmæus_[542]) is far less common in England and
Scotland, although more abundant in Ireland, where _S. vulgaris_ is
unknown. It is distinguished from the latter not only by its inferior
dimensions, but also by the circumstance that the third upper incisor is
not longer than the fourth, and by the considerably shorter length of the
forearm and manus. This species extends through Europe and Asia as far
as the inland of Saghalin. Both this and the preceding species generally
live in wooded districts, making their nests under the roots of trees, or
in slight hollows. The great mortality noticeable among the Shrews in the
early part of the autumn is probably due to insufficiency of food. The
breeding season extends from the latter part of April to the beginning of
August. The young, which are blind, naked, and toothless at birth, are
very quickly developed. The number in a litter is usually from five to
seven, but may be as many as ten.
The Alpine Shrew (_S. alpinus_), which is restricted to the Alpine region
of Central Europe, is slightly larger than the common species, from which
it is distinguished by the longer tail, the length of which exceeds that
of the head and body, by the fur being dark on both surfaces of the body,
and also by the larger size of the upper canine.
In North America _S. bendirei_ is by far the largest species of the
genus; and, as in many other species of the same country, the fourth
upper incisor is relatively small. In _S. hoyi_ (separated by some
writers as _Microsorex_), of the same country, this tooth is rudimentary.
Other North American Shrews, which are regarded by some zoologists as
generically distinct under the name of _Neosorex_, are aquatic, and
thus take the place of the Old World genus _Crossopus_. These are _S.
palustris_ of the Rocky Mountains and _S. hydrodromus_ of Unalaska
Island, both of which resemble _Crossopus_ in having the feet provided
with swimming fringes, but agree with the other species of _Sorex_ in
their dentition and the character of the tail. The former species is
about the size of _Crossopus fodiens_, while the latter is scarcely
larger than _S. pygmæus_.
_Soriculus._[543]—Dentition: _i_ ⁴⁄₂, _c_ ¹⁄₀, _p_ ¹⁻²⁄₁, _m_ ³⁄₃; total
30, or rarely 32. Opening of male or female generative organs forming
with the anal orifice a shallow cloaca. Ear and tail as in _Sorex_. First
upper incisor with an internal cusp. Habits terrestrial.
This genus is the only representative in the Oriental region of the
_Soricinæ_, which are otherwise confined to the Palæarctic and Nearctic
regions. The Indian and Burmese species comprise _S. nigrescens_, _S.
caudatus_, and _S. macrurus_.
_Notiosorex._[544]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ¹⁄₁, _m_ ³⁄₃; total
28. Tail moderate; first upper incisor without an inner cusp; other
characters as in _Soriculus_. Habits terrestrial.
This American genus is represented by _S. crawfordi_ and _S. evotis_,
which are found in Central America and Mexico, and are thus some of the
most southerly representatives of the Shrews in that continent. Their
external appearance is very similar to that of the Old World genus
_Crocidura_.
_Blarina._[545]—Dentition: _i_ ⁴⁻³⁄₂, _c_ ¹⁄₀, _p_ ²⁄₁, _m_ ³⁄₃; total
32 or 30. Ear truncated above; tail short; otherwise as in _Soriculus_.
This group of so-called Earless or Short-tailed Shrews is mainly North
American, the common forms being _B. dekayi_ and _B. brevicauda_. The
species vary considerably in size; and _B. mexicana_ and _micrura_ extend
the range of the genus into Mexico and Guatemala. The following account
of the habits of _B. brevicauda_ is taken from Dr. Merriam’s _Mammals
of the Adirondack Region_: “The rigours of our northern winters seem to
have no effect in diminishing its activity, for it scampers about on the
snow during the severest weather, and I have known it to be out when the
thermometer indicated a temperature of -20° Fahr. It makes long journeys
over the snow, burrowing down whenever it comes to an elevation that
denotes the presence of a log or stump, and I am inclined to believe that
at this season it must feed largely upon the chrysalides and larvæ of
insects that are always to be found in such places.” Dr. Merriam has made
the interesting discovery that the common short-tailed North American
Shrew supplements its insectivorous fare by feeding on beech-nuts, which
will account for the generally very worn state of the teeth in this
species.
_Crossopus._[546]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ²⁄₁, _m_ ³⁄₃; total
30. Opening of male or female generative organs enclosed within the same
ring as the anal orifice; penis broad, with lateral processes. Ears
small, not truncated. Tail long, with an inferior fringe of elongated
hair; feet also fringed. Habits aquatic. The Palæarctic Water-Shrew (_C.
fodiens_) is considerably larger than the Common Shrew, from which it is
readily distinguished externally by its shorter and much broader muzzle,
comparatively smaller eyes, and larger feet adapted for swimming,—the
sides of the feet and toes being provided with comb-like fringes of stiff
hairs. The tail is longer than the body, and possesses a well-developed
swimming fringe of moderately long, regularly arranged hairs, which
extend along the middle of the flat under surface from the end of its
basal third to its extremity. The fur of the body is long and very dense,
varying much in colour in different individuals, and this has given rise
to descriptions of many nominal species; the prevailing shades are dark
brown, almost black, above, and more or less bright ashy tinged with
yellowish beneath; sometimes in the same litter there are individuals
with the under surface more or less dark coloured. In the number as well
as in the shape of the teeth the Water-Shrew differs from the Common
Shrew: there is a premolar less on each side above; the bases of the
teeth are much more prolonged posteriorly; and their cusps are much less
stained brown, so that in old individuals with worn teeth they often
appear altogether white. This species resembles the otter in its aquatic
habits, swimming and diving with great agility. It frequents rivers and
lakes, making its burrows in the overhanging banks, from which when
disturbed it escapes into the water. Its food consists of insects and
their larvæ, small crustaceans, and probably the fry of small fishes. It
is generally distributed throughout England, is less common in Scotland,
and as yet it has not been recorded in Ireland; specimens have been
obtained from many parts of Europe, and also from Asia as far eastward as
the Altai Mountains.
Subfamily =Crocidurinæ=.—Teeth completely white.
_Myosorex._[547]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ²⁄₁₋₂, _m_ ³⁄₃; total
30 or 32. Penis cylindroid and tapering; male or female generative
organs opening close to anal orifice, but not forming a cloaca. Ears
well developed; tail long, clothed with equal or subequal hairs. Habits
terrestrial.
This genus is typically represented by _M. varius_, a very small Shrew
from the Cape, which is quite unique among the whole family in having a
rudimental seventh pair of lower teeth.
_Crocidura._[548]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ²⁻¹⁄₁, _m_ ³⁄₃; total
28 or 30. Male or female generative organs forming a short cloaca with
the anal orifice. Tail long, with a mixture of long and short hairs.
Other characters as in _Myosorex_. Habits terrestrial.
This Old World genus includes over seventy nominal species, which have
been divided into four subgenera, _C. aranea_ and _C. suaveolens_ of
Continental Europe, and _C. cœrulea_ of India, being well-known forms.
The species are very variable and difficult to discriminate. _C. aranea_
has a very wide distribution, ranging from Central and Southern Europe
to North Africa and Central Asia. The name Musk-Rat is popularly applied
in India to _C. cœrulea_, which frequents houses at night, hunting round
rooms for cockroaches and other insects, and occasionally uttering a
sharp shrill cry. The strong musky odour of this animal arises from
large glands situated beneath the skin of the side of the body, a short
distance behind the fore limbs. This odour is so powerful and penetrating
that it is popularly believed in India that if the animal runs over a
corked bottle of wine or beer it will infect the fluid within. Jerdon
says that certainly many bottles are met with quite undrinkable from the
peculiar musky odour of their contents, but, rejecting the possibility of
its passing through the glass, he attributes it to the corks having been
infected previously to bottling, stating in corroboration of this view
that he has never found the odour in liquors bottled in England.
_Diplomesodon._[549]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₀, _p_ ¹⁄₁, _m_ ³⁄₃;
total 26. Tail moderate; soles of the feet hairy. Other characters as in
_Crocidura_. Habits terrestrial.
This genus is represented only by _D. pulchellus_ of the Kirghiz steppes,
which is allied to the following form, although retaining the normal
Shrew-like external contour.
_Anurosorex._[550]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₀, _p_ ¹⁄₁, _m_ ³⁄₃; total
26. Ear very short; tail rudimental or short; soles of feet naked. Other
characters as in _Diplomesodon_.
The two species of this genus are Mole-like terrestrial forms, of which
the typical _A. squamipes_ occurs in Tibet, while _A. assamensis_ is
found in Assam. The latter species has the longer tail. The habits of
both are probably fossorial.
_Chimarrogale._[551]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ¹⁄₁, _m_ ³⁄₃;
total 28. Penis broad, with lateral processes; male or female generative
organs opening within the same integumentary ring as the anal orifice.
Tail long, with an inferior fringe of elongated hairs; ears small;
plantar callosities simple; toes free. Habits aquatic.
This genus includes _C. himalayica_ of the Himalaya and _C.
platycephalus_ of Japan. Both have the feet fringed, and, together with
the next genus, may be regarded as the eastern analogues of _Crossopus_
among the red-toothed series; their structural resemblances to the
latter, if Dr. Dobson’s classification is a natural one, being probably
due to adaptation for a similar mode of life.
_Nectogale._[552]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ¹⁄₁, _m_ ³⁄₃;
total 28. External ears not forming a conch, valvular. Plantar
callosities forming adhesive pads; toes webbed. Other characters as in
_Chimarrogale_. Habits aquatic.
[Illustration: FIG. 288.—_Nectogale elegans._ (From Milne-Edwards,
_Mammif. Tibet_.)]
The sole representative of this genus is the Tibetan Water-Shrew (_N.
elegans_, Fig. 288), which differs from all other members of the family
by the webbed toes and the presence of the disc-like adhesive pads on the
under surface of the feet, which are believed to enable the creature to
hold on to smooth rocks or stones in the beds of the streams it inhabits.
This species is probably more completely aquatic in its habits than the
allied _Chimarrogale_.
_Fossil Soricidæ._—Remains of existing species of _Sorex_ or _Crossopus_
occur in the Norfolk Forest bed, while an extinct species has been found
in the Pleistocene of Sardinia. _Crocidura_ occurs in the cavern-deposits
of Madras. Shrews from the Miocene and Upper Eocene of Europe have been
referred to _Sorex_ and the genus _Amphisorex_, which is a synonym of
_Crossopus_.
_Family_ TALPIDÆ.
Allied to the _Soricidæ_, but distinguished by the presence of a
zygomatic arch and auditory bulla in the skull, and by the form of
the teeth. The eyes are very small, and in some species covered with
skin; the ears are short and concealed by the fur; the fore limbs are
generally more or less modified for digging; there is no symphysis pubis;
the intestine has no cæcum; the tibia and fibula are united; and the
unicuspidate first upper and lower incisors are not extended horizontally
forwards.
This family is connected with the _Soricidæ_ by _Urotrichus_ and
_Uropsilus_. All the members are limited to the temperate regions
of Europe, Asia, and North America; and the majority of them are of
fossorial habits, although a few are aquatic or cursorial. The family has
been divided into two subfamilies by Professor Mivart, and since this
arrangement has been very generally adopted it will be followed here.
From the presence of intermediate forms like _Scaptonyx_ Dr. Dobson, in
the second part of his _Monograph of the Insectivora_, has proposed a
different arrangement, which, with the omission of some forms which are
of not more than subgeneric value, is as follows:—
MYOGALÆ—_Myogale_.
CONDYLURÆ—_Condylura_.
SCALOPES { _Scapanus_.
{ _Scalops_.
TALPÆ—_Talpa_.
UROTRICHI { _Scaptonyx_.
{ _Urotrichus_.
UROPSILI—_Uropsilus_.
Subfamily =Myogalinæ=.—Clavicles and humerus moderately elongated; manus
without falciform bone.
_Myogale_.[553]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃; total
44. Feet webbed. Habits aquatic. This genus is represented by the two
species _M. moschata_ (Fig. 289) and _M. pyrenaica_, of which the former
is by far the largest member of the family, its total length being about
16 inches. Its long proboscis-like snout projects far beyond the margin
of the upper lip; the toes are webbed as far as the bases of the claws;
and the long scaly tail is laterally flattened, so as to form a powerful
instrument of propulsion when swimming. This species inhabits the banks
of streams and lakes in South-East Russia, where its food consists of
various aquatic insects. _M. pyrenaica_, living in a similar manner in
the region of the Pyrenees, is very much smaller, has a round tail, and
a proportionally longer snout. Fossil remains of _M. moschata_ occur in
the Norfolk Forest bed, and were originally described under the name of
_Palæospalax_. The genus is also represented in the Middle and Lower
Miocene of the Continent.
[Illustration: FIG. 289.—The Desman (_Myogale moschata_). ¹⁄₃ natural
size.]
_Urotrichus._[554]—Dentition: _i_ ²⁄₁, _c_ ¹⁄₁, _p_ ⁴⁄₃ or ³⁄₄, _m_
³⁄₃; total 36. Feet not webbed; manus broad. Habits fossorial. The
Mole-Shrews, as these animals are called, are represented by _U.
talpoides_ of the mountains of Japan and _U. gibbsi_ of North America.
These two species are small and closely allied animals; the American form
(which it has been proposed to separate subgenerically as _Neurotrichus_)
having _p_ ³⁄₄.
_Uropsilus._[555]—Dentition: _i_ ²⁄₁, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total
34. Manus narrow; tail naked and scaly. Habits cursorial. The single
species, _U. soricipes_, from the borders of Tibet, is a slate-coloured
animal with the external form of a Shrew but the skull of a Mole.
Subfamily =Talpinæ=.—Clavicle and humerus very short and broad; manus
with a large falciform bone.
A. First upper incisor much larger than the second (New World Moles).
_Scalops._[556]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ³⁄₃, _m_ ³⁄₃; total
36. Extremity of muzzle simple; hind feet webbed; tail short and nearly
naked. Represented by three species in the United States.
_Scapanus._[557]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃; total
44. Extremity of muzzle simple. The two North American species of this
genus resemble _Scalops_ in general characters, but have a dentition like
_Condylura_. The habits are like those of the latter, and the right to
generic distinction is doubtful.
_Condylura._[558]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃;
total 44. Extremity of muzzle surrounded by filiform appendages. The
Star-nosed Mole (_C. cristata_) derives its name from the star-like ring
of appendages at the extremity of the muzzle, with the nostrils in the
centre. The general contour is Mole-like, but the tail is nearly as long
as the body, and the manus is somewhat less powerful, with its terminal
phalanges not cleft. The length of the head and body is about 5 inches.
This species is common in parts of North America, and forms tunnels in
the ground like the Common Mole.
B. First upper incisor scarcely larger than the second (Old World Moles).
_Scaptonyx._[559]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃; total
42. Manus moderately broad, as in _Urotrichus_. Represented only by _S.
fusicaudatus_ of Eastern Tibet, which may be regarded as connecting
_Talpa_ with _Urotrichus_, having the head of the former and the limbs of
the latter.
_Talpa._[560]—Dentition (usually): _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃;
total 44. Manus extremely broad.
This genus includes the true Moles, of which the common English
Mole[561] (_T. europæa_) is the type. This animal is about 6 inches in
total length, of which rather more than one inch is occupied by the
tail. The body is elongated and cylindrical, and, owing to the very
anterior position of the fore limbs, the head appears to rest between
the shoulders; the muzzle is long and obtusely pointed, terminated by
the nostrils, which are close together; the minute eye is almost hidden
by the fur; the ear is without a conch, and opens on a level with the
surrounding integument. The fore limbs are rather short and very
muscular, terminating in broad, naked, shovel-shaped feet, with the palms
normally directed outwards, and each with five subequal digits armed with
strong flattened claws. The hind feet are long and narrow, and the toes
are provided with slender claws. The body is densely covered with soft,
erect, velvety fur, the hairs being uniform in length and thickness,
except on the muzzle and short tail. The colour of the fur is generally
black, with a more or less grayish tinge, or brownish-black, but various
paler shades up to pure white have been observed.
The food of the Mole consists chiefly of the earth-worm, in pursuit of
which it forms its well-known underground excavations. Its habits were
many years ago studied and described by M. Henri le Court. Like many
other mammals, the Mole has a lair to which it may retire for security.
This consists of a central nest formed under a hillock, placed in some
protected situation, as under a bank, or between the roots of trees. The
nest, which is lined with dried grass or leaves, communicates with the
main run by four passages, of which only one joins it directly, leading
downwards for a short distance and then ascending again. The other
three are directed upwards and communicate at regular intervals with a
circular gallery constructed in the upper part of the hillock, which in
turn communicates by five passages leading downwards and outwards with
another much larger gallery placed lower down on a level with the central
nest, from which passages proceed outwards in different directions, one
only communicating directly with the main run, while the others, curving
round, either soon join or end blindly. The main run is somewhat wider
than the animal’s body: its walls are smooth, and formed of closely
compressed earth, the depth varying according to the nature of the soil,
but ordinarily from 4 to 6 inches. Along this tunnel the animal passes
backwards and forwards several times daily, and here traps are laid by
mole-catchers for its capture. From the main run numerous passages are
formed on each side, along which the animal hunts its prey, throwing out
the soil in the form of mole-hills. The Mole is one of the most voracious
of mammals, and, if deprived of food, is said to die in from ten to
twelve hours. Almost any kind of flesh is eagerly devoured by captive
Moles, which have been seen by various observers, as if maddened by
hunger, to attack animals nearly as large as themselves, such as birds,
lizards, frogs, and even snakes; toads, however, they will not touch, and
no form of vegetable food attracts their notice. If two Moles be confined
together without food, the weaker is invariably devoured by the stronger.
Moles take readily to the water, in which respect they resemble their
representatives on the North American continent. Bruce, writing in 1793,
remarks that he saw a Mole paddling towards a small island in the Loch of
Clunie, 180 yards from land, on which he noticed mole-hills.
The sexes come together about the second week in March, and the
young—generally from four to six in number—which are brought forth in
about six weeks, quickly attain their full size.
[Illustration: FIG. 290.—Skeleton of Mole × ⅔ (lower jaw removed to
show base of skull). _c_, Calcaneum; _c.h._, clavicular articulation
of the humerus; _cl._, clavicle; _e.c_, external condyle of humerus;
_f._, femur; _fb_, fibula; _fc_, falciform bone (radial sesamoid); _h_,
humerus; _i.c_, internal condyle of humerus; _il_, left ilium; _i.p_,
ramus of the ilium and pubis; _is._, ischium; _l.d_, ridge of insertion
of latissimus dorsi muscle; _l.t_, lesser trochanter; _m_, manubrium
sterni; _o_, fourth intercentral ossicle; _ol_, olecranon; _p._, pubis
widely separated from that of the opposite side; _pa._, patella; _p.m._,
ridge for insertion of pectoralis major muscle; _pt._, pectineal
eminence; _r_, radius; _rb_, first rib; _s_, plantar sesamoid ossicle
corresponding to the radial sesamoid (os falciforme) in the manus; _sc._,
scapula; _s.h._, scapular articulation of the humerus; _t_, tibia; _u_,
ulna.]
The Mole exhibits in the whole of its organisation a perfect adaptation
to its peculiar mode of life. In the structure of the skeleton (Fig.
290) very striking departures from the typical mammalian form are
noticeable. Thus the presternum is so much produced anteriorly as to
extend forward as far as a vertical line from the second cervical
vertebra, carrying with it the very short and almost quadrate clavicle,
which is articulated with its anterior extremity and distally with the
humerus; being also connected ligamentously with the scapula. The fore
limbs are thus brought opposite the sides of the neck, and from this
position a threefold advantage is derived: in the first place, as this
is the narrowest part of the body, they add but little to the general
width, which if increased, would lessen the power of movement in a
confined space; secondly, this position allows of a longer fore limb than
would otherwise be possible, and so increases its power; and, thirdly,
although the entire limb is relatively very short, its anterior position
enables the animal, when burrowing, to thrust the claws so far forward
as to be in a line with the end of the muzzle, the importance of which
is evident. Posteriorly, the hind limbs are similarly removed out of the
way by approximation of the hip-joints to the centre line of the body.
This is effected by inward curvature of the innominate bones at the
acetabula to such an extent that they almost meet in the centre, while
the pubic bones are widely separated behind. The shortness of the fore
limb is caused by the great reduction in the length of the humerus, which
has lost all resemblance to its normal shape. In addition to the usual
articulation with the glenoid cavity of the scapula, the humerus also has
a separate articulation with the extremity of the clavicle. The bones
of the manus are enormously expanded laterally; this expansion being
increased by the large sickle-like bone on the radial side of the carpus,
which is considered by some anatomists to represent the prepollex. The
skull is long and tapering, with very slender zygomatic arches and
elongated nasals, which are ankylosed together, and in advance of which
the mesethmoid is more or less ossified. The vertebræ are usually C 7,
D 13, L 6, S 6, C 10-12; all having very strong surfaces for mutual
articulation. The upper incisors are chisel-like, and the canine has two
roots; the first three upper premolars are simple and conical, but the
fourth is much larger, and canine-like. In the mandible the incisors are
small and somewhat proclivous, while the canine can only be distinguished
from them by its position: the first lower premolar is larger than the
others.
The Common Mole has an exceedingly wide distribution, ranging over the
greater part of the Palæarctic region, where it is met with in places so
widely sundered as England and Japan. It occurs in both the Himalaya and
Altai mountains. In Ireland it is unknown, and in Scotland it extends as
far north as Caithness. Eight species of the genus are recognised, which
may be grouped, from the characters of their dentition, as follows, viz.:
_i_ ³⁄₃, _c_ ¹⁄₀, _p_ ⁴⁄₄, _m_ ³⁄₃, _T. wogura_; _i_ ³⁄₃, _c_ ¹⁄₁, _p_
⁴⁄₄, _m_ ³⁄₃, _T. europæa_, _cæca_, _longirostris_, _micrura_; _i_ ³⁄₃,
_c_ ¹⁄₁, _p_ ³⁄₄, _m_ ³⁄₃, _T. leucura_, _leptura_; _i_ ³⁄₃, _c_ ¹⁄₁, _p_
³⁄₃, _m_ ³⁄₃, _T. moschata_.
Except in _T. europæa_, the eyes are covered by a membrane. In _T.
micrura_ the short tail is concealed by the fur. _T. cæca_ is found south
of the Alps; the remaining species are Asiatic, and two only—_T. micrura_
and _T. leucura_—occur south of the Himalaya. _T. moschata_, of Tibet,
is regarded by some zoologists as generically distinct under the name of
_Scaptochirus_.
Remains of _T. europæa_ occur in the Norfolk Forest bed, while extinct
species are found in the European Tertiaries as far down as the Lower
Miocene, although it has been proposed to separate some of these forms
generically. _Protalpa_, of the Upper Eocene Phosphorites of Central
France, is very closely allied, but the structure of the humerus is
somewhat less specialised.
_Extinct Genera._—A number of extinct Insectivora from the European
Tertiaries more or less closely allied to the Moles have been described,
but since our knowledge of most of them is extremely imperfect their
precise affinities are in many instances problematical. Of these, the
Lower Miocene _Tetracus_ is said to have affinity both with _Myogale_ and
_Erinaceus_; while the forms described as _Mysarachne_ and _Echinogale_,
are considered to connect the present with the two preceding families.
_Plesiosorex_ is another Lower Miocene type known only by the mandible,
in which there are ten teeth; it is generally referred to the
_Myogalinæ_. The minute _Amphidozotherium_, of the French Phosphorites,
is considered to be allied to _Urotrichus_.
_Family_ ADAPISORICIDÆ.
This extinct family is represented by the genera _Adapisorex_ and
_Adapisoriculus_, of the lowest Eocene of Rheims, which are regarded as
allied to the _Soricidæ_, but somewhat more specialised. In the type
genus the formula of the lower teeth is _i_ 2, _c_ 1, _p_ 4, _m_ 3; the
incisors and canine being proclivous, and the molars (of which the last
is small and without a third lobe) quadritubercular. _Adapisoriculus_ is
a smaller form with differently shaped molars.
[Illustration: FIG. 291.—The last left upper cheek-teeth of
_Pleuraspidotherium aumonieri_; from the Lowest Eocene of Rheims. _pr_,
protocone; _me_, metacone; _pa_, paracone; _b_, cingulum-cusp. (From
Osborn.)]
Here also may be mentioned the genera _Orthaspidotherium_ and
_Pleuraspidotherium_, from the above-mentioned deposits, which are
probably members of the present order. They appear to have been animals
somewhat smaller than a Hedgehog, with quadritubercular upper molars
(Fig. 291), and the hinder premolars more complex than those of the
_Erinaceidæ_. In the first-named genus the dental formula is _i_ ³⁄₃, _c_
¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃; the third and fourth upper premolars having one
outer column. _Pleuraspidotherium_ has apparently only three premolars,
of which the third and fourth (Fig. 291) have two outer columns. The
humerus in both has no entepicondylar foramen, the femur has a third
trochanter, and the astragalus is vertically perforated.
_Family_ POTAMOGALIDÆ.
Skull with a small brain-case, no zygomatic arch or postorbital process,
and the tympanic annulate and not forming a bulla. Upper molars with the
cusps arranged in a broad V, and somewhat intermediate in structure
between those of the preceding and succeeding families. No clavicle;
pubic symphysis ligamentous; tibia and fibula typically united distally.
No cæcum. Confined to the Ethiopian region.
[Illustration: FIG. 292.—_Potamogale velox._ × ¼. (From Allman, _Trans.
Zool. Soc._ vol. vi. pl. i.)]
_Potamogale._[562]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total
40. Represented only by _P. velox_ of Western Equatorial Africa. This
animal (Fig. 292) inhabits the banks of streams, and is thoroughly
adapted for an aquatic life; it is nearly 2 feet in length, the
tail measuring about half. The long cylindrical body is continued
uninterruptedly into the thick laterally compressed tail, the legs are
very short, and the toes are not webbed, progression through the water
evidently depending wholly on the action of the powerful tail, while the
limbs are folded inwards and backwards. The muzzle is broad and flat, and
the nostrils are protected by valves. The fur is dark brown above, the
extremities of the hairs on the back being of a metallic violet hue by
reflected light, beneath whitish. This curious animal was discovered by
M. du Chaillu.
_Geogale._[563]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ³⁄₂, _m_ ³⁄₃; total 34.
This genus is known solely by _G. aurita_, a small Mouse-like species
from Madagascar, agreeing closely with _Potamogale_ in the general form
of the skull and teeth. The tibia and fibula are distinct, but it is not
known whether a clavicle exists; and the material at present available is
insufficient to definitely fix the natural position of the genus.
_Family_ SOLENODONTIDÆ.
Skull with a small brain-case constricted between the orbits, no
zygomatic arch or postorbital process, and the tympanic annulated and not
forming a bulla. Upper molars tritubercular, the cusps being arranged in
a V. Pubic symphysis short; tibia and fibula distinct. Vertebræ: C 7, D
15, L 4, S 5, C 23. No cæcum. The penis is carried forwards and suspended
from the abdomen; the testes are received into perineal pouches; the
mammary glands are post-inguinal; the uterine cornua end in cæcal sacs.
[Illustration: FIG. 293.—_Solenodon cubanus._ × ⅕ (From Peters, _Abh.
Akad. Berlin_.)]
_Solenodon._[564]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total
40. This genus, with _S. paradoxus_ and _S. cubanus_ (Fig. 293), from
Hayti and Cuba respectively, alone represents the family. These species,
which differ chiefly in the colour and quality of the fur, have a
remarkably long cylindrical snout, a long naked tail, feet formed for
running, and the body clothed with long, coarse fur.
The position of the mammæ quite behind on the buttocks is unique among
Insectivora. The first upper incisor is much enlarged, and this and
the other incisors, canines, and premolars, closely resemble those of
_Myogale_; the second lower incisor is, as in _Potamogale_, much larger
than the anterior one, and is deeply hollowed out internally. While thus
apparently showing relationship with the _Talpidæ_, the form of the
crowns of the molar teeth connects them with the next family.
_Family_ CENTETIDÆ.
Skull (Fig. 294) with a small cylindrical brain-case not constricted
between the orbits, no zygomatic arch or postorbital process, and the
tympanic annulate and not forming a bulla. Upper molars tritubercular.
Pubic symphysis short; and the tibia and fibula either united or free.
No cæcum. The penis is pendent and retractile within the fold of the
integument surrounding the anus; the testes are abdominal; the mammæ
are thoracic and ventral; and the uterine cornua are terminated by the
Fallopian tubes. All the species are limited to Madagascar.
[Illustration: FIG. 294.—Left lateral view of the skull of the Tenrec
(_Centetes ecaudatus_). Reduced.]
Subfamily =Centetinæ=.—Tibia and fibula distinct; testes near kidneys;
fur with spines.
_Centetes._[565]—Dentition: _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total 38.
Vertebræ: C 7, D 19, L 5, S 3, C 8. The single species is the well-known
Tenrec (_C. ecaudatus_), characterised by the absence of a tail; it
reaches a total length of from 12 to 16 inches, and is the largest known
Insectivore. The adult males have long canines, the extremities of the
lower pair being received into pits in front of the upper ones (Fig.
294). It is probably the most prolific of all mammals, since as many as
twenty-one young are said to have been brought forth at a birth. The
young have strong white spines arranged in longitudinal lines along the
back, but these are lost in the adult animal, which is provided only with
a nuchal crest of long rigid hairs. In rare instances a fourth upper
molar may be developed.
_Hemicentetes._[566]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total
40. This genus is represented by the two species _H. semispinosus_ (of
which the skull is shown in Fig. 295) and _H. nigriceps_. It differs from
_Centetes_ by the presence of the third upper incisor, the much smaller
canines, and by the form of the skull. Both species are very much
smaller than _C. ecaudatus_, and the dorsal spines are retained in the
adult state. Vertebræ: C 7, D 16, L 5, S 3, C 9.
_Ericulus._[567]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total 36.
Vertebræ: C 7, D 17, L 6, S 4, C 9. The single species, _E. setosus_,
is a Hedgehog-like animal, having the whole upper surface and the short
tail densely covered with close-set spines. The facial bones are much
shorter than in any of the preceding genera, and the first upper incisor
is elongated, as in _Erinaceus_. Judging from the slight development of
the cutaneous muscles compared with those of the true Hedgehogs, it is
probable that complete involution of the body does not take place.
Subfamily =Oryzorictinæ=.—Tibia and fibula united; testes near urethra;
fur without spines.
[Illustration: FIG. 295.—Skull of _Hemicentetes semispinosus_. × 2. (From
Mivart, _Proc. Zool. Soc._ 1871.)]
_Microgale._[568]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total
40. This genus includes _M. longicaudata_ and _M. cowani_, both of which
are small Mouse-like species, the former with a tail double the length
of the head and body, and having 43 caudal vertebræ; teeth like those
of _Centetes ecaudatus_, but, owing to the comparatively much shorter
muzzle, not separated by wide spaces, and the last premolar and molar
with internal basal processes.
_Oryzorictes._[569]—Represented by two species, _O. hova_ and _O.
tetradactylus_, the latter distinguished by the presence of only four
digits in the manus, the three inner having long laterally compressed
fossorial claws. The general form of the head and body of the two species
known is like that of a Mole. These animals burrow in the rice-fields and
do much damage to the crops.
_Family_ CHRYSOCHLORIDÆ.
Skull conical, not constricted between the orbits, without postorbital
process, but with well-developed zygomatic arch and tympanic bulla. Upper
molars tritubercular, with the crowns very tall. No pubic symphysis; the
tibia and fibula united. The eyes are covered by the hairy integument;
the ears short and concealed by the fur; the internal generative organs
are as in _Centetinæ_; the mammæ are thoracic and inguinal and placed in
cup-shaped depressions. Habits fossorial. Confined to the southern part
of the Ethiopian region, not extending to Madagascar.
This family is closely allied to the _Centetidæ_, occupying the same
relative position with respect to that family that the _Talpidæ_ does
to the _Soricidæ_. Compared with the _Talpidæ_, we find the following
differences in the structural adaptation to a fossorial life; the
manubrium sterni is not anteriorly elongated, neither are the clavicles
shortened; but this is compensated for by a deep hollowing out of the
antero-lateral walls of the thorax, the ribs in these parts and the
sternum being convex inwards. The long clavicles have their distal
extremities pushed forward, and the concavities on the sides and inferior
surface of the thorax lodge the thick muscular arms.
[Illustration: FIG. 296.—The Golden Mole (_Chrysochloris obtusirostris_).]
_Chrysochloris._[570]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁻²⁄₃₋₂;
total 40 or 36. Vertebræ: C 7, D 19, L 3, S 5, C 8. This genus includes
some seven or eight South African species, commonly known as Golden
Moles (Fig. 296). Those species, in which the molars are reduced to ²⁄₂,
with a basal talon to the lower ones, and without a prominence in the
temporal fossa, have been placed in a separate genus, _Chalcochloris_,
by Professor Mivart. Nearly all the species have the fur of the upper
surface of a brilliant metallic lustre, varying from golden bronze to
green and violet of different shades. The manus has four digits, of which
the two outer are small, while the middle ones are large, with immensely
powerful claws.
_Extinct Types._—The only fossil forms which can be referred to
the section of the Insectivora with tritubercular molars are the
_Leptictidæ_, of the Eocene and Miocene of North America. This family
includes the genera _Leptictis_, _Mesodectes_, and _Ictops_, all of which
are regarded by Dr. Schlosser as true Insectivora, although they were
placed by Professor Cope with the Creodont Carnivora.
_Bibliography of Insectivora._—Peters, _Reise nach
Mossambique—Säugeth._ 1852; Id. “Ueber die Classification
der Insectivora,” _Monatsb. Akad. Wissensch. Berlin_, 1865,
and other papers; Mivart, “On the Osteology of Insectivora,”
_Journ. Anat. and Phys._ 1867, 1868, and _Proc. Zool. Soc._
1871; Gill, “Synopsis of Insectivorous Mammals,” _Bull. Geol.
and Geog. Survey, U.S.A._ Washington, 1875 (includes a
general bibliography of the order); Dobson, _Monograph of the
Insectivora, Systematic and Anatomical_, London, 1882-90.
CHAPTER XIII
THE ORDER CHIROPTERA.
Mammals, having their fore limbs specially modified for flight. The
forearm consists of a rudimentary ulna, and a long curved radius.
The carpus has six bones supporting a small pollex and four greatly
elongated fingers, between which and the sides of the body and the
hinder extremities a thin expansion of the integument (the wing-membrane
or patagium) is extended. The knee is directed backwards, owing to the
rotation of the hind limb outwards by the wing membrane; a peculiar
elongated cartilaginous process (the calcar), rarely rudimentary or
absent, arising from the inner side of the ankle-joint, is directed
inwards, and supports part of the posterior margin of an accessory
membrane of flight, extending from the tail or posterior extremity of
the body to the hinder limbs (the interfemoral membrane). The penis
is pendent; the testes are abdominal or inguinal; the mammary glands
thoracic and generally postaxillary; the uterus is simple or with more or
less long cornua; the placenta discoidal and deciduate; and the smooth
cerebral hemispheres do not extend backwards over the cerebellum. The
dental series includes incisors, canines, premolars, and molars and never
exceeds _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total 38.
The animals comprised in this order are at once distinguished by the
presence of true wings, and this peculiarity is accompanied by other
modifications of bodily structure having special relation to flight.
Thus, in contrast to most other mammals, in which the hind limbs greatly
preponderate in size over the fore, in the present order the fore limbs
immensely exceed the short and weak hinder extremities. The thorax, as
giving origin to the great muscles which sustain flight, and containing
the proportionately large lungs and heart, is remarkably capacious, and
the ribs are flattened and close together; the shoulder-girdle is also
greatly developed in comparison with the weak pelvic bones.
Linnæus included the Bats among the Primates, mainly on account of the
number of their upper incisors, supposed to be always four, the thoracic
position of the mammæ, and the pendent condition of the penis. Many
other zoologists, taking into consideration the placental characters and
the form of the uterus, have followed him; but it is evident that the
situation of the mammæ is related to the necessarily central position of
the young during flight, the shortness of the uterine cornua, observable
in so many species, to the generally uniparous gestation requiring less
room, while the discoidal deciduate placenta is equally present in and
characteristic of the Insectivora, many species of which also have the
penis pendent. Thus, the reasons for maintaining the Bats in this high
position being disposed of, we find in the low organisation of their
brain a proof of their inferior status; while furthermore, although they
differ widely from all other mammals in external form, it is evident that
this is only the result of special adaptation to aerial locomotion; and,
taking into account their whole bodily structure, we may accept the view
of Professor Huxley that they should merely be regarded as exceedingly
modified Insectivora.
So thoroughly, however, has this adaptation for flight been carried out
that of all animals the Bats are the least terrestrial, not one of them
being equally well fitted for progression on the earth. This is due to
the hind as well as the fore limbs being pressed into the service of
aerial locomotion. Thus the hind limb is so rotated outwards by the
wing-membrane that, contrary to what obtains in all other vertebrates,
the knee is directed backwards, and corresponds in position to its serial
homologue the elbow. It necessarily follows from this arrangement that
when a Bat is on the ground it rests on all fours, having the knees
directed upwards; while, in order to bring it into a position for forward
progression, the foot rotates forwards and inwards on the ankle. Walking
under these circumstances is at best only a kind of shuffle, and that
this is fully recognised by the animal is evidenced by its great anxiety
to take wing, or, if this be impracticable, to ascend to some point
where it can hitch itself up by the claws of the hind legs in its usual
position when at rest.
[Illustration: FIG. 297.—Skeleton and flying-membranes of the Noctule
Bat (_Vesperugo noctula_). × ⅓. _c_, Clavicle; _h_, humerus; _r_,
radius; _u_, ulna (rudimentary); _d¹_, pollex; _d²_, _d³_, _d⁴_, _d⁵_,
other digits of the manus supporting _wm_, the wing-membrane; _m_, _m_,
metacarpal bones; _ph¹_, first phalanx; _ph²_, second phalanx; _ph³_,
third phalanx; _am_, antebrachial membrane; _f_, femur; _t_, tibia; _fb_,
fibula (rudimentary); _c_, calcar supporting _im_, the interfemoral
membrane; _pcl_, postcalcaneal lobe.]
The bones of the skeleton are characterised by their slenderness and
the great size of the medullary canals in those of the extremities.
The vertebral column is short, and the vertebræ differ very slightly
in number and form throughout the species. The general number of the
dorso-lumbar vertebræ is 17, of which 12 are dorsal; the cervicals are
very broad, but short from before backwards, their breadth being due to
the great transverse diameter of the spinal canal rendered necessary by
the comparatively large size of the spinal cord, which, after giving off
the nerves to the fore limbs and thorax, rapidly diminishes in size,
and in the lumbo-sacral region is reduced to a fine thread. Except in
the frugivorous _Pteropodidæ_, the vertebræ, from the third cervical
backwards, are devoid of neural spines. From the first dorsal to the
last lumbar vertebra the spinal column forms a single curve backwards,
which is most pronounced in the lumbar region. The centra of the vertebræ
are but slightly movable upon each other, and in old individuals appear
to become partially ankylosed together. The caudal vertebræ are simple
cylindrical bones without processes; their number and length being
extremely variable even in closely allied species; and the anterior
caudals are generally united to the ischial tuberosities. The relative
development of the caudal vertebræ is, indeed, intimately correlated
to the habits of the animals; the long tail in the insectivorous forms
supporting and controlling the position of the large interfemoral
membrane, which appears not only to aid their rapid motions when in
pursuit of their prey by acting as a rudder, but also to assist in the
capture and retention of the larger insects. In the frugivorous types,
on the other hand, this is not required, and the tail is accordingly
rudimentary or absent. In all Bats the presternum has a prominent keel
for the attachment of the great pectoral muscles. In most species the
ribs are much flattened, and in some they are partially ankylosed by
their contiguous margins.
The skull is subject to considerable structural variations, even
within the limits of a single family. Postorbital processes to the
frontals are found only in the _Pteropodidæ_, and some _Nycteridæ_ and
_Emballonuridæ_. _Pteropus leucopterus_ and _Pteralopex_ are peculiar in
having the orbit completely surrounded by bone. A slender zygomatic arch
is present, except in some of the _Phyllostomatidæ_.
The milk-teeth are peculiar in that they are utterly unlike those of the
permanent series. They are slender, with sharp recurved cusps; and as a
rule are shed at an early period (in the _Rhinolophidæ_ before birth),
but may coexist with some of the fully developed permanent teeth. The
permanent teeth are subject to great variation of form, although they
always have distinct roots. In the Insectivorous types they are acutely
cusped, the cusps in those of the upper jaw being arranged in a more or
less distinct W; but in the frugivorous forms, like the _Pteropodidæ_ and
some of the _Phyllostomatidæ_, the molars are longitudinally grooved or
hollowed out.
The pectoral girdle maintains a very constant type. Thus the clavicle is
very long, strong, and curved; and the scapula large, oval, triangular,
with a long curved coracoid process. The humerus, though long, is
scarcely two-thirds the length of the radius. The ulna is rudimentary,
its proximal extremity, which articulates with but a small part of the
humerus, being ankylosed to the radius; and immediately beyond the joint
it is reduced to a slender splint-like bone, extending about as far
as the middle of the radius. In all species a detached sesamoid bone
exists in the tendon of the triceps muscle. The radius is very long,
in some species actually equal to the length of the head and body. The
proximal row of the carpus consists of a single bone formed by the united
scaphoid, lunar, and cuneiform; which, with the extremity of the radius,
forms the radio-carpal joint. In the distal row the trapezium, trapezoid,
and magnum vary in size in the different families, the unciform appearing
to be the most constant, and the pisiform being generally very small.
The manus is always furnished with five digits. The first, fourth, and
fifth digits consist of a metacarpal and two phalanges; but in the
second and third digits the number of phalanges is different in certain
families. The pollex always terminates in a claw, which—like the proximal
phalanx—is best developed in the frugivorous species. In most of the
frugivorous _Pteropodidæ_ the second digit is provided with a claw; but
in all other Bats this and the remaining digits are unarmed. In the
genus _Triænops_ alone a very peculiar short bony process projects from
the outer side of the proximal extremity of the terminal phalanx of the
fourth digit. The relative development of the digits and their phalanges
will be noticed under each family.
As might be expected from the small size of the posterior limbs, the
pelvic girdle is relatively weak. The ilia are long and narrow. In the
males of most species the pubic bones of opposite sides are very loosely
united in front, while in females they are widely separated; and in
the family _Rhinolophidæ_ alone do these bones form a symphysis. The
ileo-pectineal eminence develops a long pectineal process, which in the
subfamily _Hipposiderinæ_ is continued forwards to the anterior extremity
of the ilium enclosing a preacetabular foramen unique among mammals. The
acetabulum is small and directed outwards and slightly upwards; and with
this is related the peculiar position of the hind limb already noticed
as one of the chief characteristics of the order. The femur is slender
and cylindrical, with a small head and very short neck, and scarcely
differs in form throughout the order. The bones of the leg and foot are
variable; in the subfamily _Molossinæ_ alone is there a well-developed
fibula, while in all other species this bone is either very slender, or
cartilaginous and ligamentous in its upper third, or reduced to a small
bony process above the heel, as in _Megaderma_, or altogether absent, as
in _Nycteris_.
The foot consists of a very short tarsus, and of slender, laterally
compressed toes, with much curved claws. The hallux is composed of a
metacarpal, a proximal and an ungual phalanx, and is slightly shorter
than the other four toes, each of which has an additional phalanx, except
in the subfamily _Hipposiderinæ_ and in the anomalous genera _Thyroptera_
and _Myxopoda_, where all the toes have the same number of phalanges as
the first digit, and are equal to it in length. In the genus _Chiromeles_
the first digit is thumb-like and separated from the others, and in the
typical _Molossinæ_ the first and fifth digits are much thicker than the
intermediate toes.
The most noticeable peculiarities in the myology of the order consist in
the separated bands or slips into which the platysma is divided, and in
the presence of the remarkable muscle termed occipito-pollicalis, which
extends from the occipital bone to the base of the terminal phalanx of
the pollex.
Although, as already mentioned, the brain presents a low type of
organisation, yet probably no animals possess so delicate a sense of
touch as the Chiroptera. It is undoubtedly this perceptive power which
enabled the individuals deprived of sight, hearing, and smell, in
Spallanzani’s well-known experiments, to avoid the numerous threads hung
across the rooms in which they were permitted to fly about. In the
common Bats the tactile organs evidently exist, not only in the delicate
vibrissæ which spring from the sides of the muzzle, but also in the
highly sensitive and widely extended integumentary structures entering
into the formation of the wing-membranes and ear-conchs; while in many
other species, notably in the tropical Rhinolophine and Phyllostomatine
Bats, peculiar foliaceous cutaneous expansions surrounding the nasal
apertures or extending backwards behind them are added. These structures,
collectively known as the “nose-leaf” (whence the term “leaf-nosed
Bats”), have been shown by Dr. Dobson to be made up partly of the
extended and thickened marginal integument of the nostrils, and partly of
the highly differentiated glandular eminences occupying the sides of the
muzzle, in which, in all the common Bats, the vibrissæ are implanted.
In all species of leaf-nosed Bats, and especially in the _Rhinolophidæ_,
where the nasal appendages reach their highest development, the superior
maxillary division of the fifth nerve is of remarkably large calibre.
The nasal branch of this nerve, which is given off immediately beyond
the infraorbital foramen, is by far the largest portion; the palpebral
and labial branches consisting of a few slender nerve-fibres only. This
branch passes forwards and upwards on the side of the maxilla, but soon
spreads out into numerous filaments extending into the muscles and
integument above, and into the base of the nose-leaf. The nerve supply
of the nose-leaf is further augmented by the large nasal branch of the
ophthalmic division of the fifth nerve. While the many foliations,
elevations, and depressions which vary the form of the nose-leaf
greatly increase the sensory surface supplied by the fifth nerve, and
during rapid flight intensify the vibrations conveyed to it, the great
number of sweat and oil glands which enter into its structure perform
a function analogous to that of the glands of the auditory canal in
relation to the membrana tympani in maintaining its surface in a highly
sensitive condition. The nasal appendages of the Chiroptera may thus be
regarded as performing the office of an organ of a very exalted sense
of touch standing in the same relation to the nasal branches of the
fifth nerve as the aural apparatus to the auditory nerve; for, as the
latter organ collects and transmits the waves of sound, so the former
receives impressions arising from vibrations communicated to the air by
approaching objects.
In no order of mammals is the ear-conch so greatly developed or so
variable in form. Thus in most of the insectivorous species the ears
are longer than the head, while in some, as in the common Long-eared
Bat (_Plecotus auritus_), their length nearly equals that of the head
and body. The form of the conch is very characteristic of the various
families; in most the tragus is remarkably large, in some extending
nearly to the outer margin of the conch; and its function appears to be
to cause undulations in the waves of sound, and so intensify and prolong
them. It is worthy of notice that in the _Rhinolophidæ_, the only family
of insectivorous Bats wanting the tragus, the auditory bullæ reach their
greatest size, and the highly sensitive nasal appendages their highest
development; and that in the typical group of the _Molossinæ_ the
ear-conch is divided by a prominent keel; and the antitragus is unusually
large in those species in which the tragus is minute (see Fig. 298, _a_).
In the frugivorous Bats the form of the ear-conch is very simple, and but
slightly variable, throughout the various types.
[Illustration: FIG. 298.—Head of _Molossus glaucinus_. (From Dobson,
_Proc. Zool. Soc._ 1876.) _a_, Antitragus; _b_, keel of the ear-conch;
_c_, notch behind antitragus.]
In all Bats the ears are extremely mobile, each moving independently at
the will of the animal. This has been observed even in the frugivorous
_Pteropodidæ_, in which the peculiar vibratory movements first noticed in
_Artibeus perspicillatus_ may also be seen when the animals are alarmed.
The opening of the mouth is anterior in most species, but in many it is
inferior, the extremity of the nose being more or less produced beyond
the lower lip,—so much so indeed in the small South-American species
_Rhynchonycteris naso_ as to resemble that of the Shrews. The lips
exhibit the greatest variety in form, which will be referred to under
each family. The absence of a fringe of hairs is characteristic of all
fruit-eating Bats, and probably always distinguishes them from the
insectivorous species, which they may resemble in the form of their teeth
and other respects.
The œsophagus is narrow in all species, and especially so in the
sanguivorous Desmodont _Phyllostomatidæ_. The stomach presents two
principal types of structure, which correspond respectively to the two
great divisions of the order, the Megachiroptera and the Microchiroptera;
in the former (with the exception of _Harpyia_) the pyloric extremity
is more or less elongated and folded upon itself, in the latter it is
simple, as in the Insectivora Vera; a third exceptional type is met with
in the Desmodont _Phyllostomatidæ_, where the left or cardiac extremity
is greatly elongated, forming a long narrow cæcum-like appendage.
The intestine is comparatively short, varying from one and a half
to four times the length of the head and body, being longest in the
frugivorous and shortest in the insectivorous species. Only in _Rhinopoma
microphyllum_ and _Megaderma spasma_ has a very small cæcum been found.
The liver is characterised by the great size of the left lateral lobe,
which occasionally equals half the size of the whole organ; the right
and left lateral fissures are usually very deep; in the Megachiroptera
(_Harpyia_ excepted) the Spigelian lobe is ill-defined or absent, and
the caudate is generally very large; but in the Microchiroptera, on the
other hand, the Spigelian lobe is very large, while the caudate is small,
in most species forming a ridge only. The gall-bladder is generally
well developed and attached to the right central lobe, except in the
_Rhinolophidæ_, where it is connected with the left central.
In most species the hyoids are simple, consisting of a chain of
slender, elongated, cylindrical bones connecting the small basi-hyoid
with the cranium, while the pharynx is short, the larynx shallow with
feebly developed vocal cords, and guarded by a short, acutely-pointed
epiglottis, which in some genera (_Harpyia_, _Vampyrus_) is almost
obsolete. In _Epomophorus_, however, we find a remarkable departure
from the general type. Thus the pharynx is long and very capacious; the
aperture of the larynx is far removed from the fauces, and, opposite to
it, opens a canal, leading from the narial chambers, and extending along
the back of the pharynx; the laryngeal cavity is spacious and its walls
are ossified; the hyoid bone is quite unconnected, except by muscle, with
the cranium; the ceratohyals and epihyals are cartilaginous and greatly
expanded, entering into the formation of the walls of the pharynx, and in
the males of three species at least, supporting the orifices of a large
pair of air-sacs communicating with the pharynx (Fig. 299).
[Illustration: FIG. 299.—Head and neck of _Epomophorus franqueti_ (adult
male, natural size). The anterior (_a.ph.s_) and posterior (_p.ph.s_)
pharyngeal sacs are opened from without, the dotted lines indicating the
points where they communicate with the pharynx; _s_, thin membranous
septum in middle line between the anterior pharyngeal sacs of opposite
sides; _s.m._, sterno-mastoid muscle separating the anterior from the
posterior sac. (Dobson, _Proc. Zool. Soc._ 1881.)]
In extent, peculiar modifications, and sensitiveness the cutaneous
system reaches its highest development in this order. As a sensory organ
its chief modifications in connection with the external ear and with the
nasal and labial appendages have been described when referring to the
nervous system. It remains therefore to consider its relative development
as part of the organs of flight.
The extent and shape of the flying-membranes depend mainly on the form of
the bones of the anterior extremities, and on the presence or absence of
the tail. Certain modifications of these membranes, however, are met with
which do not depend on the skeleton, but are related to the habits of the
animals, and to the manner in which the wing is folded in repose.
These membranes consist of the “antebrachial membrane,” extending from
the point of the shoulder along the humerus and more or less of the
forearm to the base of the pollex, the metacarpal bone of which is
partially or wholly included in it; the “wing-membrane,” which is spread
out between the greatly elongated fingers, and extends along the sides
of the body to the posterior extremities, generally reaching to the
feet; and the “interfemoral membrane,” the most variable of all, which
is supported between the extremity of the body, the legs, and the calcar
(Fig. 297).
[Illustration: FIG. 300.—Frontal sac and nose-leaf in male and female of
_Hipposiderus larvatus_. (Dobson, _Proc. Zool. Soc._ 1873.)]
The antebrachial and wing-membranes are most developed in those species
fitted only for aerial locomotion, which when at rest hang with the body
enveloped in the wings; but in the family _Emballonuridæ_, and especially
in the subfamily _Molossinæ_ (the species of which are the best fitted
of all Bats for terrestrial progression), the antebrachial membrane is
reduced to the smallest size, and is not developed along the forearm,
leaving also the pollex quite free, and the wing-membrane is very
narrow and folded in repose completely under the forearm. The relative
development of the interfemoral membrane has been referred to above
in describing the caudal vertebræ. Its small size in the frugivorous
and sanguivorous species, in which its presence would be injurious as
impeding their motions when searching for food as they hang suspended
by their feet, is easily understood. Odoriferous glands and pouches
opening on the surface of the outer skin are developed in many species,
but in most cases more so in males than in females, and thus constitute
secondary sexual characters, which will be referred to when treating of
the peculiarities of certain species.
All the fossil Chiroptera at present known are true Bats in every sense
of the word, and therefore throw no light on the origin of the order.
The earliest representatives of the order occur in beds of Upper Eocene
(Lower Oligocene) age.
The order is divided by Dobson into the suborders Megachiroptera and
Microchiroptera.
_Suborder_ MEGACHIROPTERA.
Frugivorous Bats, generally of large size. Crowns of molars smooth,
marked with a longitudinal groove (cuspidate in _Pteralopex_); bony
palate continued behind the last molar, narrowing slowly backwards; three
phalanges in the index finger, the third phalanx generally terminated by
a claw; sides of the ear-conch forming a complete ring at the base; tail,
when present, inferior to (not contained in) the interfemoral membrane;
pyloric extremity of the stomach generally much elongated; the Spigelian
lobe of the liver ill-defined or absent, and the caudate well developed.
Limited to the tropical and subtropical parts of the eastern hemisphere.
Mr. O. Thomas[571] considers that the ordinary type of molar dentition
found in this suborder is a specialised adaptation from the cuspidate
type of the Microchiroptera; the genus _Pteralopex_ retaining the
ancestral form of teeth.
_Family_ PTEROPODIDÆ.
Since all the forms are included in this family its characters may be
taken to be the same as those of the suborder.
Subfamily =Pteropodinæ=.—Tongue moderate; molars well developed.
_Epomophorus._[572]—Dentition: _i_ ²⁻¹⁄₂, _c_ ¹⁄₁, _p_ ²⁄₃, _m_ ¹⁄₂;
total 28 or 26. Tail absent or very short, when present free from
interfemoral membrane; second digit of manus clawed; premaxillæ united.
This genus includes some seven species inhabiting Africa south of the
Sahara. The head is large and long, and the lips are expansible, and
frequently with peculiar folds. The ears have a white tuft of hair on
the margin; and in the males of most species there are large glandular
pouches in the skin of the side of the neck near the shoulder, from the
mouth of which project long and coarse yellowish hairs, forming tufts
on the shoulders, from which the genus takes its name. Another male
secondary sexual character consists in the presence of a pair of large
air-sacs extending outwards on each side from the pharynx beneath the
integument of the neck, in the position shown in Fig. 299. These sacs
are evidently capable of being greatly distended at the will of the
animal, and their inflation probably occurs under the same circumstances
that the wattles of male gallinaceous birds swell up, namely, when
engaged in courting the females. Other remarkable conditions in which
these Bats appear to differ from all other species occur in the form of
the hyoid bones and larynx. These Bats appear to live principally on
figs, the juicy contents of which their large lips and capacious mouths
enable them to swallow without loss.
[Illustration: FIG. 301.—Head of Fox-Bat (_Pteropus personatus_). From
Gray, _Proc. Zool. Soc._ 1866.]
_Pteropus._[573]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ²⁄₃; total 34.
This genus has more than forty species, and thus includes more than half
the members of the family. All are of large size, and the absence of a
tail, the long pointed muzzle (Fig. 301), and the woolly fur covering the
neck render their recognition easy. They are commonly known as “Flying
Foxes,” or Fox-Bats; and one of the species (_P. edulis_) inhabiting Java
measures 5 feet across the fully extended wings, and is thus the largest
known species of the order. All the species closely resemble one another
in dentition, and are mainly distinguished by the form of the ears and
the quality of the fur. _P. scapulatus_, from North-East Australia,
approaches the species of the second subfamily in the remarkable
narrowness of its molars and premolars.
The range of this genus extends from Madagascar and the neighbouring
islands through the Seychelles to India, Ceylon, Burma, the Malay
Archipelago, Southern Japan, New Guinea, Australia, and Polynesia (except
the Sandwich Islands, Ellice’s Group, Gilbert’s Group, Tokelau, and the
Low Archipelago). Of the islands inhabited by it some are very small and
remote from any continent, such as Savage Island in the South Pacific and
Rodriguez in the Indian Ocean. Although two species inhabit the Comoro
Islands, which are scarcely 200 miles from the African coast, not a
single species is found in Africa; but in India, separated by thousands
of miles of almost unbroken ocean, a species exceedingly closely allied
to the common Madagascar Fox-Bat is abundant. The Malay Archipelago
and Australia are their headquarters; and in some places they occur in
countless multitudes. Mr. Macgillivray remarks of _P. conspicillatus_:
“On the wooded slope of a hill on Fitzroy Island I one day fell in with
this Bat in prodigious numbers, looking while flying in the bright
sunshine (so unusual for a nocturnal animal) like a large flock of rooks.
On close approach a strong musky odour became apparent, and a loud
incessant chattering was heard. Many of the branches were bending under
their load of Bats, some in a state of inactivity, suspended by their
hind claws, others scrambling along among the boughs, and taking to wing
when disturbed.”
[Illustration: FIG. 302.—Female and young of _Xantharpyia collaris_.
(From Sclater, _Proc. Zool. Soc._ 1870, p. 127.)]
_Xantharpyia._[574]—Dentition as in _Pteropus_, but a short tail present,
and the fur on the back of the neck similar to that of the body. This
genus is represented by some nine species, which have a distribution very
similar to that of _Pteropus_, except that they extend into Africa, and
are not found in Australia and Polynesia. _X. ægyptiaca_ inhabits the
chambers of the Great Pyramid and other deserted buildings in Egypt, and
is probably the species so generally figured in Egyptian frescoes. Fig.
302 exhibits an African species of this genus in the attitude assumed by
the Fox-Bats when at rest.
_Boneia._[575]—This genus, as represented by _B. bidens_ of Borneo,
differs from _Xantharpyia_ in having only a single pair of upper incisors.
_Cynopterus._[576]—Dentition: _i_ ²⁄₂₋₁, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ²⁄₂; total
32 or 30. Muzzle short, grooved like _Pteropus_ in front; tail and fur
generally as in _Xantharpyia_, but the former sometimes wholly absent.
This genus, with seven species, is almost limited to the Oriental region.
_C. marginatus_ is very common in India, and extremely destructive to
ripe fruit of every description. Dr. Dobson states that “he gave to a
specimen of this Bat obtained at Calcutta a ripe banana, which, with the
skin removed, weighed exactly 2 ounces; the animal immediately, as if
famished with hunger, fell upon the fruit, seizing it between the thumbs
and the index fingers, and took large mouthfuls out of it, opening the
mouth to the fullest extent with extreme voracity. In the space of three
hours the whole fruit was consumed. Next morning the Bat was killed, and
found to weigh one ounce, or half the weight of the food eaten in three
hours. Indeed the animal when eating seemed to be a kind of living mill,
the food passing from it almost as fast as devoured, and apparently
unaltered, eating being, as it were, performed only for the pleasure of
eating.”
_Harpyia._[577]—Dentition: _i_ ¹⁄₀, _c_ ¹⁄₁, _p_ ²⁄₃, _m_ ²⁄₂; total 24.
Premaxillæ well developed and united in front; facial bones much elevated
above the margin of the jaw, nostrils tubular (Fig. 303); body and
limbs as in _Cynopterus_. Includes two species from the Austro-Malayan
sub-region, readily recognised by the peculiar tubular and projecting
nostrils, as shown in the accompanying woodcut.
[Illustration: FIG. 303.—Head of _Harpyia major_. (From Dobson, _Proc.
Zool. Soc._ 1877.)]
_Cephalotes._[578]—Dentition: _i_ ¹⁄₁, _c_ ¹⁄₁, _p_ ²⁄₃, _m_ ²⁄₃; total
28. Premaxillæ separate in front; nostrils simple; muzzle short; index
finger without a claw; tail short. Includes one species, having the same
distribution as _Harpyia_. The wing-membrane arises from the middle line
of the back, to which it is attached by a longitudinal very thin process
of the integument; the wings are quite naked, but the back covered by
them is clothed with hair.
_Pteralopex._[579]—External characters as in _Pteropus_; ears short
and hairy; wings arising from the middle line of the back. Muzzle very
short; plane of orbit directed more upwards than in _Pteropus_; orbit
surrounded by bone; sagittal crest strongly developed. Teeth cuspidate;
upper incisors with broad posterior ledges; upper canine short and thick,
with a stout secondary cusp in the middle of the posterior border, and
two smaller postero-internal basal cusps; cheek-teeth short and broad,
with their anterior and posterior basal ledges so developed and the main
cusps so nearly conical as to obliterate the longitudinal grooving of
_Pteropus_. Lower incisors very disproportionate, the outer pair being
nearly twenty times the bulk of the inner; lower canine stout, with a
simple posterior basal ledge. Represented by _P. atrata_ of the Solomon
Islands. As already mentioned, Mr. Thomas regards the dentition of this
genus as the most generalised type found in the suborder.
Subfamily =Carponycterinæ=.—Facial part of skull much produced; molars
narrow, and scarcely raised above the gum; and the tongue exceedingly
long, attenuated in the anterior third, and armed with long recurved
papillæ near the tip.
_Notopteris._[580]—Dentition: _i_ ²⁄₁, _c_ ¹⁄₁, _p_ ²⁄₃, _m_ ²⁄₂; total
28. Index finger without a claw; wings arising from the middle line of
the back; tail long; first upper premolar long, with two roots. The
single representative of the genus, _N. macdonaldi_, inhabits the Fiji
Islands, Aneiteum Island, and New Guinea. It is at once distinguished
from all other Bats of this family by the length of its tail, which is
nearly as long as the forearm.
_Eonycteris._[581]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ²⁄₃;
total 34. First upper premolar small, with a single root. This genus
is likewise represented by a single species (_E. spelæa_), from the
Farm Caves, Moulmein, Burma, which has somewhat the appearance of
_Xantharpyia_; but the absence of a claw to the index finger and the
characteristic tongue and teeth at once distinguish it.
_Carponycteris_[582] and _Melonycteris_,[583] each with a single
species, are closely allied; the index finger in both has a claw, and
the number of the teeth is the same as in _Eonycteris_. _Carponycteris
minima_ is the smallest known species of the suborder, being much smaller
than the common Noctule Bat of Europe, and its forearm scarcely longer
than that of the Long-eared Bat. It is nearly as common in certain
parts of India as _Cynopterus marginatus_ (compared with which it is
proportionally equally destructive to fruit), and extends eastward
through the Malay Archipelago as far as New Ireland, where it is
associated with _Melonycteris melanops_, distinguished from it by its
larger size and the total absence of the tail.
_Nesonycteris._[584]—Dentition: _i_ ²⁄₁, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ²⁄₃; total
32. Allied to _Melonycteris_, but distinguished by the absence of the
inner pair of lower incisors, and of a claw to the index finger. Tail
wanting. Represented by _N. woodfordi_, of the Solomon Islands.
_Callinycteris._[585]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ²⁄₂, _m_ ³⁄₃;
total 32. Allied to the preceding, but with a short tail; no claw to
index. One species from Celebes.
_Trygenycteris._[586]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ²⁄₃;
total 34. No external tail; a claw on index. One species from West Africa.
_Suborder_ MICROCHIROPTERA.
Insectivorous (rarely frugivorous or sanguivorous) Bats, of comparatively
small size. Crowns of molars acutely cusped, marked by transverse
grooves; bony palate narrowing abruptly, not continued backwards
laterally behind the last molar; one rudimentary phalanx (rarely two
phalanges or none) in the index finger, which is never terminated
by a claw; outer and inner sides of ear-conch commencing inferiorly
from separate points of origin; tail, when present, contained in the
interfemoral membrane, or appearing upon its upper surface; stomach
simple (except in the Desmodont _Phyllostomatidæ_); Spigelian lobe of the
liver very large, and the caudate generally small. Inhabit the tropical
and temperate regions of both hemispheres. The members of this suborder
may be divided into two sections.
_Section_ VESPERTILIONINA.
Tail contained within the interfemoral membrane; the middle pair of upper
incisors never large, and separated from each other by a more or less
wide space. Middle finger with two osseous phalanges only (except in
_Myxopoda aurita_, _Thyroptera tricolor_, and _Mystacops tuberculatus_).
First phalanx of the middle finger extended (in repose) in a line with
the metacarpal bone.
_Family_ RHINOLOPHIDÆ.
In all the species of this family the nasal appendages are highly
developed, and surround the sides of the nasal apertures, which are
situated in a depression on the upper surface of the muzzle; the ears are
large and generally separate, without trace of a tragus; the premaxillæ
are rudimentary, suspended from the nasal cartilages, and supporting
a pair of very small incisors; the molars have acute W-shaped cusps;
the skull is large, and the nasal bones which support the large nasal
cutaneous appendages are much expanded vertically and laterally; in
the females a pair of teat-like appendages are found in front of the
pubis; and the tail is long and produced to the posterior margin of the
interfemoral membrane. This family is found in the temperate and tropical
parts of the eastern hemisphere.
From whatever point of view the _Rhinolophidæ_ may be considered, they
are evidently the most highly organised of insectivorous Bats. In them
the osseous and cutaneous systems reach the most elaborate development.
Compared with those of the present family the bones of the extremities
and the flying-membranes of other Bats appear coarsely formed, and
even their teeth seem less perfectly fitted to crush the hard bodies
of insects. The very complicated nasal appendages, which evidently act
as delicate organs of special perception, here reach their highest
development, and the differences in their form afford valuable characters
in the discrimination of the species, which resemble one another very
closely in dentition and in the colour of the fur.
Subfamily =Rhinolophinæ=.—First toe with two, other toes with three,
phalanges each; ilio-pectineal spine not connected by bone with the
antero-inferior surface of the ilium.
[Illustration: FIG. 304.—Head of Indian Horse-shoe Bat (_Rhinolophus
mitratus_). (From Dobson, _Monogr. Asiat. Chiropt._)]
_Rhinolophus._[587]—Dentition: _i_ ¹⁄₂, _c_ ¹⁄₁, _p_ ²⁄₃, _m_ ³⁄₃;
total 32. Nose-leaf (Fig. 304) with a central process behind and
between the nasal orifices, posterior extremity lanceolate, antitragus
large. Includes more than twenty species. _R. luctus_, in which the
forearm has a length of 3 inches, is the largest species, inhabiting
elevated hill tracts in India and Malayana; _R. hipposiderus_ of Europe,
extending into South England and Ireland, forearm 1·5 inches, is one
of the smallest; and _R. ferrum-equinum_, with the forearm 2·3 inches
in length, represents the average size of the species, which are
mainly distinguished from one another by the form of the nose-leaf.
The last-named species extends from England to Japan, and southward to
the Cape of Good Hope. The genus is represented in the Himalaya by the
closely allied _R. tragatus_, distinguished by having three vertical
grooves on the lower lip, in place of the single groove found in _R.
ferrum-equinum_. _Rhinolophus_ is represented in the Upper Eocene
Phosphorites of Central France by _R. antiquus_ and _R. dubius_; the
former appears to have the same dental formula as in the existing
species, but differs slightly in the structure of some of the lower
molars, so that it is separated generically by some writers under the
name of _Pseudorhinolophus_. The face is also longer than in existing
forms, and there are certain differences in the structure of the skull.
_Alastor_, from the same deposits, differs from _Rhinolophus_ by the
extreme shortness of the nasal region. _Palæonycteris_, from the Lower
Miocene of France, is said to be allied to _Rhinolophus_, but the
premolars are ³⁄₃, and the limb bones are stated to resemble those of
_Molossus_.
Subfamily =Hipposiderinæ=.—Toes equal, of two phalanges each;
ilio-pectineal spine united by a bony isthmus with a process derived from
the antero-inferior surface of the ilium.
[Illustration: FIG. 305. Head of _Hipposiderus calcaratus_. (From Dobson,
_Proc. Zool. Soc._ 1877.)]
_Hipposiderus._[588]—Dentition: _i_ ¹⁄₂, _c_ ¹⁄₁, _p_ ²⁻¹⁄₂, _m_ ³⁄₃;
total 30 or 28. Tail well developed. This genus, of which more than
twenty species have been described, differs from _Rhinolophus_ in the
form of the nose-leaf, which is not lanceolate behind and is unprovided
with a central process covering the nostrils. The largest species,
_H. armiger_, appears to be the most northerly, having been taken at
Amoy in China, and in the Himalaya at an elevation of 5,500 feet. Many
of the species are provided with a peculiar frontal sac behind the
nose-leaf, rudimentary in females (Fig. 305), which the animal can evert
at pleasure; the sides of this sac secrete a waxy substance, and its
extremity supports a pencil of straight hairs.
_Anthops._[589]—Like _Hipposiderus_, but with the tail rudimentary,
consisting merely of three or four vertebræ hidden in the base of the
interfemoral membrane. Nose-leaf very complicated, its upright transverse
portion emarginate above, and the projections rounded and hollowed
behind, and their substance quite thin. Premolars ²⁄₂. Represented by _A.
ornatus_ of the Solomon Islands.
Mr. O. Thomas, the describer of this Bat, remarks that it is evidently
more nearly allied to the preceding than to the succeeding genera,
although it agrees with _Cœlops_ in the rudimentary tail.
_Rhinonycteris_[590] and _Triænops_.[591]—These are two allied genera
with well-developed tails; the former being represented by _R. aurantia_
from Australia, and the latter by _T. persicus_ from Persia and Eastern
Africa. _Triænops_ (Fig. 306) is characterised by the remarkable form of
its nasal appendages and ears, and the presence of a peculiar osseous
projection from the proximal extremity of the second phalanx of the
fourth finger.
[Illustration: FIG. 306.—Head of _Triænops persicus_. × 2. (From Dobson,
_Monogr. Asiat. Chiropt._)]
_Cœlops._[592]—This genus is known only by a single species, _C. frithi_,
from the Bengal Sunderbans, Java, and Siam (in the roof of the great
pagoda at Laos); and is distinguished, not only by the form of its
nose-leaf, but also by the great length of the metacarpal of the index
finger, as well as by the shortness of the calcar and interfemoral
membrane and the rudimental tail.
_Family_ NYCTERIDÆ.
This small family, including only two genera of Bats of peculiar aspect,
limited to the tropical and subtropical parts of the eastern hemisphere,
is distinguished from the _Rhinolophidæ_ by the presence of a distinct
tragus to the ear, and by the premaxillæ being cartilaginous or small and
separated from one another in front by a distinct space.
_Megaderma._[593]—Dentition: _i_ ⁰⁄₂, _c_ ¹⁄₁, _p_ ²⁻¹⁄₂, _m_ ³⁄₃; total
28 or 26. This genus, which is represented by five species, is readily
recognised by the absence of upper incisors, the cylindrical narrow
muzzle surmounted by an erect naked cutaneous nose-leaf, the base of
which conceals the nasal orifices, by the immense connate ears with large
bifid tragi, and by the great extent of the interfemoral membrane, in
the base of which the very short tail is concealed. _M. gigas_ (Fig.
307), from Central Queensland (length of forearm 4·2 inches), is not
only the largest species of the genus but also of the suborder. _M.
lyra_, common in India (forearm 2·7 inches), has been caught in the act
of sucking the blood, while flying, from a small species of _Vesperugo_,
which it afterwards devoured, so that it is probable that the Bats of
this genus do not confine themselves to insect prey alone, but also feed,
when they can, upon the smaller species of Bats and other small mammals.
[Illustration: FIG. 307.—_Megaderma gigas._ × ½. (From Dobson, _Proc.
Zool. Soc._ 1880.)]
The Oriental _M. spasma_ and _M. lyra_ differ from the Ethiopian _M. cor_
and _M. frons_ in having two upper premolars instead of one, and also in
the shape of the frontals and nasals.
_Nycteris._[594]—Dentition: _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ¹⁄₂, _m_ ³⁄₃; total
32. This genus, of which there are seven species, differs so much from
_Megaderma_ that it may be considered the type of a separate subfamily.
As in that genus, the frontal bones are deeply hollowed out and expanded
laterally, the muzzle presents a similar cylindrical form, and the lower
jaw also projects, but the single elevated nose-leaf is absent, and
instead of it the face is marked by a deep, longitudinal, sharp-edged
groove extending from the nostrils (which are on the upper surface of
the muzzle, near its extremity) to the low band connecting the bases of
the large ears, the sides of this depression being margined as far back
as the eyes by small horizontal cutaneous appendages. All the species
resemble one another closely, and are mainly distinguished by the form
of the tragus and the size and relative position of the second lower
premolar. With the exception of _N. javanica_, they are all limited to
the Ethiopian region.
_Family_ VESPERTILIONIDÆ.
Nostrils opening by simple crescentic or circular apertures at the
extremity of the muzzle, not surrounded by distinct foliaceous cutaneous
appendages; premaxillæ small, lateral, and separated by a wide space
in front; tragus distinct. In addition to these characters, it may be
observed that the skull is of moderate size, the nasal and frontal
bones not being much extended laterally or vertically, nor furrowed by
deep depressions. The number of incisors varies from ²⁄₃ to ¹⁄₃, rarely
(in _Antrozous_ only) ¹⁄₂, premolars ³⁄₃, or ²⁄₂, or ¹⁄₂, rarely (in
_Vesperugo noctivagans_ of North America) ²⁄₃; the upper incisors are
small, separated by a wide space in the middle line, and placed in pairs
or singly near the canine; the molars are well-developed, with acute
W-shaped cusps.
This family, which may be regarded as occupying a central position in
the suborder, includes the common simple-faced Bats of all countries,
of which the well-known Pipistrelle and the Whiskered Bat (_Vespertilio
mystacinus_) may be taken as familiar types, and its species number more
than 150, or considerably more than one-third the total number of the
known species of the entire order. The various genera may be conveniently
grouped into the _Plecotine_, _Vespertilionine_, _Miniopterine_, and
_Thyropterine_ divisions.
In the _Plecotine_ division, of which the common Long-eared Bat
(_Plecotus auritus_) is the type, the crown of the head is but slightly
raised above the face-line, the outermost upper incisor is close to the
canine, and the nostrils are margined behind by grooves on the upper
surface of the muzzle, or by rudimentary nose-leaves; the ears also are
generally very large and united.
_Plecotus._[595]—Dentition: _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ²⁄₃, _m_ ³⁄₃; total
36. Outer margin of ear-conch ending abruptly near the angle of the
mouth, the inner margin with a more or less prominent rounded projection
directed inwardly above the base; tragus very large, tapering upwards,
with a lobe at the base of its outer margin, rounded, and placed half
horizontally. This genus is represented by the European Long-eared Bat
(_P. auritus_), and _P. macrotis_, restricted to North America. The
latter is distinguished by the great size of the glandular prominences of
the sides of the muzzle, which meet in the centre above and behind the
nostrils. _P. auritus_ extends over the greater part of the Palæarctic
region, occurring in Ireland in the west and the Himalaya in the east.
_Synotus._[596]—Dentition: _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ²⁄₂, _m_ ³⁄₃; total 34.
This genus is distinguished from the preceding by the loss of one lower
premolar and by the outer margin of the ear being carried forwards above
the mouth and in front of the eye; it includes the European Barbastelle
Bat (_S. barbastellus_) and _S. darjilingensis_ from the Himalaya.
_Otonycteris._[597]—Dentition: _i_ ¹⁄₃, _c_ ¹⁄₁, _p_ ¹⁄₂, _m_ ³⁄₃; total
30. The reduction in the number of upper incisors readily characterises
this genus, which appears to connect the typical representatives of the
section, through _Scotophilus_, with the Vespertilionine division. It is
represented by a single species, _O. hemprichi_, from North Africa and
the Himalaya.
_Nyctophilus._[598]—Dentition: _i_ ¹⁄₃, _c_ ¹⁄₁, _p_ ¹⁄₂, _m_ ³⁄₃;
total 30. This and the following genera are distinguished from all the
preceding by the presence of a rudimentary nose-leaf. The present genus
contains _N. timoriensis_ of the Australian region, and _N. microtis_ of
New Guinea.
_Antrozous._[599]—Dentition: _i_ ¹⁄₂, _c_ ¹⁄₁, _p_ ¹⁄₂, _m_ ³⁄₃; total
28. Readily distinguished from the other members of the whole family
by having but two lower incisors, and from the other species of the
section by the separate ears. The single species, _A. pallidus_, inhabits
California.
The _Vespertilionine_ division includes some nine-tenths of all the
representatives of the family. They are distinguished from the preceding
section by the simple nostrils, opening by crescentic or circular
apertures at the extremity of the muzzle, the generally small size of the
ears, and the absence of grooves on the forehead.
_Vesperugo._[600]—Dentition: _i_ ²⁻¹⁄₃, _c_ ¹⁄₁, _p_ ²⁻¹⁄₂₋₃, _m_
³⁄₃; total 34, 30, or 36. This large genus comprises about one-third
of the section, and is divided into groups or subgenera, according to
the number of premolars and incisors; the latter varying from ²⁄₃ to
¹⁄₃ in the subgenera _Scotozous_ and _Rhogeëssa_, and the premolars
from ²⁄₂ to ¹⁄₂ (in the subgenus _Lasionycteris_ ²⁄₃). The Bats of
this genus are generally easily distinguished by their comparatively
thickly formed bodies, flat broad heads and obtuse muzzles, short,
broad, and triangular obtusely-pointed ears, obtuse and usually slightly
incurved tragus, short legs, and by the presence in most species of a
well-developed post-calcaral lobule. This lobule (which is supported
by a cartilaginous process derived from the calcar) may act as a kind
of adhesive disc in securing the animal’s grasp when climbing over
smooth surfaces. _Vesperugo_ probably contains the greatest number of
individuals among the genera of Chiroptera, and, with the exception of
_Vespertilio_, its species have also the widest geographical range, being
almost cosmopolitan; and one of the species, the well-known Serotine
(_V. [Vesperus] serotinus_) is remarkable as the only species of Bat
known to inhabit both the Old and the New World; one (_V. borealis_)
has been found close to the limits of the Arctic circle, and another
(_V. magellanicus_) inhabits the cold and desolate shores of the Straits
of Magellan, being doubtless the Bat referred to by Mr. Darwin in the
_Naturalist’s Voyage_. The Common Pipistrelle (_V. pipistrellus_),
ranging over the greater part of the Palæarctic region, is the best known
species.
_Chalinolobus._[601]—This genus agrees with _Vesperugo_ in the dental
formula, but is readily distinguished by the presence of a well-defined
lobe projecting near the angle of the mouth from the lower lip, and
by the unicuspidate first upper incisor. The species fall into two
subgenera—_Chalinolobus_ proper, with _p_ ²⁄₂, represented by _C. morio_
from New Zealand, Tasmania, and Australia, and three other species from
Australia; and _Glauconycteris_, with _p_ ¹⁄₂, limited to Southern
and Equatorial Africa, and known by _C. argentatus_ and two other
species, the Bats of this subgenus being especially remarkable for their
peculiarly thin membranes, traversed by very distinct reticulations and
parallel lines.
[Illustration: FIG. 308.—Head of _Scotophilus emarginatus_. (Dobson,
_Monogr. Asiat. Chiropt._)]
_Scotophilus._[602]—Dentition: _i_ ¹⁄₃, _c_ ¹⁄₁, _p_ ¹⁄₂, _m_ ³⁄₃; total
30. This genus comprises a comparatively small number of species nearly
allied to _Vesperugo_, and some of which approach so closely to the
aberrant types of the latter ranged under the subgenus _Scotozous_, as to
render the definition of the present genus almost impossible.[603] The
species are restricted to the tropical and subtropical regions of the
eastern hemisphere, though widely distributed within these limits. The
more typical species are distinguished especially by the single pair of
unicuspidate upper incisors separated by a wide space and placed close
to the canines, by the small transverse first lower premolar squeezed in
between the canine and second premolar, and, generally, by their conical
nearly naked muzzles and remarkably thick leathery membranes. _S. kuhli_
is probably the commonest species of Bat in India, and appears often on
the wing even before the sun has touched the horizon, especially when
the white-ants are swarming, feeding eagerly upon them as they rise in
the air. _S. gigas_, from Equatorial Africa, with the forearm measuring
3·4 inches, is by far the largest species. _S. albofuscus_, from the
Gambia, which is readily distinguished from the other species by its
white wings, is an aberrant form, in which the lower premolars are long
and not crowded together, and thereby so closely resembles _Vesperugo_
(_Scotozous_) _dormeri_ as to render it almost impossible to distinguish
_Scotophilus_ and _Vesperugo_. The figured species is from India.
_Nycticejus._[604]—This genus, with the same dental formula as
_Scotophilus_, is distinguished by the first lower premolar not being
squeezed in between the adjoining teeth, and by the comparatively much
greater size of the last upper molar. It includes only the common North
American _N. humeralis_ (_crepuscularis_), a small Bat scarcely larger
than the Pipistrelle. It seems, however, as pointed out by Mr. O. Thomas,
that the discovery of _Scotophilus albofuscus_ renders the generic
distinctness of _Nycticejus_ no longer tenable, and that the species
should be known as _Scotophilus humeralis_.
_Atalapha._[605]—Dentition: _i_ ¹⁄₃, _c_ ¹⁄₁, _p_ ²⁻¹⁄₂, _m_ ³⁄₃; total
32 or 30. The five species of this genus, which are confined to the
New World, are generally characterised by the interfemoral membrane
being more or less covered with hair (in the two commonest species, _A.
noveboracensis_ and _A. cinerea_, wholly covered), and by the peculiar
form of the tragus, which is expanded above and abruptly curved inwards.
These species have two upper premolars, of which the first is extremely
small and quite internal to the tooth-row.
_Harpyiocephalus._[606]—Dentition: _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ²⁄₂, _m_
³⁄₃; total 34. This genus includes some eight species of small
Bats distinguished by their prominent tube-like nostrils and hairy
interfemoral membrane. _H. suillus_, from Java and neighbouring
islands, is the best-known species, and another closely allied (_H.
hilgendorfi_)has been described by Professor Peters from Japan. The
remaining six species are known only from the Himalaya and Tibet. All
appear to be restricted to the hill tracts of the countries in which they
are found.
_Vespertilio._[607]—Dentition: _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total
38. Next to _Vesperugo_, this genus includes by far the largest number
of species, amounting to over forty; it has, however, rather a wider
geographical distribution in both hemispheres, one species at least being
recorded from the Navigators’ Islands. The species are easily recognised
by the peculiar character of the upper incisors, the crowns of which
diverge from each other; by the large number of premolars, of which the
second upper one is always very small; and by the oval elongated ear and
narrow attenuated tragus. In the British Isles this genus is represented
by four species, viz. Bechstein’s Bat (_V. bechsteini_); the Reddish-Gray
Bat (_V. nattereri_), of very local occurrence; Daubenton’s Bat (_V.
daubentoni_); and the Whiskered Bat (_V. mystacinus_).
_Cerivoula._[608]—This genus, which has the same dental formula as
_Vespertilio_, is distinguished by the parallel upper incisors, and the
comparatively large size of the second upper premolar. Some ten species
have been described from the Ethiopian and Oriental regions, of which _C.
picta_, from India and the Indo-Malayan sub-region, is the best-known,
being well characterised by its brilliantly coloured orange fur and
conspicuously marked membranes, which are variegated with orange and
black. This genus includes the most delicately formed and most truly
insectivorous, tropical, forest-haunting Bats, which appear to stand
as regards the species of _Vespertilio_ in a position similar to that
occupied by _Chalinolobus_ with respect to _Vesperugo_.
[Illustration: FIG. 309.—Side and front views of the head of _Cerivoula
hardwickei_. (Dobson, _Monogr. Asiat. Chiropt._)]
The _Miniopterine_ division includes only two genera, and is
characterised by the great elevation of the crown of the head above the
facial line, and also by the upper incisors being separated from the
canine and also in the middle line.
_Natalus._[609]—This genus, while having the divisional characters
mentioned above, agrees in the dental formula and its general external
form with _Cerivoula_, from which it is distinguished by the short
triangular tragus. It includes three species, restricted to South and
Central America and the West Indies; the head of _N. micropus_ being
shown in Fig. 310.
[Illustration: FIG. 310.—Head of _Natalus micropus_. × 3. (Dobson, _Proc.
Zool. Soc._ 1880.)]
_Miniopterus._[610]—Dentition: _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ²⁄₃, _m_ ³⁄₃; total
36. In addition to the difference in the number of the teeth, this genus
is distinguished by the shortness of the first phalanx of the middle
finger and the great length of the tail, which is wholly contained
within the interfemoral membrane; it includes four species, restricted
to the eastern hemisphere. Of these the best-known, _M. schreibersi_,
is very widely distributed, being found almost everywhere throughout
the tropical and warmer temperate regions of the eastern hemisphere;
specimens from Germany, Madagascar, Japan, and Australia differing in no
appreciable respect from one another.
The last or _Thyropterine_ division, which likewise comprises only two
genera, is characterised by the presence of an additional osseous phalanx
in the middle finger and an equal number of phalanges in the toes, and
also by peculiar accessory clinging organs attached to the extremities.
_Thyroptera._[611]—Dentition: _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total
38. In the single species _T. tricolor_ of Brazil the clinging organs
have the appearance of small, circular, pedunculated, hollow discs (Fig.
311), resembling in miniature the sucking cups of cuttle-fishes, and are
attached to the inferior surfaces of the thumbs and soles of the feet.
With these the animal is enabled to maintain its hold when creeping over
smooth vertical surfaces.
[Illustration: FIG. 311.—Suctorial discs in _Thyroptera tricolor_. _a_,
Side and _b_, concave surface, of thumb-disc; _c_, foot with disc, and
calcar with projections (all much enlarged). Dobson, _Proc. Zool. Soc._
1876.]
_Myxopoda._[612]—The second genus is likewise represented only by a
single species—_M. aurita_ of Madagascar—and is distinguished from the
preceding by the characters of the teeth and the form of the ears.
The whole inferior surface of the pollex supports a large sessile
horse-shoe-shaped adhesive pad, with the circular margin directed
forwards and notched along its edge, and a smaller pad occupies part of
the sole of the foot.
_Fossil Vespertilionidæ._—It is not improbable that _Vesperugo_ is
represented in the Upper Eocene of the Paris basin by _V. parisiensis_,
which appears to be allied to _V. serotina_, although it has been
regarded by some writers as generically distinct, under the name of
_Nyctitherium_. _Vesperugo_ (_Nyctitherium_) also occurs in the Bridger
Eocene of the United States; _Nyctilestes_ from the same deposits being
an allied extinct genus. A number of European Miocene species have been
referred to _Vespertilio_, but the term in these cases must be used in
a somewhat wide sense. _Vespertiliavus_, of the Phosphorites of Central
France, differs from _Vespertilio_ in the proportions of its premolars.
_Section_ EMBALLONURINA.
Tail perforating the interfemoral membrane and appearing on its upper
surface, or produced considerably beyond the truncated membrane; the
middle pair of upper incisors generally large and close together.
_Family_ EMBALLONURIDÆ.
First phalanx of the middle finger folded (in repose) on the dorsal
surface of the metacarpal bone (except in _Noctilio_ and _Mystacops_).
Nostrils opening by simple circular or valvular apertures at the
extremity of the muzzle, not surrounded or margined by foliaceous
cutaneous appendages; tragus distinct.
The _Emballonuridæ_ are generally easily distinguished by the peculiar
form of the muzzle, which is obliquely truncated, the nostrils projecting
more or less in front beyond the lower lip; by the first phalanx of the
middle finger being folded in repose forwards on the upper surface of the
metacarpal bone; by the tail, which either perforates the interfemoral
membrane or is produced far beyond it; and by the upper incisors, which
are generally a single pair separated from the canine and also in the
middle line. The family is cosmopolitan like the _Vespertilionidæ_, but
rarely extends north or south of the thirtieth parallel of latitude.
Subfamily =Emballonurinæ=.—Tail slender, perforating the interfemoral
membrane, and appearing upon its upper surface, or terminating in it;
legs long, fibula very slender; upper incisors weak.
In the _Furipterine_ division the tail terminates in the interfemoral
membrane; the crown of the head is greatly elevated above the face-line;
the thumb and first phalanx of the middle finger are very short; and the
dentition is _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ²⁄₃, _m_ ³⁄₃; total 38.
Represented by two genera, _Furipterus_[613] and _Amorphochilus_,[614]
each including one species of peculiar aspect; the latter distinguished
from the former by the widely separated nostrils and the great extension
backwards of the bony palate. Habitat South America.
In the typical or _Emballonurine_ division part of the tail is included
in the basal half of the interfemoral membrane, the remaining part
passing through and appearing upon its upper surface; the crown of the
head is slightly elevated; the pollex and first phalanx of the middle
finger are moderately long; and the number of the premolars is always ²⁄₂.
_Emballonura._[615]—Incisors ²⁄₃. Extremity of the muzzle more or less
produced beyond the lower lip, forehead flat. Contains some five species,
inhabiting islands from Madagascar through the Malay Archipelago to the
Navigators’ Islands.
[Illustration: FIG. 312.—Ear of _Emballonura raffrayana_, × 2. (Dobson,
_Proc. Zool. Soc._ 1878.)]
_Coleüra._[616]—Incisors ¹⁄₃. Extremity of the muzzle broad, forehead
concave. Has two species from East Africa and the Seychelles Islands.
_Rhynchonycteris._[617]—This genus is distinguished from _Coleüra_ by the
much-produced extremity of the muzzle. The single species, _R. naso_,
from Central and South America, is very common in the vicinity of streams
throughout the tropical parts of these countries; it is usually found
during the day resting on the vertical faces of rocks, or on the trunks
of trees growing over the water, and, owing to the peculiar grayish
colour of the fur covering the body and growing in small tufts from
the antebrachial membrane, so as to counterfeit the weathered surfaces
of rocks and the bark of trees, easily escapes notice. As the shades
of evening approach it appears early on the wing, flying close to the
surface of the water, and seizing the minute insects that hover over it.
_Saccopteryx._[618]—Incisors ¹⁄₃. Antebrachial membrane with a pouch
opening on its upper surface. This genus contains six species from
Central and South America. In the adult males a valvular longitudinal
opening is found on the upper surface of the membrane, varying in
position in different species. This opening leads into a small pouch (in
some species large enough to hold a pea), the interior of which is lined
with a glandular membrane secreting an unctuous substance of a reddish
colour with a strong ammoniacal odour. The presence of this sac only in
males indicates that it is a secondary sexual character analogous to the
shoulder-pouches of _Epomophorus_ and the frontal sacs of _Hipposiderus_.
It is quite rudimentary in the females.
_Taphozous._[619]—Incisors ¹⁄₂; upper pair deciduous. This genus,
represented by some ten species, inhabiting the tropical and subtropical
parts of all the eastern hemisphere except Polynesia, forms the
second group of this division, distinguished by the cartilaginous
premaxillaries, deciduous upper incisors, and the presence of only
two lower incisors. Most of the species have a peculiar glandular sac
(Fig. 313) placed between the angles of the lower jaw. This is a sexual
character, for, while always more developed in males than in females, in
some species, although distinct in the male, it is quite absent in the
female. An open gular sac is wanting in both sexes in _T. melanopogon_,
but about its usual position the openings of small pores may be seen, the
secretion exuding from which probably causes the hairs to grow very long,
forming the black beard found in many male specimens of this species.
[Illustration: FIG. 313.—Heads of _Taphozous longimanus_, showing
relative development of gular sacs in male and female. (Dobson, _Proc.
Zool. Soc._ 1873.)]
In the _Diclidurine_ division there is but a single genus, represented by
two species.
_Diclidurus._[620]—Dentition: _i_ ¹⁄₃, _c_ ¹⁄₁, _p_ ²⁄₂, _m_ ³⁄₃; total
32. Both species are from the Neotropical region, the typical _D.
albus_ ranging as far north as Central America. This Bat resembles the
species of _Taphozous_ in the form of the head and ears, but, besides
other characters, differs from all other Bats in possessing a peculiar
pouch, opening on the centre of the inferior surface of the interfemoral
membrane; the extremity of the tail enters this, and perforates its
fundus.
The _Noctilionine_ division is likewise represented only by a single
genus, with two species. This genus connects the present with the
following family, possessing characters common to both, but also so many
remarkable special peculiarities as almost to warrant the formation of a
separate family for its reception.
_Noctilio._[621]—Dentition: _i_ ²⁄₁, _c_ ¹⁄₁, _p_ ¹⁄₂, _m_ ³⁄₃; total
28. The two species _N. leporinus_ and _N. albiventer_ inhabit Central
and South America. The typical _N. leporinus_ is a Bat of very curious
aspect, with strangely folded lips, erect cutaneous processes on the
chin, and enormous feet and claws. The first upper incisors are close
together, and so large as to conceal the small outer ones, while in the
lower jaw there is one pair of small incisors. This apparent resemblance
to a Rodent actually led Linnæus to remove this species from the Bats and
place it in the Rodents. This Bat is remarkable for feeding on fish—a
circumstance which has only recently been fully authenticated.
The remaining genus of this subfamily is regarded as representing another
division, which may be known as the _Rhinopomatine_ division.
_Rhinopoma._[622]—This genus, represented by the single species _R.
microphyllum_, might also be elevated to the rank of a family, for it is
difficult to determine its exact affinities, a kind of cross relationship
attaching it to the _Nycteridæ_ on the one hand and to this family,
in which it is here placed provisionally, on the other. This species,
distinguished from all other Microchiroptera as well by the presence of
two phalanges in the index finger as by its remarkably long and slender
tail projecting far beyond the narrow interfemoral membrane, inhabits
the subterranean tombs in Egypt and deserted buildings generally from
North-East Africa to Burma.
[Illustration: FIG. 314.—Skull of _Rhinopoma microphyllum_. × 2. (Dobson,
_Monogr. Asiat. Chiropt._)]
Subfamily =Molossinæ=.—Tail thick, produced far beyond the posterior
margin of the interfemoral membrane (except in _Mystacops_); legs short
and strong, with well-developed fibula; upper incisors strong. This
subfamily includes all the species of _Emballonuridæ_ with short and
strong legs and broad feet (whereof the first toe, and in most species
the fifth also, is much thicker than the others, and furnished with long
curved hairs), well-developed callosities at the base of the thumbs,
and a single pair of large upper incisors occupying the centre of the
space between the canines. In all the species the feet are free from the
wing-membrane, which folds up perfectly under the forearm and legs; the
interfemoral membrane is retractile, being movable backwards and forwards
along the tail, and this power of varying its superficial extent must
confer upon these Bats great dexterity in quickly changing the direction
of their flight, as when obliged to double in pursuing their swift
insect prey, which their extremely expansible lips evidently enable them
to secure with ease. Like the preceding subfamily, the genera may be
arranged in divisions, of which there are two.
The _Molossine_ division is characterised by the production of the tail
beyond the posterior margin of the interfemoral membrane; it includes
three genera.
_Chiromeles._[623]—Dentition: _i_ ¹⁄₁, _c_ ¹⁄₁, _p_ ¹⁄₂, _m_ ³⁄₃; total
26. Hallux much larger than the other toes and separable from them, ears
separate. This genus is represented by a single species, _C. torquatus_,
of large size (forearm 3·1 inches) and peculiar aspect, inhabiting the
Indo-Malayan sub-region. This Bat is nearly naked, a collar only of
thinly spread hairs half surrounding the neck; and is further remarkable
for its enormous throat-sac and curious nursing-pouches. The former
consists of a great semicircular fold of skin forming a deep pouch round
the neck beneath, and concealing the orifices of large subcutaneous
pectoral glands, which discharge an oily fluid of insufferably offensive
smell. The nursing-pouch is formed on each side by an extension of a fold
of skin from the side of the body to the inferior surfaces of the humerus
and femur. In the anterior part of this pouch the mammæ are placed.
_Molossus._[624]—Dentition: _i_ ¹⁄₁₋₂, _c_ ¹⁄₁, _p_ ¹⁻²⁄₁, _m_ ³⁄₃;
total 24 or 28. Upper incisors close together in the middle line.
There are some ten species, restricted to the tropical and subtropical
regions of the New World. The woodcut of the head of _M. glaucinus_
(Fig. 315) exhibits the general physiognomy of the Bats of this genus.
_M. obscurus_, a small species, is very common in tropical America. It
inhabits the hollow trunks of palms and other trees, and also the roofs
of houses. The males and females live apart (as, indeed, appears to be
the case in most, if not in all, species of Bats). In the hollow trunk
of a palm two colonies were discovered, one consisting of from 150 to
200 individuals, exclusively males, while the other was composed almost
entirely of females.
[Illustration: FIG. 315.—Head of _Molossus glaucinus_. (Dobson, _Proc.
Zool. Soc._ 1876.)]
_Nyctinomus._[625]—Dentition: _i_ ¹⁄₃₋₂, _c_ ¹⁄₁, _p_ ²⁻¹⁄₂, _m_ ³⁄₃;
total 32 or 28. Upper incisors separated in the middle line. The
genus contains about twenty-five species, inhabiting the tropical and
subtropical parts of both hemispheres. The lips of the Bats of this genus
are even more expansible than in _Molossus_, in many of the species (as
in the woodcut of the head of _N. macrotis_, Fig. 316) showing vertical
wrinkles. _N. tæniotis_, one of the largest species, alone extends into
Europe, and has been taken as far north as Switzerland. _N. johorensis_,
from the Malay Peninsula, is remarkable from the extraordinary form of
its ears. _N. brasiliensis_ is nearly as common as _Molossus obscurus_
in tropical America, and extends farther north (California) and south
than that species.
In the _Mystacopine_ division the tail perforates the interfemoral
membrane and appears upon the upper surface.
[Illustration: FIG. 316.—Head of _Nyctinomus macrotis_. (Dobson, _Proc.
Zool. Soc._ 1876.)]
_Mystacops._[626]—This genus includes only _M. tuberculatus_ of New
Zealand, where, together with _Chalinolobus tumorio_, it represents the
whole indigenous mammalian fauna of the islands. There are three distinct
phalanges in the middle finger; the greater part of the wing-membrane is
exceedingly thin, but a narrow portion along the forearm, the sides of
the body, and the legs is remarkably thick and leathery; beneath this
thickened portion the wings are folded. With the wings thus encased, this
species is the most quadrupedal of Bats. Other peculiarities of structure
are found in the remarkable form of the claws of the thumbs and toes,
which have each a small talon projecting from its concave surface near
the base, also in the sole of the foot and inferior surface of the leg,
as shown in Fig. 317. The plantar surface, including the toes, is covered
with soft and very lax integument deeply wrinkled, and each toe is marked
by a central longitudinal groove with short grooves at right angles to
it. The lax wrinkled integument is continued along the inferior flattened
surface of the ankle and leg. These peculiarities appear to be related to
climbing habits in the species.
[Illustration: FIG. 317.—Pollex and leg and foot of _Mystacops
tuberculatus_, enlarged. (Dobson, _Proc. Zool. Soc._ 1876.)]
_Fossil Emballonuridæ._—In the cavern-deposits of Madras remains of
the existing _Taphozous saccolæmus_ are not uncommon; while in the
corresponding beds of Brazil bones of a _Molossus_, probably referable
to _M. temmincki_, now inhabiting the same region, are met with. It has
been suggested that remains from the Upper Eocene Phosphorites of Central
France may indicate the existence of the genus _Taphozous_ at that early
epoch.
_Family_ PHYLLOSTOMATIDÆ.
Middle finger with three well-developed bony phalanges; first phalanx
of the middle finger short; nostrils in the front part of the cutaneous
nasal appendages, or opening by simple apertures at the extremity of
the muzzle; chin with warts or erect cutaneous ridges; premaxillæ well
developed, united in front.
The members of this family are readily distinguished by the third phalanx
in the middle finger, associated either with distinct cutaneous nasal
appendages, or with well-developed first upper incisors, or with both.
Unlike the _Rhinolophidæ_, their eyes are generally large; and the tragus
is well developed, maintaining almost the same form throughout the
species, however much the other parts of the body may vary. The fur is of
a dull colour, and the face and back (in the _Stenodermatine_ division
especially) are often marked with white streaks, as in the _Pteropodidæ_,
of which these Bats take the place in the western hemisphere. A few
species, probably all those with the tail and interfemoral membrane well
developed, feed principally on insects, while the greater number of the
species of the _Vampirine_ and _Glossophagine_ divisions appear to live
on a mixed diet of insects and fruits; and the _Desmodontine_ division,
of which two species only are known, are true blood-suckers, and have
their teeth and intestinal tract specially modified in accordance with
their habits. The family is restricted to the tropical and subtropical
parts of Central and South America.
Subfamily =Chilonycteriinæ=.—Nostrils opening by simple apertures at the
extremity of the muzzle in front, not margined by a distinct nose-leaf;
chin with expanded leaf-like appendages. It includes two genera.
[Illustration: FIG. 318.—Head of _Mormops blainvillei_. (Dobson, _Cat.
Chiropt. Brit. Mus._)]
_Chilonycteris._[627]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ²⁄₃, _m_ ³⁄₃;
total 34. The crown of the head is moderately elevated above the facial
line, and the basicranial axis is almost in the same plane as the facial.
There are about half a dozen species.
_Mormops._[628]—The two species of this genus are distinguished from
_Chilonycteris_ by the great elevation of the crown of the head above
the line of the face, as well as by the basicranial plane being nearly
at right angles to the facial. Both species are noticeable for their
peculiar physiognomy, as is shown in the accompanying woodcut (Fig. 318).
Subfamily =Phyllostomatinæ=.—Nostrils opening on the upper surface of
the muzzle, the nasal apertures more or less surrounded or margined by
well-developed cutaneous appendages, forming a distinct nose-leaf; chin
with warts. The numerous genera, most of which can only be mentioned here
by name, may be arranged under four divisions.
In the first or _Vampirine_ division the muzzle is long and narrow in
front; the distance between the eyes is generally less than, rarely equal
to, that from the eye to the extremity of the muzzle; the nose-leaf
is well developed, horse-shoe shaped in front, and lanceolate behind;
interfemoral membrane well developed; tail generally distinct, rarely
absent; inner margin of the lips not fringed. The dentition is: _i_
²⁄₂₋₁, _c_ ¹⁄₁, _p_ ²⁄₂₋₃, _m_ ³⁄₃; total 32. The cusps of the upper
molars are usually well developed, and arranged in a W. Nearly all the
species of this division appear to be insectivorous, so that the name
applied to them must not be considered as having any relation to their
habits. _Vampyrus spectrum_, a large Bat inhabiting Brazil, of forbidding
aspect, which was long considered by naturalists to be sanguivorous
in its habits, and named accordingly by Geoffroy, has been shown by
the observations of modern travellers to be mainly frugivorous, and is
considered by the inhabitants of the countries in which it is found to
be perfectly harmless. It is the largest Bat in America, the length of
the forearm being 4·2 inches. _Otopterus waterhousei_ appears to prey
occasionally on small species of Bats, like _Megaderma lyra_ of the
eastern hemisphere, which it resembles in many respects.
_Lonchorhina_,[629] _Otopterus_,[630] _and Dolichophyllum_.[631]—These
three genera are characterised by the tail continuing to the hinder
margin of the interfemoral membrane. _Lonchorhina_ is represented by the
single species _L. aurita_, in which the nose-leaf is much elongated, and
the ear-conch and tragus are unusually large.
_Vampyrus_,[632] _etc._—In all the remaining genera of this division the
tail perforates the interfemoral membrane, so as to appear upon its upper
surface. These genera are _Vampyrus_, _Lophostoma_, _Micronycteris_,[633]
_Trachyops_, _Phylloderma_, _Phyllostoma_, _Anthorhina_,[634] _Mimon_,
_Hemiderma_[635] and _Rhinophylla_; all, with the exception of the last,
being distinguished from one another chiefly by the form of the skull
and the presence or absence of the second lower premolar. _Trachyops_,
_Phylloderma_, and the three last-named genera are each represented by a
single species. _Phyllostoma hastatum_, in which the forearm has a length
of 3·2 inches, and next in point of size to _Vampyrus spectrum_, is a
well-known species in South America; _P. elongatum_ (Fig. 319) differs
in its smaller size and much larger nose-leaf. _Hemiderma brevicauda_
is a small species, which forms a connecting link between this and the
next division. _Rhinophylla pumilio_, the smallest known species of the
family, is further distinguished by the narrowness of its molars, which
do not form W-shaped cusps, and by the very small size of the last upper
molar; characters connecting it with the _Stenodermatine_ division.
[Illustration: FIG. 319.—Head of _Phyllostoma elongatum_. (From Dobson,
_Proc. Zool. Soc._ 1866.)]
In the second or _Glossophagine_ division of the subfamily the muzzle
is long and narrow; the tongue remarkably long and extensible, much
attenuated towards the tip, and beset with very long filiform recurved
papillæ; lower lip with a wide groove above, and in front margined by
small warts; nose-leaf small; tail short or absent. Dentition: _i_ ¹⁄₁,
_c_ ²⁄₂, _p_ ²⁻³⁄₃₋₂, _m_ ²⁄₃₋₂; teeth very narrow; molars with narrow
W-shaped cusps, sometimes indistinct or absent; lower incisors very small
or deciduous.
The ten species included in this division are arranged under seven
genera,[636] distinguished principally by differences in the form and
number of the teeth and the presence or absence of the zygomatic arch.
The form and position of the upper incisors are extremely variable.
In _Glossophaga_ and _Phyllonycteris_ the upper incisors form, as in
the _Vampyrine_ division, a continuous row between the canines; in
_Monophylla_ and _Leptonycteris_[637] they are separated into pairs by
a narrow interval in front; while in _Lonchoglossa_, _Glossonycteris_,
and _Chœronycteris_ they are widely separated and placed in pairs near
the canines. In the first four genera the lower incisors are present (at
least up to a certain age), while in the last three they are deciduous
even in youth. The zygomatic arch is wanting in _Phyllonycteris_,
_Glossonycteris_, and _Chœronycteris_.
The typical species is _Glossophaga soricina_, which so closely resembles
_Hemiderma brevicauda_, both in external form and dentition, that it has
frequently been confounded with it. Its long fimbriated tongue, which
it possesses in common with other species of the division, led Spix to
describe it as a blood-sucker, believing that this organ was used to
increase the flow of blood. This view is, however, without foundation,
and from later observations it is evident that the peculiarly shaped
tongue is used by the animal to lick out the pulpy contents of fruits
having hard rinds. The food of the species of this division appears to
consist of both fruit and insects, and the long tongue may also be used
for extracting the latter from the deep corollæ of certain flowers. This
type of tongue is shown in the woodcut of the head of _Chœronycteris_
(Fig. 320); and it is paralleled among the Megachiroptera by the
Carponycteriine _Pteropodidæ_.
[Illustration: FIG. 320.—Head of _Chœronycteris mexicana_, showing
fimbriated tongue. (Dobson, _Cat. Chiropt. Brit. Mus._)]
The _Stenodermatine_ division is characterised by the muzzle being very
short and generally broad in front, the distance between the eyes nearly
always exceeding (rarely equal to) that from the eye to the extremity
of the muzzle; nose-leaf short, horse-shoe shaped in front, lanceolate
behind (except in _Brachyphylla_ and _Centurio_); interfemoral membrane
always concave behind; tail none; inner margin of the lips fringed
with conical papillæ. Dentition: _i_ ²⁄₂₋₁, _p_ ²⁄₂, _m_ ³⁻²⁄₃₋₂; the
number of the molars being either ³⁄₃, ²⁄₃, or ²⁄₂ in different species;
premolars and molars very broad (except in _Sturnira_), the latter with
concave or flat crowns margined externally by raised cutting-edges.
Although the members of this division are usually distinguished from
those of the Vampirine division by the peculiar shortness and breadth of
the muzzle and the form of the molars, yet certain species of the latter
closely resemble those of the former in external appearance, agreeing
almost absolutely in the form of the nose-leaf, of the ears and tragus,
and of the warts on the chin. These resemblances indicate that, while
the form of the teeth and jaws has become modified to suit the nature of
the food, the external characters, being but slightly affected by this
cause, have remained much the same. The food of these Bats appears to
be wholly or in great part fruit. The twenty species have been grouped
into nine genera, distinguished by the form of the skull and teeth.
_Artibeus_, with six species, includes the well-known frugivorous Bat,
_A. perspicillatus_. Waterton believed that _A. planirostris_, a common
Bat in British Guiana, usually found in the roofs of houses, and now
known to be frugivorous, was the true blood-sucking Vampire. _Stenoderma
achradophilum_, found in Jamaica and Cuba, associated with _Artibeus
perspicillatus_, from which it is scarcely distinguishable externally
except by its much smaller size, differs altogether in the absence of
the horizontal plate of the palatal bones. _Sturnira lilium_, while
agreeing with the above in the form of the nose-leaf and ears, differs
from all the species of the family in its longitudinally-grooved molars,
which resemble those of the _Pteropodidæ_ more closely than those of
any other Bats; and the presence of tufts of long differently coloured
hairs over glands in the sides of the neck shows another common character
still more remarkable, which can scarcely be considered the result of
adaptive change. _Centurio senex_ is the type of a genus distinguished
from _Stenoderma_ and other genera of this division by the absence
of a distinct nose-leaf; its facial aspect, as shown in Fig. 321, is
altogether bizarre.
[Illustration: FIG. 321.—Head of _Centurio senex_. (Dobson, _Cat.
Chiropt. Brit. Mus._)]
In the last or _Desmodont_ division the muzzle is conical and short;
there is a distinct nose-leaf; the interfemoral membrane is very
short; and the tail is wanting. Dentition: _i_ ¹⁄₂, _c_ ¹⁄₁, _p_ ²⁄₃,
_m_ ¹⁻⁰⁄₁₋₀; total 24 or 20. Upper incisors very large, trenchant,
occupying the whole space between the canines; premolars very narrow,
with sharp-edged longitudinal crowns; molars rudimentary or wanting;
stomach greatly elongated, intestiniform. There are only two genera, the
single species of each of which are the true blood-sucking Vampires.
They appear to be confined chiefly to the forest-clad parts, and their
attacks on men and other warm-blooded animals were noticed by some of
the earliest writers. Thus Peter Martyr (Anghiera), who wrote soon after
the conquest of South America, says that in the Isthmus of Darien there
were Bats which sucked the blood of men and cattle when asleep to such a
degree as to kill them. Condamine, a writer of the eighteenth century,
remarks that at Borja (Ecuador) and in other places they had entirely
destroyed the cattle introduced by the missionaries. Sir Schomburgk
relates that at Wicki, on the river Berbice, no fowls could be kept on
account of the ravages of these creatures, which attacked their combs,
causing them to appear white from loss of blood. Although these Bats
were known thus early to Europeans, the species to which they belonged
were not determined until about sixty years ago, several of the large
frugivorous species having been wrongly set down as blood-suckers and
named accordingly; and it fell to the lot of Darwin to determine at least
one of the blood-sucking species, the following being his account of the
circumstances under which the discovery of the sanguivorous habits of
_Desmodus rufus_ was made: “The Vampire Bat is often the cause of much
trouble by biting the horses on their withers. The injury is generally
not so much owing to the loss of blood as to the inflammation which
the pressure of the saddle afterwards produces. The whole circumstance
has lately been doubted in England; I was therefore fortunate in
being present when one was actually caught on a horse’s back. We were
bivouacking late one evening near Coquimbo, in Chili, when my servant,
noticing that one of the horses was very restive, went to see what was
the matter, and, fancying he could detect something, suddenly put his
hand on the beast’s withers and secured the Vampire.”
These Bats present, in the extraordinary differentiation of the
manducatory and digestive apparatus, a departure from the type of
other members of the family unparalleled in any of the other orders of
Mammalia, standing apart from all other mammals as being fitted only
for a diet of blood, and capable of sustaining life upon that alone.
Travellers describe the wounds inflicted by the large sharp-edged
incisors as similar to those caused by a razor when shaving: a portion of
the skin being shaved off and a large number of severed capillary vessels
thus exposed, from which a constant flow of blood is maintained. From
this source the blood is drawn through the exceedingly narrow gullet—too
narrow for anything solid to pass—into the intestine-like stomach, whence
it is probably gradually drawn off during the slow process of digestion,
while the animal, sated with food, is hanging in a state of torpidity
from the roof of a cave or the inner side of a hollow tree.
[Illustration: FIG. 322.—Head of Vampire Bat (_Desmodus rufus_).]
_Desmodus._[638]—No true molar, and no calcar. The Common Vampire (_D.
rufus_) is widely spread over the tropical and subtropical parts of
Central and South America from Oaxaca to Southern Brazil and Chili. It is
a comparatively small species, a little larger than the common Noctule,
the head and body being about 3 inches in length, the forearm 2½, with a
remarkably long and strong thumb; it is destitute of a tail, and has a
peculiar physiognomy, well represented in Fig. 322. The body is covered
with rather short fur of a reddish-brown colour, but varying in shade;
the extremities of the hairs being sometimes ashy. The teeth are peculiar
and admirably adapted for the purposes for which they are employed. The
upper incisor is greatly enlarged, and of somewhat triangular shape (Fig.
323); the canine, although smaller than the incisor, is large and sharp;
but the cheek-teeth are very small, with laterally compressed crowns
rising but slightly above the level of the gum, their longitudinally
disposed cutting-edges being continuous with the base of the canine and
with each other. The lower incisors are small, bifid, and separated from
the canine, with a space in front. The lower cheek-teeth are narrow, like
those in the upper jaw, but the anterior tooth is slightly larger than
the others, and separated by a small space from the canine. Behind the
lower incisors the jaw is deeply hollowed out to receive the extremities
of the large upper incisors. The exceedingly narrow œsophagus opens at
right angles into the slender, intestine-like stomach, which almost
immediately terminates on the right, without a distinct pylorus, in the
duodenum, but on the left forms a greatly elongated fundus, bent and
folded upon itself, appearing at first sight like part of the intestines.
This cardiac extremity of the stomach is, for a short distance, to the
left of the entrance of the œsophagus, still very narrow, but soon
increases in size, till near its termination it attains a diameter quite
three times that of the short pyloric portion. The length of this cardiac
diverticulum of the stomach appears to vary from 2 to 6 inches, the size
in each specimen probably depending on the amount of food obtained by the
animal before it was captured.
[Illustration: FIG. 323.—Dentition of _Desmodus rufus_. _a_, Front view
of upper teeth; _b_, left lateral view of upper and lower teeth.]
_Diphylla._[639]—A small true molar in each jaw, and a rudimentary
calcar. The single species _D. ecaudata_ inhabits Brazil, and appears to
be much less abundant than _Desmodus rufus_, from which, in addition to
the characters already mentioned, it is distinguished by its slightly
smaller size, the absence of a groove in the front of the lower lip,
the non-development of the interfemoral membrane in the centre, and the
peculiar form of the lower incisors, which are much expanded in the
direction of the jaws and pectinated, forming a semicircular row touching
each other, the outer pair being wider than the inner ones, and having
six notches, the inner pair having only three notches.
_Fossil Phyllostomatidæ._—Remains of _Vampyrus spectrum_, as well as of
several species of _Phyllostoma_ or closely allied types, are found in
the cavern deposits of Brazil. The mandible of a large Bat from the Upper
Eocene Phosphorites of Central France, described as _Necromantis_, has
been referred to this family—a determination which, if confirmed, will be
of great interest from a distributional point of view.
_Bibliography of Chiroptera._—G. E. Dobson, _Catalogue of the
Chiroptera in the Collection of the British Museum_, 1878,
including descriptions of all the species of Bats then known;
subsequent papers by the same author in _Rep. Brit. Assoc._,
_Proc. Zool. Soc._, _Ann. Mag. Nat. Hist._, and _Bull. Soc.
Zool. de France_; by Peters in _Monatsb. Akad. Wiss. Berlin_;
by O. Thomas in _Ann. Mag. Nat. Hist._, _Proc. Zool. Soc._,
and _Ann. Mus. Genova_; and by J. Scully in _Ann. Mag. Nat.
Hist._ and _Journ. As. Soc. Bengal_; H. A. Robin, _Recherches
Anatomiques sur les Mammifères de l’Ordre des Chiroptères_,
Paris, 1881; W. T. Blanford, “Notes on Indian Chiroptera,”
_Journ. As. Soc. Bengal_, vol. lviii. (1888). See also papers
by Jentink, Bocage, and others.
CHAPTER XIV
THE ORDER PRIMATES
This order in the system of Linnæus includes Man, the Monkeys, the
Lemurs, and the Bats. By common consent of all zoologists the last-named
animals have been removed into a distinct order; but with regard to the
association of the others there has been, and still is, much difference
of opinion.
That all the Monkeys, from the highest Anthropoid Apes to the lowest
Marmosets, form a natural and tolerably homogeneous group seems never
to have been questioned; but whether the Lemurs on the one hand and Man
on the other should be united with them in the same order are points of
controversy. If, in accordance with the traditional views of zoologists,
the former are still considered to be members of this order, they must
form a suborder apart from all the others, with which they have really
very little in common except the opposable hallux of the hind foot, a
character also met with in the Opossums, and which is therefore of very
secondary importance.[640]
Using the term Primates in this wider sense it is not easy to give
any precise definition of the order. The dentition is diphyodont and
heterodont; the number of incisors being very generally ²⁄₂, and that
of the molars, with the exception of the _Hapalidæ_, being ³⁄₃. The
cheek-teeth are adapted for grinding, the molars being more complex than
the premolars, and usually having four main tubercles, which may be
either subconical or more or less compressed. The orbit is invariably
surrounded by a ring of bone; the clavicles are well developed; and the
radius and ulna are never united. The scaphoid and lunar of the carpus,
and commonly also the centrale, remain distinct from one another. There
are usually five digits furnished with well-developed nails in both
the manus and the pes; but the pollex may be rudimentary or wanting.
The hallux, except in Man, is opposable to the other digits, and has a
flat nail (absent in _Simia_); and the pollex, when present, is usually
also more or less opposable. The terminal phalanges of the digits are
flattened (except in the second digit of the pes of the Lemuroidea), and
not cleft at their extremities. The fingers and toes generally do not
taper towards their extremities, but (except in _Chiromys_) are dilated,
flattened, and rounded at their tips. The humerus has no entepicondylar
foramen, nor the femur a third trochanter. In the alimentary canal
(Fig. 324) the stomach is generally simple, although sacculated in the
subfamily _Semnopithecinæ_ of the _Cercopithecidæ_; and there is always
a cæcum, which is generally of large size. The placenta may be either
non-deciduous, or discoidal and deciduous. There are always two mammæ in
the pectoral region, except in _Chiromys_; and the testes descend into a
scrotum.
[Illustration: FIG. 324.—Alimentary canal of _Galago_, the greater part
of the small intestine being omitted. _d_, duodenum; _i_, ileum; _cm_,
cæcum; _r_, rectum.]
The Lemuroidea are decidedly low in the scale of organisation, their
placentation being of a lower type than that of the Insectivora; and all
the Primates retain generalised features in their pentadactylate limbs
and more or less bunodont cheek-teeth. In respect to cerebral characters
and other features the higher representatives of the order have, however,
acquired a specialisation clearly indicating their right to occupy
the highest position in the animal kingdom. So far as the available
material admits of forming an opinion, fossil forms appear to indicate
an intimate connection between the Lemuroidea and Insectivora, so that
in some cases it is almost impossible to determine whether an extinct
type should be referred to the former or to the latter group. It is
noteworthy that while in all existing Primates the upper molars are of
a quadrituberculate type, in the extinct Lemuroid genus _Anaptomorphus_
they are trituberculate.
_Suborder_ LEMUROIDEA.
The Latin term _Lemur_ was applied by Linnæus to the typical
representatives of the present group of Primates, having been suggested
by the nocturnal habits and strange ghost-like appearance of some of
its members. As these animals had previously no vernacular appellation
in English, this name has been generally adopted, and is now completely
anglicised, making “Lemurs” in the plural. The French call them _Makis_,
and the Germans _Halbaffen_, in allusion to their forming a transition
from monkeys to ordinary quadrupeds. For the same reason they are called
_Prosimiæ_ by some systematic writers. When the name was bestowed by
Linnæus only five species were known, of which one, _L. volans_, Linn.
(_Galeopithecus volans_ of modern writers), is now removed by common
consent from the group. Notwithstanding the discovery of many new and
curious forms, the Lemurs remain a very natural and circumscribed
division of the animal kingdom, though no longer considered a single
genus, but divided up into many genera and even families.
The existing species are not numerous, and do not diverge widely in their
organisation or habits, being all of small or moderate size, all adapted
to an arboreal life, climbing with ease, and, as they find their living,
which consists of fruits, leaves, birds’ eggs, small birds, reptiles, and
insects, among the branches of the trees, they rarely have occasion to
descend to the ground. None are aquatic, and none burrow in the earth.
Many of the species, although by no means all, are nocturnal in their
habits, spending the day in sleeping in holes, or rolled up in a ball,
perched on a horizontal branch, or in the fork of a tree, and seeking
their food by night. Their geographical distribution is very peculiar; by
far the larger proportion of species, including all those to which the
term “Lemur” is now especially restricted, being exclusively inhabitants
of Madagascar, where they are so abundant and widely distributed that
it is said by M. Grandidier, who has contributed more than any other
traveller to enrich our knowledge of the structure and manners of these
animals, that there is not a little wood in the whole island in which
some of them cannot be found. From Madagascar as a centre a few species
less typical in character extend through the African continent westward
as far as Senegambia, and others are found in the Oriental region as far
east as the Philippine Islands and Celebes.
The following are the essential characters by which the suborder as a
whole is distinguished from the Anthropoidea. Skull with the orbit
opening freely into the temporal fossa beneath the postorbital bar
(except in _Tarsius_); and the lachrymal foramen situated externally to
the margin of the orbit (Fig. 327). The pollex and hallux are always
well developed, the latter being especially large; the second or index
digit of the manus may be rudimentary; while in the pes the second digit
invariably terminates in a long pointed claw. The cerebral hemispheres do
not completely overlap the cerebellum, and are but slightly convoluted.
The uterus is bicornuate. The placenta is non-deciduate, and either
diffused or bell shaped—the whole of the chorion except the cephalic
pole being covered with villi; and the allantois is of very great size.
There may be abdominal mammæ. Except in _Chiromys_, the first pair of
upper incisors are separated in the middle line. In marked contrast to
the Anthropoidea, the middle or transverse portion of the colon is almost
always folded or convoluted on itself. (See Fig. 324.)
In subdividing the group for the purpose of a more detailed description
of the different animals of which it is composed it must first be noted
that there are two very aberrant forms, each represented by a single
species—the little _Tarsius_ of the Indian archipelago, and the singular
_Chiromys_ or Aye-aye, which, though an inhabitant of Madagascar, the
headquarters of the suborder, and living in the same forests and under
the same external conditions as the most typical Lemurs, exhibits a most
remarkable specialisation in the structure of its limbs and teeth, the
latter being modified so as to resemble, at least superficially, those of
the Rodents, in which order it was once placed. The differences between
these two forms and the remaining Lemurs are so great that the whole
suborder naturally divides itself into three families, the first of which
may be again divided into four subfamilies.
_Family_ LEMURIDÆ.
Upper incisors two on each side, small and separated by an interval in
the middle line. Upper canine large, conical, compressed, and pointed.
Premolars two or three, molars three on each side above and below, with
numerous more or less pointed cusps. In the front of the lower jaw are
on each side two or three closely approximated, long, slender teeth
lying almost horizontally and projecting forwards. These are generally
considered to represent the incisors and canine, but there is some doubt
about their homologies, and they may be all considered as incisors, the
canine being absent. The first lower premolar larger than those behind
it, and shaped like a canine, of which it performs the function (Fig.
327). The orbit and temporal fossa widely continuous beneath the bar
of bone (formed by the frontal and jugal) constituting the posterior
boundary of the former cavity. The fibula well developed and distinct
from the tibia. All the digits of both feet (except the second of the
hind foot) with flat nails, and corresponding form of ungual phalanges.
Subfamily =Indrisinæ=.—The dentition of the adult consists of thirty
teeth, usually expressed by the formula _i_ ²⁄₁, _c_ ¹⁄₁, _p_ ²⁄₂, _m_
³⁄₃; but, as indicated above, they may be _i_ ²⁄₂, _c_ ¹⁄₀, _p_ ²⁄₂, _m_
³⁄₃. In the milk-dentition there are twenty-two teeth, the true molars
of course not being represented, but there are two additional teeth in
the fore part of the lower jaw which have no successors in the permanent
series. Hind limbs greatly developed, but the tarsus normal. Hallux of
large size, and very opposable. The other toes united at their base by a
fold of skin, which extends as far as the end of the first phalanx. Mammæ
two, pectoral. Cæcum very large, and colon extremely long and spirally
coiled.
The animals of this group are, as their organisation indicates,
essentially arboreal, and feed exclusively on fruit, leaves, buds, and
flowers. They are restricted geographically to the island of Madagascar.
Among them are the largest members of the suborder. A detailed and
beautifully illustrated account of their characters, external and
internal, and distribution and habits, is given in the _Histoire
Naturelle de Madagascar_, by A. Grandidier and Alphonse Milne-Edwards
(1875). The species are not numerous and are distributed into three
genera.
_Indris._[641]—Upper incisors subequal in size. Upper canine larger than
the first premolar. Muzzle moderately long. Ears exserted. Carpus without
an os centrale. Tail rudimentary. Vertebræ: C 7, D 12, L 9, S 4, C 9.
The only well-established species is the Indris (_I. brevicaudata_, Fig.
325), discovered by Sonnerat in 1780. It is the largest of the Lemurs,
the length of the head and body being about 2 feet, and the tail 2
inches. It is very variable in colour, for although usually nearly black,
marked with whitish spots principally in the lumbar region and forearm,
individuals have been found quite white. It inhabits exclusively the
forests of a part of the east coast of Madagascar, living in small troops
of four or five in number, and resembling in most of its habits the
animals of the next genus.
_Propithecus._[642]—Second upper incisor much smaller than the first.
Upper canine larger than the first premolar. Muzzle rather short. Ears
short, concealed by the fur. An os centrale in the carpus. Tail long.
Vertebræ: C 7, D 12, L 8, S 3, C 28.
[Illustration: FIG. 325.—Indris (_Indris brevicaudata_). From
Milne-Edwards and Grandidier, _Mammifères de Madagascar_, pl. 12.]
The species are all subject to great variations in colour, which has
led to much difficulty in discriminating them, and to much confusion of
synonymy. Grandidier and Milne-Edwards recognise three as certainly
distinct—_P. diadema_, _P. verreauxii_, and _P. coronatus_ (Fig. 326).
Some of these are to be found in almost every part of the island of
Madagascar, living in the woods in small bands of six or eight together,
and feeding exclusively on buds, flowers, and berries. Their powerful
hind limbs enable them to leap from tree to tree, often to a distance of
10 yards, without any apparent effort, and thus seeming to fly through
the air. When obliged to descend to the ground to pass from one clump
of trees to another they do not run on all fours, but stand erect, and
throwing their arms above their heads progress by a series of short
jumps, producing an effect which is described by travellers who have
seen them thus in their native haunts as exceedingly ludicrous. They are
not nocturnal, but most active in the morning and evening, remaining
seated or coiled up among the branches during the heat of the day. They
are naturally of a quiet and gentle disposition, and do not show much
intelligence. All the species are also less vociferous than the true
Lemurs, only when alarmed or angered making a noise which has been
compared to the clucking of a fowl. Like the rest of the subfamily they
never have more than a single young one at a time.
[Illustration: FIG. 326.—_Propithecus coronatus._ (From Milne-Edwards and
Grandidier, _Mammifères de Madagascar_, pl. 7.)]
_Avahis._[643]—Second upper incisor larger than the first. Upper canine
scarcely larger than the first premolar. Muzzle very short. Ears very
small and hidden in the fur, which is very soft and woolly. Carpus
without an os centrale. Tail long. Vertebræ: C 7, D 11, L 9, S 3, C 23.
One species, _A. laniger_, the Woolly Lemur, or Avahis, considerably
smaller than any of the last genus. It differs from them in its habits,
being quite nocturnal, and not associating in small troops, but being
always met with either alone or in pairs. It is very slow in its
movements, and rarely descends to the ground, but when it does it walks
upright like the other _Indrisinæ_. It is found throughout the forests
which clothe the mountains on the east coast of Madagascar, and also in a
limited district on the north-west coast, the specimens from the latter
locality being of smaller size and rather different in colour.
Subfamily =Lemurinæ=.—The dentition in the adult consists of thirty-six
teeth, which, as usually enumerated, are _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ³⁄₃, _m_
³⁄₃. In the fore part of the lower jaw are on each side three elongated,
compressed, procumbent teeth, of which the outer, usually considered
the homologue of the canine, is larger than the others. All the forms
have long tails. Hind limbs not of the same disproportionate size as in
the last group; and the cæcum much less developed. Tarsus but slightly
elongated, the calcaneum being always less than one-fourth the length of
the tibia. Toes of the hind feet free to the base. Habitat, Madagascar,
and some of the adjacent Comoro Islands.
[Illustration: FIG. 327.—Skull of Ring-tailed Lemur (_Lemur catta_). × ⅓;
_uc_, Upper canine; _lc_, lower canine; _pm_, premolars; _m_, molars.]
This group contains the typical Lemurs, or rather those to which the
term is now chiefly restricted. Two somewhat aberrant members make it
necessary to divide it into three genera.
_Lemur._[644]—Upper incisors separated by an interval in the middle, and
not in contact with each other or the canine, in front of which they are
both placed. Muzzle elongated. Ears conspicuous and tufted. Mammæ two,
pectoral. Vertebræ: C 7, D 12, L 7 (or D 13, L 6), S 3, C 27.
[Illustration: FIG. 328.—The Ring-tailed Lemur (_Lemur catta_).]
Animals much about the size of a common Cat, with Fox-like faces, soft
thick fur, and long tails well clothed with hair. Not having the same
disproportionate size of the limbs as the last group, they are much
more quadrupedal in their actions, walking on the ground or running
along the branches of trees on all four feet, but also jumping with
marvellous agility. They are gregarious, living in small troops, are
diurnal in their habits, but most active towards evening, when they make
the woods resound with their loud cries. They feed not only on fruits
and buds, but also on eggs, young birds, and insects. When at rest or
sleeping they generally coil their long, bushy tails around their bodies,
apparently for the sake of the warmth it affords. They have either one
or two young ones at a birth, which are at first nearly naked, and are
carried about, hanging close to and almost concealed by the hair of the
mother’s belly. After a while they change their position and mount upon
the mother’s back, where they are carried about until they are able to
climb and leap by themselves. Though no member of the _Indrisinæ_ has as
yet lived long enough in captivity to be brought alive to Europe, various
species of _Lemurinæ_ are commonly seen in menageries, and often breed in
England. They present a great tendency to variation in their colouring,
in consequence of which many nominal species have been made. The most
distinct, and at the same time most beautiful, is the Ring-tailed Lemur
(_L. catta_, Fig. 328), of a delicate gray colour, and with a long tail
marked with alternating rings of black and white. This is said by Mr.
G. A. Shaw[645] to be an exception to all the other Lemurs in not being
arboreal, but living chiefly among rocks and bushes. Pollen, however,
says that it inhabits the forests of the south-west parts of Madagascar,
living, like its congeners, in considerable troops, and not differing
from them in its habits. He adds that it is extremely gentle, and active
and graceful in its movements, and utters at intervals a little plaintive
cry like that of a domestic cat. All the others have the tail of uniform
colour. The largest species is _L. varius_, the Ruffed Lemur, sometimes
black and white, and sometimes reddish-brown, the variation apparently
not depending on sex or age, but on the individual. In _L. macaco_ the
male is black and the female red. _L. mongoz_, _L. collaris_, and _L.
albifrons_ are other well-known species.
_Hapalemur._[646]—Upper incisors very small, subequal, separated widely
in the middle line. Those of either side in contact with each other and
with the canine, the posterior one being placed on the inside, and not in
front of the latter. Muzzle very short and truncated. Mammæ four. There
is apparently but one species, _H. griseus_, smaller than any of the true
Lemurs, of a dark gray colour, with round face and short ears. It is
quite nocturnal, and lives chiefly among bamboos, subsisting on the young
shoots. A second species has been named _H. simus_, but it is doubtful if
it is more than a variety.
_Lepidolemur._[647]—Upper incisors absent or rudimentary. Muzzle more
elongated than in the last. No distinct os centrale in the carpus.
_L. mustelinus_ is the best-known species. It has, at all events when
adult, no upper incisors. It is rare, and like _Hapalemur_ nocturnal in
its habits. A second closely allied species, but with better developed
premaxillæ, containing a pair of small styliform incisors, has been
described by Peters[648] under the name of _Myxocebus caniceps_.
Subfamily =Galaginæ=.—Dentition as in _Lemurinæ_, from which the members
of this subfamily are distinguished by the elongation of the tarsus,
caused by a peculiar modification of the calcaneum and the navicular, the
distal portion of the former and the whole of the latter having the form
of almost cylindrical rods placed side by side, while the other bones
retain nearly their normal form and proportion.
_Chirogaleus._[649]—Last upper premolar very much smaller than the first
molar, with only one external cusp. The animals included under this name
appear to form a transition between the true Lemurs and the Galagos. The
genus was originally established by Geoffroy St. Hilaire in 1812 for
the reception of three species only known at that time by drawings made
in Madagascar by the traveller Commerson. Subsequent discoveries have
brought to light several others that may be referred to it, including
one or two which are sometimes considered as forming a genus apart under
the name of _Microcebus_. They are all small, some being less than a
rat in size, long-tailed, and nocturnal in their habits. One of the
largest, _C. furcifer_, is of a reddish-gray colour, and distinguished
by a dark median stripe on its back which divides on the top of the head
into two branches, one of which passes forwards above each eye. The most
interesting peculiarity of these animals, a knowledge of which we owe
to M. Grandidier, is that certain species (_C. samati_, _C. gliroides_,
_C. milii_, etc.) during the dry season coil themselves up in holes of
trees and pass into a state of torpidity like that of the hibernating
animals in the winter of northern climates. Before this takes place
an immense deposit of fat accumulates upon certain parts of the body,
especially upon the basal portion of the tail, which has then dimensions
corresponding to that of the well-known fat-tailed Sheep of the Cape, but
which by the time they emerge from their torpor has acquired its normal
proportions. The smallest species, to which many names have been given
(_C. pusillus_, _rufus_, _smithi_, etc.), lives among the small branches
on the tops of the highest trees, feeding on fruit and insects, and
making nests which resemble those of birds.
_Galago._[650]—Last upper premolar with two large external cusps, and
nearly equalling the first molar in size. Calcaneum about one-third the
length of the tibia, and the navicular much longer than the cuboid.
Vertebræ: C 7, D 13, L 6, S 3, C 22-26. Tail long, and generally bushy.
Ears large, rounded, naked, and capable of being folded at the will of
the animal. Mammæ four, two pectoral and two inguinal.
The Galagos differ from all the Lemuroids previously mentioned, inasmuch
as they are inhabitants, not of Madagascar, but of the African continent,
being widely distributed in the wooded districts from Senegambia in the
west to Abyssinia in the east, and as far south as Natal. They pass the
day in sleep, but are very active at night, feeding on fruit, insects,
and small birds. When they descend to the ground they sit upright, and
move about by jumping with their hind legs, like jerboas and kangaroos.
They are pretty little animals, varying in size from that of a small cat
to less than a rat, with large eyes and ears, soft woolly fur, and long
tails. There are several species, of which _G. crassicaudatus_, from
Mozambique, is the largest. A similar species, or perhaps variety, from
Angola is _G. montieri_. _G. garnetti_, _alleni_, _maholi_, _demidoffi_,
and _senegalensis_ are other recognised species. The last-mentioned was
the first known to science, having been brought from Senegal by Adanson,
and described in 1796 by Geoffroy, who adopted the name _Galago_, by
which it was said to be called by the natives.
Subfamily =Lorisinæ=.—Dental formula as in _Lemurinæ_. Index finger very
short, sometimes rudimentary and nailless. Fore and hind limbs nearly
equal in length. Tarsus not specially elongated. Pollex and hallux
diverging widely from the other digits, the hallux especially being
habitually directed backwards. Tail short or quite rudimentary. Mammæ
two, pectoral.
A small group of very peculiar animals, of essentially nocturnal habits,
and remarkable for the slowness of their movements. They are completely
arboreal, their limbs being formed only for climbing and clinging to
branches, not for jumping or running. They have rounded heads, very
large eyes, short ears, and thick, short, soft fur. They feed not only
on vegetable substances, but, like many of the _Lemuridæ_, on insects,
eggs, and also birds, which they steal upon while roosting at night. None
of the species are found in Madagascar. One of the greatest anatomical
peculiarities of these animals is the breaking up of the large arterial
trunks of the limbs into numerous small parallel branches, constituting a
_rete mirabile_, which is found also in the Sloths, with which the Loris
are sometimes confounded on account of the slowness of their movements.
The animals of this group are usually divided into four genera, though
the characters by which they are separated are very trivial. There are
more properly two natural divisions.
_A._ Characterised by the index finger being small, but having the
complete number of phalanges, and by their Asiatic habitat.
These form the genus _Loris_ of Geoffroy St. Hilaire (1796), _Stenops_
of Illiger (1811), but they were in 1812 divided by Geoffroy into two
genera, _Nycticebus_ and _Loris_, a division which has been accepted by
most modern zoologists.
_Nycticebus._[651]—First upper incisor larger than the second, which is
often early deciduous. Inner margins of the orbits separated from each
other by a narrow flat space. Nasal and premaxillary bones projecting
but very slightly in front of the maxillæ. Body and limbs stout. No
external tail. Vertebræ: C 7, D 17, L 6, S 3, C 12. The species are _N.
tardigradus_, the common Slow Lemur or Loris, of the Malay Countries,
Sumatra, and Borneo; _N. javanicus_, of Java; and _N. cinereus_ (Fig.
329) of Siam and Cochin China. The habits of all are much alike. They
lead a solitary life in the recesses of large forests, chiefly in
mountainous districts, where they sleep during the day in holes or
fissures of large trees, rolled up into a ball, with the head between the
hind legs. On the approach of evening they awake; and during the night
they ramble among the branches of trees, slowly and quietly, in search
of their food, which consists of tender leaves and fruit, small birds,
insects, and mice. When in quest of living prey they move noiselessly
till quite close, and then suddenly seize it with one of their hands. The
female produces but one young one at a time. _L. tardigradus_ was placed
by Linnæus at the head of the list of species of his genus _Lemur_, and
its habits doubtless suggested the generic name which was transferred by
Geoffroy to the less nocturnal and spectre-like Madagascar members of the
group.[652]
[Illustration: FIG. 329.—The Gray Loris (_Nycticebus cinereus_). From A.
Milne-Edwards, _N. Archives du Muséum_, vol iii. pl 3.]
_Loris_.[653]—Upper incisors very small and equal. Orbits very large,
and only separated in the middle line above by a thin vertical plate of
bone. Nasals and premaxillæ produced forwards considerably beyond the
anterior limits of the maxillæ, and supporting a pointed nose. Body and
limbs slender. No external tail. Vertebræ: C 7, D 14, L 9, S 3, C 6.
This genus is represented only by the Slender Loris (_L. gracilis_) of
Southern India and Ceylon (Fig. 330). This species is common in some
of the forest regions of Southern India, and may be purchased in the
bazaars at Madras, its eyes being regarded as a remedy by the natives for
ophthalmic diseases. It is a strange-looking creature, about the size
of a squirrel, of a yellowish-brown colour, with large, prominent eyes,
pointed nose, long thin body, long, angularly bent, slender limbs, and no
tail. Its habits, according to Mr. W. T. Blanford,[654] are “very similar
to those of _Nycticebus tardigradus_, except that the Slender Loris is
rather quicker in its movements, though still slow in general. Like its
ally, it is purely nocturnal and arboreal, living upon shoots and young
leaves, insects, birds’ eggs, birds, and lizards. It is said to be very
fond of honey or syrup. It sleeps rolled up in a ball with its head
between its legs, grasping its perch with its arms.”
[Illustration: FIG. 330.—The Slender Loris (_Loris gracilis_). From
Blanford, _Mammalia of British India_, p. 47.]
_B._ Index fingers reduced to a mere tubercle without nail. Both the
known species are from West Africa.
_Perodicticus._[655]—A short tail, about a third of the length of the
trunk. Two or three of the anterior dorsal vertebræ have very long
slender spinous processes which in the living animal project beyond the
general level of the skin, forming distinct conical prominences, covered
only by an exceedingly thin and naked integument. The Potto, _P. potto_,
is one of the oldest known members of the lemuroid group, having been
described in 1705 by Bosman, who met with it in his voyage to Guinea.
It was, however, lost sight of until 1825, when it was rediscovered in
Sierra Leone, and fully described by Bennett in 1830 under the name of
_Perodicticus geoffroyi_. Bennett’s generic name has been retained, but
the specific name bestowed by Gmelin, adopted from Bosman, has been
restored. It is also found in the Gaboon. It is strictly nocturnal,
and slower in its movements even than _Nycticebus tardigradus_, which
otherwise it much resembles in its habits.
A second species, the Awantibo (_P. calabarensis_), rather smaller and
more delicately made, with smaller hands and feet and rudimentary tail,
constitutes the genus _Arctocebus_ of Gray. It is found at Old Calabar,
and is very rare, only a few individuals having as yet been met with.
Vertebræ: C 7, D 15, L 7, S 3, C 9.[656]
_Family_ TARSIIDÆ.
Dentition: _i_ ²⁄₁, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total 34. The first upper
incisor large, and in contact with its fellow of the opposite side.
Canine of moderate size. Molars with numerous pointed cusps. Lower canine
semi-erect, its apex diverging from that of the single incisor. First
lower premolar smaller than those behind it. Orbit to a large extent
separated from the temporal fossa by a bony partition. Fibula slender,
with its lower half confluent with the tibia. Second and third digits of
the hind foot with compressed claws; all the other digits of both feet
with flat nails. Calcaneum and navicular bone of the foot elongated as in
the Chirogales and Galagos, but to a still greater extent. Colon short
and not folded. Vertebræ: C 7, D 13, L 6, S 3, C 27.
_Tarsius._[657]—The family contains the single genus _Tarsius_, of which
but one species is known, _T. spectrum_, the Tarsier, a very singular
little animal, rather smaller than an English squirrel, with very large
eyes and ears, a long thin tail, tufted at the end, and immensely
elongated tarsal portion of the foot, in allusion to which its generic
name was given to it. It inhabits the forests of many of the islands of
the Indo-Malayan archipelago, including Sumatra, Borneo, Celebes, and
some of the Philippines, feeds chiefly on insects and lizards, sleeps
during the day, but is tolerably active at night, moving chiefly by
jumping from place to place, an action for which the structure of its
hind legs, which present a curious resemblance to those of a frog, seems
particularly well adapted. It is rare, not more than two being generally
found together, and only brings forth one young at a time.[658]
_Family_ CHIROMYIDÆ.
Dentition of adult: _i_ ¹⁄₁, _c_ ⁰⁄₀, _p_ ¹⁄₀, _m_ ³⁄₃; total 18.
Incisors very large, compressed, curved, with persistent pulps and enamel
only in front, as in Rodents. Teeth of cheek series with flat, very
indistinctly tuberculated crowns. In the young the first set of teeth
more resemble those of the normal lemurs, being _i_ ²⁄₂, _c_ ¹⁄₀, _m_
²⁄₂, all very small. Orbit surrounded by a ring of bone posteriorly,
beneath which it communicates freely with the temporal fossa. Fibula well
developed and distinct from the tibia. All the digits of both feet with
pointed rather compressed claws, except the hallux, which has a flattened
nail. Middle digit of the hand excessively attenuated. Vertebræ: C 7, D
12, L 6, S 3, C 27.
[Illustration: FIG. 331.—Skull of Aye-aye (_Chiromys madagascariensis_).
× ⅙ Mus. Roy. Coll. Surgeons.]
_Chiromys._[659]—This family, like the last, is formed for the
reception of a single genus, _Chiromys_,[660] containing one species,
_C. madagascariensis_, the Aye-aye, an animal about the size of a cat,
with a broad rounded head, short face, and large and naked ears. It has
very large hands and long thin fingers with pointed claws, one of which
(the middle or third) is remarkable for its extreme slenderness. The
foot resembles that of the other lemurs in its large opposable hallux,
with a flat nail, but all the other toes have pointed compressed claws,
like that of the second toe in the _Lemurinæ_ and the second and third
in the _Tarsiidæ_. Tail long and bushy. General colour dark brown, the
outer fur being long and rather loose, with a woolly undercoat. Mammæ
two, inguinal in position. It is a native of Madagascar, where it was
discovered by Sonnerat in 1780. The specimen brought to Paris by that
traveller was the only one known until 1860. Since then many others have
been obtained, and they may frequently be seen living in the gardens of
the Zoological Society of London. Like so many of the Lemurs, the Aye-aye
is completely nocturnal in its habits, living either alone or in pairs,
chiefly in the bamboo forests. Observations upon captive specimens have
led to the conclusion that it feeds principally on succulent juices,
especially of the sugar-cane, which it obtains by tearing open the hard
woody circumference of the stalk with its strong incisor teeth. It is
said also to devour certain species of wood-boring caterpillars, which
it obtains by first cutting down with its teeth upon their burrows, and
then picking them out of their retreat with the claw of its attenuated
middle finger. It constructs large ball-like nests of dried leaves,
lodged in a fork of the branches of a tree with the opening on one side.
The resemblance of its teeth to those so characteristic of the Rodentia
caused it to be placed formerly in that order, and it was only when its
anatomical characters were fully known that its true affinities with the
Lemurs became apparent.[661]
_Extinct_ LEMUROIDS.
The discoveries of the last few years have revealed the former existence,
both in Europe and North America, of a number of extinct animals more
or less closely allied to the living Lemurs, which are of especial
interest as showing in some instances characters of a more generalised
type than is the case with the living representatives of the suborder.
It is, however, in some cases very difficult to determine whether these
extinct forms should be referred to the Lemuroidea or Insectivora; and
if those naturalists are right who regard these groups as survivors of a
very generalised ancestral type of mammalian organisation, it is to be
expected that as we recede in time we should find that the two groups
show more and more marked signs of a natural connection. The earliest
reference of one of these extinct Upper Eocene types to the Primates was
made in 1862 by Professor L. Rütimeyer, of Basle, who described part of
an upper jaw with three teeth from the so-called Bohnerz of Egerkingen,
near Soleure in Switzerland, under the name of _Cænopithecus lemuroides_,
regarding the animal to which the specimen belonged as partaking of
the characters both of the Lemurs and the American Monkeys. Most other
palæontologists refused, however, to accept this determination, and it
was not until many years later that the researches of Gaudry and Filhol
showed not only that _Cænopithecus_ was indeed a true Lemuroid, but also
that it was either identical with or closely allied to a form described
by Cuvier in the early part of this century under the name of _Adapis_
and regarded as referable to the Ungulata. Later researches have brought
to light other Lemuroids in the Tertiaries of both the Old and the New
World; and it is very noteworthy that all these types seem to have
disappeared from both regions with the close of the upper portion of the
Eocene period.
[Illustration: FIG. 332.—The last five right upper cheek-teeth of
_Microchœrus antiquus_ (_A_) and _Microchœrus erinaceus_ (_B_). Twice
natural size, and natural size.]
Among the more interesting of the forms which are generally regarded
as true Lemuroids we may first mention a small species from the Quercy
Phosphorites, of which the hinder cheek-teeth are shown in Fig. 332,
_A_, which was originally described as _Necrolemur antiquus_, but
appears to be generically identical with _Microchœrus erinaceus_, of the
upper Eocene of Hampshire, of which the corresponding teeth are shown
in _B_ of the same figure. In this genus, according to Dr. Schlosser,
the dental formula is _i_ ²⁄₁, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃, or the same
as in the existing _Tarsius_; but it is not improbable that in some
instances the first lower premolar may have been developed. The upper
molars of _M. erinaceus_ differ from those of _M. antiquus_ by the
simpler structure of their columns and the smaller size of the external
cingulum, which lacks the median cusp found in the latter. The angle of
the mandible is produced into a large hook-like flange which at once
distinguishes the genus from all existing Lemurs; and the anterior lower
premolar is not canine-like. _M. antiquus_ is of very small size, but
the larger _M. edwardsi_ of the same deposits comes nearer in dimensions
to _M. erinaceus_. The upper molars decrease in size from the first to
the third, the first and second having a median cusp in the external
cingulum, by which they are readily distinguished from the corresponding
teeth of the under-mentioned genus _Hyopsodus_. The third upper molar
differs from that of _Hyopsodus_ by its small size and the abortion of
its posterior columns. The skull approximates to that of the living genus
_Galago_, exhibiting the same inflation of the auditory bulla. The upper
molars are also not unlike one species of that genus, but the fourth
upper premolar has but one outer cusp, as in _Chirogaleus_.
The small _Anaptomorphus_, from the North American Eocene, has a skull of
about the same size as that of the smallest species of _Microchœrus_, but
the dental formula is _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ²⁄₂, _m_ ³⁄₃, and the upper
molars are of the tritubercular type.
[Illustration: FIG. 333.—The left upper cheek-teeth of _Adapis magna_,
from the Upper Eocene of Hampshire.]
The well-known _Adapis_ (_Aphelotherium_ or _Palæolemur_), of the Upper
Eocene of France and England, differs from all existing Lemuroids in
possessing four premolars[662]; the dental formula being _i_ ²⁄₂, _c_
¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃. The fourth upper premolar has two outer cusps,
and the upper molars (Fig. 333) resemble those of _Lepidolemur_ and
_Hapalemur_, while the lower canine is a well-developed tooth performing
the usual function of biting against the canine of the upper jaw. The
lower incisors have upright, spatulate crowns, as in the true Apes. The
skull is said to approximate in contour to that of _Propithecus_. The
typical _A. parisiensis_ is of comparatively small size, but the species
of which the upper cheek-teeth are shown in the woodcut is of much larger
dimensions. The skull of _A. magna_, which measures upwards of 4 inches
in length, resembles that of _A. parisiensis_ in its general characters,
but is modified much in the way that the skulls of larger animals differ
from the smaller ones of the same natural group. Thus the brain-chamber
and orbits are relatively smaller, the face larger, the muscular crests
more developed, and the constriction between the cerebral and the facial
portion of the skull more marked. These modifications remove the skull
in its general characters still farther from the existing Lemurs—so
much so that M. Filhol refers it and the other species of _Adapis_ to
a distinct zoological type, intermediate between the lemurs and the
pachyderms, to which he gives the name of _Pachylemuriens_, but later
researches do not support this view. As mentioned above, it has been
suggested that _Cænopithecus lemuroides_ is inseparable from _Adapis
parisiensis_, but the postero-internal column of the upper molars is said
to be larger. The genera _Tomitherium_ and _Notharctus_, of the Eocene
of the United States, appear to be allied to _Adapis_, but the second
has a larger lower canine. The same deposits have also yielded more or
less imperfect remains of other forms departing more widely from the
existing Lemuroid type. Of these _Hyopsodus_, of the Wasatch and Bridger
Eocene of the United States, has the dental formula _i_ ²⁄₂, _c_ ¹⁄₁,
_p_ ⁴⁄₄, _m_ ³⁄₅. The quadrituberculate upper molars have well-developed
accessory intermediate columns (protoconule and metaconule), and thus
resemble those of _Microchœrus_; the external surfaces of the outer
columns of their teeth being flattened, with vertical ridges and a
distinct cingulum. The third upper molar has its postero-internal column
(hypocone) partly aborted, but is otherwise as well developed as the
preceding molars. _Microsyops_, of the North American Eocene, appears
to have been an allied form in which there were probably only three
premolars.
[Illustration: FIG. 334.—The right upper cheek-teeth of _Plesiadapis
remensis_; from the Lowest Eocene of Rheims. × ³⁄₂. _p_, 3, 4, premolars;
_m_, 1, 2, 3, molars. (From Osborn.)]
The genera _Protoadapis_ and _Plesiadapis_, from the lowest Eocene of
Rheims, may not improbably be regarded as primitive Lemuroids. The lower
molars are quinquetubercular, and not unlike those of _Microsyops_; the
dental formula of the lower jaw is _i_ 2, _c_ 1, _p_ 3-4, _m_ 3 in the
first-named genus, but in the second the dentition is reduced to _i_
²⁄₁, _c_ ¹⁄₀, _p_ ²⁄₂, _m_ ³⁄₃. In _Plesiadapis_ the lower and the first
upper incisor are enlarged, the upper molars (Fig. 334) tritubercular,
and the lower quadritubercular. _Indrodon_, of the lowest Eocene of the
United States, resembles _Plesiadapis_ in its tritubercular upper molars,
and appears to have a nearly similar dental formula. _Mixodectes_, of
the same deposits, was probably a more or less closely allied type.
_Pelycodus_ of the Wasatch Eocene of North America, in which the hallux
was not opposable, and _Cryptopithecus_ of the German Eocene, may be
regarded as very generalised Lemuroids.
_Bibliography._—Besides the works and memoirs on particular
families and genera referred to above, see St. G. Mivart,
“Notes on the Crania and Dentition of the _Lemuridæ_,” in
_Proc. Zool. Soc._ 1864 (pp. 611-648) and 1867 (pp. 960-975);
Mivart and Murie, “On the Anatomy of the _Lemuroidea_,” in
_Trans. Zool. Soc._ 1872, vol. vii. pp. 1-113; W. Turner, “On
the Placentation of the Lemurs,” in _Phil. Trans._ vol. clxvi.
pp. 569-587; F. Pollen and D. C. Van Dam, _Recherches sur la
Faune de Madagascar_. 2ᵐᵉ parte, “Mammifères,” 1868. For the
fossil types see M. Schlosser, “Die Affen, Lemuren, etc., des
Europäischen Tertiärs,” in _Beitr. Pal. Œstr-Ungar_, 1888.
_Suborder_ ANTHROPOIDEA.
This suborder includes the whole of the remaining members of the
Primates, namely, those animals commonly known as Marmosets, Monkeys,
Baboons, and Apes, together with Man himself. The characters by which
the Anthropoidea are distinguished as a whole from the Lemuroidea may be
summarised as follows. Skull with the orbit separated from the temporal
fossa by a vertical plate of bone joining the postorbital bar, and
the lachrymal foramen situated within the margin of the orbit. Pollex
sometimes rudimentary or absent; second digit of manus always well
developed, and that of the pes usually with a flattened nail (not so in
_Hapalidæ_). The cerebral hemispheres of the brain either completely
or almost completely cover the cerebellum, and are much convoluted.
Uterus not bicornuate. The placenta is deciduate and discoidal; and the
allantois is small. There are never abdominal mammæ. As additional points
of distinction from the Lemuroidea, it may be mentioned that the anterior
cornu of the hyoid is shorter than the posterior; the inner pair of upper
incisors are in contact in the middle line; and the transverse portion of
the colon extends uninterruptedly across the abdomen.
The Anthropoidea may be divided into the five families—_Hapalidæ_,
_Cebidæ_, _Cercopithecidæ_, _Simiidæ_, and _Hominidæ_, of which the first
and second are confined to the New, and the third and fourth to the Old
World.
In noticing some of the salient features in the external and internal
structure of the Anthropoidea it will be found convenient to allude to
all the members of the first four families as Apes, in contradistinction
to Man. In respect to relative size the extremes are found in the Gorilla
on the one hand and _Hapale_ on the other; the difference in this
respect between these two forms being greater than that between Man and
a Squirrel. The relative proportions between the limbs and the body, and
also between the fore and hind limbs, are subject to great variation.
Thus in _Hylobates_ and _Ateles_ both pairs of limbs are much elongated;
in the former case the pectoral being much longer than the pelvic pair
(Fig. 335). In other cases, as in the Orang (Fig. 354), while the arms
are very long, the legs are short; but in the subfamily _Cercopithecinæ_
both pairs are short and subequal. Only in the _Hapalidæ_ and some of the
_Cebidæ_ are the legs proportionately as long as in Man.
The tail is as much as three times the length of the body in _Ateles_;
while in the _Simiidæ_ it is totally absent. In the majority of genera it
is long in all the species; but in some cases, as in _Macacus_, it may be
either long, short, or absent in the different species of a single genus.
Equally marked variations occur in the shape of the head. Thus in
_Ateles_ it is rounded; while in the Orang it is elevated vertically;
in _Chrysothrix_ it is produced posteriorly; and in the Baboons
(_Cynocephalus_) it is characterised by the great production of
the muzzle and the terminal position of the nostrils, whereby a
characteristic Dog-like form is assumed. The eyes are always directed
forwards, and are never more separated from one another than in Man,
although, as in _Chrysothrix_, they may be closer together. They are
of very large size in _Nyctipithecus_, while in the Baboons they are
relatively small in proportion to the size of the head. The ears
are invariably well developed, and are usually pointed at their
postero-superior angle. Those of man are characterised by the soft
depending portion known as the “lobule,” of which there is a rudiment
in the Gorilla. In the majority of Apes the nose is but very slightly
prominent; but it attains an extraordinary development in _Nasalis
larvatus_, and is scarcely less remarkable in _Semnopithecus roxellanæ_
(Fig. 349). Among the Gibbons the Hoolock has a distinctly aquiline nose.
The nostrils are terminal in the true Baboons; and while in all the Old
World Apes they are approximated, in those of the New World they are
separated by a broad septum. With the exception of the Orang, the lips of
the Apes are thin.
The pollex makes a nearer approach in form to the human thumb in the
Chimpanzee than in any other Ape. Man differs from all the Apes in having
the hallux frequently longer instead of shorter than the other digits of
the foot. The hallux of the Orang is peculiar in having no nail, but in
other cases the nail is flat; the nails of the other digits of the Apes
are never quite flat, and in some of the _Cebidæ_ they are decidedly
compressed laterally, while in the _Hapalidæ_ they assume the form of
sharp and curved claws.
All the Apes have the greater part of the body well clothed with hair. In
the Gibbons and the _Cercopithecidæ_ the buttocks have naked ischiatic
callosities, which attain their greatest development in _Cynocephalus_
and its allies. The male of the Orang has a well-developed beard, and in
_Cercopithecus diana_ there is long hair on the cheeks and chin, while
in _Macacus silenus_ the face is surrounded by a fringe of long hair,
separated by an interval on the forehead. Long hair is found on the
head in _Hapale œdipus_ and in some species of _Semnopithecus_; while
in the Bonnet Monkey (_Macacus sinicus_) it radiates in all directions
from a central point on the vertex. Long hair clothes the shoulders
in _Cynocephalus hamadryas_ and _Hapale humeralifer_; and the end of
the tail has a tuft in two species of _Cynocephalus_ and in _Macacus
sinicus_. Many of the African _Colobi_ and some species of the Howlers
have very long hair on the flanks; and in _Pithecia_ this development of
hair extends to the greater part of the body and the tail, _P. satanas_
also having a long beard. In all the lower Apes the hairs on the arm and
forearm are directed towards the hand quite down to the wrist; and the
same arrangement obtains in _Hylobates_. In the other _Simiidæ_, however
(as in man), the points of the hairs of the arm and forearm converge
at the elbow. Darwin’s explanation of this peculiarity is that these
Apes are accustomed to sit with the arms bent, so that the rain is thus
enabled to run off at the elbow.
In one species of _Hapale_ the hair is of a silky texture, and in the
South American _Eriodes_, and _Macacus tibetanus_ (as in all the mammals
inhabiting the arid and severe climate of Tibet) it becomes woolly.
The development of very brilliant colours on the naked parts of the body,
such as the face, sexual organs, and ischiatic callosities is a marked
feature of many of the _Cercopithecidæ_ and some other Apes.
With the exception of the long tail found in most forms, the general
structure of the skeleton of the Apes is very similar to that of man,
but there are marked differences in the form of the jaws and of the
innominate bones. The proportion of the facial to the cranial region
of the skull varies with the shape of the head, of which brief mention
has already been made; the greatest development of the facial portion
being in the Baboons. Curiously enough, some of the lower American
Monkeys, and more especially _Chrysothrix_, have the greatest relative
development of the cranial part of the skull of all the Apes; this
character being, however, one common to all the smaller representatives
of particular groups, and obviously necessary to provide the requisite
amount of brain-space. In the convexity of the frontal region of the
skull the American forms, and more especially _Pithecia_, make the
nearest approximation to man, and the same is true with regard to the
occipital production, which is most developed in _Chrysothrix_. Most of
the _Simiidæ_ exhibit, however, a distinct convexity of the occiput,
and thereby differ markedly from the _Cercopithecidæ_, in which this
region is flat. The rotundity of the cranium is obscured in the larger
Apes, such as the Orang (Fig. 353) and Gorilla, by the development of
prominent bony ridges for muscular attachment; these attaining their
maximum in the males of the species last named, where the sagittal crests
and the supraorbital ridges are very prominent. The mastoid process is
always smaller in the Apes than in Man, and as it diminishes in size the
petrosal tends to assume an inflated or bullate condition. The orbits in
shape are most like that of Man in the Gorilla; and, in accordance with
the size of the eyes, they are of enormous dimensions in _Nyctipithecus_.
The angle formed by the plane of the foramen magnum with that of the
basicranial axis is subject to variation according to the degree of
convexity of the occiput, but is generally smaller than in Man, although
larger in _Chrysothrix_. There is an external bony meatus auditorius in
Man, the _Simiidæ_, and the _Cercopithecidæ_, but none in the _Cebidæ_
and _Hapalidæ_.
The premaxillæ of the Apes are always large; and, except in the
Chimpanzee, the premaxillo-maxillary suture persists until after the
permanent dentition has been developed. The nasals are smaller and
flatter than in Man, but are largest in _Mycetes_. The two rami of the
mandible are invariably completely ankylosed at the symphysis in the
adult. The Siamang (_Hylobates syndactylus_) is the only ape in which the
mandibular symphysis slows a slight projection in front corresponding
to the human chin. In _Mycetes_ the angle of the mandible attains an
enormous development (Fig. 338) to protect the huge inflated basihyal.
The frontal sinuses, though present, in the _Simiidæ_, are generally
replaced in the _Cercopithecidæ_ by a coarse diploë, but they are present
in the _Cebidæ_ and _Hapalidæ_, being especially large in _Cebus_. In
fully adult individuals the cranial sutures become obliterated, the
internasal suture disappearing at an early age in the _Simiidæ_ and most
of the _Cercopithecidæ_. As in many Carnivora, the tentorium, or membrane
separating the cerebrum from the cerebellum, may become ossified in some
of the American forms.
The number of the teeth in the Old World Apes is invariably the same as
in Man, namely _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ²⁄₂, _m_ ³⁄₃, total 32; but in the
_Cebidæ_ the cheek-teeth are _p_ ³⁄₃, _m_ ³⁄₃, and in the _Hapalidæ_ _p_
³⁄₃, _m_ ²⁄₂. It is probable that the two pairs of incisors correspond
to the first and third of the typical series of three. In all Apes the
dental series is interrupted by a diastema, and the canines of the
males are large. Man alone has an uninterrupted dental series of a
horse-shoe-form, without prominent canines.
According to recent researches the Chimpanzee and some of the other
_Simiidæ_ exhibit a more or less close approximation to the sigmoid
curvature of the vertebral column which is so characteristic of Man,
and there is also some approach to it in the Baboons. The number of
dorsal vertebræ in the Apes may vary from eleven, as in some species
of _Cercopithecus_ and _Macacus_, to fourteen in certain forms of
_Hylobates_, and to fifteen in _Nyctipithecus_. The _Cebidæ_ generally
have thirteen; and the same number obtains in the Chimpanzee and Gorilla,
while the Orang resembles Man in having but twelve. The lumbar vertebræ
show a range in number of from four to seven. In the _Simiidæ_ there are
four or five of these vertebræ, the length of the lumbar region being
shorter in this family than in the other Apes, with the exception of
_Ateles_. The shortness of the lumbar region in the last-named genus is
compensated by the relative length of the dorsal region, as is shown in
Fig. 335.
[Illustration: FIG. 335.—Skeleton of the Black-handed Spider Monkey
(_Ateles geoffroyi_). From De Blainville.]
The sacrum is longest in the _Simiidæ_ and Man, its greatest absolute
length occurring in the Gorilla, and the relative greatest length being
found in _Hylobates_. The _Simiidæ_ never have less than five, and may
have six sacral vertebræ; while in the lower forms there are generally
only two or three, although occasionally four in some of the American
forms. The Orang and some of the Baboons make the nearest approximation
to Man in the marked angle formed at the junction of the sacrum with
the lumbar vertebræ. Except in the _Simiidæ_ and _Macacus inuus_, the
number of caudal vertebræ in the Apes always exceeds four, but they may
be reduced to five in the Mandrill (_Cynocephalus maimon_). In _Macacus_
and _Uacaria_ the shortness of the tail is attained by the small size
of the vertebræ themselves, the number of which may be from fifteen to
seventeen. Other forms usually have from twenty to thirty-three caudals,
the latter number occurring in _Ateles_ (Fig. 335), where the tail is
relatively the longest. The tail is, however, absolutely longest in
_Semnopithecus_, _Colobus_, and their allies, the length being partly
due to the size of the component vertebræ. Chevron bones are present in
all forms having a distinct tail; and, together with other processes for
muscular attachment, attain their greatest development in _Ateles_.
The vertebral processes known as metapophyses and anapophyses, which
are generally inconspicuous in Man, and are but small in the _Simiidæ_,
attain a large development in the lower forms. The metapophyses
generally commence in the eighth or ninth dorsal, and continue to the
anterior caudals, where they gradually merge in the prezygapophyses.
The anapophyses, which are most developed in the _Cebidæ_, project
outwards and backwards from one vertebra to embrace the prezygapophyses
of the succeeding one. They occur generally in the same region as the
metapophyses, but usually cease at the penultimate lumbar, although in
some cases they can be traced on to the posterior cervicals and anterior
caudals, in the latter region passing into the transverse processes.
In most Apes the sternum is narrow, and consists of a more or
less enlarged manubrium, followed by a chain of subequal and
antero-posteriorly elongated bones, from three to six in number. In
the _Simiidæ_ alone is there a broad sternum, or one consisting of a
manubrium, followed by a single bone only, as in _Hylobates_. The Orang
presents a peculiarity, in that the sternum long remains made up of
ossifications arranged in pairs, side by side, successively. The true
ribs are seven in number on each side in the highest forms, but in
_Hylobates_ there are sometimes eight. In _Ateles_ there are sometimes
nine pairs. In _Hapale_ the number varies from six to eight, and it is
seven or eight in the other genera. The angles of the ribs are never so
marked as in Man; although most marked in _Hylobates_. _Pithecia_ is
distinguished by the greater relative breadth of the ribs. In no Ape is
the thorax half as broad again as it is deep from back to breast; but in
the _Simiidæ_ its transverse diameter exceeds its depth by from about
one-fourth to a little under one-third of the latter. In _Ateles_, and
sometimes in _Mycetes_, the thorax is wider than deep, but in all the
rest it is deeper than wide.
In regard to the appendicular skeleton it may be observed that the
Gorilla and Orang make the nearest approach to Man in the form of the
scapula; and that the supraspinous fossa of this bone is largest in
_Gorilla_ and _Mycetes_, being remarkably small in _Simia_. The _Cebidæ_
have a distinct suprascapular notch which is often converted by a bar of
bone into a foramen; this bar in _Mycetes_ giving rise to a peculiar flat
process. The acromion and coracoid processes are most developed in the
_Simiidæ_ and _Ateles_.
The relative length of the fore and hind limbs has been already briefly
touched upon. The humerus closely resembles that of Man throughout the
suborder; the nearest approximation occurring in the _Simiidæ_. As in the
Lemuroidea, this bone never has an entepicondylar foramen, but in many
of the American forms it has a supracondylar perforation. The radius and
ulna, like the tibia and fibula, are always perfectly distinct throughout
their length; and the hand can be pronated and supinated upon the
forearm. Man, the Gorilla, and the Chimpanzee differ from other forms in
having no os centrale in the carpus.
The brain of Apes is always much smaller in absolute dimensions than in
Man. Thus, according to Professor Mivart,[663] “the cranial capacity is
never less than 55 cubic inches in any normal human subject, while in
the Orang and Chimpanzee it is but 26 and 27½ cubic inches respectively.
The relative size of the brain varies inversely with the size of the
whole body, but this is the case in warm-blooded vertebrates generally.
The extreme length of the cerebrum never exceeds, as it does in Man, two
and a quarter times the length of the basicranial axis. The proportion
borne by the brain to its nerves is less in the Apes than in Man, as also
is that borne by the cerebrum to the cerebellum. In general structure
and form the brain of Apes greatly resembles that of Man. Each half
of the cerebrum contains a triradiate lateral ventricle, and though
in some _Cercopithecidæ_ the posterior cornu is relatively shorter
than in man, it again becomes elongated in the _Cebidæ_, and in many
of the latter it is actually longer relatively than it is in man. The
posterior lobes of the cerebrum are almost always so much developed as
to cover over the cerebellum, the only exceptions being the strangely
different forms _Mycetes_ and _Hylobates syndactylus_. In the latter
the cerebellum is slightly uncovered, but it is so considerably in the
former. In _Chrysothrix_ the posterior lobes are much more largely
developed relatively than they are in man. The cerebrum has almost always
a convoluted external surface. In this group, however, as in mammals
generally, a much-convoluted cerebrum is correlated with a considerable
absolute bulk of body. Thus in _Hapale_ (and there only) we find the
cerebrum quite smooth, the only groove being that which represents the
Sylvian fissure. In _Simia_ and _Gorilla_ and _Anthropopithecus_, on the
contrary, it is very richly convoluted. A hippocampus minor is present
in all Apes, and in some of the _Cebidæ_ it is much larger relatively
than it is in Man, and is absolutely larger than the hippocampus major.
Of all Apes, the Orang has a brain which is most like that of Man;
indeed, it may be said to be like Man’s in all respects, save that it
is much inferior in size and weight, and that the cerebrum is more
symmetrically convoluted and less complicated with secondary and tertiary
convolutions. If the brain of _Simia_ be compared with that of _Gorilla_
and _Anthropopithecus_, we find the height of the cerebrum in front
greater in proportion in the former than in the latter; also the bridging
convolutions, though small, are still distinguishable, while they are
absent in the Chimpanzee. Nevertheless this character cannot be of much
importance, since it reappears in _Ateles_, while two kinds of the genus
_Cebus_ (so closely allied as to have been sometimes treated as one
species) differ strangely from each other in this respect. The corpus
callosum, in Apes generally, does not extend so far back as in Man, and
it is very short in _Pithecia_. In the Orang and Chimpanzee there are,
as in Man, two corpora albicantia, while in the lower Monkeys there is
but one. The vermis of the cerebellum is larger in the _Cebidæ_ than
in the _Simiidæ_ and _Cercopithecidæ_. In all Apes below the _Simiidæ_
each lateral lobe of the cerebellum gives off a small lobule, which is
received into a special fossa of the petrous bone. Certain prominences
of the medulla oblongata, termed corpora trapezoidea, which are found in
lower mammals, begin to make their appearance in the _Cebidæ_.”
The organs connected with the functions of alimentation, circulation,
and excretion, as well as the muscles, conform generally to the type
obtaining in Man, of which full description will be found in works on
human anatomy. The tongue is longer in Apes than in Man; and a uvula is
generally present, although rudimentary in the _Cebidæ_. The peculiar
sacculation of the stomach in the subfamily _Semnopithecinæ_ has been
already mentioned; this sacculation is most developed at the cardiac
extremity, where it somewhat resembles a colon spirally coiled. In
_Hylobates_ the stomach is very like that of Man, differing only in the
more elongated and distinct pylorus. _Pithecia_ has a more globular
stomach, while in _Hapale_ the cardiac and pyloric apertures are
approximated. The intestine of Apes is devoid of valvulæ conniventes,
and it is only in Man and the _Simiidæ_ that the colon is furnished with
a vermiform appendage. The colon varies from a fully sacculated form in
_Hylobates_ to a smooth one in _Cebus_.
The liver of Apes is subject to a considerable amount of variation. In
the _Simiidæ_ it comes more or less close to the human type; that of
the Orangs being usually divided only into two principal lobes by the
umbilical vein, and showing no trace of lateral fissures. In the Gorilla
these fissures are present, so as to produce right and left lateral
and central lobes. _Hylobates_ has a liver (Fig. 352) which perhaps
is nearer to the human than that of any of the other _Simiidæ_. In the
_Cercopithecidæ_ the liver differs from that of the _Simiidæ_ by the
deeply cleft lateral fissures, and has a comparatively small and pointed
caudate lobe. The enormous size of the stomach in _Colobus_ causes the
liver to be very narrow, and pushed to the left side. The liver of the
_Cebidæ_ (Fig. 336) and _Hapalidæ_, in addition to the deeply cleft
lateral fissures, is characterised by the great size and quadrangular
form of the caudate lobe (_c_), which attains its maximum development in
_Ateles_. The gall-bladder is always present.
[Illustration: FIG. 336.—Under surface of the liver of the Black-handed
Spider Monkey (_Ateles melanochir_). _u_, Umbilical fissure; _vc_, vena
cava; _ll_, left lateral lobe; _lc_, left central lobe; _rc_, right
central lobe; _rl_, right lateral lobe; _s_, Spigelian lobe; _c_, caudate
lobe; _g_, gall-bladder.]
The larynx is in many Apes furnished with sac-like appendages, which are
variable in different species as regards number, size, and situation.
They may be dilatations of the laryngeal ventricle, as in _Simia_,
_Gorilla_, and _Anthropopithecus_, or they may open above the false
vocal chords so as to be extensions of the thyro-hyoid membrane,
as in _Hylobates_. There may be but a single median opening in the
front part of that membrane at the base of the epiglottis, as in the
_Cercopithecidæ_. There may be a single median opening at the back of the
trachea, just below the cricoid cartage, as in _Ateles_; there may be but
a single sac, or there may be five, as sometimes in _Mycetes_. These may
be enormous, meeting in the middle line in front and extending down to
the axillæ, as in the Gorilla and Orang. A sac may occupy the cavity of
the expanded body of the hyoid, as in _Mycetes_.
The hyoid has its basilar part generally somewhat more convex and
enlarged than in Man; but in _Mycetes_ it becomes greatly enlarged and
deeply excavated, so as to form a great bony bladder-like structure. The
posterior cornua of the hyoid (thyrohyals) are never entirely absent, but
the anterior or lesser cornua may be so, as in _Mycetes_. The anterior
cornua never exceed the posterior cornua in length; but they may be
(_e.g._ in _Cercopithecus_) more largely developed relatively than in
Man, and may even be jointed, as in _Lagothrix_.
The lungs have generally the form of those of man; but the right lung
may have four lobes, as in _Hylobates_. The great arterial trunks in
_Simia_, _Gorilla_, and _Anthropopithecus_ are arranged as in Man. In
_Hylobates_ and the lower Apes, however, the left carotid artery may take
its origin from the innominate artery.
In regard to their distribution in time the earliest record that we as
yet have of the occurrence of Apes is in the Middle Miocene of Europe,
where forms are met with apparently so closely allied to some of the
higher existing types that it is evident we must look much farther
back before we can get any clue to the origin of the suborder. Since
all the known fossil Old World Apes are referable to the _Simiidæ_ or
_Cercopithecidæ_, and no representatives of these families have been
obtained from the Tertiaries of America, it would appear that the
distinction of the Apes of the Old World from those of the New is of very
old standing.
At the present day Apes are mainly confined to tropical and subtropical
regions. In the Old World _Macacus inuus_ is found as far north as
Gibraltar, _M. tibetanus_ and _Semnopithecus roxellanæ_ inhabit western
Tibet, while in Japan we have _M. speciosus_. In the New World one
species of _Ateles_ is known to occur as far north as latitude 19° in
Southern Mexico, and may range a few degrees higher. To the southward
species are found near the Cape, in Timor, and the Malay Archipelago;
while in America they range in Brazil and Paraguay to about latitude 30°.
The Tibetan species are found at a very high elevation; and in the outer
Himalaya the Langurs (_Semnopithecus_) may be seen in winter and spring
leaping from bough to bough of snow-covered pines.
Apes are very abundant in the Ethiopian and Oriental regions, as well as
in that part of America which extends from Panama to Southern Brazil.
Ceylon, Borneo, Sumatra, and Java may be mentioned as islands where
Ape-life attains great development; but they are unknown in Madagascar
and the West Indian Islands, and of course in the Australasian region.
We have already alluded to the circumstance that while the _Simiidæ_
and _Cercopithecidæ_ are exclusively confined to the Old World, the
_Cebidæ_ and _Hapalidæ_ are equally restricted to the New, and we may
accordingly proceed to notice a few points in relation to generic
distribution. Of the larger _Simiidæ_ the Gorilla and Chimpanzee
are confined to Equatorial Africa, and the Orang to Malayana; but
there is evidence of the former existence of a species of Chimpanzee
(_Anthropopithecus_) and not improbably of an Orang (_Simia_) in Northern
India. The Gibbons (_Hylobates_) are now exclusively Oriental. Europe
has only _Macacus inuus_ of Gibraltar, also found in Africa north of
the Sahara, and therefore strictly Palæarctic in distribution. The
Ethiopian region includes in the _Cercopithecidæ_ the genus _Colobus_
(the African analogue of _Semnopithecus_), _Cercopithecus_, and the
Baboons (_Cynocephalus_, etc.) The Baboons range, however, into Arabia
and Syria, and also existed during the Pliocene epoch in Northern
India. _Semnopithecus_ and _Macacus_ are very characteristic of the
Oriental region; but, as already mentioned, outlying species extend into
various parts of the Palæarctic region. _Macacus_ has indeed a very
wide distribution, extending from Gibraltar and North Africa to Japan.
The allied _Cynopithecus_, represented only by _C. niger_ of Celebes,
approximates to the Baboons; while the one species of _Nasalis_ is
peculiar to Borneo. Remains of _Semnopithecus_ and _Macacus_ occur in the
Tertiaries of India and Europe, which also yield allied extinct types
noticed in the sequel.
In America, north of Panama, the genera known to be represented are
_Chrysothrix_, _Nyctipithecus_, _Cebus_, _Ateles_, _Mycetes_ and _Hapale_
in Veragua; _Nyctipithecus_, _Cebus_, _Ateles_, and _Mycetes_ in Costa
Rica and Nicaragua; _Ateles_ and _Mycetes_ in Guatemala; and _Ateles_
in Southern Mexico. Brazil is the headquarters of the American Apes;
but different portions of that vast region have a somewhat distinct
Ape fauna. Thus the genus _Eriodes_ appears in South-Eastern Brazil
to represent the species of _Ateles_ inhabiting the more northern and
western parts of the empire. Southwards, the genera _Cebus_, _Mycetes_,
_Chrysothrix_, and _Callithrix_ extend farthest; but they do not probably
all extend to the farthest limit yet known, namely 30° S. The species
found farthest south are _Mycetes caraya_, _Cebus fatuellus_, and
_Callithrix personatus_.
_Family_ HAPALIDÆ.
Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ²⁄₂; total 32. No bony external
auditory meatus, a broad internarial septum, and no cheek-pouches. Tail
non-prehensile; no ischiatic callosities. Pollex not opposable; a long,
curved, and pointed claw to all the digits except the hallux.
This family, which includes the smallest representatives of the suborder,
commonly known as Marmosets, is confined to the New World. In addition
to the diagnostic characters given above, it may be mentioned that the
pollex is elongated and the hallux very small, while the pectoral limbs
are not longer than the pelvic pair; and the tail is long and more or
less thickly covered with elongated hairs.
The dentition of the Marmosets sufficiently distinguishes them from all
other members of the suborder, although they are evidently nearly allied
to the _Cebidæ_. The small size of the hallux, and the total incapacity
of the pollex to oppose itself in the least degree to the other digits,
as well as the presence of claws on all the digits of the manus, are,
however, equally characteristic features. These animals (Fig. 337) are
not larger than Squirrels, and are of active arboreal habits, living
in small companies, and adding insects to the ordinary fruit diet.
Frequently, as in the figured species, the head is furnished on either
side with a long tuft of hair projecting outwards and backwards. They
give birth to as many as three young ones at a time, and thereby differ
from all other members of the suborder, in which one is the normal
number. They are divided into two genera, according to the proportionate
size of the lower canine to the incisors; but some species present an
intermediate condition, so as to render this distinction of somewhat
doubtful value.
_Hapale._[664]—Lower canine not longer than the incisors. A number of
species have been described, among which may be mentioned _H. jacchus_,
_H. albicollis_, _H. aurita_, and _H. humeralifer_. Remains of species of
this genus have been found in the cavern-deposits of Brazil.
[Illustration: FIG. 337.—The Golden Marmoset (_Midas chrysoleucas_). From
_Proc. Zool. Soc._ 1868, pl. 24.]
_Midas._[665]—Lower canine considerably longer than the incisors. No
less than twenty-four species of this genus have been named, among
which the Silky Marmoset (_M. rosalia_) of Columbia, the Pinche Monkey
(_M. œdipus_) of South-Eastern Brazil, and the Golden Marmoset (_M.
chrysoleucas_, Fig. 337) are well-known types.
_Family_ CEBIDÆ.
Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total 36. Tail frequently
prehensile; digits with nails; other characters as in the _Hapalidæ_.
The members of this American family are at once distinguished by the
dental formula, which is numerically higher than in any other Apes.
The various species range over the whole of tropical America, but are
most abundant in the dense forest regions of Brazil, where they live
a completely arboreal life, to which the prehensile tails of many of
them are so specially adapted. They are in most respects closely allied
to the _Hapalidæ_, but the pollex diverges somewhat from the plane of
the other digits; while the retention of the third molar is a very
distinctive feature. None of the species attain the dimensions of the
larger _Cercopithecidæ_ of the Old World. The genera are usually arranged
in five subfamilies.
Subfamily =Mycetinæ=.—Lower incisors vertical; hyoid bones enormously
inflated; tail long and prehensile, naked beneath at the end; pollex well
developed.
[Illustration: FIG. 338.—Side view of skull and hyoid bone of the Red
Howling Monkey (_Mycetes seniculus_). From De Blainville.]
_Mycetes._[666]—The sole representatives of this subfamily are the
well-known Howling Monkeys, all of which are included in the genus
_Mycetes_. They are of more bulky build, and have more produced muzzles
than the other members of the family. The truncated occipital region, and
the extraordinary development of the rami of the mandible, especially
of their angular and ascending portions, are the chief peculiarities
by which the skulls (Fig. 338) of the members of this genus are
characterised. The last named character, which is more marked in the male
than in the female sex, is related to the enormous size of the vocal
organs, which the rami of the mandible enclose and protect. The inflated
hyoid bone, which forms a deep cup, is shown in the figure. The Howlers
are subject to great individual and sexual variation of colours, so that
the discrimination of species from local races is difficult. In one
species the male is black and the female straw-coloured; and several of
the species have bright red or golden hair on the flanks. In disposition
these creatures are sluggish and stupid, but their chief characteristic
is their prodigious power of voice. Mr. Bates, in his _Naturalist on the
Amazons_, observes that “when Howlers are seen in the forest there are
generally three or four of them mounted on the topmost branches of a
tree. It does not appear that their harrowing roar is emitted from sudden
alarm; at least it was not so in captive individuals. It is probable,
however, that the noise serves to intimidate their enemies.”
Several species have been described, the Red Howler (_M. seniculus_) and
the Ursine Howler (_M. ursinus_) being well-known forms. Remains of this
genus probably referable to existing types are found fossilised in the
cavern-deposits of Brazil. An allied fossil form from the South American
Pleistocene has been described as _Protopithecus_.
Subfamily =Pitheciinæ=.—Lower incisors inclined forward at their
summits; hyoid bone normal; tail long or short, non-prehensile; pollex
well developed. Two genera are included in this subfamily, readily
distinguished by the length of the tail.
_Pithecia._[667]—The Sakis, as the representatives of this genus are
commonly termed, are readily characterised by the length of the tail; the
angle of the mandible is expanded, although less so than in _Mycetes_. A
number of species have been described, the Black Saki (_P. satanas_) of
the Lower Amazons, being one of the best known. While some species, like
_P. hirsuta_, have long hair covering the whole of the head, body, and
tail, in others only the head, or the cheeks and chin, are so clothed.
_Uacaria._[668]—The Uakari Monkeys differ from all the other _Cebidæ_
by their short Baboon-like tail. The Bald Uakari (_U. calva_) of the
Rio Negro, and the closely allied _U. rubicunda_ of the Upper Amazons,
are remarkable for their scarlet face, which forms a striking contrast
to the long, silky, whitish hair covering the body. According to Mr.
Bates, the Uakaris live in forests which are inundated during a great
part of the year, and never descend to the ground; they appear to be
rare and of local distribution. The third species, _U. melanocephala_,
differs considerably from both the others. The cæcum of _U. calva_,
according to Mr. F. E. Beddard, measures upwards of “10 inches along
the greater curvature; it is separated from the colon by a very marked
constriction; it is not sacculated, and when fully distended with air is
curved on itself into a little less than a circle; it is furnished with a
well-developed median frenum carrying blood-vessels.” A similar type of
cæcum is also found in _Callithrix_ and _Pithecia_.
Subfamily =Nyctipithecinæ=.—Lower incisors vertical; hyoid normal; tail
long, non-prehensile; pollex well developed.
Three genera are included in this subfamily, the species being partly
insectivorous.
[Illustration: FIG. 339.—The Moloch Teetee (_Callithrix moloch_). From
_Archives du Muséum_, vol. iv. pt. 3.]
_Callithrix._[669]—Head small, depressed, and not elongated; nares widely
separated; canines small; angle of mandible expanded as in _Pithecia_;
tail with long hair.
This genus comprises several small species, mostly from Brazil and the
Amazons, and commonly known as Teetees, one of the best-known species
(_C. moloch_, Fig. 339) being represented in the accompanying woodcut.
The smaller eyes and the more widely separated nostrils distinguish them
from _Nyctipithecus_; while the small canines and the bushy tail readily
mark their distinction from _Chrysothrix_. Remains of _Callithrix_ have
been found in the Brazilian caves.
_Chrysothrix._[670]—Head greatly elongated; orbits large and closely
approximated; canines well developed; tail with comparatively short hair.
[Illustration: FIG. 340.—The Lemurine Douroucouli (_Nyctipithecus
lemurinus_). From _Archives du Muséum_, vol. iv, pl. 2.]
The small Squirrel Monkeys, of which four species have been described,
are characterised by the great backward projection of the occipital
region of the skull, and by orbits approximating in size to those of the
next genus.
_Nyctipithecus._[671]—Head rounded; orbits very large, separated by a
narrow septum; nares somewhat approximated.
The Douroucoulis (Fig. 340), as the members of this genus are called, are
of nocturnal habits, in association with which the eyes are of enormous
dimensions, as in the Lemuroid genus _Loris_. The following account, of
two species of this genus is taken from Mr. Bates’s _Naturalist on the
Amazons_: “They sleep all day long in hollow trees, and come forth to
prey on insects and eat fruit only in the night. They are of small size,
the body being about a foot long, and the tail 14 inches, and are thickly
clothed with soft gray and brown fur, similar in substance to that of the
Rabbit. Their physiognomy reminds one of the Owl or Tiger-Cat; the face
is rounded and encircled by a ruff of whitish fur; the muzzle is not at
all prominent; the mouth and chin are small; the ears are very short,
scarcely appearing above the hair of the head; and the eyes are large
and yellowish in colour, imparting the staring expression of nocturnal
birds of prey. The forehead is whitish, and decorated with black stripes,
which in one of the species (_N. trivirgatus_) continue to the crown,
and in the other (_N. felinus_) meet on the top of the forehead. _N.
trivirgatus_ was first described by Humboldt, who discovered it on the
banks of the Cassiquiare, near the headquarters of the Rio Negro.”
Subfamily =Cebinæ=.—Lower incisors vertical; hyoid bone normal; tail long
and prehensile; pollex present or absent.
This subfamily includes the typical members of the family, which are
arranged in four genera.
_Ateles._[672]—Form slender; limbs very long; fur not woolly; pollex
absent; tail naked beneath distally; nails not much laterally compressed
and pointed.
This genus includes the well-known Spider Monkeys (Fig. 341), which by
their long limbs and tail are admirably adapted to a purely arboreal
life, although they lack the active and agile habits of the Old World
Gibbons. The tail with the under surface of its extremity naked affords
the most completely prehensile type of this organ, and can sustain the
weight of the whole body. Objects are not unfrequently grasped by it and
brought within reach of the hand or mouth. Owing to the absence of the
pollex the power of grasping is very imperfect in the hand. At least
fourteen species of this genus have been described, among the best-known
being _A. melanochir_ (Fig. 341), _A. paniscus_ of Guiana, _A. geoffroyi_
of Central America, _A. ater_ of Eastern Peru, and _A. hybridus_ of
Colombia.
_Eriodes._[673]—Form slender; limbs very long; fur woolly; internasal
septum narrower than usual in the family; pollex rudimentary; tail naked
beneath distally; nails exceedingly compressed laterally, and pointed.
This genus is represented by three species from South-East Brazil, which,
while closely allied to the true Spider Monkeys, differ by their woolly
hair, the narrow internasal septum, the presence of a rudimentary pollex,
and the great compression of the nails. The species are _E. arachnoides_,
_E. hemidactylus_, and _E. hypoxanthus_.
_Lagothrix._[674]—Form rather robust; limbs moderate; fur woolly; pollex
well developed; tail distally naked beneath.
[Illustration: FIG. 341.—The Black-handed Spider Monkey (_Ateles
melanochir_). From _Proc. Zool. Soc._ 1871, pl. 15.]
The Woolly Monkeys differ from the preceding genera by the presence
of a well developed pollex. They resemble _Eriodes_ in their fur and
compressed nails, but differ in the more widely separated nares. The tail
resembles that of the preceding genera. Speaking of these Monkeys Mr.
Bates observes that “the Barrigudos are very bulky animals, whilst the
Spider Monkeys are remarkable for the slenderness of their bodies and
limbs. I obtained specimens of what have been considered two species,
one (_L. olivaceus?_) having the head clothed with gray, the other (_L.
humboldti_, Fig. 342) with black fur. They both live together in the same
places, and are probably only differently coloured individuals of one and
the same species. I sent home a very large male of one of these kinds,
which measured 27 inches in length of trunk, the tail being 26 inches
long; it was the largest monkey I saw in America, with the exception of
a black Howler, whose body was 28 inches in height. The skin of the face
in the Barrigudo is black and wrinkled, the forehead is low, with the
eyebrows projecting.... In the forests the Barrigudo is not a very active
animal; it lives exclusively on fruits, and is much persecuted by the
Indians on account of the excellence of its flesh as food.” Five species
are usually recognised, viz. _L. canus_, _L. humboldti_, _L. castelnaui_,
_L. tschudii_, and _L. geoffroyi_.
[Illustration: FIG. 342.—Humboldt’s Lagothrix (_Lagothrix humboldti_).
From _Proc. Zool. Soc._ 1863, pl. 31.]
_Cebus._[675]—Form rather robust; limbs moderate; fur not woolly; pollex
well developed; tail not naked beneath distally.
This, the typical, genus includes the Sapajous or Capuchins (Fig.
343), which are so commonly seen in this country in captivity, being
the favourite Monkeys of itinerant musicians. They are smaller and
stouter in build than the Spider Monkeys, from which they are readily
distinguished by the well-developed pollex, and the absence of a naked
under surface to the extremity of the tail. At least twenty species
have been described (_C. fatuellus_, _C. lunatus_, _C. capucinus_, _C.
albifrons_, _C. hypoleucus_, etc.), but it is probable that some of these
are not entitled to stand, since there is a large amount of individual
variation. Fossil remains of species of _Cebus_ have been described from
the Pleistocene cavern-deposits of Brazil.
[Illustration: FIG. 343.—The White-cheeked Sapajou (_Cebus lunatus_).
From _Proc. Zool. Soc._ 1865, pl. 45.]
_Family_ CERCOPITHECIDÆ.
Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ²⁄₂, _m_ ³⁄₃; total 32. Crowns of molars
elongated antero-posteriorly, with the tubercles forming a pair of
imperfect transverse ridges, and the last lower molar usually with a hind
talon. A bony external auditory meatus. A narrow internarial septum. Tail
non-prehensile. Ischiatic callosities present. Cheek-pouches present or
absent. Pollex, when present, opposable. Pelvic limbs never much longer
than pectoral. Sternum narrow. Cæcum without vermiform appendage.
This family includes all the Old World Apes, with the exception of the
_Simiidæ_, and may be divided into the subfamilies _Cercopithecinæ_ and
_Semnopithecinæ_.
Subfamily =Cercopithecinæ=.—Pelvic and pectoral limbs approximately
equal; tail variable; cheek-pouches present; stomach simple.
This subfamily comprises, the African Baboons, the common Indian
Monkeys constituting the genus _Macacus_, together with the African
_Cercopithecus_ and _Cercocebus_ and a few allied types.
_Cynocephalus._[676]—Muzzle much elongated (Fig. 344), with the nostrils
terminal; ischial callosities very large; tail more or less short; muzzle
swollen by enlargement of the maxillæ. Now confined to Africa and Arabia.
[Illustration: FIG. 344.—Skeleton of the Chacma Baboon (_Cynocephalus
porcarius_). From De Blainville.]
This genus comprises the typical Baboons, and we may select the
well-known Mandrill (_C. maimon_), of tropical West Africa, as a good
illustrative example. It may be mentioned in passing that the name
Mandrill appears to have been first introduced into English literature by
William Smith in his _New Voyage to Guinea_, published in 1744, wherein
he mentions among the animals of Sierra Leone one “called by the white
men in this country Mandrill,” but adds, “why it is so called I know
not.”[677] Smith gives sufficiently accurate details to show that his
animal is not that now called Mandrill, but the Chimpanzee. Buffon,
however, while quoting Smith’s description, transferred the name to the
very different species now under consideration, and to that it has been
attached ever since.
The Baboons generally are distinguished from most other Monkeys by
the comparative equality of the length of their limbs, which with the
structure of the vertebral column adapts them rather for quadrupedal
progression on the ground than for climbing among the branches of trees;
and some of them, like the South African Chacma (_C. porcarius_), of
which the skeleton is shown in Fig. 344, live habitually among rocks,
and are much less completely frugivorous than other Apes. They are also
remarkable for the great size of their face and jaws as compared with the
part of the skull which encloses the brain. The Mandrill, in addition
to these characters, is distinguished by the heaviness of its body,
stoutness and strength of its limbs, and exceeding shortness of its tail,
which is a mere stump, not 2 inches long, and usually carried erect. It
is, moreover, remarkable for the prominence of its brow ridges, beneath
which the small and closely approximated eyes are deeply sunk; the
immense size of the canine teeth; the great development of a pair of oval
bony prominences on the maxillary bones in front of the orbits, rising on
each side of the median line of the face, and covered by a longitudinally
ribbed naked skin; and more especially for the extraordinarily vivid
colouring of some parts of the skin. The body generally is covered with a
full soft coating of hair of a light olive-brown above and silvery-gray
beneath, and the chin is furnished underneath with a small pointed
yellow beard. The hair of the forehead and temples is directed upwards
so as to meet in a point on the crown, which gives the head a triangular
appearance. The ears are naked and of a bluish-black colour. The hands
and feet are naked and black. A large space around the greatly developed
ischial callosities, as well as the upper part of the insides of the
thighs, are naked and of a crimson colour, shading off on the sides to
lilac or blue, which, depending not upon pigment but upon injection of
the superficial blood-vessels, varies in intensity according to the
condition of the animal—increasing under excitement, fading during
sickness, and disappearing after death. But it is in the face that the
most remarkable disposition of vivid hues occur, more resembling those
of a brilliantly coloured flower than what might be expected in the
cutaneous covering of a mammal. The cheek-prominences are of an intense
blue, the effect of which is heightened by deeply sunk longitudinal
furrows of a darker tint, while the central line and termination of the
nose are a bright scarlet. Notwithstanding the beauty of these colours
in themselves, the whole combination, with the form and expression of
features, quite justifies Cuvier’s assertion that “il serait difficile de
se figurer un être plus hideux que le Mandrill.”
It is only to fully adult males that this description applies. The female
is of much smaller size, and of more slender make; and, though the
general tone of the hairy parts of the body is the same, the prominences,
furrows, and colouring of the face are very much less marked. The young
males have black faces. At the age of three the blue of the cheeks begins
to appear, but it is not until they are about five, when they cut their
great canine teeth, that they acquire the characteristic red of the end
of the nose.
[Illustration: FIG. 345.—The Yellow Baboon (_Cynocephalus babuin_). From
_Archives du Muséum_, Vol. ii. pl. 34.]
The Mandrills, especially the old males, are remarkable for the ferocity
of their disposition, as well as for other disagreeable qualities, which
are fully described in Cuvier’s account of the animal in _La Ménagerie
du Muséum d’Histoire Naturelle_ (1801), but when young they can easily
be tamed. Like the rest of the Baboons, they appear to be rather
indiscriminate eaters, feeding upon fruit, roots, reptiles, insects,
scorpions, etc., and inhabit open rocky ground rather than forests. Not
much is known of the Mandrill’s habits in the wild state, nor of the
exact limits of its geographical distribution. The specimens brought to
Europe all come from the west coast of tropical Africa, from Guinea to
the Gaboon.
An allied species, the Drill (_C. leucophæus_), which resembles the
Mandrill in size, general proportions, and shortness of tail, but wants
the bright colouring of the face which makes that animal so remarkable,
inhabits the same district. Other well-known species are the Yellow
Baboon (_C. babuin_), of West Africa (Fig. 345); the Arabian Baboon
(_C. hamadryas_), of Arabia and Abyssinia; and the Anubis Baboon (_C.
anubis_), of West Africa.
It is very noteworthy from a distributional point of view, as showing
the former intimate connection between the faunas of the Oriental and
Ethiopian regions, that fossil remains of Baboons have been found in the
Pleistocene cavern-deposits of Madras, and also in the older Pliocene
beds of the Siwalik Hills in Northern India; the two species from the
latter deposits having been described as _C. subhimalayanus_ and _C.
falconeri_.
_Theropithecus._[678]—Distinguished from _Cynocephalus_ by the nostrils
not being terminal, but situated as in _Macacus_. This genus is
represented by the Abyssinian Gelada (_T. gelada_) and the allied _T.
obscurus_.
_Cynopithecus._[679]—The Black Ape of Celebes (_C. niger_) forms a
connecting link between the Baboons and the genus _Macacus_; the skull
differing from that of the latter in the development of longitudinal
ridges on the sides of the upper surface of the maxillæ, as in some of
the species of _Cynocephalus_. The muzzle is also more produced than in
_Macacus_.
[Illustration: FIG. 346.—The Tibetan Macaque (_Macacus tibetanus_). From
Milne-Edwards, _Recherches des Mammifères_, pl. 34.]
_Macacus._[680]—Muzzle considerably produced; nostrils not terminal;
cheek-pouches and ischial callosities well developed; tail long, short,
or absent; a distinct talon to the third lower molar.
With the exception of the Barbary Ape (_M. inuus_) of Northern Africa
and Gibraltar, the Macaques are now exclusively Asiatic, one species
(Fig. 346) occurring in Tibet, and another (_M. speciosus_) being found
in Japan. All these Monkeys are of stout build, and it is chiefly by the
greater production of the muzzle, the larger ischiatic callosities, and
the frequent shortness of the tail that they are distinguished from the
under-mentioned African genera. The transition from the longer-tailed
to the short-tailed forms is so complete that the proposed generic
separation of the latter as _Innus_ is impracticable. In _M. innus_ the
tail is wanting; in _M. tibetanus_ (Fig. 346) and _M. nemestrinus_ of
Tenasserim it is short; in the common Bengal Monkey (_M. rhesus_) it is
about one-half the length of the head and body, while in _M. cynomolgus_
and its allies it is still longer. In the Indian Lion-tailed Monkey (_M.
silenus_) it is tufted at the end.
The following summary of the habits of the Macaques is taken from Mr. W.
T. Blanford’s _Mammals of British India_: “The species of the present
genus resemble each other in their habits; they are found in flocks,
often of considerable size, and generally composed of individuals
of both sexes and of all ages. They are active animals, though less
rapid in their movements, whether on trees or on the ground than the
_Semnopitheci_. Their food is varied, most of the species, if not all,
eating insects as well as seeds, fruits, etc., and one kind feeding
partly on crustacea. They have occasionally been known to devour lizards,
and, it is said, frogs also. All have the habit of cramming food into
their cheek-pouches for mastication at leisure—a practice that must be
familiar to any one who has fed monkeys in confinement. The voice and
gestures of all the species are similar, and differ entirely from those
of both the Gibbons and _Semnopitheci_.... The majority of the species
are very docile when young. They thrive well, and several of them have
bred in confinement. The period of gestation is almost seven months, only
a single young one, as a rule, being produced at a birth. They become
adult at the age of four or five years, but breed earlier.”
The Common Indian _M. rhesus_ is found in the Himalaya at an elevation of
over 8000 feet.
Fossil remains of _Macacus_ are found in India in the Pleistocene of
Madras and the Pliocene of the Punjab; and they also occur in the
Pliocene of France and Italy, those from the latter deposits having been
incorrectly separated as _Aulaxinuus_. Part of the jaw of a Monkey from
the Pleistocene of Essex has been described as _Macacus pliocenus_, and
is very interesting as showing the presence of Apes in Europe at that
late period.
_Cercocebus._[681]—An African genus agreeing with _Macacus_ in the
presence of a hind talon to the third lower molar, but with the other
characters of _Cercopithecus_. The species of this genus are known as
Mangabeys, or White-eyelid Monkeys, and include _C. collaris_, _C.
fuliginosus_, _C. æthiops_, and _C. albigena_; all being from West Africa.
_Cercopithecus._[682]—Muzzle more or less short; ischial callosities
moderate; tail long; no talon to third lower molar. Build more slender
than in _Macacus_. Confined to Africa.
The members of this and the last genus include those Monkeys which in
their comparative slender build and length of tail make the nearest
approach to the next subfamily. There are numerous species, among which
the Green Monkey (_C. cullitrichus_), the Grivet (_C. griseo-viridis_),
the Vervet (_C. lalandi_), the Pluto Monkey (_C. pluto_, Fig. 347). The
Patas (_C. ruber_), the Diana Monkey (_C. diana_), and the Mona Monkey
(_C. mona_) are well-known types.
Subfamily =Semnopithecinæ=.[683]—Pelvic limbs longer than the pectoral,
tail very long; no cheek-pouches; stomach sacculated. Build slender.
[Illustration: FIG. 347.—The Pluto Monkey (_Cercopithecus pluto_). From
Gray, _Proc. Zool. Soc._ 1848, p. 57.]
This subfamily is represented by three genera, of which one is African
and two are Asiatic. Mr. W. T. Blanford, in his _Mammals of British
India_, observes that “the members of this subfamily are readily
distinguished by their slender form, and by the absence of cheek-pouches.
They are more purely herbivorous than the Macaque Monkeys, and a
considerable portion of their food consists of leaves and young shoots.
In consequence probably of the nature of their food, these Monkeys are
more delicate than the species of _Macacus_, and are thus less easily
kept in captivity. They are consequently far less well represented in
European museums, and have been less studied by European naturalists.
Very little is known of their general life-history or of their feeding
habits.”
Their digestive organs are much modified, the stomach attaining an
extraordinary complexity, which may be described as follows. An ordinary
stomach must be supposed to lie immensely elongated, and gradually
tapering from the cardiac end to a very prolonged, narrow, pyloric
extremity. Then two longitudinal muscular bands, corresponding in
situation to the greater and lesser curvatures of an ordinary stomach—the
former commencing just below the fundus, and the latter at the cardiac
orifice, and both proceeding towards the pylorus—are developed, so as
to pucker up the cavity into a number of pouches, exactly in the same
principle as the human colon is puckered up by its three longitudinal
bands. These pouches are largest and most strongly marked at the
œsophageal end, and becoming less and less distinct, quite cease several
inches before the pylorus is reached, the last part of the organ being
a simple smooth-walled tube. The fundus, or cardiac end of the stomach,
is formed by a single large sac, slightly constricted on its under
surface by the prolongation of the interior longitudinal band, or that
corresponding to the great curvature. The œsophagus enters into the upper
part of the left, or pyloric end of this sac, or rather at the point
of junction between it and the second (also a very large) sacculus.
Furthermore, the whole of this elongated sacculated organ is, by the
brevity, as it were, of the lesser curvature, coiled upon itself in an
irregularly spiral manner, so that when _in situ_ the pylorus comes to be
placed very near the œsophageal entrance.
[Illustration: FIG. 348.—Lateral view of the skull and palatal aspect of
the cranium of _Semnopithecus nemæus_. (From De Blainville.)]
_Nasalis._[684]—Skull resembling that of the _Cercopithecinæ_ in that the
lower border of the nasal bones extends considerably below the lower
border of the orbits, whereas in the other _Semnopithecinæ_ the aperture
of the nares extends upwards between the orbits. Nose produced into a
large proboscis. Other characters as in _Semnopithecus_.
This genus includes only the Proboscis Monkey (_N. larratus_) of Borneo,
remarkable for the great prolongation of the nose in the adult. In young
animals the nose is relatively much shorter, and bent upwards after the
manner of that of _Semnopithecus roxellanæ_ (Fig. 349).
[Illustration: FIG. 349.—_Semnopithecus roxellanæ._ (From Milne-Edwards,
_Recherches des Mammifères_, pl. 36.)]
_Semnopithecus._[685]—Pollex small; narial aperture extending upwards
between the orbits. Now confined to Asia.
This genus is characteristic of South-Eastern Asia from the Himalaya
southwards, the Oriental region being its headquarters. The development
of the muzzle is less than in the Macaques, and the facial angle is
higher, but it does not appear that this indicates greater intellectual
capacity. The outlying _S. roxellanæ_[686] (Fig. 349), of the highlands
of Eastern Tibet and Kansu, is remarkable for the peculiar upturned nose,
in which respect, as already mentioned, it recalls the young of _Nasalis
larvatus_. The genus is represented in India and Burma by no less than
fourteen species, of which the common Indian Langur, or Hanuman Monkey
(_S. entellus_) and the larger Himalayan Langur (_S. schistaceus_) are
two of the best known. In the former the length of the head and body is
about 24, and that of the tail 38 inches in adult males. This monkey,
owing to the veneration in which it is held by the Hindus, is a great
pest in many parts of India, frequently pilfering grain from the shops
in the native bazaars. According to Mr. Blanford, it “is usually found
in smaller or larger communities, composed of individuals of both sexes
and of all ages, the youngest clinging to their mothers and being carried
by them, especially when alarmed. An old male is occasionally found
solitary, as with so many other mammals.... Apart from villages, the
high trees on the banks of streams or of tanks, and, in parts of Central
India, rocky hills are the favourite haunts of these monkeys. Whether
on trees, on rocks, or on the ground, they are exceedingly active.” The
closely allied _S. schistaceus_ attains a larger average size, full grown
males attaining a length of 30 inches, the tail measuring 36 inches.
In the spring and winter this species may be observed in the Kashmir
Himalaya leaping among the snow-laden trees of the forest. In a fossil
state _Semnopithecus_ occurs in the Pleistocene and Pliocene of India,
and it has also been recorded from the Pliocene of France and Italy.
_Colobus._[687]—This African genus differs from _Semnopithecus_ in that
the pollex is absent or reduced to a small tubercle, which may or may not
carry a nail. About eleven species have been described, some of which are
remarkable for the beautiful mantle of long silky hair which hangs down
from each side of the body, and for their tufted tails. In _C. guereza_
from Abyssinia these are white, and the rest of the body and limbs black.
Others (as _C. satanas_) are entirely black. The skins of the long-haired
species are largely imported into Europe for the manufacture of ladies’
muffs, etc.
_Extinct Genera._—Certain types of Apes from the European Tertiaries
indicate genera referable to the _Cercopithecidæ_, but distinct from
any of those now living. Of these _Mesopithecus_,[688] from the Lower
Pliocene Pikermi beds of Attica, is known by almost complete skeletons,
and resembles _Macacus_ in the shortness and stoutness of the limbs, but
agrees with _Semnopithecus_ in the characters of the skull and teeth. An
allied Monkey from the Lower Pliocene of Perpignan, in France, differs
from _Mesopithecus pentelici_ by its superior size, proportionately more
produced muzzle, and larger hind talon to the last lower molar; it has
been described under the name of _Dolichopithecus_.[689]
The genus _Oreopithecus_[690] was founded upon the remains of an Ape
from the Middle Miocene of Monte Bamboli, in Tuscany, of somewhat larger
size than a Gibbon, and apparently presenting characters connecting
the _Cercopithecidæ_ and _Simiidæ_. According to Dr. Ristori,[691] it
resembles the former, especially _Cynocephalus_ and _Semnopithecus_, in
the long dental series and the elongation of the last molars; but in the
shortness of the face, rounding of the chin, and the diagonal arrangement
of the molar tubercles, it approximates to the _Simiidæ_, of which it may
have been an ancestral type.
_Family_ SIMIIDÆ.
Crowns of molars relatively wide, with the angles more or less rounded
off, the tubercles not forming transverse ridges, and the last lower
molar without a hind talon. No tail. No cheek-pouches. Ischiatic
callosities, if present, small. Pectoral limbs much longer than pelvic.
Sternum broad. Cæcum with vermiform appendage. Centrale of carpus
sometimes absent. Other characters as in _Cercopithecidæ_.
This family contains the true Anthropoid Old World Apes, namely the
Gibbons, Orangs, Chimpanzees, and Gorillas, which are the most highly
organised of all the Apes, and thus make the nearest approach to Man.
_Hylobates._[692]—Skull not produced at the vertex; body and limbs
slender, the pectoral limbs being so elongated that the hands reach
the ground when walking upright; hallux well developed; a centrale in
the carpus; and small ischiatic callosities. Size smaller than in the
following genera, the height of the largest species (_H. syndactylus_)
not much exceeding 3 feet. Now confined to Asia.
The Gibbons, or Long-armed Apes (Figs. 350, 351), are readily
distinguished from the remaining members of the family by the characters
given above, as well as by the circumstance that they are the only Apes
which habitually walk in an upright position. It is in these animals
that we meet with the last traces of the ischial callosities so largely
developed in the _Cercopithecidæ_. The species are now restricted to
South-Eastern Asia, being especially abundant in the Malay Archipelago
and adjacent regions.
The largest species is the Sumatran Siamang (_H. syndactylus_), which
attains a height of 3 feet, and has been generically separated by some
writers as _Siamanga_. It is remarkable as having a better developed
chin and wider sternum than any other Ape, and differs from the other
members of the genus by the circumstance that the second and third digits
of the pes are united by skin as far as their last joints. Exclusive of
this species, the Gibbons differ but little from one another in size and
general conformation, and since the colour of individuals undoubtedly
referable to a single species is remarkably variable, there is much
uncertainty about the number of species, and much confusion in the
nomenclature. Among well-marked species we may mention the Hoolock (_H.
hoolock_), ranging from the South of Assam through Sylhet and Cachar
to the Irawadi Valley near Bhamo, the White-handed Gibbon (_H. lar_,
Fig. 350), which is found in Tenasserim and throughout Malayana, the
Dun-coloured Gibbon (_H. entelloides_, Fig. 351) of Malayana, and the
Tufted Gibbon (_H. pileatus_) of Siam and Cambogia.
[Illustration: FIG. 350.—The White-handed Gibbon (_Hylobates lar_). From
Blanford, _Mammals of British India_, p. 8.]
The following account of the habits of the Gibbons is taken from Mr.
W. T. Blanford’s _Mammals of British India_. “Gibbons are thoroughly
arboreal, and Hoolocks are almost, if not entirely, confined to
hill-forest. They move chiefly by means of their long arms, by which
they swing themselves for prodigious distances from branch to branch
and from tree to tree. They descend hillsides at a surprising pace,
their descent being accomplished by grasping bamboos or branches that
bend beneath their weight, and allow them to drop until they can seize
the ends of other bamboos or branches lower on the slope, and take
another mighty swing downwards. They also ascend with great rapidity,
swinging themselves from tree to tree. When walking on the ground the
Hoolock rests on its hind feet alone, with the sole flat on the ground,
and the great toe widely separated from the other digits. The arms are
usually held upwards, sometimes horizontally, their great length giving
the animal a very peculiar aspect. Gibbons walk rather quickly, with a
waddling gait, and can easily be overtaken by men when on the ground. The
food of these Apes consists of fruit, leaves, young shoots, spiders (of
which they are very fond), insects, birds’ eggs, and almost certainly of
young birds, if not of any birds they can capture. Anderson found that
small birds were killed and devoured by Hoolocks in confinement with a
method and eagerness that showed this prey to be the natural food of the
Apes. The Hoolock drinks with its lips, putting its head down to the
water as Monkeys do. All species of _Hylobates_ have a powerful voice,
and the common name of the Hoolock is taken from its peculiar double
call, which is repeated several times. At a distance the sound much
resembles a human voice; it is a peculiar wailing note, audible from
afar, and in the countries inhabited by these animals is one of the most
familiar forest sounds. The calls commence at daybreak, and are continued
till 9 or 10 A.M., several of the flock joining in the cry, like hounds
giving tongue. After 9 or 10 o’clock in the morning the animals feed or
rest, and remain silent throughout the middle of the day, but recommence
calling towards evening, though to a less extent than in the earlier part
of the day.”
[Illustration: FIG. 351.—The Dun-coloured Gibbon (_Hylobates
entelloides_). From _Archiv. du Muséum_, vol. ii. pl. 29.]
The skull of the Gibbons, although agreeing with that of other Apes in
its prognathism, presents a somewhat human appearance, and the molar
teeth are also very like diminutive human molars. In the anterior inward
inclination of the two series of cheek-teeth and the inward position
of the upper premolars the Gibbons make an approach to the human type
unknown in other Apes.
The figure of the liver of one species of this genus is introduced to
show the general absence of lateral fissures and the small size of the
caudate lobe (_c_) characteristic of the liver of all the _Simiidæ_,
except _Gorilla_ (see p. 706), as well as that of Man. Another specimen
of the liver of the same species showed scarcely any trace of a caudate
lobe.
[Illustration: FIG. 352.—Under surface of the liver of _Hylobates lar._
_u_, Umbilical fissure; _p_, portal fissure; _vc_, vena cava; _l_, left
lobe; _r_, right lobe; _s_, Spigelian lobe; _c_, caudate lobe; _g_,
gall-bladder.]
A fossil Ape from the Middle Miocene of France, originally described as
_Pliopithecus_, indicates an extinct Gibbon which does not appear to be
generically separable from _Hylobates_.
_Simia._[693]—Skull (Fig. 353) produced at the vertex; body and limbs
massive; the pectoral limbs reaching to the ankle; a centrale in the
carpus; hallux very small; sixteen dorso-lumbar vertebræ, and twelve
pairs of ribs; no ischiatic callosities. Oriental.
[Illustration: FIG. 353.—Side view of the skull of adult Orang (_Simia
satyrus_). From _Trans. Zool. Soc._ vol. i. pl. 53.]
This genus includes the large red-haired Apes from Sumatra and Borneo
commonly known as Orangs, or Orang-Utans,[694] of which there is probably
only a single species (_S. satyrus_). These animals inhabit the swampy
forests near the coasts; and the males attain a height of about 4 feet 4
inches. The body is very bulky and the legs exceedingly short, but the
arms are very long, reaching in the erect posture down to the ankles.
The Orang walks resting on the knuckles of the hands and the outer sides
of the feet, with the soles of the latter turned mainly inwards, as in
Fig. 354. Its movements appear to be slow and deliberate, and in those
specimens which have been kept in captivity in this country the demeanour
is languid and melancholy, although this is far from being the case with
those shown in the more congenial climate of the Zoological Gardens at
Calcutta. The habits of these animals are arboreal, and they build a kind
of shelter or nest of boughs and leaves; their food appears to consist
mainly of fruits, and is exclusively of a vegetable nature. The whole
of the body is clothed with long hair of a reddish-brown colour, and
full-grown males have a well developed beard; the males not unfrequently
also develop a large warty protuberance, formed of fibro-cellular tissue,
on either side of the face. The hands are long, and are characterised
by the small size of the pollex, which does not reach to the end of
the metacarpal of the index finger. The feet have a similar structure,
the hallux only reaching to the middle of the proximal phalange of the
adjacent toe, and being often destitute not only of a nail, but likewise
of the terminal phalange. The presence of a centrale in the carpus is a
feature in which _Simia_ agrees with _Hylobates_ and the lower Apes, and
differs from the two following genera and Man. With very rare exceptions
the number of dorso-lumbar vertebræ is sixteen, of which twelve carry
ribs, and therefore belong to the dorsal series, while the remaining
four are lumbar. The distinction between the last lumbar and the first
sacral vertebræ is clearly marked in young skeletons by the additional
pleurapophysial ossifications (sacral ribs) in the transverse processes
of the latter. Thus though _Simia_ presents a closer resemblance to
Man than does _Anthropopithecus_ in the number of ribs, it differs
in the more important characters of that of the whole series of
trunk-vertebræ.[695] The hemispheres of the brain are much convoluted;
the whole brain being more human-like than in any other Ape. The larynx
is remarkable for having a prolongation from each ventricle, which in the
adult become of enormous dimensions, and unite in front of the trachea to
form one large sac extending downwards between the muscles to the axilla.
[Illustration: FIG. 354.—The Orang-Utan (_Simia satyrus_). From Mr.
Wolf’s sketch at the Zoological Gardens.]
The skull of the Orang (Fig. 353) is characterised by its highly vaulted
cranial portion, which is comparatively short (brachycephalic). The
sagittal crest is well developed on the vertex, and has a highly convex
contour; the superciliary ridges are but moderately developed, and do not
stand out in the prominent manner so characteristic of the Gorilla. The
aperture of the nares in the skull is more pear-shaped than in the two
following genera.
The canines of the male Orang attain a great development; and the molars
are characterised by the complex structure of their cusps and the
numerous rugosities on the crown surface. The outer border of the upper
premolars is placed in the same line as that of the molars.
The broken canine tooth of a large Anthropoid Ape from the Lower Pliocene
of the Siwalik Hills probably indicates the existence at that period of a
species of _Simia_ in Northern India.
_Gorilla._[696]—Skull not produced at the vertex; body and limbs massive,
the pectoral limb not reaching below the middle of the lower leg (Fig.
355); no centrale in the carpus: hallux well developed; seventeen
dorso-lumbar vertebræ, of which thirteen carry ribs; no ischiatic
callosities. Male much larger than female, and with very strongly marked
cranial ridges, which are wanting in the latter. Mandibular symphysis
long. Ethiopian.
The well-known Gorilla (Fig. 356), of which there seems to be only one
species (_G. savagei_), is found in Western Equatorial Africa, chiefly or
entirely in the district enclosed by the Cameroon and Congo rivers. It
is the largest of all the Apes, its bulk considerably exceeding that of
man, although from the shortness of the legs it appears never to attain a
greater height than 5½ feet. The first introduction of this animal to the
notice of zoologists was made in 1847 by Dr. Thomas Savage, but it was
not fully known till many years later.
[Illustration: FIG. 355.—Skeleton of the Gorilla. (From De Blainville.)]
The skin of the Gorilla is entirely black, the hair being blackish, but
turning more or less gray in old individuals. The arms reach down as far
as the middle of the lower leg; while the pollex extends only a short
distance beyond the base of the first phalange of the index finger,
and the hallux reaches nearly as far as the distal extremity of the
corresponding digit of the foot. The digits of both the hand and foot are
united together by integument as far as the distal extremities of the
first phalanges. The larynx has very capacious air-sacs, which meet in
front of the trachea and communicate with the ventricles; and in advanced
age these sacs may extend to the axilla. The ears are relatively small.
The skull is of an elongated or dolichocephalic type; that of the adult
male being characterised by the enormous development of the supraorbital
ridges, which form a kind of penthouse over the eyes, and contribute to
the peculiarly ferocious appearance of the animal. The sagittal crest is
also very large. The canine teeth of the male are very large, and are
inclined outwards in both jaws. In the cheek-teeth the upper premolars
are of considerable antero-posterior extent, with their outer border
placed in the same line as that of the molars; and the third upper molar
is larger than either of the others.
[Illustration: FIG. 356.—The Gorilla (_Gorilla savagei_). From _Trans.
Zool. Soc._ vol. iv. pl. 43.]
The posterior cervical vertebræ are characterised by the great height
of their neural spines, which thus form a strong basis for the powerful
cervical muscles supporting the massive skull. In some instances
the fourth lumbar vertebra becomes ankylosed to the sacrum, as is
occasionally found to be the case in some of the lower human races.
In the absence of a centrale to the carpus, and also in the number of
the dorso-lumbar vertebræ, the present and following genus resemble man;
although they both differ in having thirteen in place of twelve pairs of
ribs.
The brain of the Gorilla, according to Dr. Hartmann, resembles that
of the Orang in the complexity of its convolutions, and is thereby
distinguished from that of the Chimpanzee. In form it is of the long oval
characteristic of Man; the brain of the Chimpanzee and Orang being more
rounded.
Gorillas live in family parties in the depths of the dense forests of
Western Equatorial Africa, seeking their food during the day, while at
night it is said that the female and young ascend a tree at the foot of
which the male sleeps. They walk with the backs of their closed hands and
the flat soles of the feet placed on the ground. Although there has been
much exaggeration on this point, it appears certain that the male Gorilla
is an extremely ferocious and dangerous animal when brought to bay, but
the statements as to its making unprovoked assaults on men do not appear
authentic. They utter deep guttural sounds, which on some occasions may
be described as grunts and at others as a roar.
_Anthropopithecus._[697]—One of the most important differences of this
genus from the preceding is the absence of any marked disparity between
the two sexes, either in the size or the conformation of the skull,
although the male can always be distinguished by the larger size of the
canine teeth. The mandibular symphysis is also much shorter. Differences
in the characters of the teeth are described below. The genus is confined
at the present day to the Ethiopian region.
The Chimpanzees (Fig. 357) inhabit Western and Central Equatorial
Africa; and there has been much discussion whether they should all be
included under one specific name (_A. troglodytes_), or whether there are
really two or more species. A female specimen now living in the London
Zoological Gardens, characterised among other distinctive features by the
nearly bald head, clearly indicates, however, a second species, which
probably corresponds to the imperfectly defined _A. calvus_ of Du Chaillu.
The region inhabited by the Chimpanzees extends from the Gambia to the
Benguela, reaching as far inland as 28° E. long. The Common Chimpanzee is
a smaller animal than the Gorilla, its height not exceeding 5 feet. In
colour it is darker than the latter, and the ears are relatively larger.
In the upright position the arms reach only a short distance below the
knee, in which respect the Chimpanzee is more human-like than any of the
other Apes. The face is furnished with distinct whiskers, eyebrows, and
eyelashes. The pollex reaches nearly or quite to the base of the first
phalange of the index finger, and the hallux to the base of the second
phalange of the corresponding digit of the foot. The laryngeal sacs are
as largely developed as in the Gorilla.
[Illustration: FIG. 357.—The Chimpanzee (_Anthropopithecus troglodytes_).
From Mr. Wolf’s drawing of a young individual in the Zoological Society’s
Gardens.]
Although the skull of the Chimpanzee has distinct superciliary ridges,
yet the high bony crests of the calvarium of the male Gorilla are
wanting, and the whole coronal region of the skull is more rounded and
far less rugged.
The canine teeth of the male Chimpanzee are relatively much smaller than
in the Gorilla and Orang. The upper molars are characterised by the
third one being smaller than either of the other two, as well as by the
presence of an indistinct cingulum on their inner surfaces. The upper
premolars differ from those of the other genera of the family by the
shortness of their antero-posterior diameter, and also by the larger
size of their external as compared with their internal cusps; while the
outer border of these teeth is placed internally to that of the upper
molars. In all these respects the teeth of the Chimpanzee make a decided
approximation to the human type.
Many young individuals of the Chimpanzee have been brought to Europe, but
they appear to succumb sooner or later to the effects of an unsuitable
climate. All these examples show that the disposition of this Ape is
gentle, lively, and intelligent, and in all respects markedly opposite
to that of the Orang. In a wild state these Apes are essentially
forest-dwellers, and are more arboreal in their habits than the Gorilla.
They live either in families, or in small parties of several families.
Frequently at least they construct a kind of nest in the trees as a
sleeping-place; the male being said to sleep on a forked branch below the
level of this nest. In walking the Chimpanzee usually supports himself on
the backs of his closed fingers, and either on the soles of the feet or
on the closed toes.
From a distributional point of view the discovery of a fossil Ape in the
Pliocene of the Punjab, apparently closely allied to the Chimpanzee,
is of great interest. This determination rests upon the evidence of an
imperfect palate originally described under the name of _Palæopithecus_,
but subsequently referred to the present genus. The teeth of this jaw
present all the essential characters of those of the Chimpanzee, but
the two series of cheek-teeth have a slight anterior convergence, the
premolars are shorter in the antero-posterior direction than is usually
the case in that species, and the outer incisor is relatively narrower
than in the latter. In these features the extinct _A. sivalensis_ makes a
nearer approximation to the human type than is the case with its living
congeners.
_Dryopithecus._[698]—The extinct _Dryopithecus_ of the Middle Miocene of
France is represented by a single species of the approximate size of the
Chimpanzee, and appears to be the most generalised member of the family.
According to the recent observations of Professor Gaudry,[699] while it
resembles the Gorilla in that the two series of lower cheek-teeth diverge
anteriorly and the penultimate premolar is larger than the last of that
series, it differs in having a much longer and narrower mandibular
symphysis, and thus indicates a transition to the _Cercopithecidæ_. A
gradual transition in the form of the mandible may, indeed, be traced
from _Dryopithecus_, through _Gorilla_, to _Anthropopithecus_; the latter
having a short and wide symphysis, with the two series of cheek-teeth
slightly converging anteriorly, and the penultimate premolar being not
larger than the last. In all these specialised characters the jaw of
the Chimpanzee approximates to that of Man, in which the symphysis is
still further shortened and widened, and the anterior convergence of the
cheek-teeth so much increased as to produce a horse-shoe-like form in the
whole dental series.
_Family_ HOMINIDÆ.
In the _Systema Naturæ_ of Linnæus Man was separated only generically
from the Apes, but in the next great work which exercised a widespread
influence over the progress of zoological science, the _Règne Animal_ of
Cuvier, he forms a distinct order under the name of Bimana, the Monkeys
and Lemurs being associated together as Quadrumana. This has been the
prevailing arrangement in the zoological systems of the present century,
though in the classification of Owen his position is still farther
removed from that of the Monkeys, as in it the genus _Homo_ forms one
of the four primary divisions or subclasses of the Mammalia, called
Archencephala, the Quadrumana being united with the Carnivora, Ungulata,
and others in another division called Gyrencephala. On the other hand,
the tendency of most modern systematists, for reasons which have been
fully stated by Professor Huxley,[700] is to revert towards the Linnæan
position.
Considering solely the facts of Man’s bodily structure, it can be
clearly demonstrated that the points in which he differs from the Ape
most nearly resembling him are not of greater importance than those by
which that Ape differs from other universally acknowledged members of
the group; and therefore, in any natural system, if Man is to be made a
subject of zoological classification upon the same principles as those
applied elsewhere, he must be included in the order which comprises
the Monkeys. We say upon the same principles as are applied elsewhere,
since zoological classification has never taken into consideration
the psychological characteristics which distinguish the subjects of
its investigations, but only their tangible and physical structure,
otherwise endless confusion would result, at all events with our very
imperfect knowledge of animal psychology. The essential attributes which
distinguish Man, and give him a perfectly isolated position among living
creatures, are not to be found in his bodily structure, and should
therefore either be left entirely out of consideration, or have such
weight given to them as would remove him completely out of the region
of zoological classification. To profess to classify Man as if he were
one of the animals (as in all points of the structure and functions of
his organs he undoubtedly is), to place him in the class Mammalia, and
then to allow other considerations to influence the judgment as to the
particular position he should occupy in the class, is most illogical.
Man, therefore, considered from a zoological point of view, must be
included in the order Primates, even if the Lemurs be removed from it,
since his structural affinities with the Monkeys are far closer than
are those of the so-called “Half-Apes.” We may, without treading upon
debatable ground, go farther, and say that the differences between Man
and the Anthropoid Apes are really not so marked as those which separate
the latter from the American Monkeys. This being admitted, perhaps the
best exposition relating to the present condition of the order will be
to regard Man as representing a fifth family of the Anthropoidea, which
should be known as the _Hominidæ_. In thus ranking Man as one of the five
principal families or sections of the suborder it should, however, be
observed that this course does not in the least degree imply that such
families are precisely equivalent to one another, or that the intervals
by which they are separated are of equal importance; all that we commit
ourselves to being that they are five perfectly distinct groups, all
branches from a common stem, and in the present state of nature not
united by any intermediate types.
The distinctions between the _Hominidæ_ and _Simiidæ_ are chiefly
relative, being greater size of brain and of brain-case as compared
with the facial portion of the skull, smaller development of the
canine teeth of the males, complete adaptation of the structure of the
vertebral column to the vertical position, greater length of the lower
as compared with the upper extremities, and greater length of the hallux
or great toe, with almost complete absence of the power of bringing it
in opposition to the other four toes. The last feature together with the
small size of the canine teeth are perhaps the most marked and easily
defined distinctions that can be drawn between the two groups.
Man is universally admitted to form a single genus, _Homo_ of Linnæus,
but a question of considerable importance in treating of him from a
zoological point of view, and one which has been a subject of much
controversy, is whether all men should be considered as belonging to a
single or to several species. This question is perhaps of less importance
now than formerly, when those who maintained a plurality of species
associated with the hypothesis plurality of origin. One of the strongest
arguments against the view that the various races of Man represent more
than one species is that none of those who have maintained it have been
able to agree as to how many distinct specific modifications can be
defined, almost every number from three to twenty or more having been
advocated by different authors. If the distinguishing characters of
the so-called species had been so marked, there could not be such a
remarkable diversity of opinion upon them. Again, the two facts—(1) that,
however different the extremes of any two races may be in appearance
(and it must be admitted that, as advocated by many polygenists, the
differences are greater than many which are considered specific among
other animals), every intermediate gradation can be found through which
the one passes into the other, and (2) that all races are fertile _inter
se_—are quite conclusive in favour of considering Man as representing a
single species in the ordinary sense in which the word is now used, and
of treating of all his various modifications as varieties or races.
The great problem at the root of all zoology, the discovery of a natural
classification which shall be an expression of our knowledge of the real
relationship or consanguinity of different forms, is also applicable to
the study of the races of Man. When we can satisfactorily prove that any
two of the known groups of mankind are descended from the same common
stock, a point is gained. The more such points we have acquired the more
nearly shall we be able to picture to ourselves, not only the present,
but also the past distribution of the races of Man upon the earth, and
the mode and order in which they have been derived from one another.
But the difficulties in the way of applying zoological principles to
the classification of Man are vastly greater than in the case of most
animals. When groups of animals become so far differentiated from each
other as to represent separate species, they remain isolated; they
may break up into further subdivisions—in fact, it is only by further
subdivision that new species can be formed; but it is of the very essence
of species, as now universally understood by naturalists, that they
cannot recombine, and so give rise to new forms. With the varieties of
Man it is otherwise. They have never so far separated as to answer to
the physiological definition of species. All races, as said above, are
fertile with one another, though perhaps in different degrees. Hence new
varieties have constantly been formed, not only by the segmentation of
portions of one of the old stocks, but also by various combinations of
those already established.
Without entering into the difficult question of the method of Man’s first
appearance upon the world, we must assume for it vast antiquity,—at all
events as measured by any historical standard. Of this there is now
ample proof. During the long time Man existed in a savage state—a time
compared to which the dawn of our historical period is as yesterday—he
was influenced by the operation of those natural laws which have
produced the variations seen in other regions of organic nature. The
first Men may very probably have been all alike; but when spread over
the face of the earth and subjected to all kinds of diverse external
conditions,—climate, food, competition with members of their own
species or with wild animals,—racial differences began slowly to be
developed through the potency of various kinds of selection acting upon
the slight variations which appeared in individuals in obedience to the
tendency planted in all living things. These differences manifested
themselves externally in the colour of the skin, the colour, quality,
and distribution of the hair, the form of the head and features, and the
proportions of the limbs, as well as in the general stature.
Geographical position must have been one of the main elements in
determining the formation and permanence of races. Groups of Men isolated
from their fellows for long periods, such as those living on small
islands, to which their ancestors may have been accidentally drifted,
would naturally, in course of time, develop a new type of features, of
skull, of complexion, or hair. A slight set in one direction in any of
these characters would constantly tend to intensify itself, and so new
races would be formed. In the same way different intellectual or moral
qualities would be gradually developed or transmitted in different groups
of Men. The longer a race thus formed remained isolated the more strongly
impressed and the more permanent would its characteristics become, and
less liable to be changed or lost when the surrounding circumstances
were altered or under a moderate amount of intermixture from other
races—the more “true,” in fact, would it be. On the other hand, on large
continental tracts, where no mountain ranges or other natural barriers
form obstacles to free intercourse between tribe and tribe, there would
always be a tendency towards uniformity, from the amalgamation of races
brought into close relation by war or by commerce. Smaller or feebler
races would be destroyed or absorbed by others impelled by superabundant
population or other causes to spread beyond their original limits; or
sometimes the conquering race would itself disappear by absorption into
the conquered.
Thus for untold ages the history of Man has presented a shifting
kaleidoscopic scene: new races gradually becoming differentiated out of
the old elements, and, after dwelling a while upon the earth, becoming
either suddenly annihilated or gradually merged into new combinations;
a constant destruction and reconstruction; a constant tendency to
separation and differentiation, and a tendency to combine again into
a common uniformity—the two tendencies acting against and modifying
each other. The history of these processes in former times, except in
so far as they may be inferred from the present state of things, is
a difficult study, owing to the scarcity of evidence. If we had any
approach to a complete palæontological record, the history of Man could
be reconstructed; but nothing of the kind is forthcoming. Evidence of
the anatomical characters of Man as he lived on the earth during the
time when the most striking racial characteristics were being developed,
during the long ante-historic period in which the Negro, the Mongolian,
and the Caucasian were being gradually fashioned into their respective
types, is entirely wanting, or if any exists it is at present safely
buried in the earth, perhaps to be revealed at some unexpected time and
in some unforeseen manner. Even the materials from which a history of
the modifications of the human species as known to our generation must
be constructed are rapidly passing away, since the age in which we live
is an age in which, in a far greater degree than any previous one, the
destruction of races, both by annihilation and absorption, is going
on. Owing to the rapid extension of maritime discovery and commerce,
changes such as have never been witnessed before are now taking place
in the ethnology of the world—changes especially affecting the island
populations among which, more than elsewhere, the solution of many of
those problems may be looked for. The subject is, however, attracting the
attention of observers of all countries to a greater degree than it ever
has before, and such progress has been made in perfecting the methods of
investigation of racial characteristics that we are beginning to learn
what lines of research are profitable and what are barren, so that we
may hope the time is not far distant when we may get some clear insight
into the knowledge of the natural classification and relationships of the
races of Man.
The following is a brief summary of the principal results which appear to
have been attained up to the present time by the study of this somewhat
difficult subject.[701]
The most ordinary observation is sufficient to demonstrate the fact
that certain groups of men are strongly marked from others by definite
characters common to all members of the group, and transmitted regularly
to their descendants by the laws of inheritance. Thus the Chinaman
and the Negro, the native of Patagonia and the Andaman Islander, are
as structurally distinct from each other as are many of the so-called
species of any natural group of animals. Indeed, it may be said with
truth that their differences are even greater than those which mark the
groups called genera by many naturalists of the present day. Nevertheless
the difficulty of parcelling out all the individuals composing the
human species into certain definite groups, and of saying of each man
that he belongs to one or other of such groups, is insuperable. No such
classification has ever been, or, indeed, can ever be obtained. There
is not one of the most characteristic and most extreme forms, like
those just named, from which transitions cannot be traced by almost
imperceptible gradations to any of the other equally characteristic
and equally extreme forms. Indeed, a large proportion of mankind is
made up, not of extreme or typical, but of more or less generalised
or intermediate forms, the relative numbers of which are continually
increasing, as the long-existing isolation of nations and races breaks
down under the ever-extending intercommunication characteristic of the
period in which we live.
The difficulties of framing a natural classification of Man, or one
really representing the relationship of the various minor groups to each
other, are well exemplified by a study of the numerous attempts which
have been made from the time of Linnæus and Blumenbach onwards. Even in
the first step of establishing certain primary groups of equivalent rank
there has been no accord. Thus four primitive types were sketched out by
Linnæus—the European, Asiatic, African, and American. These were expanded
into five by Blumenbach by the addition of the Malay,[702] and reduced by
Cuvier to three by the suppression of the last two. Many later writers
have largely increased the number of these so-called primary divisions,
but the conclusion, so often arrived at by various anthropologists, and
so often abandoned for some more complex system, that the primitive
man, whatever he may have been, has in the course of ages divaricated
into three extreme types, represented by the Caucasian of Europe, the
Mongolian of Asia, and the Ethiopian of Africa, and that all existing
individuals of the species can be ranged around these types, or somewhere
or other between them, seems, on the whole, to give the clearest view
of the facts of the case. Large numbers are doubtless the descendants
of direct crosses in varying proportions between well-established
extreme forms; for, notwithstanding opposite views formerly held by some
authors on this subject, there is now abundant evidence of the wholesale
production of new races in this way. Others may be the descendants of
the primitive stock before the strongly marked existing distinctions had
taken place, and therefore present, though from a different cause from
the last, equally generalised characters. In these cases it can only be
by most carefully examining and balancing all characters, however minute,
and finding out in what direction the preponderance lies, that a place
can be assigned to them. It cannot be too often insisted on that the
various groups of mankind, owing to their probable unity of origin, the
great variability of individuals, and the possibility of all degrees of
intermixture of races at remote or recent periods of the history of the
species, have so much in common that it is extremely difficult to find
distinctive characters capable of strict definition by which they may be
differentiated. It is more by the preponderance of certain characters
in a large number of members of a group, than by the exclusive or even
constant possession of these characters in each of its members, that the
group as a whole must be characterised.
Bearing these principles in mind, we may endeavour to formulate, as far
as they have as yet been worked out, the distinctive features of the
typical members of each of the three great divisions, and then show into
what subordinate groups each of them seems to be divided.
We begin with the Ethiopian, Negroid, or Melanian, or “black” type. It
is characterised by a dark, often nearly black, complexion; black hair,
of a kind called “frizzly” or, incorrectly, “woolly,” _i.e._ each hair
is closely rolled up on itself, a condition always associated with a
more or less flattened or elliptical transverse section; a moderate
or scanty development of beard, an almost invariably dolichocephalic
skull; small and moderately retreating jugal bones (mesopic face); a
very broad and flat nose, platyrhine in the skeleton; moderate or low
orbits; prominent eyes; thick, everted lips; prognathous jaws; large
teeth (macrodont); a narrow pelvis (index in the male 90 to 100); a
long forearm (humero-radial index 80); and certain other proportions of
the body and limbs which are being gradually worked out, and reduced to
numerical expression as material for so doing accumulates.
The most characteristic examples of the second great type, the Mongolian
or Xanthous, or “yellow,” have a yellow or brownish complexion; black
coarse straight hair, without any tendency to curl, and nearly round
in section; on all other parts of the surface except the scalp scanty
and late in appearing; a skull of variable form, mostly mesocephalic
(though extremes both of dolichocephalism and brachycephalism are found
in certain groups of this type); a broad and flat face, with prominent,
anteriorly-projecting jugal bones (platyopic face); nose small, mesorhine
or leptorhine; orbits high and round, with very little development of
glabella or supraciliary ridges; eyes sunken, and with the aperture
between the lids narrow; in the most typical members of the group with a
vertical fold of skin over the inner canthus, and with the outer angle
slightly elevated; jaws mesognathous; teeth of moderate size (mesodont).
The proportions of the limbs and form of the pelvis have yet to be worked
out, the results at present obtained showing great diversity among
different individuals of what appear to be well-marked races of the
group, but this is perhaps due to the insufficient number of individuals
as yet examined with accuracy.
The last type, which, for want of a better name, we must still call by
the misleading one that has the priority, Caucasian, or “white,” has
usually a light-complexioned skin (although in some, in so far aberrant
cases, it is as dark as in the Negroes); hair fair or black, soft,
straight, or wavy, in section intermediate between the flattened and
cylindrical form; beard fully developed; form of cranium variable, mostly
mesocephalic; jugal bones retreating; face narrow and projecting in
the middle line (pro-opic); orbits moderate; nose narrow and prominent
(leptorhine); jaws orthognathous; teeth small (microdont); pelvis
broad (pelvic index of male 80); forearm short, relatively to humerus
(humero-radial index 74).
In endeavouring to subdivide into minor groups the numerous and
variously-modified individuals which cluster around one or other of
these great types—a process quite necessary for many practical or
descriptive purposes—the distinctions afforded by the study of physical
characters are often so slight that it becomes necessary to take other
considerations into account, among which geographical distribution and
language hold an important place.
I. The Ethiopian or Negroid races may be primarily arranged as follows:—
A. African or Typical Negroes.—Inhabitants of all the central portion
of the African continent, from the Atlantic on the west to the Indian
Ocean on the east, greatly mixed all along their northern frontier with
Hamitic and Semitic Melanochroi, a mixture which, taking place in various
proportions and under varied conditions, has given rise to many of the
numerous races and tribes inhabiting the Sudan.
A branch of the African Negroes are the Bantu—distinguished chiefly,
if not entirely, by the structure of their language. Physically
indistinguishable from the other negroes with whom they come in contact
in the Equatorial regions of Africa, the Southern Bantu, or Kaffirs,
as they are generally called, show a marked modification of type,
being lighter in colour, having a larger cranial capacity, less marked
prognathism, and smaller teeth. Some of these changes are probably due to
crossing with other races.
B. The Negrillos—diminutive sub-brachycephalic tribes, inhabiting the
dense forests of Central and Western Equatorial Africa—represent a
distinct section of the Negro race. They form the only exceptions to the
general dolichocephaly of the African branch of the Negroid division, and
when found in a pure state are the smallest of all known human races,
averaging scarcely more than 4 feet in height. The colour of their skin
is yellowish rather than black.
C. The Bushmen (Bosjesmen, men of the woods, of the Dutch colonists of
South Africa) constitute a very distinct modification of the Negro type.
The hair shows the extreme of the frizzly character; being shorter and
less abundant than that of the ordinary Negro, it has the appearance of
growing in separate tufts, which coil up together into rounded balls
compared to “peppercorns.” In their yellow complexion, wide cheek-bones,
and peculiar form of the eyes they so much resemble some of the Mongolian
races that anthropologists have been inclined to trace affinities to
or admixture with them, although the character of the hair makes such
a supposition almost inadmissible. The width of the cheek-bones and
the narrowness of the forehead and chin give a lozenge shape to the
front view of the face. The forehead is prominent and straight; the
nose extremely flat and broad, more so than in any other race; the lips
prominent and thick, although the jaws are less prognathous than in the
true Negro races. The cranium has many special characters by which it
can be easily distinguished from that of any other race. The average
height of the males is about 4 feet 8 inches. There is every reason to
believe that the Bushmen represent the earliest race of which we have
any knowledge inhabiting the southern part of the African continent, but
that long before the advent of Europeans upon the scene they had been
invaded from the north by Negro tribes, who, being superior in size,
strength, and civilisation, had taken possession of the greater part of
their territories, and, mingling freely with the aborigines, had produced
the mixed race called Hottentots, who retained the culture and settled
pastoral habits of the Negroes, with many of the physical features of the
Bushmen. These in their turn, encroached upon by the Kaffirs from the
north and by Europeans from the south, are now greatly diminished, and
threatened with the same fate which will surely soon befall the scanty
remnant of the early inhabitants who still retain their primitive type.
D. Oceanic Negroes or Melanesians.—These include the Papuans of New
Guinea and the majority of the inhabitants of the islands of the Western
Pacific, and form also a substratum of the population, greatly mixed with
other races, of regions extending far beyond the present centre of their
area of distribution.
They are represented, in what may be called a hypertypical form, by the
extremely dolichocephalic Kai Colos, or mountaineers of the interior of
the Fiji Islands, although the coast population of the same group has
lost the distinctive characters by crossing. In many parts of New Guinea
and the great chain of islands extending eastwards and southwards ending
with New Caledonia they are found in a more or less pure condition,
especially in the interior and more inaccessible portions of the islands,
almost each of which shows special modifications of the type recognisable
in details of structure. Taken altogether, their chief physical
distinction from the African Negroes lies in the fact that the glabella
and supraorbital ridges are generally well developed in the males,
whereas in Africans this region is usually smooth and flat. The nose
also, especially in the northern part of their geographical range, New
Guinea, and the neighbouring islands, is narrower (often mesorhine) and
prominent. The cranium is generally higher and narrower. It is, however,
possible to find African and Melanesian skulls quite alike in essential
characters.
The now extinct inhabitants of Tasmania were probably pure, but aberrant,
members of the Melanesian group, which had undergone a modification from
the original type, not by mixture with other races, but in consequence
of long isolation, during which special characters had been gradually
developed. Lying completely out of the track of all civilisation and
commerce, even of the most primitive kind, they were little liable to
be subject to the influence of any other race; and there is in fact
nothing among their characters which could be accounted for in the way
above suggested, as they were intensely, even exaggeratedly, Negroid in
the form of nose, projection of mouth, and size of teeth, typically so
in character of hair, and aberrant chiefly in the width of the skull in
the parietal region. A cross with any of the Polynesian or Malay races
sufficiently strong to produce this would, in all probability, have also
left some traces on other parts of their organisation.
On the other hand, in many parts of the Melanesian region there
are distinct evidences of large admixture with Negrito, Malay, and
Polynesian elements in varying proportions, producing numerous physical
modifications. In many of the inhabitants of the great island of New
Guinea itself and of the islands lying around it this mixture can be
traced. In the people of Micronesia in the north and New Zealand in the
south, although the Melanesian element is present, it is completely
overlaid by the Polynesian, but there are probably few, if any, of the
islands of the Pacific in which it does not form some factor in the
composite character of the natives.
The inhabitants of the continent of Australia have long been a puzzle to
ethnologists. Of Negroid complexion, features, and skeletal characters,
yet without the characteristic frizzly hair, their position has been
one of great difficulty to determine. They have, in fact, been a
stumbling-block in the way of every system proposed. The solution,
supported by many considerations too lengthy to enter into here, appears
to lie in the supposition that they are not a distinct race at all, that
is, not a homogeneous group formed by the gradual modification of one
of the primitive stocks, but rather a cross between two already-formed
branches of these stocks. According to this view, Australia was
originally peopled with frizzly-haired Melanesians, such as those who
still do, or did before the European invasion, dwell in the smaller
islands which surround the north, east, and southern portions of the
continent, but that a strong infusion of some other race, probably a
low form of Caucasian Melanochroi, such as that which still inhabits
the interior of the southern parts of India, has spread throughout the
land from the north-west, and produced a modification of the physical
characters, especially of the hair. This influence did not extend across
Bass’s Straits into Tasmania, where, as just said, the Melanesian element
remained in its purity. It is more strongly marked in the northern
and central parts of Australia than on many portions of the southern
and western coasts, where the lowness of type and more curly hair,
sometimes closely approaching to frizzly, show a stronger retention
of the Melanesian element. If the evidence should prove sufficiently
strong to establish this view of the origin of the Australian natives,
it will no longer be correct to speak of a primitive Australian, or even
Australoid, race or type, or look for traces of the former existence of
such a race anywhere out of their own land. Absolute proof of the origin
of any race is, however, very difficult, if not impossible, to obtain,
and there is nothing to exclude the possibility of the Australians being
mainly the direct descendants of a very primitive human type, from which
the frizzly-haired Negroes may be an offset. This character of hair is
probably a specialisation, for it seems very unlikely that it was the
attribute of the common ancestors of the human race.
E. The fourth branch of the Negroid race consists of the diminutive
round-headed people called Negritos, still found in a pure or unmixed
state in the Andaman Islands, and forming a substratum of the population,
though now greatly mixed with invading races, especially Malays, in the
Philippines, and many of the islands of the Indo-Malayan Archipelago,
and of some parts of the southern portion of the mainland of Asia. They
also contribute to the varied population of New Guinea, where they appear
to merge into the taller, longer-headed, and longer-nosed Melanesians
proper. They show in a very marked manner some of the most striking
anatomical peculiarities of the Negro race, such as the frizzly hair,
the proportions of the limbs, especially the humero-radial index, and
the form of the pelvis; but they differ in many cranial and facial
characters, both from the African Negroes on the one hand, and the
typical Oceanic Negroes, or Melanesians, on the other, and thus form a
very distinct and well-characterised group. Wherever they are still found
they are obviously holding their own with difficulty, if not actually
disappearing, and there is much about their condition of civilisation and
the situations in which they occur to induce us to look upon them, as in
the case of the Negrillos of Central and the Bushmen of South Africa, as
the remains of a population which occupied the land before the incoming
of the present dominant races.
II. The principal groups that can be arranged round the Mongolian type
are as follows:—
A. The Eskimo appear to be a branch of the typical North Asiatic Mongols,
who in their wanderings northwards and eastwards across the American
continent, where they have been isolated almost as perfectly as an island
population would be, hemmed in on one side by the eternal Polar ice,
and on the other by hostile tribes of American Indians, with which they
rarely, if ever, mingled, have gradually developed characters, most of
which are strongly-expressed modifications of those seen in their allies
who still remain on the western side of Behring Strait. It has also been
shown that these special characteristics gradually increase from west to
east, and are seen in their greatest perfection in the inhabitants of
Greenland, at all events in those where no crossing with the Danes has
taken place. A typical Eskimo skull presents a combination of characters
by which it can be at once distinguished from that of any other of the
groups of mankind. Such scanty remains as have yet been discovered of the
earliest inhabitants of Europe do not present any structural affinities
to this type, and there is therefore no justification for the supposition
that they belonged to the same race, although it is not unlikely that
similar external conditions may have led them to adopt similar modes of
life.
B. The typical Mongolian races constitute the present population of
Northern and Central Asia. They are not very distinctly, but still
conveniently for descriptive purposes, divided into a Northern and a
Southern group.
_a._ The members of the former, Mongolo-Altaic or Sibiric group, are
united by the affinities of their language. These people, from the cradle
of their race in the great plateau of Central Asia, have at various
times poured out their hordes upon the lands lying to the west, and
thence penetrated almost to the heart of Europe. The Lapps, Finns, the
Magyars, and the Turks are each the descendants of one of these waves of
incursion, but they have for so many generations intermingled with the
peoples through whom they have passed in their migrations, or whom they
have found in the countries in which they have ultimately settled, that
their original physical characters have been completely modified. Even
the Lapps, that diminutive tribe of nomads inhabiting the most northern
parts of Europe, supposed to be of Mongolian descent, show so little of
the special attributes of that branch that it is difficult to assign them
a place in it in a classification based upon physical characters. The
Japanese are said by their language to be allied rather to the Northern
than to the following branch of the Mongolian stock.
_b._ The southern Mongolian or Sinitic group, divided from the former
chiefly by language and habits of life, includes the greater part of the
population of China, Tibet, Burma, and Siam.
C. The next great division of Mongoloid people is the Malay, forming the
bulk of the population of the Indo-Malayan Archipelago and (mixed with
the Negro) of Madagascar, subtypical it is true, but to which an easy
transition can be traced from the most characteristic members of the type.
D. The brown Polynesians, Malayo-Polynesians, Mahoris, Sawaioris, or
Kanakas, as they have been variously called, seen in their greatest
purity in the Samoan, Tongan, and Eastern Polynesian Islands, are still
more modified, and possess less of the characteristic Mongolian features;
but yet it is difficult to place them anywhere else in the system. The
large infusion of the Melanesian element throughout the Pacific must
never be forgotten in accounting for the characters of the people now
inhabiting the islands—an element in many respects so diametrically
opposite to the Mongolian that it would materially alter the characters,
especially of the hair and beard, which has been with many authors a
stumbling-block to the affiliation of the Polynesian with the Mongolian
stock. This mixture is physically a fine one, and in some proportions
produces a combination, as seen, for instance, in the Maories of New
Zealand, which in all definable characters approaches quite as near, or
nearer, to the Caucasian type than to either of the stocks from which it
may be presumably derived. This resemblance has led some ethnologists
to infer a real extension of the Caucasian element at some very early
period into the Pacific Islands, and to look upon their inhabitants as
the product of a mingling of all the three great types of men. Though
this is a very plausible theory, it rests on little actual proof,
since the combination of Mongolo-Malayan and Melanesian characters in
different degrees, together with the local variations certain to arise
in communities so isolated from each other and exposed to such varied
conditions as the inhabitants of the Pacific Islands, would probably
account for all the modifications observed among them.
E. The native population (before the changes wrought by the European
conquest) of the great continent of America, excluding the Eskimo,
present, considering the vast extent of the country they inhabit and
the great differences of climate and other surrounding conditions, a
remarkable similarity of essential characters with much diversity of
detail.
The construction of the numerous American languages, of which as many
as twelve hundred have been distinguished, is said to point to unity of
origin, as, though widely different in many respects, they are all, or
nearly all, constructed on the same general grammatical principle—that
called _polysynthesis_—which differs from that of the languages of any
of the Old World nations. The mental characteristics of all the American
tribes have much that is in common, and the very different stages of
culture to which they had attained at the time of the conquest, as that
of the Incas and Aztecs and the hunting or fishing tribes of the north
and south, which have been quoted as evidence of diversities of race,
were not greater than those between different nations of Europe, as
Gauls and Germans on the one hand, and Greeks and Romans on the other,
in the time of Julius Cæsar. Yet all these were Aryans, and in treating
the Americans as one race it is not intended to imply that they are more
closely allied than the different Aryan peoples of Europe and Asia. The
best argument that can be used for the unity of the American race—using
the word in a broad sense—is the great difficulty of forming any natural
divisions in it founded upon physical characters. Thus there is no
difference throughout the whole continent in the important character of
the hair, this being always straight and lank, long and abundant on the
scalp, but sparse elsewhere. The colour of the skin, notwithstanding the
enormous differences of climate under which many members of the group
exist, varies but little. It is true that in the features and cranium
certain special modifications prevail in different districts, but the
same forms reappear at widely separated parts of the continent. Thus
skulls almost undistinguishable from one another may be met with from
Vancouver’s Island, from Peru, and from Patagonia.
Naturalists who have admitted but three primary types of the human
species have always found a difficulty with the Americans, hesitating
between placing them with the Mongolian or so-called “yellow” races, or
elevating them to the rank of a primary group. Cuvier, indeed, does not
seem to have been able to settle this point to his own satisfaction, and
leaves it an open question. Although the large majority of Americans have
in the special form of the nasal bones, leading to the characteristic
high bridge of the nose of the living face, in the well-developed
superciliary ridge and retreating forehead, characters which distinguish
them from the typical Asiatic Mongol, yet in many other respects they
resemble them so closely that, while still admitting the difficulties
of the case, we are inclined to include them as aberrant members of the
Mongolian type.[703] It is, however, quite open to any one adopting the
Negro, Mongolian, and Caucasian groups as primary divisions to place the
Americans apart as a fourth.
Now that the high antiquity of man in America—perhaps as high as that
which he has in Europe—has been discovered, the puzzling problem, from
which part of the Old World the people of America have sprung, has lost
its significance. It is, indeed, quite as likely that the people of Asia
may have been derived from America as the reverse. However this may be,
the population of America, except at the extreme north, was, before the
time of Columbus, practically isolated from the rest of the world.
Such visits as those of the early Norsemen to the coasts of Greenland,
Labrador, and Nova Scotia, or the occasional accidental stranding of
a canoe containing survivors of a voyage across the Pacific or the
Atlantic, can have had little appreciable effect upon the characteristics
of the people. It is difficult, therefore, to look upon the anomalous and
special characters of the American people as the effects of crossing, as
was suggested in the case of the Australians—a consideration which gives
more weight to the view of treating them as a distinct primary division.
III. The Caucasian, Eurafrican, or white division, includes the two
groups called by Professor Huxley Xanthochroi and Melanochroi, which,
though differing in colour of eyes and hair, agree so closely in all
other anatomical characters, so far, at all events, as has at present
been demonstrated, that it seems preferable to consider them both as
modifications of one great type than as primary divisions of the species.
Whatever their origin may have been, they are now intimately blended,
though in different proportions, throughout the whole of the region of
the earth they inhabit; and it is to the rapid extension of both branches
of this race that the great changes now taking place in the ethnology of
the world are mainly due.
A. The Xanthochroi, or blonde type, with fair hair, eyes, and complexion,
chiefly inhabit Northern Europe (Scandinavia, Scotland, and North
Germany), but, although much mixed with the next group, they also extend
as far as Northern Africa and Afghanistan. Their mixture with Mongoloid
people has given rise to the Lapps, Finns, and some of the tribes of
Northern Siberia.
B. Melanochroi, with black hair and eyes, and skin of almost all shades
from white to black. They comprise the great majority of the inhabitants
of Southern Europe, Northern Africa, and South-West Asia, and consist
mainly of the Aryan, Semitic, and Hamitic families. The Dravidians of
India, the Veddahs of Ceylon, and probably the Ainos of Japan, and the
Maoutze of China, also belong to this race, which may have contributed
something to the mixed character of some tribes of Indo-China and
the Polynesian Islands, and, as before said, have given at least the
characters of the hair to the otherwise Negroid inhabitants of Australia.
In Southern India they are largely mixed with a Negrito element, and in
Africa, where their habitat becomes coterminous with that of the Negroes,
numerous cross-races have sprung up between them all along the frontier
line. The ancient Egyptians were nearly pure Melanochroi, though often
showing in their features traces of their frequent intermarriages with
their Ethiopian neighbours to the south. The Copts and fellahs of modern
Egypt are their little-changed descendants.
In offering this scheme of classification of the varieties of the human
species, it is not suggested that it is one universally accepted by
anthropologists, or that it is likely to be final. Whatever care be
bestowed upon the arrangement of already acquired details, or whatever
judgment be shown in their due subordination one to another, the
acquisition of new knowledge may at any time call for a complete or
partial rearrangement of the system. The difficulties which encompass
the subject have, indeed, been already indicated, and will be found
abundantly illustrated in the writings of those authors who have
specially devoted themselves to its elucidation.
_Bibliography._—P. Topinard, _Éléments d’Anthropologie
Générale_, 1885; A. de Quatrefages, _Histoire Générale
des Races Humaines_ (1. _Questions Générales_, 1887; 2.
_Classification des Races Humaines_, 1889); Quatrefages and
Hamy, _Crania Ethnica_ (1873-1879); D. G. Brinton, _Races and
Peoples_, 1890.
FOOTNOTES
[1] Galton’s _South Africa_, p. 187.
[2] L. F. E. Rousseau, _Anatomie comparée du Système dentaire chez
l’Homme et chez les principaux Animaux_, 2d ed., 1839; F. Cuvier, _Des
Dents des Mammifères considérées comme caractères zoologiques_, 1822-25;
R. Owen, _Odontography_, 1840-45; C. G. Giebel, _Odontographie_, 1855; C.
S. Tomes, _Manual of Dental Anatomy, Human and Comparative_, 3d ed., 1889.
[3] The lower incisors of some species of Shrews are, however, said to
become ankylosed to the jaw in adult age.
[4] The teeth of the extinct Dinosaurian reptile _Triceratops_ have two
distinct roots, placed transversely to the axis of the jaws.
[5] This and other questions concerning the homologies, notation, and
succession of the teeth of mammals are more fully developed in two
memoirs by one of the present writers:—“Remarks on the Homologies and
Notation of the Teeth of the Mammalia,” in the _Journal of Anatomy and
Physiology_, vol. iii. p. 262, 1869; and “Notes on the First or Milk
Dentition of the Mammalia,” in the _Trans. Odontological Society of Great
Britain_, 1871. See also an important memoir by Oldfield Thomas on the
“Homologies and Succession of the teeth in the Dasyuridæ,” _Phil. Trans._
1887, pp. 443-462.
[6] By many writers the letters indicating the different kinds of teeth
are printed in capitals, as _I_, _C_, _P_, and _M_; while very frequently
the symbol _Pm_ is employed in place of _p_.
[7] According to Mr. G. E. Dobson there are four upper incisors in some
of the _Soricidæ_.
[8] See for the principal modifications of the skeleton of the class,
the large and beautifully illustrated _Ostéographie_ of De Blainville,
1835-54; the section devoted to the subject in Bronn’s _Klassen und
Ordnungen des Thier-Reichs_, by Giebel, 1874-79; and _An Introduction to
the Osteology of the Mammalia_, by W. H. Flower, 3d ed., 1885.
[9] This and many of the following figures in this chapter are taken from
Flower’s _Osteology of the Mammalia_.
[10] For the sake of uniformity, in all the following descriptions of
the vertebral column, the long axis of the body is supposed to be in the
horizontal position.
[11] The opinion has recently been expressed by Baur that bone termed
radiale in Fig. 17 is really a second centrale, and that the radiale is
represented by a minute bone generally known as the radial sesamoid. The
mammalian scaphoid is accordingly also regarded as a second centrale. In
the same communication, Dr. Baur expresses his disbelief in the existence
of remnants of a prepollex and of a seventh digit in mammals and other
vertebrates. (See _Anat. Anzeiger_, vol. iv. pp. 49-52, 1889.)
[12] On the Præpollex and Præhallux, etc., _Proc. Zool. Soc._ 1889, pp.
259-262.
[13] Cope and Baur consider that the astragalus corresponds only with the
intermedium, and that the tibiale may exist as a distinct element.
[14] For further details of these modifications, see Flower’s “Lectures
on the Comparative Anatomy of the Organs of Digestion of the Mammalia,”
_Medical Times and Gazette_, Feb.-Dec. 1872.
[15] G. Gulliver, _Proc. Zool. Soc._, 1862, p. 91.
[16] The modifications of these bones are fully described by A. Doran,
“Morphology of the Mammalian _Ossicula auditus_,” _Trans. Linn. Soc._
ser. 2, vol. i. pp. 371-497, pl. lviii.-lxiv. (1878).
[17] See B. H. Caldwell—“The Embryology of Monotremata and Marsupialia,”
_Phil. Trans._ for 1887, p. 463.
[18] _Proc. Acad. Nat. Sci. Philadelphia_, 1881, p. 468.
[19] “_Studien ueber Entwickelungeschichte der Thiere_,” pt. 4,
Wiesbaden, 1886.
[20] _Journal of Morphology_, vol. i. p. 373 (1887).
[21] For a full exposition of the present state of knowledge on this
subject, see the various memoirs of Sir William Turner, also F. M.
Balfour’s _Treatise on Comparative Embryology_, vol. ii. (1881), and J.
A. Ryder in _American Naturalist_, vol. xxi. p. 780 (1887).
[22] _Proceedings of the Royal Society of London_, vol. xxviii. p. 395
(1879).
[23] “The Relations between the Theromorphous Reptiles and the Monotreme
Mammalia,” _Proceedings of the American Association for the Advancement
of Science_, vol. xxxiii. p. 471 (1885).
[24] “On the Phylogenetic Arrangement of the Sauropsida,” _Journal of
Morphology_, vol. i. pp. 93-104 (1887).
[25] The names of the groups containing only extinct forms are printed in
heavier type than those which contain species still existing.
[26] On this subject see A. Murray, _Geographical Distribution of
Mammals_, 1866; and especially A. R. Wallace, _The Geographical
Distribution of Animals_, 2 vols., 1876, and _Island Life_, 1881; also A.
Heilprin, _The Geographical and Geological Distribution of Animals_, 1887.
[27] _Distribution of Animals._
[28] Generally known, as _Hyomoschus_, but first described as an extinct
form under the above name.
[29] The fore limb from S. Africa described as _Theriodesmus_, which
appears to be mammalian, and may belong to _Tritylodon_.
[30] The subjects referred to under this heading are mostly described
and figured in detail in Owen’s “Monograph of the Fossil Mammalia of the
Mesozoic Formations,” _Palæontographical Society’s Publications_, 1871;
and in various papers by Marsh, in the _American Journal of Science and
Arts_, 1878-89. Important contributions to our knowledge of these forms
have also been made by Professors Cope and Osborn, and the reader should
especially consult the memoir by the latter writer on the “Structure and
Affinities of the Mesozoic Mammals,” published in the _Journal of the
Philadelphia Academy_ (1888), vol. ix.
[31] The whole discussion is contained in the following memoirs: (1)
H. Falconer, “Description of Two Species of the Fossil Mammalian genus
_Plagiaulax_, from Purbeck,” _Quart. Journ. Geol. Soc._ vol. xiv.
1857; (2) R. Owen, art. “Palæontology,” _Encyclopædia Britannica_, 8th
ed., 1859; (3) H. Falconer, “On the Disputed affinity of the Mammalian
genus _Plagiaulax_,” _Quart. Journ. Geol. Soc._ vol. xviii. 1862; (4)
R. Owen, “Monograph of the Fossil Mammalia of the Mesozoic Formation,”
_Palæontographical Society_, 1871.
[32] Blumenbach, _Voigts Magazin_, vol. ii. p. 205 (1800).
[33] _Proceedings of the Royal Society of London_, vol. xliii. p. 353
(1888).
[34] _Ibid._ vol. xlvi. p. 126 (1889).
[35] Cuvier, _Tableau Élémentaire d’Hist. Nat._ p. 143 (1798).
[36] Gervais, _Ostéographie des Monotremes_, p. 43 (1877).
[37] For the detailed characters of all the genera and species of
Marsupials the reader should consult the British Museum _Catalogue of
Marsupialia and Monotremata_, by Oldfield Thomas, 1888.
[38] Except in _Petaurus (Belideus) breviceps_ (Forbes, _Proc. Zool.
Soc._ 1881, p. 188).
[39] Including the transitional Austro-Malayan region.
[40] Illiger, _Prod. Syst. Mamm. et Aves_, p. 76 (1811).
[41] Linn. _Syst. Nat._ Ed. 12, vol. i. p. 71 (1766).
[42] Temminck, _Monographies de Mammalogie_, vol. i. p. 60 (1827).
[43] F. Cuvier, _Hist. Nat. des Mammifères_, iv. (1837).
[44] Geoffroy, _Bull. Soc. Philom._ vol. i. p. 106 (1796).
[45] Temminck, _Monographies de Mammalogie_, vol. i. p. 56 (1827).
[46] Thomas, _Ann. Mus. Genov._ sér. 2, vol. iv. p. 503 (1887).
[47] Krefft, _Proc. Zool. Soc._ 1866, p. 434.
[48] Waterhouse, _Proc. Zool. Soc._ 1836, p. 69.
[49] Geoffroy, _Bull. Soc. Philom._ vol. iii. p. 249 (1803).
[50] Grey, in _Grey’s Australia_, vol. ii, p. 401 (1841).
[51] Ogilby, _Proc. Zool. Soc._ 1838, p. 25.
[52] Geoffroy, _Ann. du Muséum_, vol. ii. p. 365 (1803).
[53] Owen, _Phil. Trans._ 1872, p. 257.
[54] Gervais and Verraux, _Proc. Zool. Soc._ 1842, p. 1.
[55] Storr, _Prodromus Meth. Mamm._ p. 33 (1780). Syn. _Phalangista_,
Geoffroy, _Bull. Soc. Philom._ vol i. p. 106 (1796).
[56] Lesson, _Dict. Class. d’Hist. Nat._ vol. xiii. p. 333 (1828).
[57] Ogilby, _Proc. Zool. Soc._ 1836, p. 26.
[58] Thomas, _Cat. Marsupials Brit. Mus._ p. 163 (1888).
[59] Gray, _Proc. Zool. Soc._ 1858, p. 109.
[60] Shaw, _Naturalist’s Miscellany_, vol. ii. pl. lx. (1791).
[61] M’Coy, _Ann. Mag. N. H._ (3) xx. p. 287 (1867).
[62] Grey, in _Grey’s Australia_, appendix, vol. ii. p. 407 (1841).
[63] Peters, _Ann. Mus. Genov._ vol. vi. p. 303 (1874).
[64] Desmarest, _Nouv. Dict. d’Hist. Nat._ sér. 2, vol. xxv. p. 405
(1817).
[65] _Cf._ W. A. Forbes, “Anatomy of the Koala,” _Proc. Zool. Soc._ 1881,
p. 180.
[66] Blainville, _Bull. Soc. Philom._ 1816, p. 116.
[67] Owen, in _Gervais’s Zool. et Pal. françaises_, 1st ed. pt. i. p. 192
(1849-52).
[68] Ramsay, _Proc. Linn. Soc. N. S. Wales_, vol. i. p. 33 (1876).
[69] De Vis, _Proc. Roy. Soc. Queensland_, ser. 2, vol. iii. p. 8 (1888).
[70] Desmarest, _Nouv. Dict. d’Hist. Nat._ sér. 1, vol. xxiv. _Table
Méth._ p. 20 (1804). Syn. _Hypsiprymnus_, Illiger, _Prodromus Syst.
Mamm._ p. 79 (1811).
[71] Gray, _Charlesworth’s Mag. Nat. Hist._ vol. i. p. 584 (1837).
[72] Thomas, _Cat. Marsup. Brit. Mus._ p. 114 (1888).
[73] Garrod, _Proc. Zool. Soc._ 1875, p. 59.
[74] Thomas, _Proc. Zool. Soc._ 1886, p. 544.
[75] Schlegel and Müller, _Verh. Nat. Ges. Nederland_, p. 138 (1839-44).
[76] Schlegel and Müller, _Verh. Nat. Ges. Nederland_, p. 130 (1839-44).
[77] Gould, _Monograph of Macropodidæ_, pl. xiii. (1841).
[78] Grey, in _Grey’s Australia_, vol. ii. appendix, p. 402 (1841).
[79] Gray, _Charlesworth’s Mag. Nat. Hist._ vol. i. p. 583 (1837).
[80] Shaw, _Naturalist’s Miscellany_, vol. i. pl. xxxiii. (1790).
[81] For the characters of these species and the under-mentioned distinct
genera, see Owen’s _Extinct Mammals of Australia_ (1877), and Lydekker’s
_Catalogue of Fossil Mammalia in the British Museum_, pt. v. (1887).
[82] Owen, _Phil. Trans._ 1874, p. 264.
[83] Owen, _op. cit._ p. 788.
[84] Owen, _op. cit._ p. 797.
[85] Owen, in _Mitchell’s Eastern Australia_, 2d ed. vol. ii. p. 362
(1838).
[86] Owen, _Cat. Mamm. and Aves, Mus. R. Coll. Surgeons_, p. 314 (1845).
[87] The characters of the chief groups of the Eutheria here given are,
in some measure, a fuller recapitulation of those already detailed in
Chapter III., pp. 83-88.
[88] The name Paratheria has been suggested for this proposed subclass.
[89] In some few Armadillos the suture between the premaxilla and maxilla
passes behind the first upper tooth; but in all other known members of
the order all the teeth are implanted in the maxilla.
[90] See Flower, “On the Mutual Affinities of the Animals composing the
Order Edentata,” _Proceedings of the Zoological Society_, 1882, p. 358.
[91] An attempt has been made to represent these views by the following
classification:
Order EDENTATA.
Suborder PILOSA.
_Bradypodidæ._
_Megatheriidæ._
_Myrmecophagidæ._
Suborder LORICATA.
_Dasypodidæ._
Suborder SQUAMATA.
_Manidæ._
Suborder TUBULIDENTATA.
_Orycteropodidæ._
It may be objected to this arrangement that the _present_ divergence
between the Sloths and Anteaters is hardly sufficiently indicated by
their association in one suborder.—Flower, “On the Arrangement of the
Orders and Families of Mammals,” _Proc. Zool. Soc._ 1883, p. 178.
[92] Linn. _Syst. Nat._ 12th ed. vol. i. p. 50 (1766).
[93] Illiger, _Prodromus Syst. Mamm. et Avium_, p. 108 (1811).
[94] Burmeister, _Sitzb. Ak. Berlin_, vol. xxviii. p. 613 (1882).
[95] Lydekker, in Nicholson and Lydekker’s _Manual of Palæontology_,
vol. ii. p. 1299 (1889). Originally described under the preoccupied name
_Cœlodon_.
[96] Cuvier, _Tableau Élém. d’Hist. Nat. des Animaux_, p. 146 (1798).
[97] An excellent figure of this skeleton, which unfortunately was
incorrectly articulated, and wanted the greater part of the tail,
was published by Pander and D’Alton in 1821, and has been frequently
reproduced in subsequent works.
[98] See E. D. Cape, _Amer. Naturalist_, vol. xxiii. p. 152 (1889).
[99] Linn. _Syst. Nat._ 12th ed. vol. i. p. 51 (1766).
[100] Professor Cope has recently come to the conclusion that there are
three species; but further evidence is required in support of this view.
[101] Gray, _Annals of Philosophy_, new series, vol. x. p. 343 (1825).
[102] Gray, _Annals of Philosophy_, new series, vol. x. p. 343 (1825).
[103] Harlan, _Ann. New York Lyceum Nat. Hist._ vol. i. p. 237
(1824).—Amended from _Chiamyphorus_.
[104] Linn. _Syst. Nat._, 12th ed. vol. i. p. 54 (1766).
[105] Wagler, _Syst. Amphibien_, etc., p. 36 (1830).
[106] F. Cuvier, _Hist. Nat. des Mammifères_ (1822).—_Priodontes._
[107] Illiger, _Prodromus Syst. Mamm. et Avium_, p. 111 (1811).
[108] Lesson, _Man. de Mammalogie_, p. 309 (1827); _ex._ F. Cuvier,
_Tatusie_.
[109] A single imperfect skin, brought from the province of Ceara in
Brazil, indicates a very remarkable form of Armadillo, named by A.
Milne-Edwards _Scleropleura brunetti_ (_Ann. Sc. Nat._ xvi. p. 8, 1872).
The dermal scutes are said to be much less developed than in other
members of the family, and confined to the sides, all the median portion
of the back being clothed with a flexible hairy skin. The head is broad
and short, the ears small and far apart. The tail is long, and almost
entirely devoid of scutes. The feet are unknown.
[110] Linn. _Syst. Nat._ 12th ed. vol. i. p. 52 (1766).
[111] _Mammalian Descent_, p. 95.
[112] _Mammalian Descent_, p. 99.
[113] Forsyth-Major, _Comptes Rendus_, vol. cvii. p. 1180 (1888).
[114] Geoffroy, _Décade Philosophique_, 1795 (_teste_ Agassiz).
[115] _Proceedings of the Royal Society_; vol. xlvii. p. 246 (1890).
[116] Storr, _Prodromus Meth. Mamm._ p. 41 (1780).
[117] _Zool. Jahrbuch_, vol. i. p. 1 (1886).
[118] Illiger, _Prodromus Syst. Mamm. et Avium_, p. 140 (1811).
[119] Illiger, _Prodromus Syst. Mamm. et Avium_, p. 141 (1811).—Amended
from _Rytina_.
[120] Nordenskiöld, during his voyage in the _Vega_, obtained some
information from the natives of Behring Island which led him to believe
that a few individuals may have survived to a much later date, even to
1854; but this conclusion is disputed by later writers.
[121] Kaup, _Neues Jahrbuch_, 1838, pp. 319 and 536.
[122] This is an important distinction from the Sirenia, but a character
common to nearly all other mammals. It is doubtful whether there is any
foundation for the statement that these epiphyses remain ununited for an
exceptionally long period in the Cetacea.
[123] A character repeated in some of the Seals.
[124] These have been described in detail by Professor Struthers in the
_Journal of Anatomy and Physiology_, 1881.
[125] The ankylosed mass of cervical vertebræ, on which the genus
_Palæocetus_ was established, was regarded by its describer as having
probably come from the Kimeridge Clay, but the mineral condition of the
specimen points to the Red Crag as the place of origin.
[126] There is much resemblance in the larynx of the Hippopotamus, but
none in that of the Seal, to the same organ in the Cetacea.
[127] German _Meerschwein_, whence the French _Marsouin_. “Porpoise” is
said to be derived from “_Porc-poisson_.”
[128] Icel. _hvalr_; Dan. and Swed. _hval_; Anglo-Saxon _hwæl_; Germ.
_wal_, _walfisch_. The meaning apparently is “roller,” the word being
closely allied to “wheel” (Skeat).
[129] These were discovered in the Greenland Whale by Geoffroy St.
Hilaire, whose observations were confirmed and extended to other genera
by Eschricht. They have been very fully described in _Balænoptera
rostrata_ by Julin (_Archives de Biologie_, i. 1880).
[130] For the structure of whalebone see Hunter, “Observations on the
Structure and Economy of Whales,” _Phil. Trans._ 1787; Eschricht and
Reinhardt, _On the Greenland Right Whale_, English translation by the Ray
Society, 1866, pp. 67-78; and Sir W. Turner, in _Trans. Roy. Soc. Edin._
1870.
[131] Linn. _Syst. Nat._ 12th ed. vol. i. p. 105 (1766).
[132] Gray, _Suppl. Cat. Seals and Whales in Brit. Mus._ p. 39 (1871).
[133] Cope, _Proc. Ac. Nat. Sci. Philad._ 1869, p. 15.
[134] Gray, _Zoology of Erebus and Terror_, p. 16 (1846).
[135] See J. Struthers, “On the Anatomy of _Megaptera longimana_,”
_Journ. Anatomy and Physiology_, 1887-89.
[136] Lacépède, “Table des Ordres,” _Hist. Nat. des Cétacés_, p. xxxvi.
(1804).
[137] See P. J. Van Beneden, “Histoire Naturelles des Balénoptères,”
_Mém. Acad. Belgique_, xli. 1887.
[138] In a recent memoir Professor D’Arcy Thompson has brought forward
some arguments to show that the Zeuglodonts have no direct affinities
with the Cetacea, but have on the other hand the strongest possible
relation with the Pinnipede Carnivora. “On the Systematic position of
Zeuglodon,” _Studies from the Museum of Zoology, Dundee_, vol. i. No. 9,
1890.
[139] An appearance in one specimen has been described by C. G. Carus
as indicating a vertical succession of the teeth, but the evidence upon
which this rests is by no means satisfactory, and appears to admit of
another explanation.
[140] A mutilated humerus of _Zeuglodon cetoides_ has given rise to many
conjectures, appearing to some anatomists to indicate seal-like freedom
of motion at the elbow-joint, while to others its characters appear to be
truly Cetacean.
[141] See _Trans. Geol. Soc._ ser. 2, vol. vi. p. 67.
[142] Linn. _Syst. Nat._ 12th ed. vol. i. p. 107 (1766).
[143] Gray, _Zoology of Erebus and Terror_, p. 22 (1846). Usually spelt
_Kogia_.
[144] Lacépède, “Table des Ordres,” _Hist. Nat. des Cétacés_, p. xliv.
(1804).
[145] See the figures in the _Proc. Zool. Soc._ 1882, pp. 728, 729.
[146] Cuvier, _Ossemens Fossiles_, 2d ed. vol. v. p. 352 (1823).
[147] Gervais, _Ann. Sci. Nat._ ser. 3, vol. xiv. p. 16 (1850). For the
very complicated synonymy of this genus, see _Trans. Zool. Soc._ vol.
viii. p. 208.
[148] Duvernoy, _Ann. Sci. Nat.-Zoologie_, sér. 3, vol. xv. p. 41 (1851).
[149] Duvernoy, _op. cit._ p. 61.
[150] Grateloup, _Act. Ac. R. Sci. Bordeaux_, 1840, p. 208.
[151] Wagler, _Syst. Amphib._ etc., p. 35 (1830).
[152] The anatomy of _Platanista_ is fully described by J. Anderson,
_Zoological Results of Two Expeditions to Western Yunnan_, 1878.
[153] D’Orbigny, _Nouv. Ann. Mus. Paris_, vol. iii. p. 31 (1834).
[154] Gray, _Zoology of Erebus and Terror_, p. 46 (1846).
[155] Linn. _Syst. Nat._ 12th ed. vol. i. p. 105 (1766).
[156] Lacépède, _Hist. Nat. des Cétacés_, p. xli. (1804).
[157] Cuvier, _Règne Animal_, vol. i. p. 279 (1817).
[158] _Zoology of Erebus and Terror_, p. 30 (1846). The name is
preoccupied by Lamarck for a genus of Polyzoa (1816).
[159] Gray, _Cat. Cetacea Brit. Mus._ p. 106 (1850).
[160] Gray, _Cat. Seals and Whales in Brit. Mus._ p. 285 (1866).
[161] _Anatomical and Zoological Researches, comprising an Account of the
Zoological Results of the two Expeditions to Western Yunnan, in 1868 and
1875_ (1878).
[162] Gray, _Zoology of Erebus and Terror_, p. 33 (1846).
[163] Reinhardt, _Overs. Dan. Sezsk. Forh._ 1862, p. 151.
[164] Lesson, _N. Tab. d. Règne Animal—Mamm._ p. 200 (1842).
[165] Gray, _Zoology of Erebus and Terror_, p. 30 (1846).
[166] Gray, _Proc. Zool. Soc._ 1870, p. 77.
[167] Gray, _Zoology of Erebus and Terror_, p. 35 (1846).
[168] Linn. _Syst. Nat._ 12th ed. vol. i. p. 108 (1766).
[169] Gervais, _Hist. Nat. des Mammifères_, vol. ii. p. 323 (1855).
[170] Gervais, _Ostéographie des Cétacés_, p. 604 (1880).
[171] Gray, _Zoology of Erebus and Terror_, p. 43 (1846).
[172] Gray, _Cat. Seals and Whales Brit. Mus._ 2d ed. p. 393 (1866).
[173] Since this was in type the discovery of transient rudimentary
clavicles in the embryo of the Sheep has been announced by Wineza
(_Morpholog. Jahrb._ xvi. p. 647).
[174] Also known as Diplarthra.
[175] The pollex is present in the manus of the extinct _Cotylops_.
[176] In the table on p. 89 the Peccaries are included in the _Suidæ_.
[177] Linn. _Syst. Nat._ 12th ed. vol. i. p. 101 (1766).
[178] Linn. _Syst. Nat._ 12th ed. vol. i. p. 102 (1766).
[179] If from any accidental circumstances these teeth are not constantly
worn down by friction, they grow into a complete circle, the point
penetrating the bone of the jaw close to the root of the tooth. The
natives of the Fiji Islands avail themselves of this circumstance to
produce one of their most valued ornaments—a circular boar’s tusk: the
upper canines being extracted, the lower ones are allowed to grow to the
desired form.
[180] See Garson, _Proc. Zool. Soc. Lond._ 1883, p. 413.
[181] Lesson, _Man. d. Mamm._, p. 337 (1827), “Babirusa.”
[182] Cuvier, _Règne-Animal_, vol. i. p. 236 (1817).
[183] Cuvier, _Règne Animal_, vol. i. p. 237 (1817).
[184] Professor Cope considers that there is a third species, for which
he has proposed the name _D. angularis_.
[185] This name (Leidy, 1851) is preoccupied by _Orodus_ (Agassiz, 1838).
[186] The stomach of the Camel inhabiting the Arabian desert is commonly
looked upon as a striking example of specialised structure, adapted or
modified in direct accordance with a highly specialised mode of life; it
is therefore very remarkable to find an organ exactly similar, except in
some unessential details, in the Llamas of the Peruvian Andes and the
Guanacos of the Pampas. No hypothesis except that of a common origin will
satisfactorily account for this, and, granting that this view is correct,
it becomes extremely interesting to find for how long a time two genera
may be isolated and yet retain such close similarities in parts which in
other groups appear readily subject to adaptive modifications.
[187] Linn. _Syst. Nat._ 12th ed. vol. i. p. 90 (1766).
[188] There is much confusion as to the proper use of the names Camel and
Dromedary. It is now generally accepted that the former is the common
term for all the members of the genus, and that Dromedary should be
confined to the lighter and swifter breeds of the one-humped species. One
of the oldest pictures of the two-humped Camel extant, painted on the
wall of the Chapter House of Westminster Abbey, has, however, “Dromedary”
inscribed under it.
[189] Illiger, _Prodromus Syst. Mamm._ p. 103 (1811).
[190] _Natural History of the Strait of Magellan_, 1871.
[191] Pallas, _Spicilegia Zoologica_, vol. xiii. p. 27 (1779).
[192] Kaup, _Ossemens Fossiles de Darmstadt_, pt. 5, p. 92 (1836). This
name, which was proposed for a fossil species, antedates _Hyomoschus_,
Gray, applied to the living form.
[193] For the anatomy of this group see A. H. Garrod, _Proc. Zool. Soc._
1877, p. 2.
[194] Linn. _Syst. Nat._ 12th ed. vol. i. p. 91 (1766).
[195] For the anatomy of _Moschus_ see Flower, _Proc. Zool. Soc._ 1875,
p. 159; and Garrod, _ibid._ 1877, p. 287.
[196] _Proc. Zool. Soc._ 1878, p. 889.
[197] De Blainville, _Bull. Soc. Philom._ 1816, p. 74.
[198] Milne-Edwards, _Nouv. Arch. du Muséum_, vol. vii. Bull. p. 93
(1872).
[199] Linn. _Syst. Nat._ 12th ed. vol. i. p. 92 (1766).
[200] Hamilton-Smith, in _Griffith’s Animal Kingdom_, vol. v. p. 304
(1827).
[201] Hamilton-Smith, in _Griffith’s Animal Kingdom_, vol. v. p. 303
(1827).
[202] Scott, _Proc. Ac. Nat. Sci. Philad._ 1885, p. 181.
[203] Hamilton-Smith, in _Griffith’s Animal Kingdom_, vol. v. p. 313
(1827).
[204] Swinhoe, _Proc. Zool. Soc._ 1870, p. 90.
[205] Gray, _Proc. Zool. Soc._ 1850, p. 237.
[206] Gray, _Proc. Zool. Soc._ 1850, p. 242.
[207] This accessory column is shown in the figure of the molar of
_Boselaphus_ on p. 311.
[208] Zimmermann, _Geograph. Geschichte_, vol. ii. p. 125 (1780).
[209] Ord. _Journ. de Physique_, vol. lxxxvii. p. 149 (1818).
[210] Blainville, _Bull. Soc. Philom._ 1816, p. 75.
[211] Lichtenstein, _Berlin Ges. Natuforsch. Freunde Magazin_, vol. vi.
pp. 152, 165 (1814).
[212] F. E. Blaauw, _Proc. Zool. Soc._ 1889, p. 2.
[213] Hamilton-Smith, in _Griffith’s Animal Kingdom_, vol. iv. p. 258
(1827). Taken to include _Grimmia_, _Terphone_, etc., of Gray.
[214] Leach, _Trans. Linn. Soc._ vol. xiv. p. 524 (1823).
[215] Hamilton-Smith, in _Griffith’s Animal Kingdom_, vol. iv. p. 269
(1827).
[216] _Geology and Zoology of Abyssinia_, p. 268.
[217] Sundevall, _Kongl. Vetensk. Akad. Handl._ for 1844, p. 191. Taken
to include _Calotragus_, _Scopophorus_, _Nesotragus_, _Pediotragus_, and
_Oreotragus_ of Gray.
[218] See V. Brooke, _Proc. Zool. Soc._ 1872, pp. 642 and 875.
[219] Gray, _Cat. Ungulate Mamm. Brit. Mus._ p. 90 (1852).
[220] Andrew Smith, _Illustrations of Zoology of South Africa_, No. 12
(1840), “Kobus.” Is taken to include _Adenota_ and _Onotragus_ of Gray.
[221] De Blainville, _Bull. Soc. Philom._ 1816, p. 75. Syn. _Eleotragus_.
[222] Pallas, _Spicilegia Zoologica_, vol. i. p. 3 (1767).
[223] Sundevall, _Kongl. Vetensk. Akad. Handl._ for 1845, p. 271.
[224] Gray, _List Mamm. Brit. Mus._ p. 160 (1843).
[225] Hodgson, _Proc. Zool. Soc._ 1834, p. 81.
[226] De Blainville, _Bull. Soc. Philom._ 1816, p. 75. Is taken to
include _Procapra_ and _Tragops_.
[227] _Proc. Zool. Soc._ 1873, p. 537. Three species subsequently
described are here added to the list.
[228] Sundevall, _Kongl. Vetensk. Akad. Handl._ for 1844, p. 196.
[229] De Blainville, _Bull. Soc. Philom._ 1816, p. 75.
[230] Rafinesque, _Anal. Nat._ 1815, p. 56.
[231] De Blainville, _Bull. Soc. Philom._ 1816, p. 75. Syn. _Portax_,
Hamilton-Smith.
[232] De Blainville, _Bull. Soc. Philom._ 1816, p. 75. Includes
_Euryceros_, Gray.
[233] Gray, _List. Mamm. Brit. Mus._ p. 155 (1843).
[234] Desmarest, _Mammalogie_, p. 471 (1822).
[235] De Blainville, _Bull. Soc. Philom._ 1816, p. 75.
[236] Hamilton-Smith, in _Griffith’s Animal Kingdom_, vol. v. p. 352
(1827).
[237] Hamilton-Smith, in _Griffith’s Animal Kingdom_, vol. v. p. 354
(1827). Amended from “Aplocerus.”
[238] Hodgson, _Journ. As. Soc. Bengal_, vol. xix. p. 65 (1850).
[239] See A. O. Hume, _Proc. Zool. Soc._ 1887, pp. 483-486.
[240] Linn. _Syst. Nat._ 12th ed. vol. i. p. 94 (1766).
[241] _Proc. Zool. Soc._ 1886, p. 314; and 1887, p. 552.
[242] Specimens referred by Dinnik to _C. caucasica_ have been made the
types of another species—_C. severtzovi_.
[243] Linn. _Syst. Nat._ 12th ed. vol. i. p. 97 (1766).
[244] There may be a beard on the throat, as in _O. cycloceros_.
[245] _Proc. Zool. Soc._ 1884, p. 326.
[246] De Blainville, _Bull. Soc. Philom._ 1816, p. 76.
[247] _Zoologist_, September 1877.
[248] Linn. _Syst. Nat._ 12th ed. vol. i. p. 98 (1766).
[249] _Proc. Zool. Soc._ 1873, p. 474.
[250] Sir V. Brooke states that this species is distinguished from _B.
pumilus_ by the absence of a fringe to the ears, but specimens in the
British Museum show that this is not the case.
[251] _The Extirpation of the American Bison_, 1889.
[252] The late Mr. Alston, _Fauna of Scotland_, “Mammalia” (Glasgow,
1880), p. 25, considers that the Chillingham cattle are descendants of a
race which had escaped from domestication.
[253] Wanting in the aberrant _Chalicotherium_.
[254] See W. N. Parker, _Proc. Zool. Soc._ 1882, p. 775.
[255] Cuvier, _Tableau Élément. de l’Hist. Nat._ p. 152 (1798); _ex_
Brisson.
[256] See J. Murie, _Journ. Anat. and Physiol._ vol. vi. p. 131, 1871;
W. N. Parker. _Proc. Zool. Soc._ 1882, p. 768; and F. E. Beddard, _Proc.
Zool. Soc._ 1889, p. 252.
[257] The Swiss _P. siderolithicus_ has only one cusp in the last upper
premolar.
[258] Leidy, _Proc. Ac. Nat. Sci. Philad._ 1858, p. 26.
[259] Christol, _Ann. Sci. Indust. Mid. France_, vol. i. p. 180 (1832).
[260] Linn. _Syst. Nat._ 12th ed. vol. i. p. 100 (1766).
[261] Darwin, _Variation of Animals and Plants under Domestication_,
1868, vol. i. chap. ii.
[262] See _Nature_, 21st August 1884, and _Zool. Garten._ vol. xxviii. p.
453.
[263] See Sclater, _Proc. Zool. Soc._ 1884, p. 542.
[264] See Blanford, _Zoology and Geology of Eastern Persia_ (_Journeys of
the Persian Boundary Commission_), p. 84.
[265] This must not be confounded with the navicular of the tarsus.
[266] Want of space and of the necessary illustrations rendered it
impossible to give an account of mammalian myology in the earlier
chapters of this work.
[267] Linn. _Syst. Nat._ 12th ed. vol. i. p. 104 (1766).
[268] Many authors use Cuvier’s name, _R. indicus_, in preference to
this, on the ground that there are more than one species with one
horn, forgetting that the name substituted is equally inconvenient,
as more than one species live in India. The fact of a specific name
being applicable to several members of a genus is no objection to its
restriction to the first to which it was applied; otherwise changes
in old and well-received names would constantly have to be made in
consequence of new discoveries.
[269] _Trans. Zool. Soc._ vol. xii.; see also _Proc. Zool. Soc._ 1889, p.
9.
[270] See Beddard and Treves, _Proc. Zool. Soc._ 1889, p. 9.
[271] For the internal anatomy of _R. sumatrensis_ see Garrod, _Proc.
Zool. Soc._ 1873, p. 92; and Beddard and Treves, _loc. cit._
[272] Those external points of distinction from _R. simus_ are taken from
a paper by Sclater in the _Proc. Zool. Soc._ 1886, p. 143.
[273] _Proc. Zool. Soc._ 1881, p. 726.
[274] This name is the earliest, but is preoccupied.
[275] Hermann, _Tab. Affinit. Anim._ p. 115 (1783). It has recently
been proposed to substitute the earlier name _Procavia_ in lieu of
_Hyrax_. The anatomy of Hyrax was first described by Pallas (_Spicilegia
Zoologica_). Besides minor memoirs, two detailed accounts of its
structure have appeared—one by Brandt, in _Mém. Acad. Nat. Scien. St.
Pétersbourg_, 7ⁱᵉᵐᵉ sér. vol. xiv. No. 2, 1869; and another by George,
in _Annales des Sciences Naturelles_, 6ⁱᵉᵐᵉ sér. tom. i. 1874, in which
references to all the previous literature will be found. The mechanism
by which the sole of the foot is enabled to adhere to smooth surfaces is
fully described by G. E. Dobson, _Proc. Zool. Soc._ 1876, p. 526.
[276] Gray, _Ann. Mag. Nat. Hist._ ser. 4. vol. i. p. 48 (1868).
[277] See a paper by J. V. Barboza du Bocage, in the _Jorn. Sci. Phys.
Nat. Lisboa_ (2), vol. i. p. 186 (1889), where a list of all the known
species will be found.
[278] These teeth are by some writers classed as canines, as their roots
are implanted in the maxillæ; but, as in Rodents, they are originally
developed in the gum covering the premaxillæ, in which bones their
primitive alveoli are sunk. As growth proceeds, however, firm support
for such massive and weighty bodies can only be obtained by their roots
gradually sinking through the premaxillæ into the great and specially
modified alveolar processes of the maxillæ, but this does not vitiate
their homology with the incisors of other mammals.
[279] Linn. _Syst. Nat._ 12th ed. vol. i. p. 48 (1766).
[280] In the Gulf of Cambay,—not the island of the same name in the Red
Sea.
[281] The word Mammoth was introduced into the languages of Western
Europe about two centuries ago from the Russian, and is thought by
Pallas and Nordenskiöld to be of Tartar origin, but others, as Witzen,
Strahlenburg, and Howorth, have endeavored to prove that it is a
corruption of the Arabic word _Behemoth_, or great beast.
[282] The best known of these is the etching upon a portion of tusk
found in the cave of La Madelaine in the Dordogne, figured in Lartet and
Christy’s _Reliquiæ Aquitanicæ_, and in many other works bearing on the
subject of the antiquity of man.
[283] Cuvier, _Ann. du Muséum_, vol. viii. p. 270 (1806).
[284] This, and the larger number of ridges in the latter, are the only
absolute distinctions which Falconer could find between _Mastodon_ and
_Elephas_ (_Palæont. Memoirs_, ii. p. 9), and it is clear that they are
somewhat arbitrary. The line between the two genera is drawn at this
point more as a matter of convenience for descriptive purposes than as
indicating any great natural break in the sequence of modifications of
the same type.
[285] Also found beyond the extreme north-western frontier of India.
[286] Kaup, _Isis_, vol. xxii. p. 401 (1829).
[287] Leidy, _Proc. Ac. Nat. Sci. Philad._ 1872, p 169.
[288] For detailed descriptions and figures of this group, see Marsh,
“Monograph of the Dinocerata,” _Rep. U.S. Geol. Surv._ vol. x. (1884).
[289] Owen, _Brit. Foss. Mamm. and Birds_, p. 299 (1846).
[290] See G. E. Dobson, _Journ. Anat. Phys._ vol. xvii.
[291] Waterhouse, _Proc. Zool. Soc._ 1842, p. 124.
[292] _Proc. Zool. Soc._ 1882, p. 8.
[293] Linn. _Syst. Nat._ 12th ed. vol. i. p. 86 (1766).
[294] Gray, _Ann. Mag. Nat. Hist._ ser. 3, vol. xx. p. 272 (1867).
[295] Hemprich and Ehrenberg, _Symbol. Phys. Mamm._ vol. i. (1832).
[296] Illiger, _Prodromus Syst. Mamm._ p. 83 (1811).
[297] Some American zoologists have recently proposed to raise a large
number of the forms usually regarded as local races to the rank of
species.
[298] Cuvier, _Leçons d’Anatomie Comp._ (1800).
[299] Cuvier, _Ann. du Muséum_, vol. x. p. 126 (1825).
[300] O. Thomas, _Journ. As. Soc. Bengal_, vol. lvii. p. 256 (1888).
[301] Schreber, _Säugethiere_, vol. iv. p. 721 (1792).
[302] Rafinesque, _Amer. Monthly Mag._ vol. ii. p. 45 (1817).
[303] F. Cuvier, _Mém. du Muséum_, vol. vi. p. 293 (1822).
[304] Richardson, _Zool. Journ._ vol. iv. p. 334 (1829). Amended.
[305] Linn. _Syst. Nat._ 12th ed. vol. i. p. 78 (1766).
[306] For a monograph of the _Myoxidæ_, see C. L. Reuvens, _Die Myoxidæ_,
etc., 4to, Leyden, 1890.
[307] Schreber, _Säugethiere_, vol. iv. p. 824 (1792).
[308] Wagner, _Abh. baier. Akad._ vol. iii. p. 179 (1843).
[309] F. Cuvier, _Mammifères_, 60ᵐᵉ livr. (1845).
[310] Jentink, _Notes Leyd. Mus._ vol. x. p. 41 (1888).
[311] Kaup, _Entwickl. Europ. Thierwelt_, p. 139 (1829).
[312] A. Milne-Edwards, _L’Institut_, vol. xxxv. p. 46 (1867).
[313] _Sminthus_ is referred to the _Dipodidæ_.
[314] Geoffrey, _Ann. du Muséum_, vol. vi. p. 81 (1805).
[315] For the anatomy of this animal see B. C. A. Windle, _Proc. Zool.
Soc._ 1887, p. 53.
[316] O. Thomas, _Proc. Zool. Soc._ 1889, p. 247.
[317] Blyth, _Proc. As. Soc. Bengal_, vol. xxviii. p. 289 (1859).
[318] Desmarest, _Nouv. Dict. d’Hist. Nat._ vol. xxiv. p. 22 (1804).
[319] Lataste, _Le Nat._ vol. i. p. 314 (1880).
[320] Wagner, _Wiegmann’s Archiv_, 1841, p. 132.
[321] F. Cuvier, _Dents des Mammifères_, p. 168 (1825).
[322] Peters, _Monatsber. Ak. Berlin_, 1875, p. 12.
[323] A. Milne-Edwards, _Bull. Soc. Philom._ sér. 6, vol. xi. p. 9 (1877).
[324] _Nesocia_ was included by Alston in this subfamily.
[325] Waterhouse, _Proc. Zool. Soc._ 1839, p. 108.
[326] Andrew Smith, _S. African Quart. Journ._ vol. ii. p. 158 (1834).
[327] Peters, _Reise n. Mossambique_, vol. i. p. 162 (1852).
[328] Peters, _Monatsber. Ak. Berlin_, 1874, p. 234.
[329] Cuvier, _Règne Animal_, vol. i. p. 198 (1817).
[330] _Proc. Zool. Soc._ 1888, p. 133.
[331] _Proc. Zool. Soc._ 1884, p. 451.
[332] Brandt, _Mém. Acad. Imp. St. Pétersbourg_, sér. 3, iii. p. 428
(1835).
[333] Say and Ord, _Journ. Acad. Philad._ vol. iv. p. 352 (1825).
[334] Waterhouse, _Proc. Zool. Soc._ 1837, p. 29.
[335] Coues, _Proc. Acad. Philad._ 1874, p. 184.
[336] Say and Ord, _Journ. Acad. Philad._ vol. iv. p. 346 (1825).
[337] Grandidier, _Rev. and Mag. Zool._ 1869, p. 388.
[338] Peters, _Sitzber. Ges. Nat. Freunde_, 1870, p. 54 (1871).
[339] Günther, _Proc. Zool. Soc._ 1875, p. 79.
[340] Jentink, _Notes Leyd. Mus._ vol. i. p. 107, note 27 (1879).
[341] Milne-Edwards, _Ann. Sci. Nat._ sér. 6, vol. xx. art. 1, _bis_, p.
1 (1886).
[342] Merriam, _Fauna of North America_, No. 2, p. 28 (1889).
[343] Lacépède, _Mém. de l’Institut_, vol. iii. p. 495 (1801). Many
writers employ the earlier name _Microtus_ for the true Voles.
[344] Baird, _Mamm. North America_, pp. xliv. 558 (1857).
[345] Pallas, _Zoogr. Rosso-Asiat._ vol. i. p. 173 (1811).
[346] Wagler, _Isis_, 1832, p. 1220.
[347] Cuvier, _Leçons d’Anatomie Compar._ tab. 1 (1800).
[348] True, _Proc. U.S. Nat. Mus._ vol. vii. p. 170 (1884).
[349] Fischer, _Zoognosia_, vol. iii. p. 72 (1814).
[350] Brants, _Het. Geslact der Muizen_, p. 20 (1827).
[351] O. Thomas. _Proc. Zool. Soc._ 1888, p. 130.
[352] Linn. _Syst. Nat._ 12th ed. vol. i. p. 79 (1766).
[353] Gray, _Ann. Mag. Nat. Hist._ vol. x. p. 264 (1842). Amended from
_Nesokia_.
[354] Gray, Charlesworth’s, _Mag. Nat. Hist._ vol. i. p. 586 (1837). Syn.
_Pelomys_, Peters (1852).
[355] Peters, _Monatsber. Ak. Berlin_, 1867, p. 343.
[356] O. Thomas, _Proc. Zool. Soc._ 1888, p. 237.
[357] Lichtenstein, _Darst. neu. Säugethiere_, pt. iv. pl. 29 (1829).
[358] O. Thomas, _Ann. Mag. Nat. Hist._ ser. 5, vol. ix. p. 413 (1882).
[359] Geoffroy, _Ann. Sci. Nat._ sér. 2, vol. x. p. 126 (1840). _Acomys._
[360] Gray, _Proc. Zool. Soc._ 1867, p. 599. Amended from _Echimys_.
[361] Milne-Edwards, _Bull. Soc. Philom._ sér. 6, vol. xi. p. 9 (1877).
[362] Waterhouse, _Proc. Zool. Soc._ 1840, p. 2.
[363] Peters, _Monatsber. Ak. Berlin_, 1846, p. 258.
[364] Güldenstädt, _Nov. Comment. Petrop._ vol. xiv. art. i. p. 409
(1770).
[365] Gray, _Proc. Zool. Soc._ 1830, p. 95.
[366] Illiger, _Prodromus Syst. Mamm._ p. 86 (1811).
[367] Illiger, _loc. cit._ p. 87.
[368] O. Thomas, _Proc. Zool. Soc._ 1890, p. 448 = _Heliophobius_;
Peters, _Monatsber. Ak. Berlin_, 1846, p. 243.—Preoccupied.
[369] Rüppel, _Mus. Senkenb._ vol. i. Säugeth. p. 99 (1834).
[370] Including the _Saccomyidæ_ of Coues.
[371] Rafinesque, _Amer. Monthly Mag._ vol. ii. p. 45 (1817).
[372] Wied, _Nova Acta Ac. Cæs. Leop.-Car._ vol. xix. pt. i. p. 383
(1839).
[373] Gray, _Ann. Mag. Nat. Hist._ vol. vii. p. 521 (1840).
[374] Wied, _Nova Acta Ac. Cæs. Leop.-Car._ vol. xix. pt. i. p. 369
(1839).
[375] Desmarest, _Mammalogie_, p. 313 (1820).
[376] Keyserling und Blasius, _Wirbelthiere Europ._ p. 38 (1840).
[377] Coues, _Bull. U.S. Geol. Surv. Terrs._ ser. 2, No. 5, p. 253
(1873). Syn. _Jaculus_, Wagler.
[378] Gmelin, _Syst. Nat._, vol. i. p. 157 (1788).
[379] F. Cuvier, _Proc. Zool. Soc._ 1836, p. 141.
[380] Brandt, _Bull. Ac. St. Pétersbourg_, 1844, p. 209.
[381] = _A. jaculus_, Auct.
[382] Illiger, _Prodromus Syst. Mamm._ p. 81 (1811).
[383] Gray, _Spicilegia Zoologica_, p. 10 (1830).
[384] Blyth, _Journ. As. Soc. Bengal_, vol. xxxiv. p. 294 (1855).
[385] Bennett, _Proc. Zool. Soc._ 1832, p. 46.
[386] Waterhouse, _Proc. Zool. Soc._ 1837, p. 30. Amended from _Abrocoma_.
[387] Waterhouse, _Proc. Zool. Soc._ 1841, p. 91.
[388] De Blainville, _Bull. Soc. Philom._ 1826, p. 62.
[389] Wagler, _ibid._ p. 1219.
[390] Andrew Smith, _S. African Quart. Journ._ vol. ii. p. 2 (1831).
[391] Geoffroy, _Ann. du Muséum_, vol. vi. p. 81 (1805).
[392] Desmarest, _Mém. Soc. d’Hist. Nat._ vol. i. p. 44 (1822).
[393] For description and anatomy of this species see Dobson, _Proc.
Zool. Soc._ 1884, p. 233.
[394] Temminck, _Monographies des Mammifères_, vol. i. p. 245 (1827).
[395] Cuvier, _Ann. Sci. Nat._ sér. 2, vol. vi. p. 347 (1836). Amended.
[396] Illiger, _Prodromus Syst. Mamm._ p. 90 (1811).
[397] Desmarest, _Nouv. Dict. d’Hist. Nat._ vol. x. p. 45 (1817). Amended
from _Echimys_.
[398] Wagner, _Wiegmann’s Archiv_, 1845, pt. 2, p. 145.
[399] Geoffroy, _Ann. Sci. Nat._ sér. 2, vol. x. p. 126 (1838).
[400] F. Cuvier, _Mammifères_, 6ᵐᵉ livr. (1829).
[401] Waterhouse, _Nat. Hist. of Mamm._ vol. ii. p. 351 (1848).
[402] F. Cuvier, _Dents des Mammifères_, p. 256 (1825).
[403] F. Cuvier, _Mém. du Muséum_, vol. ix. p. 413 (1822). “Sinéthère.”
[404] Gray, _Proc. Zool. Soc._ 1843, p. 21.
[405] Linn. _Syst. Nat._ 12th ed. vol. i. p. 76 (1766).
[406] Cuvier, _Règne-Animal_, 2d ed. vol. i. p. 215 (1829). “Atherure.”
[407] Günther, _Proc. Zool. Soc._ 1876, p. 739.
[408] Bennett, _Gardens, etc. Zool. Soc._ pt. i. p. i. (1829).
[409] Meyer, _Nova Acta Ac. Cæs. Leop.-Car._ vol. xvi. p. 576 (1833).
[410] Brooks, _Trans. Linn. Soc._ vol. xvi. p. 102 (1828).
[411] Foster, _Second Rep. Geol. of Ohio_, p. 81 (1838).
[412] Illiger, _Prodromus Syst. Mamm._ p. 93 (1811).
[413] F. Cuvier, _Ann. du Muséum_, vol. x. p. 203 (1807).
[414] Peters, _Monatsber. Ak. Berlin_, 1873, p. 551.
[415] Pallas, _Misc. Zool._ p. 30 (1766); _ex_ Klein.
[416] Desmarest, _Mammalogie_, p. 360 (1822).
[417] Erxleben, _Syst. Règ. Animal_, p. 191 (1777); _ex_ Brisson.
[418] Cuvier, _Tabl. Élément. de l’Hist. Nat._ p. 132 (1798).
[419] Linn. _Syst. Nat._ 12th ed. vol. i. p. 77 (1766).
[420] From the absence of the Common Hare in Scandinavia it is considered
probable that the name _L. timidus_ was really applied to the Mountain
Hare, and some writers accordingly use the name _L. europæus_ for the
former.
[421] _Variations of Animals and Plants_, 2d ed. vol. i. p. 119.
[422] The Feræ of Linnæus included all the then known species of the
modern orders Carnivora, Insectivora, and Marsupialia.
[423] The tusks of the Walrus, altogether so aberrant in its dentition,
are partial exceptions to this statement, but in old individuals the
pulp-cavity fills up, and they cease to grow.
[424] See Flower, “On the Value of the Characters of the Base of the
Cranium in the Classification of the Order _Carnivora_,” _Proc. Zool.
Soc._ 1869, p. 4; Mivart, “On the Classification and Distribution of
the _Æluroidea_,” _ibid._ 1882, pp. 135 and 459; see also _The Cat, an
Introduction to the Study of Backboned Animals, especially Mammals_, by
the same author, 1881.
[425] Linn. _Syst. Nat._ 12th ed. vol. i. p. 60 (1766).
[426] _The Cat_, pp. 392-426 (1881).
[427] _Fauna of British India_, “Mammalia,” pp. 56-90 (1888).
[428] _Zoology and Geology of Eastern Persia_ (1876).
[429] See Blanford, _Fauna of British India_, “Mammalia,” p. 57 (1883).
[430] _Transactions of the Zoological Society_, vol. i. p. 165 (1835).
[431] _A Hunter’s Wanderings in Africa_, 1881, p. 258.
[432] Mr. Selous, whose opportunities for obtaining evidence upon this
subject were very large, says that in the region of South Africa,
between the Zambesi and the Limpopo rivers, he never saw a lion with
any long hair under the body, and that the manes of the wild lions of
that district are far inferior in development to those commonly seen in
menageries in Europe.
[433] _The Lion and the Elephant_, 1873, p. 19.
[434] Hon. W. H. Drummond, _The Large Game and Natural History of South
and South-East Africa_, 1875, p. 278.
[435] _Fauna of British India_, “Mammalia,” p. 59 (1888).
[436] See W. T. Blanford, _Fauna of British India_, “Mammalia,” p. 69
(1888).
[437] _Monographs of the Palæontographical Society_, 1872.
[438] Syn. _F. macrocelis_.
[439] Syn. _F. maniculata_ and _caligata_.
[440] Wagler, _Syst. Amphib._ etc. p. 30 (1830).
[441] Bennett, _Trans. Zool. Soc._ vol. i. p. 137 (1833).
[442] Linn. _Syst. Nat._ 12th ed. vol. i. p. 63 (1766).
[443] Gray, _Proc. Zool. Soc._ 1864, p. 518.
[444] Cuvier, _Règne-Animal_, vol. i. p. 156 (1817).
[445] Horsfield, _Zool. Research. Java_ (1824).—_Prionodontidæ._
[446] Gray, _Proc. Zool. Soc._ 1864, p. 520.
[447] F. Cuvier, _Hist. Nat. des Mammifères_, No. 186 (1821).
[448] See W. T. Blanford, _Proc. Zool. Soc._ 1885, p. 780.
[449] _Fauna of British India_, “Mammalia,” p. 108 (1888).
[450] Gray, _Proc. Zool. Soc._ 1864, p. 542, _ex_ Petero.
[451] Jourdan, _Comptes Rendus_, vol. v. p. 442 (1837). Amended.
[452] Temminck, _Prospectus de Monographies des Mammifères_, March 1824;
_Monographies_, vol. i. p. xxi. (1827).
[453] Gray, _List of Mamm. Brit. Mus._ p. 54 (1843).
[454] Gray, _Proc. Zool. Soc._ 1836, p. 88.
[455] Illiger, _Prodromus Syst. Mamm._ p. 135 (1811).
[456] Gray, _Proc. Zool. Soc._ 1861, p. 308.
[457] Peters, _Mith. Ges. Nat. Freunde Berlin_, 19th November 1850.
[458] Ogilby, _Proc. Zool. Soc._ 1833, p. 48.
[459] Gray, _Proc. Zool. Soc._ 1864, p. 573.
[460] F. Cuvier, _Hist. Nat. des Mammifères_, No. 199 (1825).
[461] Desmarest, “Tabl. Méth. Mamm.” in _Nouv. Dict. d’Hist. Nat._ vol.
xxiv. (1804).
[462] Geoffroy, _Comptes Rendus_, 1837, p. 578.
[463] Geoffroy, _Mag. de Zool._ 1839, pp. 27, 37.
[464] Doyère, _Ann. Sci. Nat._ vol. iv. p. 281 (1835).
[465] Jourdan, _Comptes Rendus_, 1837, p. 422. Amended.
[466] Geoffroy, _Mém. du Muséum_, vol. xi. p. 354 (1824).
[467] For Anatomy of _Proteles_ see Flower, _Proc. Zool. Soc._ 1869, p.
474.
[468] Zimmermann, _Specimen Zoologiæ Geographicæ_, p. 365 (1777).
[469] _Fauna of British India_, “Mammalia,” p. 133 (1888).
[470] The anatomical peculiarities of _Hyæna crocuta_ have been fully
elucidated in a series of papers by Morrison Watson in the _Proceedings
of the Zoological Society_ for 1877, 1878, 1879, and 1881, in which
references to previous authors on the subject will be found.
[471] Linn. _Syst. Nat._ 12th ed. vol. i. p. 56 (1766).
[472] In Domestic Dogs a hallux is frequently developed, though often in
a rudimentary condition, the phalanges and claw being suspended loosely
in the skin, without direct connection with the other bones of the foot;
it is called by dog-fanciers the “dew claw.”
[473] _Proc. Zool. Soc. Lond._, 1880, p. 238. See also Mivart, _Dogs,
Jackals, Wolves, and Foxes; a Monograph of the Canidæ_ (1890).
[474] _Fauna of British India_, “Mammalia,” pp. 153, 154 (1888).
[475] Brookes, _Griffith’s Animal Kingdom_, vol. v. p. 151 (1827).
[476] Lund, _K. Danks. Vid. Selsk. Afhand._ vol. xi. p. 62 (1845).
[477] Lichtenstein, _Wiegmann’s Archiv._ 1838, vol. i. p. 290.
[478] _Arch. Mus. Lyon._ vol. iii. art. 1, p. 85 (1881).
[479] _Proc. Amer. Phil. Soc._ vol. xviii. p. 452 (1880).
[480] For full details of the Arctoidea see Mivart, _Proc. Zool. Soc._
1885, p. 340.
[481] Linn. _Syst. Nat._ 12th ed. vol. i. p. 69 (1766).
[482] Meyer, _Uebersicht d. neu. Zool. Entdeckungen_, etc. p. 155 (1793).
[483] A. Milne-Edwards, _Nouv. Arch. du Muséum_, vol. vii. _Bull._ p. 88
(1871). Amended from “Ailuropus.”
[484] F. Cuvier, _Hist. Nat. des Mammifères_ (1825). Amended from
“Ailurus.” For anatomy, see Flower, _Proc. Zool. Soc._, 1870, p. 752.
[485] _Fauna of British India_, “Mammalia,” p. 189 (1888).
[486] Storr, _Prodromus Meth. Mamm._ p. 35 (1780).
[487] A corruption of the North American Indian “arrathkune” or
“arathcone.” The French _raton_ or _raton laveur_, German _Waschbär_, and
other European names are derived from a curious habit the Raccoon has of
dipping or washing its food in water before eating it.
[488] Lichtenstein, _Isis_, 1831, p. 512.
[489] Allen, _Proc. Ac. Nat. Sci. Philad._ 1876, p. 20.
[490] Storr, _Prodromus Meth. Mamm._ p. 35 (1780).
[491] Illiger, _Prodromus Syst. Mamm. et Avium_, p. 127 (1811).
[492] Also in two other species noticed below. One extinct Otter has two
upper molars.
[493] Erxleben, _Syst. Règn. Animal_, p. 445 (1777).
[494] See Thomas, _Proc. Zool. Soc._ 1889, p. 190.
[495] The synonymy of this species is not settled, and the adoption of
the name given here only preliminary.
[496] Gloger, _Nova Acta Ac. Cæs. Leop.-Car._ vol. xiii. pt. 2, p. 511
(1827): Syn. _Enhydra_; Fleming, _Philosophy of Zoology_, vol. ii. p. 187
(1822). Preoccupied by _Enhydris_, Merrem, _Tent. Syst. Amphib._ p. 140
(1820).
[497] Cuvier, “Tabl. de Classif.” in _Leçons d’Anat. Compar._ vol. i.
(1800).
[498] Gray, _Ann. Mag. Nat. Hist._ ser. 2, vol. i. p. 581 (1837).
[499] F. Cuvier, _Hist. Nat. des Mammifères_ (1825).
[500] Possibly the name should be Bálu-soor (Sand-pig).
[501] F. Cuvier, _Hist. Nat. des Mammifères_ (1825).
[502] Storr, _Prodromus Meth. Mamm._ p. 34 (1780).
[503] Waterhouse, _Proc. Zool. Soc._ 1838, p. 154.
[504] Storr, _Prodromus Meth. Mamm._ p. 34 (1780).
[505] Gray, _Proc. Zool. Soc._ 1831, p. 94.
[506] Garrod, _ibid._ 1879, pl. xxix.
[507] Kaup, _Thierreich_, vol. i. p. 352 (1835).
[508] Bell, _Proc. Zool. Soc._ 1837, p. 45.
[509] Linn. _Syst. Nat._ 12th ed. vol. i. p. 66 (1766).
[510] By all old authors of authority, as Ray, Pennant, Shaw, and
Fleming, the word is written “Martin,” but this form of spelling is
now generally reserved by way of distinction for the bird. The term
“Marten-Cat,” often used, is a misnomer.
[511] See Rolleston, “On the Domestic Cats, _Felis domesticus_ and
_Mustela foina_, of Ancient and Modern Times,” _Journal of Anatomy and
Physiology_, vol. ii. p. 47, 1868.
[512] O. Thomas, _Ann. Mag. Nat. Hist._ ser. 5, vol. xi. p. 370 (1883).
[513] Gervais, _Dict. Univ. d’Hist. Nat._ t. iv. p. 685 (1849).
[514] Storr, _Prodromus Meth. Mamm._ p. 34 (1780).
[515] _Proc. Zool. Soc._ 1885, p. 497.
[516] Péron, _Voyage aux Terres Australes_, vol. ii. p. 37 note (1816).
[517] “On the structure of Hooker’s Sea-Lion (_Arctocephalus hookeri_),”
_Trans. Zool. Soc._ vol. xii. p. 369 (1890).
[518] Linn, _Syst. Nat._ 12th ed. vol. i. p. 49 (1766).
[519] The former word is a modification of the Scandinavian _vallross_ or
_hvalros_ (“whale-horse”), the latter an adaptation of the Russian name
for the animal.
[520] Nilsson, _Faun. Scandinav._ vol. i. p. 377 (1820).
[521] Linn. _Syst. Nat._ 12th ed. vol. i. p. 55 (1766).
[522] Fleming, _Philosophy of Zoology_, vol. ii. p. 187 (1822).
[523] For details of these and the other genera see Mivart, _Proc. Zool.
Soc._ 1885, p. 486, _et seq._
[524] Peters, _Monatsb. K. P. Akad. Wissensch. zu Berlin_, p. 393 (1875),
substituted for _Stenorhynchus_, F. Cuvier; preoccupied for a genus of
Crustacea.
[525] Gray, _Zoology of Erebus and Terror_, vol. i. p. 5 (1844).
[526] New name, _Syn. Leptonyx_, Gray, _Charlesworth’s Mag. Nat. Hist._
vol. i. p. 582 (1837); preoccupied by Swainson, 1821.
[527] Gray, _Zoology of Erebus and Terror_, vol. i. p. 7 (1844).
[528] Nilsson, _Faun. Scandinav._ vol. i. p. 382 (1820).
[529] F. Cuvier, _Mém. du Muséum_, vol. xi. p. 200 (1824), “Macrorhine.”
[530] Pallas, _Acta Acad. Sci. Imp. Petropolis_, vol. iv. pt. 1, p. 208
(1780).
[531] _Ueber die Säugethiergattung Galeopithecus._ _Sv. Ak. Handl._ vol.
xxi. pt. xi. (1886).
[532] Raffles, _Trans. Linn. Soc._ vol. xiii. p. 256 (1822).
[533] Gray, _Proc. Zool. Soc._ 1848, p. 23.
[534] Andrew Smith, _S. African Quart. Journ._ vol. ii. No. 1, p. 64
(1833).
[535] The above correct formula of the dentition of this family has been
recently worked out by O. Thomas, _Proc. Zool. Soc._ 1890, pp. 445, 446.
[536] Peters, _Bericht k. preuss. Ak. Wiss._ 1847, p. 36.
[537] Horsfield and Vigors, _Zool. Journ._ vol. iii. p. 246 (1828).
[538] Linn. _Syst. Nat._ 12th ed. vol. i. p. 75 (1766).
[539] Originally given incorrectly as _Neurogymnurus_.
[540] _Proc. Zool. Soc._ 1890, p. 49.
[541] Linn. _Syst. Nat._ 12th ed. vol. i. p. 73 (1766).
[542] Syn. _S. minutus_.
[543] Blyth, _Journ. As. Soc. Bengal_, vol. xxiv. p. 36 (1855).
[544] Coues, _Bull. U.S. Geol. Surv. Terrs._ vol. iii. p. 646 (1877).
[545] Gray, _Proc. Zool. Soc._ 1837, p. 124.
[546] Wagler, _Isis_, 1832, p. 275.
[547] Gray, _Proc. Zool. Soc._ 1837, p. 124.
[548] Wagler, _Isis_, 1832, p. 275.
[549] Brandt, in _Lehmann’s Reise.-Zool. Anh._ p. 299 (1852).
[550] Milne-Edwards, _Comptes Rendus_, vol lxx. p. 341 (1870).
[551] Anderson, _Journ. As. Soc. Bengal_, vol. xlvi. p. 262 (1877).
[552] Milne-Edwards, _Comptes Rendus_, vol. lxx. p. 341 (1870).
[553] Cuvier, “Tabl. de Classif.” in _Leçons d’Anat. Compar._ vol. i.
(1800).
[554] Temminck, _Fauna Japonica_, vol. i. p. 22 (1842).
[555] Milne-Edwards, _Arch. du Muséum_, vol. vii. Bull. p. 92 (1872).
[556] Cuvier, “Tabl. de Classif.” in _Leçon d’Anat. Comp._ vol. i. (1800).
[557] Pomel, _Arch. Sci. Phys. Nat._ vol. ix. p. 247 (1848).
[558] Illiger, _Prodromus Syst. Mamm. et Avium_. p. 125 (1811).
[559] Milne-Edwards, _N. Arch. du Muséum_, vol. vii. Bull. p. 92 (1872).
[560] Linn, _Syst. Nat._ 12th ed. p. 73 (1766).
[561] The following account is taken almost entirely from Dr. Dobson.
[562] Du Chaillu, _Proc. Boston Soc. Hist. Nat._ vol. vii. p. 363 (1860).
[563] Milne-Edwards, _Ann. Sci. Nat._ vol. xv. p. 5 (1872).
[564] Brandt, _Mém. Ac. Imp. St. Pétersbourg_, 1833, vol. ii. p. 459.
[565] Illiger, _Prodromus Syst. Mamm. et Avium_, p. 124 (1811).
[566] Mivart, _Proc. Zool. Soc._ 1871, p. 72.
[567] I. Geoffroy, _Ann. Sci. Nat._ sér. 2, vol. viii. p. 60 (1837).
[568] Thomas, _Journ. Linn. Soc.—Zool._ vol. xvi. p. 319 (1882).
[569] Grandidier, _Rev. and Mag. Zool._ 1870, p. 50.
[570] Lacépède, _Mém. de l’Institut_, vol. iii. p. 493 (1801—read 1799).
[571] _Proc. Zool. Soc._ 1888, p. 473.
[572] Bennett, _Trans. Zool. Soc._ vol. ii. p. 38 (1835).
[573] Geoffroy, _Ann. du Muséum_, vol. xv. p. 90 (1810).—_Ex._ Brisson.
[574] Gray, _List. Spec. Mamm. Brit. Mus._ pp. 37, 38 (1843): Syn.
_Cynonycteris_.
[575] Jentink, _Notes Leyd. Mus._ vol. i. p. 117 (1879).—Amended.
[576] F. Cuvier, _Dents des Mammifères_, p. 39 (1825).
[577] Illiger, _Prodromus Syst. Mamm. et Avium_, p. 118 (1811).
[578] Geoffroy, _Ann. du Muséum_, vol. xvi. p. 99 (1810).
[579] O. Thomas, _Ann. Mag. Nat. Hist._ ser. 6, vol. i. p. 155 (1888).
[580] Gray, _Proc. Zool. Soc._ 1859, p. 36.
[581] Dobson, _Journ. As. Soc. Bengal_, vol. xlii. p. 204 (1873).
[582] New name: Syn. _Macroglossus_, F. Cuvier, _Dents des Mammifères_,
p. 40 (1825). Preoccupied by _Macroglossum_, Scopoli, 1777.
[583] Dobson, _Proc. Zool. Soc._ 1877, p. 119.
[584] O. Thomas, _Ann. Mag. Nat. Hist._ ser. 5, vol. xix. p. 417 (1887).
[585] Jentink, _Notes Leyd. Mus._ vol. xi. p. 209 (1889).
[586] New name: Syn. _Megaloglossus_; Pagenstecher, _J. B. Mus. Hamburg_,
vol. ii. p. 125 (1885). Preoccupied by _Megaglossa_, Rond., 1865.
[587] Geoffroy, _Nouv. Dict. d’Hist. Nat._ vol. xix. p. 383 (1803).
[588] Gray, _Proc. Zool. Soc._ 1834, p. 53. The Bats of this genus are
usually described as _Phyllorhina_, but this use has been shown to be
incorrect; see Blanford, _Proc. Zool. Soc._ 1887, p. 637.
[589] O. Thomas, _Ann. Mag. Nat. Hist._ ser. 6, vol. i. p. 156 (1888).
[590] Gray, _Proc. Zool. Soc._ 1847, p. 16.
[591] Dobson, _Journ. As. Soc. Bengal_, vol. xl. p. 455 (1871).
[592] Blyth, _Journ. As. Soc. Bengal_, vol. xvii. p. 251 (1848).
[593] Geoffroy, _Ann. du Muséum_, vol. xv. p. 197 (1810).
[594] Geoffroy, _Nouv. Dict. d’Hist. Nat._ vol. xv. p. 501 (1803).
[595] Geoffroy, _Descript. de l’Egypte_, vol. ii. p. 112 (1812).
[596] Keyserling and Blasius, _Wirbelthiere Europ._ p. 55 (1840).
[597] Peters, _Monatsber. Ak. Berlin_, 1859, p. 222.
[598] Leach, _Trans. Linn. Soc._ vol. xiii. p. 78 (1822).
[599] Allen, _Proc. Ac. Nat. Sci. Philad._ 1862, p. 247.
[600] Keyserling and Blasius, _Wiegmann’s Archiv_, 1839, p. 312.
[601] Peters, _Monatsber. Ak. Berlin_, 1866, p. 672.
[602] Leach, _Trans. Linn. Soc._ vol. xiii. p. 71 (1822).
[603] See O. Thomas, _Ann. Mus. Genova_ (2), vol. ix. pp. 84-88 (1890).
[604] Rafinesque, _Journ. de Physique_, vol. lxxxviii. p. 417 (1819).
[605] Rafinesque, _Précis des Decouvértes et Trav. Somiol._ p. 12 (1814).
[606] Gray, _Ann. Mag. Nat. Hist._ vol. x. p. 259 (1842).
[607] Linn. _Syst. Nat._ 12th ed. vol. i. p. 46 (1766).
[608] Gray, _Ann. Mag. Nat. Hist._ vol. x. p. 258 (1842), _Kerivoula_.
[609] Gray, _Mag. Zool. Bot._ vol. ii. p. 496 (1838).
[610] Bonaparte, _Fauna Italica_, fasc. xxi. (1837).
[611] Spix, _Sim. and Vesp. Bresil_, p. 61 (1823).
[612] A. Milne-Edwards, _Bull. Soc. Philom._ sér. 7, vol. ii. p. 1 (1878).
[613] Bonaparte, _Faun. Ital._ vol. i. (1832-41): Syn. _Furia_, F.
Cuvier, _Mém. du Muséum_, vol. xvi. p. 150 (1828). Preoccupied by Linn.
1766.
[614] Peters, _Monatsber. Ak. Berlin_, 1877, p. 185.
[615] Temminck (Van der Hoeven), _Tijdsch. Nat. Ges._ 1839, p. 22.
[616] Peters, _Monatsber. Ak. Berlin_, 1867, p. 479.
[617] Peters, _loc. cit._ p. 477.
[618] Illiger, _Prodromus Syst. Mamm. et Avium_, p. 121 (1811).
[619] Geoffroy, _Descript. de l’Egypte_, vol. ii. p. 126 (1812).
[620] Wied, _Isis_, 1819, p. 1629.
[621] Linn. _Syst. Nat._ 12th ed. vol. i. p. 88 (1766).
[622] Geoffroy, _Descript. de l’Egypte_, vol. ii. p. 123 (1812).
[623] Horsfield, _Zool. Research Java_ (1824).
[624] Geoffroy, _Ann. du Muséum_, vol. vi. p. 154 (1805).
[625] Geoffroy, _Descript. de l’Egypte_, vol. ii. p. 114 (1812).
[626] New name: Syn. _Mystacina_; Gray, _Voyage of the “Sulphur,”_
“Mamm.” p. 23 (1843). Preoccupied by _Mystacina_, Boie, 1822.
[627] Gray, _Ann. Mag. Nat. Hist._ vol. iv. p. 4 (1839).
[628] Leach, _Trans. Linn. Soc._ vol. xiii. p. 76 (1820-22).—Amended.
[629] Tomes, _Proc. Zool. Soc._ 1863, p. 81.
[630] New name: Syn. _Macrotus_; Gray, _Proc. Zool. Soc._ 1843, p. 21.
Preoccupied by _Macrotis_, Dej. 1833.
[631] New name: Syn. _Macrophyllum_; Gray, _Mag. Zool. Bot._ vol. ii. p.
489 (1838). Preoccupied by _Macrophylla_, Hope, 1837.
[632] Leach, _Trans. Linn. Soc._ vol. xiii. pp. 74, 75 (1822). For the
references to the other genera see Dobson, _Cat. Chiropt. Brit. Mus._
[633] Gray, _Proc. Zool. Soc._ 1866, p. 113. Syn. _Schizostoma_; Gervais,
1855. Preoccupied by Broun, 1835.
[634] New name: Syn. _Tylostoma_; Gervais, 1855. Preoccupied by Sharpe,
1849.
[635] Gervais, Castlenau’s _Exped.-Zool._ p. 43 (1855): Syn. _Carollia_,
Gray, 1838. Preoccupied by _Carolia_, Cantraine, 1837.
[636] The references to the genera of this and the following division
will be found in Dobson’s _Catalogue_.
[637] New name: Syn. _Ischnoglossa_, Saussure, 1860. Preoccupied by
Kraatz, 1856.
[638] Wied, _Beitr. Natgesch. Brasil_, vol. ii. p. 231 (1826).
[639] Spix, _Sim. et Vesp. Brasil_, p. 68 (1823).
[640] For the arguments in favour of placing the Lemurs in a separate
order see Milne-Edwards, “Observations sur quelques points de
l’embryologie des Lemuriens et sur les affinités zoologiques de ces
animaux,” in the _Ann. des Sciences Nat._ October 1871; and P. Gervais,
“Encephale des Lemures,” in _Journ. de Zoologie_, tom. i. p. 7. For those
for retaining them among the Primates, see Mivart, “On _Lepilemur_ and
_Chirogaleus_, and on the Zoological Rank of the Lemuroidea,” in _Proc.
Zool. Soc._ 1873, p. 484.
[641] Geoffroy, _Mag. Encyclop._ 2d ann. vol. i. p. 46 (1796), “Indri.”
[642] Bennett, _Proc. Zool. Soc._ 1832, p. 20.
[643] Jourdan, _Mém. de l’Institut_, vol. ii. p. 231 (1834).
[644] Linn. _Syst. Nat._ 12th ed. vol. i. p. 44 (1766).
[645] _Proc. Zool. Soc._ 1879, p. 132.
[646] Gray, _Proc. Zool. Soc._ 1870, p. 829.
[647] I. Geoffroy, _Cat. Mus. Hist. Nat. Paris_, p. 75 (1851). Amended
from _Lepilemur_.
[648] _Monatsb. Ak. Berlin_, 1874, p. 690.
[649] Geoffroy, _Ann. du Muséum_, vol. xix. p. 171 (1812).
[650] Geoffroy, _Mag. Encyclop._ 2d ann. vol. i. p. 49 (1796).
[651] Geoffroy, _Ann. du Muséum_, vol. xix. pp. 162, 163 (1812).
[652] For the anatomy of this genus, see J. L. C. Shroeder van der Kolk
and W. Vrolik, “Recherches d’Anatomie comparée sur le genre _Stenops_
d’Illiger,” in _Bijdragen tot de Dierkunde_, Part 1, Amsterdam, 1848-54.
[653] Geoffroy, _Mag. Encyclop._ 2d ann. vol. i. p. 48 (1796).
[654] _Mammalia of British India_, p. 48 (1888).
[655] Bennett, _Proc. Zool. Soc._ 1839, p. 109.
[656] For the anatomy of _P. potto_, see Van der Hoeven and Van Campen
(_Ontleedkundige Onderzoek van den Potto van Bosman_, 1859) for _P.
calabarensis_, Huxley, _Proc. Zool. Soc._ 1864, p. 314.
[657] Storr, _Prodromus Meth. Mamm._ (1780).
[658] H. Burmeister, _Beiträge zur nähreren Kenntniss der gattung
Tarsius_, 1846.
[659] Cuvier, “Table de Class.” in _Leçons d’Anat. Comp._ vol. i. (1800).
[660] It was first named _Daubentonia_ by Geoffroy; but this name
was withdrawn by its author in favour of _Chiromys_, as it had been
previously given to a genus in the vegetable kingdom. This would not,
however, constitute preoccupation according to the modern rules of
nomenclature.
[661] R. Owen, “On the Aye-aye,” in _Trans. Zool. Soc._ 1862, vol. v.
p. 33; W. Peters, “Ueber die Säugethiergattung _Chiromys_,” in _Abhand.
Königl. Akad. der Wissenschaften_, Berlin, 1865, p. 79.
[662] One specimen has been seen with only three lower premolars.
[663] Article Ape, _Encyclopædia Britannica_, ninth edition.
[664] Illiger, _Prodromus Syst. Mamm. et Avium_, p. 71 (1811).
[665] Geoffroy, _Ann. du Muséum_, vol. xix. p. 120 (1812).
[666] Illiger, _Prodromus Syst. Mamm. et Avium_, p. 70 (1811).
[667] Geoffroy, _Ann. du Muséum_, vol. xix. p. 115 (1812).
[668] Gray, _Proc. Zool. Soc._ 1849, p. 9. Amended from _Ouakaria_: Syn.
_Brachyurus_; Spix, _Sim. et Vesp. Brasil_, p. 11 (1823). Preoccupied by
Fischer, 1814.
[669] Geoffroy, _Ann. du Muséum_, vol. xix. p. 112 (1812).
[670] Kaup, _Thierreich_, vol i. p. 51 (1835).
[671] Spix, _Sim. et Vesp. Brasil_, p. 25 (1823).
[672] Geoffroy, _Ann. du Muséum_, vol. vii. p. 260 (1806).
[673] I. Geoffroy, _Dict. Class._ vol. xv. p. 443 (1829).
[674] Geoffrey, _Ann. du Muséum_, vol. xix. p. 106 (1812).
[675] Erxleben, _Syst. Règne Animal_, p. 44 (1777).
[676] Lacépède, “Nouv. tabl. méth.” (1799) in _Mém. de l’Institut_, vol.
iii. p. 490 1801.
[677] “‘Mandrill’ seems to signify a ‘man-like Ape,’ the word ‘Drill’
or ‘Dril’ having been anciently employed in England to denote an Ape or
Baboon. Thus in the fifth edition of Blount’s ‘_Glossographia_, or a
dictionary interpreting the hard words of whatsoever language now used
in our refined English tongue ... very useful for all such as desire
to understand what they read,’ published in 1681, I find ‘Dril, a
stonecutter’s tool wherewith he bores little holes in marble, etc. Also a
large overgrown Ape and Baboon, so called.’ ‘Drill’ is used in the same
sense in Charlton’s _Onomasticon Zoicon_, 1668. The singular etymology of
the word given by Buffon seems hardly a probable one.”—Huxley’s _Man’s
Place in Nature_, p. 10, 1863.
[678] I. Geoffroy, _Arch. du Muséum_, vol. ii. p. 576 (1841).
[679] I. Geoffroy, _Voyage de Belanger_, p. 66 (1834).
[680] Lacépède, _Mém. de l’Institut_, vol. iii. p. 450 (1801). Amended.
[681] Geoffroy, _Ann. du Muséum_, vol. xix. p. 97 (1812).
[682] Erxleben, _Syst. Règne. Animal_, p. 22 (1777).
[683] Or _Colobinæ_.
[684] Geoffroy, _Ann. du Muséum_, vol. xix. p. 90 (1812).
[685] F. Cuvier, _Hist. Nat. des Mammifères_ (1821), “Semno-pithèque.”
[686] Separated generically by some writers as _Rhinopithecus_.
[687] Illiger, _Prodromus Syst. Mamm. et Avium_, p. 69 (1811).
[688] Wagner, _Gelehrte Anzeigen_, vol. viii. No. 38, p. 310 (1839).
[689] Depéret, _Comptes Rendus_, vol. cix. p. 982 (1889); see also _Mém.
Soc. Géol. France_, “Palæontologie,” vol. i. (1890).
[690] Gervais, _Comptes Rendus_, vol. lxxiv. p. 1217 (1872).
[691] Scimmie Fossili Italiane, _Boll. Comm. Geol._ 1890.
[692] Illiger, _Prodromus Syst. Mamm. et Avium_, p. 67 (1811).
[693] Linn. _Syst. Nat._ 12th ed. vol. i. p. 34 (1766).
[694] A Malay word, signifying “Man of the Woods.”
[695] One skeleton in the Museum of the Royal College of Surgeons has
five lumbar vertebræ, and has thus given rise to the statement that the
number of vertebræ in the Orang is the same as in Man.
[696] I. Geoffroy, _Comptes Rendus_, vol. xxxiv. p. 84 (1852).
[697] De Blainville, _Leçons Orales_ (1839). The Chimpanzees have been
very generally described under the name of _Troglodytes_, but since this
name is preoccupied for a genus of birds, it is incumbent to follow the
strict rule, and adopt the name _Anthropopithecus_, although both the
present writers have elsewhere expressed the opposite opinion.
[698] Lartet, _Comptes Rendus_, vol. xliii. p. 219 (1856).
[699] _Mém. Soc. Géol. France_, “Palæontologie,” vol. i. Mém. No. 1
(1890).
[700] _Man’s Place in Nature_, 1863, and _Anatomy of Vertebrated
Animals_, 1871. See also the more recent investigations of Broca into the
comparative structure of Man and the higher Apes, published mostly in the
_Revue d’Anthropologie_.
[701] “On the Classification of the Varieties of the Human Species,” by
W. H. Flower, _Journal of the Anthropological Institute of Great Britain
and Ireland_, May 1885.
[702] The Malay of Blumenbach was a strange conglomeration of the then
little known Australian, Papuan, and true Malay types.
[703] No one can have seen a group of Botocudos from Brazil or of
natives of Tierra del Fuego without being struck by their markedly
Mongolian external characteristics.
INDEX
Aard-Wolf, 540
Aard-Vark, 211
Absorbent system, 63
_Acanthoglossus_, 125
_Acanthomys_, 476
_Aceratherium_, 411
_Achænodon_, 292
_Achyrodon_, 114
_Acrobates_, 155
_Acrotherium_, 440
_Adapis_, 697
_Adapisorex_, 634
_Adapisoricidæ_, 634
_Adapisoriculus_, 634
_Addax_, 345
_Adenota_, 339
_Adinotherium_, 440
_Ælurictis_, 524
_Ælurodon_, 562
_Æluroidea_, 501
_Æluropus_, 560
_Ælurus_, 562
_Æpyceros_, 341
_Æpyprymnus_, 164
_Agabelus_, 260
Agouti, 488
_Agriochœrus_, 293
Ai, 182
Air-sacs, 68
_Alactaga_, 480
Albinism, 10
_Alcelaphus_, 334
_Alces_, 326
Allantois, 77
_Allodon_, 111
_Allops_, 413
Allotheria, 109
Alpaca, 303
_Amblotherium_, 114
Amblypoda, 436
_Amorphochilus_, 666
_Amphictis_, 539
_Amphicyon_, 555
_Amphidozotherium_, 634
_Amphilestes_, 114
_Amphiperatherium_, 135
_Amphisorex_, 628
_Amphitherium_, 114
_Amphitragulus_, 330
_Amynodon_, 412
_Anaptomorphus_, 697
_Anchilophus_, 376
_Anchippodus_, 441
_Anchitherium_, 376
Ancylopoda, 413
_Ancylotherium_, 413
_Anoa_, 361
_Anomaluridæ_, 449
_Anomalurus_, 449
_Anoplotheriidæ_, 293
_Anoplotherium_, 294
Anteater, 191
Scaly, 205
Antebrachium, 47
_Antechinomys_, 139
Antelopes, 334
_Anthops_, 657
_Anthorhina_, 674
_Anthracotheriidæ_, 292
Anthropoidea, 699
_Anthropopithecus_, 736
_Antilocapra_, 333
_Antilocapridæ_, 333
_Antilope_, 340
Antlers, 308
_Antrozous_, 661
_Anurosorex_, 626
Aoudad, 356
Apar, 199
Ape, 699
_Aphelops_, 411
_Aphelotherium_, 697
_Archælurus_, 524
Archæoceti, 246
_Archæomys_, 484
_Archizonurus_, 157
_Arctictis_, 534
_Arctocebus_, 693
_Arctocephalus_, 595
_Arctocyon_, 609
_Arctocyonidæ_, 609
_Arctogale_, 533
Arctoidea, 556
Arctomyinæ, 454
_Arctomys_, 454
_Arctonyx_, 574
_Arctotherium_, 561
Argali, 355
Armadillo, 195
_Artibeus_, 676
Artiodactyla, 275
_Arvicola_, 466
Arvicolinæ, 465
Ass, 383
_Atalapha_, 663
_Ateles_, 715
_Atherura_, 487
_Auchenia_, 298
_Aulacodus_, 483
_Aulaxinuus_, 723
Aurochs, 367
Australasian region, 102
_Avahis_, 686
Axis, 320
Aye-aye, 695
_Babirusa_, 287
Baboon, 719
_Bachitherium_, 307
Badger, 575
American, 576
Sand, 575
_Balæna_, 236
_Balænidæ_, 234
_Balænodon_, 251
Balænoidea, 234
_Balænoptera_, 242
_Balænotus_, 240
Bandicoot, 141
Banteng, 365
_Bassaricyon_, 566
_Bassaris_, 566
Bats, 641
_Bathyergus_, 478
_Bdeogale_, 537
Bear, 558
Beaver, 458
Beisa, 343
Beluga, 262
_Berardius_, 256
_Bettongia_, 163
Bharal, 356
_Bibos_, 360
Bighorn, 355
Binturong, 534
Bison, 362
Black-Fish, 269
Bladder, 69
_Blarina_, 624
_Blastomeryx_, 330
Blaubok, 343
Blessbok, 335
Blood, 63
_Bolodon_, 111
_Boncia_, 653
Bontebok, 334
Bosch-Vark, 286
_Boselaphus_, 345
_Bothriolabis_, 291
Bottlenose, 253, 270
_Bovidæ_, 334
Brachium, 47
_Brachyphylla_, 675
_Brachytarsomys_, 465
_Brachyurus_, 712
_Bradypodidæ_, 179
_Bradypus_, 181
Brain, 69
_Bramatherium_, 333
Brocket, 330
_Brontotherium_, 413
Bruta, 176
_Bubalus_, 361
_Budorcas_, 351
Buffalo, 361
Bush-dog, 553
Cachalot, 249
_Cadurcotherium_, 412
Cæcum, 59
_Cælogenys_, 489
_Cænopithecus_, 696
_Cænotheriidæ_, 294
_Cænotherium_, 294
_Callinycteris_, 655
_Callithrix_, 713
_Callophoca_, 606
_Calomys_, 463
_Caloprymnus_, 164
_Calotragus_, 339
Camel, 296
_Camelidæ_, 295
_Camelus_, 296
_Canidæ_, 544
_Canis_, 546
_Capra_, 352
_Capreolus_, 327
_Capromys_, 482
Capybara, 491
Caracal, 518
_Cardiatherium_, 491
_Cardiomys_, 491
_Cariacus_, 329
Caribou, 324
Carnivora, 496
_Carollia_, 674
_Carponycteris_, 654
Carpus, 48
_Carterodon_, 484
_Castor_, 457
_Castoridæ_, 457
_Castoroididæ_, 488
_Castoroides_, 488
Cat, 517
_Cavia_, 489
_Caviidæ_, 489
Cavy, 490
_Cayluxotherium_, 621
_Cebidæ_, 711
_Cebochœrus_, 292
_Cebus_, 717
Cement, 15
_Centetes_, 637
_Centetidæ_, 637
_Centurio_, 676
_Cephalogale_, 562
_Cephalophus_, 338
_Cephalorhynchus_, 266
_Cephalotes_, 653
_Cercocebus_, 723
_Cercoleptes_, 567
_Cercomys_, 483
_Cercopithecidæ_, 718
_Cercopithecus_, 724
_Cerivoula_, 664
_Cervalces_, 327
_Cervicapra_, 340
_Cervidæ_, 313
_Cervinæ_, 316
_Cervulus_, 316
_Cervus_, 319
_Cetacea_, 225
_Cetotherium_, 245
_Chænohyus_, 291
_Chætomys_, 486
_Chalcochloris_, 639
_Chalicomys_, 458
_Chalicotheriidæ_, 413
_Chalicotherium_, 413
_Chalinolobus_, 662
Chamois, 349
_Champsodelphis_, 259
Cheeta, 523
Chevrotain, 305
Water, 306
_Chilonycteris_, 672
_Chimarrogale_, 626
Chimpanzee, 736
_Chinchilla_, 487
_Chinchillidæ_, 487
_Chirogaleus_, 689
_Chiromeles_, 669
_Chiromyidæ_, 694
_Chiromys_, 695
_Chironectes_, 134
Chiroptera, 641
Chiru, 341
_Chiruromys_, 476
_Chlamydophorinæ_, 196
_Chlamydophorus_, 196
_Chlamydotherium_, 201
_Chœronycteris_, 674
_Chœropotamidæ_, 292
_Chœropotamus_, 292
_Chœropsis_, 280
_Chœropus_, 143
_Cholœpus_, 182
Chorion, 77
_Chrysochloridæ_, 638
_Chrysochloris_, 639
_Chrysothrix_, 714
_Cimoliomys_, 113
Circulation, 63
Civet, 526
Palm, 532
Classification, 84, 88
_Claviglis_, 460
Claws, 12
Coati, 566
_Cobus_, 339
_Cœlodon_, 184
_Cœlops_, 658
_Cogia_, 250
_Coleüra_, 667
_Colobus_, 727
Colour, 8
_Comphotherium_, 621
Condylarthra, 438
_Condylura_, 630
_Conepatus_, 574
_Connochætes_, 336
_Contracavia_, 491
_Coryphodon_, 437
_Coryphodontidæ_, 438
Cotylophora, 307
_Cotylopidæ_, 293
_Cotylops_, 293
Coypu, 482
Cranium, 35
_Crassitherium_, 223
Creodonta, 606
_Cricetodipus_, 479
_Cricetodon_, 464
_Cricetomys_, 477
_Cricetus_, 463
_Criotherium_, 349
_Crocidura_, 626
_Crossarchus_, 537
_Crossopus_, 625
Crusta Petrosa, 15
_Cryptophractus_, 201
_Cryptopithecus_, 699
_Cryptoprocta_, 525
_Ctenacodon_, 112
_Ctenodactylus_, 481
_Ctenomys_, 482
_Cuniculus_, 470
_Cuscus_, 149
_Cyclopidius_, 293
_Cycloturus_, 193
_Cynælurus_, 523
_Cynictis_, 537
_Cynocephalus_, 719
_Cynodictis_, 555
_Cynogale_, 534
_Cynohyænodon_, 608
Cynoidea, 544
_Cynomys_, 455
_Cynonycteris_, 652
_Cynopithecus_, 722
_Cynopterus_, 653
_Cyon_, 551
_Cystophora_, 605
_Dacrytherium_, 294
_Dactylomys_, 483
_Dactylopsila_, 152
_Damalis_, 351
_Daphœnus_, 555
_Dasymys_, 462
_Dasypodidæ_, 194
_Dasypodinæ_, 197
_Dasypotherium_, 201
_Dasyprocta_, 488
_Dasyproctidæ_, 488
_Dasypus_, 197
_Dasyuridæ_, 136
_Dasyurus_, 138
_Daubentonia_, 695
Deer, 317, 319
_Delphinapterus_, 262
_Delphinidæ_, 260
Delphinoidea, 247
_Delphinus_, 271
_Dendrohyrax_, 418
_Dendrolagus_, 165
_Dendromys_, 463
Dental system, 13
Dentine, 14
_Deomys_, 473
Dermoptera, 614
Desman, 629
_Desmodus_, 677
_Desmotylus_, 223
Diaphragm, 67
_Diceratherium_, 411
_Dichobunus_, 294
_Dichodon_, 294
_Dichodontidæ_, 294
_Diclidurus_, 668
_Dicolpomys_, 484
_Dicotyles_, 289
_Dicotylidæ_, 289
Didelphia, 128
_Didelphyidæ_, 133
_Didelphys_, 134
_Didymictis_, 539
Digestive system, 53
_Dinictis_, 523
_Dinoceras_, 437
_Dinocyon_, 556
_Dinomyidæ_, 489
_Dinomys_, 489
_Dinotheriidæ_, 435
_Dinotherium_, 435
_Dinoziphius_, 251
_Diobroticus_, 458
_Dioplotherium_, 223
_Diphylla_, 678
Diphyodont, 20
Diplarthra, 275
_Diplomesodon_, 626
_Dipodidæ_, 479
_Dipodomys_, 479
_Dipodops_, 479
_Diprotodon_, 171
Diprotodontia, 144
_Diprotodontidæ_, 171
_Dipus_, 480
_Distœchurus_, 155
_Dœdicurus_, 203
Dog, 551
_Dolichophyllum_, 673
_Dolichopithecus_, 728
_Dolichotis_, 490
Dolphin, 270
_Dorcatherium_, 306
_Dorcopsis_, 166
Dormouse, 459
Douroucouli, 714
_Dremotherium_, 330
_Dromatherium_, 113
_Dromicia_, 154
_Dryolestes_, 114
_Dryopithecus_, 738
Duck-bill, 120
Ductless glands, 65
Dugong, 221
Duikerbok, 338
Duplicidentata, 491
_Echidna_, 125
_Echidnidæ_, 124
_Echinogale_, 634
_Echinomys_, 483
_Echinothrix_, 477
Edentata, 176
Effodientia, 178
Eland, 348
_Elaphodus_, 318
_Elasmognathus_, 371
_Elasmotherium_, 411
_Eleotragus_, 340
Elephant, 424
_Elephantidæ_, 423
_Elephas_, 424
_Eleutherocercus_, 203
_Eliomys_, 459
_Eliurus_, 465
Elk, 326
_Ellobius_, 472
_Elotherium_, 292
_Emballonura_, 667
_Emballonuridæ_, 666
Enamel, 15
_Enhydra_, 570
_Enhydriodon_, 570
_Enhydrocyon_, 562
Entomophaga, 178
_Eohippus_, 374
_Eomys_, 464
_Eonycteris_, 654
_Eotherium_, 224
_Epiblema_, 488
Epiglottis, 67
_Epihippus_, 374
_Epomophorus_, 650
_Eporeodon_, 293
_Equidæ_, 376
_Equus_, 381
_Erethizon_, 484
_Ericulus_, 638
_Erinaceidæ_, 619
_Erinaceus_, 620
_Eriodes_, 715
Ermine, 590
_Eschatius_, 303
Ethiopian region, 98
_Eucastor_, 458
_Eucetus_, 251
_Eupetaurus_, 454
_Eupleres_, 538
_Euryceros_, 346
_Euryurus_, 203
_Eusmilus_, 524
_Eutatus_, 201
Eutheria, 173
_Evotomys_, 467
Eye, 72
Fallow Deer, 323
_Felidæ_, 502
_Felis_, 502
_Felsinotherium_, 223
Fennec, 553
_Fennecus_, 553
_Feresia_, 270
_Fiber_, 470
Flying Fox, 651
Lemur, 615
Squirrel, 453
Foot, 52
_Fossa_, 527
Foussa, 525
Fox, 552
Fox-Bat, 651
_Furia_, 666
_Furipterus_, 666
_Galago_, 690
_Galeopithecidæ_, 614
_Galeopithecus_, 614
_Galera_, 579
_Galictis_, 579
_Galidea_, 538
_Galidictis_, 538
Gaur, 365
Gayal, 365
_Gazella_, 341
_Gelocus_, 294
Gemsbok, 343
Genet, 528
_Genetta_, 528
_Geogale_, 635
Geographical distribution, 93
Geological distribution, 107
_Geomyidæ_, 478
_Geomys_, 478
_Georychus_, 478
Gerbillinæ, 462
_Gerbillus_, 462
Gibbon, 728
_Giraffa_, 331
_Giraffidæ_, 330
Glands, 12
_Glauconycteris_, 662
_Globicephalus_, 268
_Glossonycteris_, 674
Glossophaga, 674
Glutton, 591
_Glyptodon_, 203
_Glyptodontidæ_, 202
Gnu, 336
_Golunda_, 476
Goat, 352
Gopher, 478
Goral, 351
_Gorilla_, 734
Grampus, 267
_Grampus_, 270
_Graphiurus_, 459
Greenland Whale, 236
_Grimmia_, 338
_Grisonia_, 579
Ground Sloth, 184
_Gryphoca_, 606
_Grypotherium_, 189
Guanaco, 301
Guib, 347
Guinea-Pig, 490
_Gulo_, 591
_Gymnobelideus_, 154
_Gymnoptychus_, 454
_Gymnura_, 619
_Habrocoma_, 482
_Habrothrix_, 464
Hair, 7
_Halichœrus_, 601
_Halicore_, 220
_Halicoridæ_, 220
_Halitheriidæ_, 222
_Halitherium_, 222
_Hallomys_, 465
Hamster, 463
_Hapale_, 710
_Hapalemur_, 689
_Hapalidæ_, 709
_Hapalotis_, 476
_Haploceros_, 351
_Haplodon_, 457
_Haplodontidæ_, 457
Hare, 492
_Harpyia_, 653
_Harpyiocephalus_, 663
Harte-beest, 335
Hearing, 73
Heart, 63
Hedgehog, 620
_Helicophora_, 340
_Helictis_, 578
_Heliophobius_, 478
_Helladotherium_, 333
_Helogale_, 537
_Hemiauchenia_, 303
_Hemicentetes_, 637
_Hemiderma_, 674
_Hemigale_, 533
_Hemigalidea_, 538
_Hemitragus_, 354
_Herpestes_, 535
_Herpetocetus_, 245
_Herpetotherium_, 135
_Heterocephalus_, 478
_Heterocetus_, 245
Heterodont, 23
_Heterohyrax_, 418
_Heteromys_, 479
_Hipparion_, 380
_Hippodactylus_, 381
_Hippohyus_, 291
_Hippopotamidæ_, 278
_Hippopotamus_, 278
_Hipposiderus_, 657
_Hippotigris_, 384
_Hippotragus_, 343
_Holochilus_, 464
_Holomeniscus_, 303
_Homalodontotherium_, 412, 414
_Hominidæ_, 740
_Homo_, 739
Homodont, 22
Hoofs, 12
Hoolock, 729
_Hoplocetus_, 251
_Hoplophoneus_, 524
_Hoplophorus_, 202
Horns, 310
Horse, 382
Hunting dog, 553
_Hyæna_, 540
_Hyænarctus_, 561
_Hyænidæ_, 540
_Hyænocyon_, 562
_Hyænodon_, 608
_Hyænodontidæ_, 608
_Hydaspitherium_, 333
_Hydrochœrus_, 490
Hydromyinæ, 461
_Hydromys_, 461
_Hydropotes_, 328
_Hylobates_, 728
_Hylomys_, 619
Hyoid, 39
_Hyomoschus_, 306
_Hyopotamus_, 292
_Hyopsodus_, 698
_Hyotherium_, 291
_Hypertragulus_, 307
_Hypogeomys_, 465
_Hypsiprymnodon_, 162
_Hypsiprymnodontinæ_, 162
_Hypsiprymnopsis_, 111
_Hypsiprymnus_, 163
_Hyrachyus_, 373
_Hyracidæ_, 415
_Hyracodon_, 412
_Hyracodontotherium_, 439
Hyracoidea, 415
_Hyracotherium_, 373
_Hyrax_, 417
_Hystricidæ_, 484
Hystricomorpha, 480
_Hystrix_, 486
Ibex, 353
Ichneumon, 535
_Icticyon_, 553
_Ictitherium_, 539
_Ictonyx_, 579
_Ictops_, 640
_Indris_, 684
_Indrodon_, 699
_Inia_, 259
Insectivora, 610
Intestine, 59
_Inuus_, 723
_Ischnoglossa_, 674
_Isectolophus_, 374
_Issiodoromys_, 491
Ivory, 14
_Ixacanthus_, 259
Jackal, 550
Jaguar, 521
Jerboa, 480
Kangaroo, 159
_Kerivoula_ = _Cerivoula_
Kidney, 69
Killer, 267
Kinkajou, 567
Koala, 156
_Koalemus_, 157
_Kobus_ = _Cobus_
_Kogia_ = _Cogia_
Kudu, 348
Kusimanse, 538
_Lagenorhynchus_, 270
_Lagidium_, 488
_Lagomyidæ_, 491
_Lagomys_, 491
_Lagorchestes_, 166
_Lagostomus_, 488
_Lagostrophus_, 165
_Lagothrix_, 716
_Lambdotheriidæ_, 413
_Lambdotherium_, 413
Langur, 727
_Lantanotherium_, 618
Larynx, 67
_Lasionycteris_, 661
_Latax_, 570
Leg, 51
Lemming, 467
_Lemur_, 687
_Lemuridæ_, 683
Lemuroidea, 682
Leopard, 514
_Lepidolemur_, 689
_Leporidæ_, 492
_Leptictidæ_, 640
_Leptictis_, 640
_Leptobos_, 367
_Leptomeryx_, 307
_Leptonycteris_, 674
_Leptonyx_, 605
_Leptotragulus_, 304
_Lepus_, 492
_Lestodon_, 189
_Leucocyon_, 553
_Limnosyops_, 413
Linsang, 530
Lion, 504
_Liotomus_, 113
_Listriodon_, 291
Liver, 60
Llama, 299, 302
_Lobodon_, 605
_Loncheres_, 483
_Lonchoglossa_, 674
_Lonchorhina_, 673
_Lophiodon_, 373
_Lophiodontidæ_, 373
_Lophiomeryx_, 294
_Lophiomyidæ_, 460
_Lophiomys_, 460
_Lophiotherium_, 374
_Lophocetus_, 259
_Lophostoma_, 673
Loricata, 179
_Loris_, 692
_Loxolophodon_, 437
Lungs, 68
_Lutra_, 567
_Lycalopex_, 552
_Lycaon_, 553
Lymphatics, 65
_Lyncodon_, 590
Lynx, 518
_Macacus_, 722
_Machærodus_, 524
_Macrauchenia_, 414
_Macraucheniidæ_, 414
_Macroglossus_, 654
_Macrophyllum_, 673
_Macropodidæ_, 158
_Macropodinæ_, 164
_Macropus_, 167
_Macrorhinus_, 606
_Macroscelides_, 618
_Macroscelididæ_, 618
_Macrotherium_, 413
_Macrotus_, 673
_Malacomys_, 462
Mammary glands, 75
Mammoth, 428
Man, 739
Manatee, 215
_Manatidæ_, 215
_Manatus_, 215
Mandrill, 719
_Manidæ_, 204
_Manis_, 204
Manus, 48
Maral, 322
Markhoor, 354
Marmoset, 709
Marmot, 454
Prairie, 456
Marsupialia, 128
Marten, 580
_Martes_, 580
_Mastacomys_, 476
_Mastodon_, 431
Megachiroptera, 650
_Megaderma_, 658
_Megaloglossus_, 655
_Megamys_, 488
_Megaptera_, 241
_Megatheriidæ_, 183
_Megatherium_, 185
Melanism, 9
_Meles_, 575
_Mellivora_, 576
_Melonycteris_, 654
_Melursus_, 560
_Menacodon_, 115
_Meniscoëssus_, 113
_Meniscomys_, 454
_Meniscotherium_, 439
_Menodus_, 413
_Mephitis_, 572
_Merychippus_, 380
_Merycochœrus_, 293
_Mesodectes_, 640
_Mesohippus_, 376
_Mesomys_, 483
_Mesonychidæ_, 609
_Mesonyx_, 609
_Mesopithecus_, 727
_Mesoplodon_, 254
_Mesotaria_, 606
_Mesotherium_, 440
Mesozoic mammals, 108
Metacarpus, 49
_Metamynodon_, 412
Metatheria, 128
_Metriotherium_, 294
_Miacidæ_, 539
_Miacis_, 539
_Microcavia_, 491
_Microcebus_, 690
_Microchœrus_, 696
_Microchiroptera_, 655
Microconodon, 113
_Microgale_, 638
_Microlestes_, 111
_Micromeryx_, 330
_Micronycteris_, 673
_Microsorex_, 624
_Microsyops_, 698
_Microtus_, 466
_Midas_, 710
Milk-teeth, 20
_Mimon_, 674
_Miniopterus_, 664
Mink, 586
_Miohippus_, 376
_Miosiren_, 223
_Mixodectes_, 699
Mole, 630
Golden, 639
Star-nosed, 630
Mole-Rat, 477
_Molossus_, 670
_Monachus_, 604
_Monatherium_, 606
Monkey, 699
Monodelphia, 173
_Monodon_, 260
_Monophylla_, 674
Monophyodont, 20
Moose, 326
_Morenia_, 484
_Mormops_, 672
_Moropus_, 413
_Morotherium_, 413
Morse, 597
_Moschinæ_, 314
_Moschus_, 314
Moufflon, 356
Mouse, 475
Mouth, 54
Mulita, 201
Multituberculata, 109
Mungoose, 535
Muntjac, 316
_Muridæ_, 461
_Mus_, 473
_Muscardinus_, 460
Musk Deer, 314
Ox, 358
Rat, 470, 626
Musquash, 470
_Mustela_, 579
_Mustelidæ_, 567
_Mycetes_, 711
_Mydaus_, 575
_Mylodon_, 189
_Myodes_, 467
_Myogale_, 628
_Myolagus_, 492
Myomorpha, 459
_Myopotamus_, 482
_Myoscalops_, 478
_Myosorex_, 625
_Myoxidæ_, 459
_Myoxus_, 459
_Myrmecobiinæ_, 140
_Myrmecobius_, 140
_Myrmecophaga_, 190
_Myrmecophagidæ_, 190
_Mysarachne_, 634
_Mystacina_, 671
Mystacoceti, 234
_Mystacops_, 671
_Mystromys_, 462
_Myxocebus_, 689
_Myxopoda_, 665
Nails, 12
Nakong, 346
_Nandinia_, 534
_Nanotragus_, 339
Nares, 66
Narwhal, 261
_Nasalis_, 725
_Nasua_, 566
_Natalus_, 664
Nearctic region, 102
_Necrogymnurus_, 621
_Necrolemur_, 696
_Necromantis_, 679
_Nectogale_, 627
_Nectomys_, 464
_Nemorhædus_, 350
_Neobalæna_, 241
_Neofiber_, 472
_Neomeris_, 266
_Neoplagiaulax_, 113
_Neosorex_, 624
_Neotoma_, 464
_Neotragus_, 338
Neotropical region, 103
Nerves, 71
_Nesocerodon_, 491
_Nesocia_, 475
_Nesodon_, 439
_Nesomys_, 465
_Nesonycteris_, 655
_Nesotragus_, 339
_Neurotrichus_, 629
Nilghai, 345
_Nimravus_, 524
_Noctilio_, 668
Nostrils, 66
_Notharctus_, 698
_Nothropus_, 183
_Nothrotherium_, 184
_Notiosorex_, 624
_Notopteris_, 654
_Nototheriidæ_, 172
_Nototherium_, 171
_Nyctereutes_, 552
_Nycteridæ_, 658
_Nycteris_, 659
_Nycticebus_, 691
_Nycticejus_, 662
_Nyctilestes_, 665
_Nyctinomus_, 670
_Nyctipithecus_, 714
_Nyctitherium_, 665
_Nyctophilus_, 661
Ocelot, 521
_Ochetodon_, 464
_Octodon_, 481
_Octodontidæ_, 480
_Odobænus_, 597
Odontoceti, 247
_Ogmorhinus_, 605
_Ommatophoca_, 605
_Onotragus_, 339
_Onychogale_, 166
_Onychomys_, 463
Opossum, 133
Orang, 731
_Orca_, 267
_Orcella_, 267
_Oreas_, 348
_Oreodon_, 293
_Oreopithecus_, 728
_Oreotragus_, 339
Oriental region, 100
Ornithodelphia, 117
_Ornithorhynchidæ_, 119
_Ornithorhynchus_, 119
_Orohippus_, 374
_Orotherium_, 374
_Orthaspidotherium_, 634
_Orthomys_, 484
_Orycteropodidæ_, 208
_Orycteropus_, 208
_Oryx_, 343
_Oryzomys_, 463
_Oryzorictes_, 638
_Otaria_, 593
_Otariidæ_, 593
_Otocyon_, 554
_Otomys_, 462
_Otonycteris_, 661
_Otopterus_, 673
Otter, 568
Sea, 571
Ounce, 517
Ovaries, 75
_Ovibos_, 357
Oviduct, 75
_Ovis_, 354
Oxen, 360
_Oxhyæna_, 608
_Oxymycterus_, 464
Paca, 489
_Pachyacanthus_, 224
Pachydermata, 87
_Pachynolophus_, 374
_Pachyuromys_, 462
_Paciculus_, 465
Palæarctic region, 97
_Palæocastor_, 458
_Palæocetus_, 245
_Palæoerinaceus_, 621
_Palæolemur_, 697
_Palæomanis_, 208
_Palæomeryx_, 330
_Palæonycteris_, 657
_Palæophoca_, 606
_Palæopontoporia_, 259
_Palæoprionodon_, 539
_Palæoreas_, 348
_Palæoryx_, 344
_Palæospalax_, 629
_Palæosyops_, 413
_Palæotapirus_, 373
_Palæotheriidæ_, 375
_Palæotherium_, 375
_Palæotragoceros_, 349
_Palauchenia_, 303
_Palhyæna_, 544
Palla, 341
Palm-Civet, 532
_Paloplotherium_, 375
_Palorchestes_, 170
Panda, 562
Pangolin, 205
_Panochthus_, 203
Panther, 514
_Pantholops_, 341
_Paradoxurus_, 532
_Paramys_, 457
_Parasorex_, 618
Peccary, 289
Pecora, 307
_Pectinator_, 481
_Pedetes_, 480
_Pediotragus_, 339
_Pelea_, 339
_Pellegrinia_, 484
Pelvis, 50
_Pelycodus_, 699
_Peragale_, 143
_Peralestes_, 115
_Peramelidæ_, 141
_Perameles_, 142
_Peratherium_, 135
_Periptychus_, 439
Perissodactyla, 368
_Perodicticus_, 693
_Perognathus_, 479
Pes, 52
_Petauroides_, 152
_Petaurus_, 153
_Petrodromus_, 618
_Petrogale_, 167
_Petromys_, 482
_Phacochœrus_, 288
_Phalanger_, 149
_Phalangeridæ_, 147
_Phalangerinæ_, 149
Phalanges, 49
_Phalangista_, 149
_Phascolarctinæ_, 155
_Phascolarctus_, 156
_Phascologale_, 139
_Phascolomyidæ_, 144
_Phascolomys_, 145
_Phascolonus_, 146
_Phascolotherium_, 114
_Phenacodus_, 439
_Phenacomys_, 466
Phlœomyinæ, 462
_Phlœomys_, 462
_Phloramys_, 484
_Phoca_, 601
_Phocæna_, 263
_Phocanella_, 606
_Phocidæ_, 600
_Phylloderma_, 674
_Phyllonycteris_, 674
Phyllophaga, 178
_Phyllorhina_, 657
_Phyllostoma_, 674
_Phyllostomatidæ_, 672
_Physeter_, 248
_Physeteridæ_, 247
_Physeterinæ_, 248
_Physeterula_, 251
_Physetodon_, 251
_Physodon_, 251
Pica, 492
Pichiciago, 196
Pig, 282
Pilosa, 179
Pinnipedia, 592
_Pithanotomys_, 484
_Pithechirus_, 477
_Pithecia_, 712
Placenta, 75
_Plagiaulacidæ_, 113
_Plagiaulax_, 111
_Plagiodon_, 483
_Platacanthomyinæ_, 461
_Platacanthomys_, 462
_Platanista_, 258
_Platanistidæ_, 257
_Platycercomys_, 480
_Platygonus_, 291
_Platyonyx_, 188
_Platyphoca_, 606
_Platypus_, 120
_Plecotus_, 660
_Plesiadapis_, 698
_Plesiarctomys_, 457
_Plesictis_, 590
_Plesiocetus_, 245
Plesiometacarpalia, 316
_Plesiosorex_, 634
_Plesispermophilus_, 457
_Pleuraspidotherium_, 634
_Pleurolichus_, 479
_Plexochœrus_, 491
_Pliauchenia_, 304
_Pliolagostomus_, 488
_Pliolophus_, 374
_Pliopithecus_, 731
_Poëbrotherium_, 304
_Pœcilogale_, 590
_Pœcilophoca_, 605
_Poëphagus_, 360
_Pogonodon_, 524
_Poiana_, 531
Polecat, 587
_Polymastodon_, 113
Polyprotodontia, 133
_Pontistes_, 259
_Pontoporia_, 259
Porcupine, 486
Tree, 485
Porpoise, 263
_Potamarchus_, 488
_Potamochœrus_, 286
_Potamogale_, 635
_Potamogalidæ_, 634
_Potamophilus_, 534
_Potamotherium_, 570
_Potoroinæ_, 162
Potoroo, 163
_Potorous_, 163
Pouched-Rat, 478
_Praopus_, 201
Prehallux, 49
Prepollex, 49
Primates, 680
_Priodon_, 198
_Prionodon_, 530
_Priscodelphinus_, 259
_Proælurus_, 523
Proboscidea, 418
_Probubalus_, 361
_Procamelus_, 304
_Procapra_, 341
_Procavia_, 417
_Procoptodon_, 170
_Procyon_, 564
_Procyonidæ_, 562
_Prodelphinus_, 271
_Prodremotherium_, 307
_Proechidna_, 126
_Prohalicore_, 223
_Prohyæna_, 562
_Prolagostomus_, 488
_Promegatherium_, 189
_Promylodon_, 190
Prong-buck, 333
_Prophoca_, 606
_Propithecus_, 684
_Prorastomatidæ_, 224
_Prorastomus_, 224
_Protechinomys_, 484
_Proteleidæ_, 539
_Proteles_, 539
_Proterotheriidæ_, 414
_Proterotherium_, 414
_Protoadapis_, 698
_Protohippus_, 380
_Protolabis_, 304
_Protoreodon_, 293
Prototheria, 117
_Protoxodon_, 440
_Protragelaphus_, 349
_Protragoceros_, 349
_Proviverra_, 608
_Proviverridæ_, 608
_Prox_, 317
_Pseudælurus_, 523
_Pseudalopex_, 552
_Pseudochirus_, 151
_Pseudois_, 355
_Pseudorca_, 268
_Pseudorhinolophus_, 657
_Pseudosciurus_, 454
_Psittacotherium_, 442
_Pteralopex_, 654
_Pterodon_, 608
_Pteromys_, 453
_Pteropodidæ_, 650
_Pteropus_, 651
_Ptilocercus_, 618
_Ptilodus_, 113
_Pudua_, 330
Puma, 520
_Putorius_, 585
Quagga, 384
Rabbit, 494
Bandicoot, 143
Raccoon, 565
_Rangifer_, 324
Rasse, 527
Rat, 474
Ratel, 576
Rat-Kangaroo, 163
Red Deer, 322
Rehbok, 339
Reitbok, 349
Reproductive organs, 74
Respiratory system, 63
_Rhabdosteus_, 259
_Rhachianectes_, 241
_Rhinoceros_, 402
_Rhinocerotidæ_, 402
_Rhinogale_, 537
_Rhinolophidæ_, 656
_Rhinolophus_, 656
_Rhinonycteris_, 658
_Rhinophylla_, 674
_Rhinopithecus_, 726
_Rhinopoma_, 669
_Rhipidomys_, 463
_Rhithrodon_, 464
_Rhithrosciurus_, 452
_Rhizomys_, 477
_Rhizoprion_, 257
_Rhogeëssa_, 661
_Rhynchocyon_, 618
_Rhynchonycteris_, 667
_Rhytina_, 221
_Rhytinidæ_, 221
Ribs, 44
River-Hog, 286
Rock-Wallaby, 167
Rodentia, 443
Roe, 327
Rorqual, 242
_Rosmarus_, 597
Ruminants, 307
_Rupicapra_, 349
_Rytiodus_, 223
Sable, 584
_Saccomys_, 479
_Saccopteryx_, 667
_Saccostomus_, 477
Sacrum, 43
_Saiga_, 341
Saki, 712
Salivary glands, 55
Sambur, 320
_Samotherium_, 333
Sapajou, 717
_Sarcophilus_, 137
_Scaldicetus_, 251
Scales, 11
_Scalops_, 630
_Scapanus_, 630
_Scapteromys_, 464
_Scaptochirus_, 633
_Scaptonyx_, 630
_Scelidotherium_, 188
_Schizodelphis_, 259
_Schizodon_, 482
_Schizostoma_, 673
_Sciuravus_, 457
_Sciuridæ_, 450
_Sciurodon_, 454
_Sciuroides_, 454
Sciuromorpha, 448
_Sciuropterus_, 453
_Sciurus_, 450
_Scopophorus_, 339
_Scotophilus_, 662
_Scotozous_, 661
Sea-Leopard, 605
Sea-otter, 571
Seal, 600
Eared, 594
_Selenacodon_, 113
_Semnopithecus_, 726
Sense organs, 69
Serow, 351
Sheep, 354
Shoulder-girdle, 46
Shrew, 622
Tree, 617
Water, 625
Siamang, 728
_Siamanga_, 728
Sight, 72
_Sigmodon_, 464
_Simia_, 731
_Simiidæ_, 728
_Simocyon_, 562
Simplicidentata, 448
_Siphneus_, 472
Sirenia, 212
_Sivatherium_, 322
Skeleton, 33
Skull, 34
Skunk, 572
Sloth, 180
Sloth, Ground, 184
Smell, 72
_Sminthopsis_, 139
_Sminthus_, 479
_Solenodon_, 636
_Solenodontidæ_, 635
_Sorex_, 622
_Soricidæ_, 621
_Soriculus_, 624
_Sotalia_, 272
Souslik, 456
_Spalacidæ_, 477
_Spalacopus_, 482
_Spalacotherium_, 115
_Spalax_, 477
_Spaniotherium_, 294
_Spermophilus_, 456
Sperm Whale, 249
Spider Monkey, 715
_Spilogale_, 574
Spiny Anteater, 124
Spleen, 65
_Squalodon_, 257
_Squalodontidæ_, 257
Squamata, 179
Squirrel, 451
_Stegodon_, 427
_Steneofiber_, 458
_Steno_, 271
_Stenoderma_, 676
_Stenoplesictis_, 539
_Stenops_, 691
_Stenorhynchus_, 605
_Stereognathus_, 110
Sternum, 44
_Sthenurus_, 170
Stoat, 590
Stomach, 57
_Strepsiceros_, 347
_Sturnira_, 676
_Stylacodon_, 114
_Stylinodon_, 442
_Styloceros_, 317
_Stylodon_, 114
_Stypolophus_, 608
Subungulata, 414
_Suidæ_, 281
Suina, 278
_Suricata_, 538
_Sus_, 281
_Syllophodus_, 484
_Symborodon_, 413
_Synaptomys_, 467
_Synetheres_, 485
_Synotus_, 661
_Systemodon_, 374
Takin, 351
_Talpa_, 630
_Talpidæ_, 628
_Tamandua_, 192
_Tamias_, 452
_Taphozous_, 667
Tapir, 371
_Tapiridæ_, 370
_Tapirulus_, 294
_Tapirus_, 370
Tardigrada, 178
_Tarsiidæ_, 694
_Tarsipedinæ_, 148
_Tarsipes_, 148
_Tarsius_, 694
Taste, 72
Tatouay, 198
_Tatusia_, 200
_Tatusiinæ_, 200
_Taxidea_, 576
Tayra, 579
Teetee, 713
Teeth, 13
Tegument, 7
Teledu, 575
Telemetacarpalia, 323
_Temnocyon_, 555
Tenrec, 637
_Terphone_, 338
Tertiary mammals, 115
_Tetraceros_, 338
_Tetraconodon_, 292
_Tetracus_, 634
_Tetrastylus_, 488
_Theridomyidæ_, 484
_Theridomys_, 484
_Theropithecus_, 722
Thigh, 51
_Thomomys_, 478
_Thoracophorus_, 203
Thylacine, 137
_Thylacinus_, 136
_Thylacoleo_, 157
Thymus gland, 66
Thyroid body, 66
_Thyroptera_, 665
Tiger, 511
Tillodontia, 441
_Tillotherium_, 441
_Tinoceras_, 437
_Titanomys_, 492
_Titanotheriidæ_, 413
_Titanotherium_, 413
_Tolypeutes_, 199
_Tomitherium_, 698
_Toxodon_, 439
Toxodontia, 439
Touch, 72
Trachea, 67
_Trachyops_, 674
_Trachytherium_, 224
_Tragelaphus_, 346
_Tragoceros_, 349
_Tragops_, 341
_Tragulidæ_, 305
Tragulina, 305
_Tragulus_, 305
_Trechomys_, 484
_Triacanthodon_, 113
_Triænops_, 658
_Trichechidæ_, 596
_Trichechus_, 597
_Trichosurus_, 150
_Trichys_, 487
_Triclis_, 162
_Triconodon_, 113
_Trilodon_, 484
Trituberculism, 30
_Tritylodon_, 111
_Trochictis_, 570
_Troglodytes_, 736
_Trogontherium_, 458
_Trygenycteris_, 655
Tubulidentata, 179
_Tupaia_, 617
_Tupaiidæ_, 617
_Tursiops_, 271
Tylopoda, 295
_Tylostoma_, 674
_Typhlomys_, 477
_Typotherium_, 440
_Uacaria_, 712
Uakari, 712
_Uintatheriidæ_, 437
_Uintatherium_, 436
Umbilical vesicle, 77
Unau, 183
Ungulata, 273
Urinary organs, 69
_Urocyon_, 553
_Uromys_, 476
_Uropsilus_, 629
_Urotrichus_, 629
_Ursidæ_, 557
_Ursus_, 557
Urus, 367
Uses of mammals, 4
Uterus, 75
Vampyre, 676
_Vampyrus_, 673
Vertebræ, 39
_Vesperimus_, 463
_Vespertiliavus_, 666
_Vespertilio_, 663
_Vespertilionidæ_, 660
_Vesperugo_, 661
Vicugna, 300
Viscacha, 488
_Vishnutherium_, 332
_Viverra_, 526
_Viverricula_, 527
_Viverridæ_, 525
Vole, 465
_Vulpes_, 552
Vulpine Phalanger, 150
Wallaby, 169
Walrus, 597
Wapiti, 322
Wart-Hog, 288
Weasel, 589
Whale, 225
White Whale, 262
Wolf, 548
Wolverene, 591
Wombat, 145
_Xantharpyia_, 652
_Xenurus_, 198
_Xeromys_, 461
_Xerus_, 452
_Xiphodon_, 294
Yak, 364
Yapock, 134
Yolk-sac, 77
_Zapus_, 480
Zebra, 385
_Zeuglodon_, 246
_Zeuglodontidæ_, 246
_Ziphiinæ_, 251
_Ziphius_, 254
Zoological regions, 96
THE END
_Printed by R. & R. CLARK, Edinburgh_
*** END OF THE PROJECT GUTENBERG EBOOK AN INTRODUCTION TO THE STUDY OF MAMMALS LIVING AND EXTINCT ***
Updated editions will replace the previous one—the old editions will
be renamed.
Creating the works from print editions not protected by U.S. copyright
law means that no one owns a United States copyright in these works,
so the Foundation (and you!) can copy and distribute it in the United
States without permission and without paying copyright
royalties. Special rules, set forth in the General Terms of Use part
of this license, apply to copying and distributing Project
Gutenberg™ electronic works to protect the PROJECT GUTENBERG™
concept and trademark. Project Gutenberg is a registered trademark,
and may not be used if you charge for an eBook, except by following
the terms of the trademark license, including paying royalties for use
of the Project Gutenberg trademark. If you do not charge anything for
copies of this eBook, complying with the trademark license is very
easy. You may use this eBook for nearly any purpose such as creation
of derivative works, reports, performances and research. Project
Gutenberg eBooks may be modified and printed and given away—you may
do practically ANYTHING in the United States with eBooks not protected
by U.S. copyright law. Redistribution is subject to the trademark
license, especially commercial redistribution.
START: FULL LICENSE
THE FULL PROJECT GUTENBERG LICENSE
PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK
To protect the Project Gutenberg™ mission of promoting the free
distribution of electronic works, by using or distributing this work
(or any other work associated in any way with the phrase “Project
Gutenberg”), you agree to comply with all the terms of the Full
Project Gutenberg™ License available with this file or online at
www.gutenberg.org/license.
Section 1. General Terms of Use and Redistributing Project Gutenberg™
electronic works
1.A. By reading or using any part of this Project Gutenberg™
electronic work, you indicate that you have read, understand, agree to
and accept all the terms of this license and intellectual property
(trademark/copyright) agreement. If you do not agree to abide by all
the terms of this agreement, you must cease using and return or
destroy all copies of Project Gutenberg™ electronic works in your
possession. If you paid a fee for obtaining a copy of or access to a
Project Gutenberg™ electronic work and you do not agree to be bound
by the terms of this agreement, you may obtain a refund from the person
or entity to whom you paid the fee as set forth in paragraph 1.E.8.
1.B. “Project Gutenberg” is a registered trademark. It may only be
used on or associated in any way with an electronic work by people who
agree to be bound by the terms of this agreement. There are a few
things that you can do with most Project Gutenberg™ electronic works
even without complying with the full terms of this agreement. See
paragraph 1.C below. There are a lot of things you can do with Project
Gutenberg™ electronic works if you follow the terms of this
agreement and help preserve free future access to Project Gutenberg™
electronic works. See paragraph 1.E below.
1.C. The Project Gutenberg Literary Archive Foundation (“the
Foundation” or PGLAF), owns a compilation copyright in the collection
of Project Gutenberg™ electronic works. Nearly all the individual
works in the collection are in the public domain in the United
States. If an individual work is unprotected by copyright law in the
United States and you are located in the United States, we do not
claim a right to prevent you from copying, distributing, performing,
displaying or creating derivative works based on the work as long as
all references to Project Gutenberg are removed. Of course, we hope
that you will support the Project Gutenberg™ mission of promoting
free access to electronic works by freely sharing Project Gutenberg™
works in compliance with the terms of this agreement for keeping the
Project Gutenberg™ name associated with the work. You can easily
comply with the terms of this agreement by keeping this work in the
same format with its attached full Project Gutenberg™ License when
you share it without charge with others.
1.D. The copyright laws of the place where you are located also govern
what you can do with this work. Copyright laws in most countries are
in a constant state of change. If you are outside the United States,
check the laws of your country in addition to the terms of this
agreement before downloading, copying, displaying, performing,
distributing or creating derivative works based on this work or any
other Project Gutenberg™ work. The Foundation makes no
representations concerning the copyright status of any work in any
country other than the United States.
1.E. Unless you have removed all references to Project Gutenberg:
1.E.1. The following sentence, with active links to, or other
immediate access to, the full Project Gutenberg™ License must appear
prominently whenever any copy of a Project Gutenberg™ work (any work
on which the phrase “Project Gutenberg” appears, or with which the
phrase “Project Gutenberg” is associated) is accessed, displayed,
performed, viewed, copied or distributed:
This eBook is for the use of anyone anywhere in the United States and most
other parts of the world at no cost and with almost no restrictions
whatsoever. You may copy it, give it away or re-use it under the terms
of the Project Gutenberg License included with this eBook or online
at www.gutenberg.org. If you
are not located in the United States, you will have to check the laws
of the country where you are located before using this eBook.
1.E.2. If an individual Project Gutenberg™ electronic work is
derived from texts not protected by U.S. copyright law (does not
contain a notice indicating that it is posted with permission of the
copyright holder), the work can be copied and distributed to anyone in
the United States without paying any fees or charges. If you are
redistributing or providing access to a work with the phrase “Project
Gutenberg” associated with or appearing on the work, you must comply
either with the requirements of paragraphs 1.E.1 through 1.E.7 or
obtain permission for the use of the work and the Project Gutenberg™
trademark as set forth in paragraphs 1.E.8 or 1.E.9.
1.E.3. If an individual Project Gutenberg™ electronic work is posted
with the permission of the copyright holder, your use and distribution
must comply with both paragraphs 1.E.1 through 1.E.7 and any
additional terms imposed by the copyright holder. Additional terms
will be linked to the Project Gutenberg™ License for all works
posted with the permission of the copyright holder found at the
beginning of this work.
1.E.4. Do not unlink or detach or remove the full Project Gutenberg™
License terms from this work, or any files containing a part of this
work or any other work associated with Project Gutenberg™.
1.E.5. Do not copy, display, perform, distribute or redistribute this
electronic work, or any part of this electronic work, without
prominently displaying the sentence set forth in paragraph 1.E.1 with
active links or immediate access to the full terms of the Project
Gutenberg™ License.
1.E.6. You may convert to and distribute this work in any binary,
compressed, marked up, nonproprietary or proprietary form, including
any word processing or hypertext form. However, if you provide access
to or distribute copies of a Project Gutenberg™ work in a format
other than “Plain Vanilla ASCII” or other format used in the official
version posted on the official Project Gutenberg™ website
(www.gutenberg.org), you must, at no additional cost, fee or expense
to the user, provide a copy, a means of exporting a copy, or a means
of obtaining a copy upon request, of the work in its original “Plain
Vanilla ASCII” or other form. Any alternate format must include the
full Project Gutenberg™ License as specified in paragraph 1.E.1.
1.E.7. Do not charge a fee for access to, viewing, displaying,
performing, copying or distributing any Project Gutenberg™ works
unless you comply with paragraph 1.E.8 or 1.E.9.
1.E.8. You may charge a reasonable fee for copies of or providing
access to or distributing Project Gutenberg™ electronic works
provided that:
• You pay a royalty fee of 20% of the gross profits you derive from
the use of Project Gutenberg™ works calculated using the method
you already use to calculate your applicable taxes. The fee is owed
to the owner of the Project Gutenberg™ trademark, but he has
agreed to donate royalties under this paragraph to the Project
Gutenberg Literary Archive Foundation. Royalty payments must be paid
within 60 days following each date on which you prepare (or are
legally required to prepare) your periodic tax returns. Royalty
payments should be clearly marked as such and sent to the Project
Gutenberg Literary Archive Foundation at the address specified in
Section 4, “Information about donations to the Project Gutenberg
Literary Archive Foundation.”
• You provide a full refund of any money paid by a user who notifies
you in writing (or by e-mail) within 30 days of receipt that s/he
does not agree to the terms of the full Project Gutenberg™
License. You must require such a user to return or destroy all
copies of the works possessed in a physical medium and discontinue
all use of and all access to other copies of Project Gutenberg™
works.
• You provide, in accordance with paragraph 1.F.3, a full refund of
any money paid for a work or a replacement copy, if a defect in the
electronic work is discovered and reported to you within 90 days of
receipt of the work.
• You comply with all other terms of this agreement for free
distribution of Project Gutenberg™ works.
1.E.9. If you wish to charge a fee or distribute a Project
Gutenberg™ electronic work or group of works on different terms than
are set forth in this agreement, you must obtain permission in writing
from the Project Gutenberg Literary Archive Foundation, the manager of
the Project Gutenberg™ trademark. Contact the Foundation as set
forth in Section 3 below.
1.F.
1.F.1. Project Gutenberg volunteers and employees expend considerable
effort to identify, do copyright research on, transcribe and proofread
works not protected by U.S. copyright law in creating the Project
Gutenberg™ collection. Despite these efforts, Project Gutenberg™
electronic works, and the medium on which they may be stored, may
contain “Defects,” such as, but not limited to, incomplete, inaccurate
or corrupt data, transcription errors, a copyright or other
intellectual property infringement, a defective or damaged disk or
other medium, a computer virus, or computer codes that damage or
cannot be read by your equipment.
1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the “Right
of Replacement or Refund” described in paragraph 1.F.3, the Project
Gutenberg Literary Archive Foundation, the owner of the Project
Gutenberg™ trademark, and any other party distributing a Project
Gutenberg™ electronic work under this agreement, disclaim all
liability to you for damages, costs and expenses, including legal
fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT
LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE
PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE
TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE
LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR
INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH
DAMAGE.
1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a
defect in this electronic work within 90 days of receiving it, you can
receive a refund of the money (if any) you paid for it by sending a
written explanation to the person you received the work from. If you
received the work on a physical medium, you must return the medium
with your written explanation. The person or entity that provided you
with the defective work may elect to provide a replacement copy in
lieu of a refund. If you received the work electronically, the person
or entity providing it to you may choose to give you a second
opportunity to receive the work electronically in lieu of a refund. If
the second copy is also defective, you may demand a refund in writing
without further opportunities to fix the problem.
1.F.4. Except for the limited right of replacement or refund set forth
in paragraph 1.F.3, this work is provided to you ‘AS-IS’, WITH NO
OTHER WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PURPOSE.
1.F.5. Some states do not allow disclaimers of certain implied
warranties or the exclusion or limitation of certain types of
damages. If any disclaimer or limitation set forth in this agreement
violates the law of the state applicable to this agreement, the
agreement shall be interpreted to make the maximum disclaimer or
limitation permitted by the applicable state law. The invalidity or
unenforceability of any provision of this agreement shall not void the
remaining provisions.
1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the
trademark owner, any agent or employee of the Foundation, anyone
providing copies of Project Gutenberg™ electronic works in
accordance with this agreement, and any volunteers associated with the
production, promotion and distribution of Project Gutenberg™
electronic works, harmless from all liability, costs and expenses,
including legal fees, that arise directly or indirectly from any of
the following which you do or cause to occur: (a) distribution of this
or any Project Gutenberg™ work, (b) alteration, modification, or
additions or deletions to any Project Gutenberg™ work, and (c) any
Defect you cause.
Section 2. Information about the Mission of Project Gutenberg™
Project Gutenberg™ is synonymous with the free distribution of
electronic works in formats readable by the widest variety of
computers including obsolete, old, middle-aged and new computers. It
exists because of the efforts of hundreds of volunteers and donations
from people in all walks of life.
Volunteers and financial support to provide volunteers with the
assistance they need are critical to reaching Project Gutenberg™’s
goals and ensuring that the Project Gutenberg™ collection will
remain freely available for generations to come. In 2001, the Project
Gutenberg Literary Archive Foundation was created to provide a secure
and permanent future for Project Gutenberg™ and future
generations. To learn more about the Project Gutenberg Literary
Archive Foundation and how your efforts and donations can help, see
Sections 3 and 4 and the Foundation information page at www.gutenberg.org.
Section 3. Information about the Project Gutenberg Literary Archive Foundation
The Project Gutenberg Literary Archive Foundation is a non-profit
501(c)(3) educational corporation organized under the laws of the
state of Mississippi and granted tax exempt status by the Internal
Revenue Service. The Foundation’s EIN or federal tax identification
number is 64-6221541. Contributions to the Project Gutenberg Literary
Archive Foundation are tax deductible to the full extent permitted by
U.S. federal laws and your state’s laws.
The Foundation’s business office is located at 809 North 1500 West,
Salt Lake City, UT 84116, (801) 596-1887. Email contact links and up
to date contact information can be found at the Foundation’s website
and official page at www.gutenberg.org/contact
Section 4. Information about Donations to the Project Gutenberg
Literary Archive Foundation
Project Gutenberg™ depends upon and cannot survive without widespread
public support and donations to carry out its mission of
increasing the number of public domain and licensed works that can be
freely distributed in machine-readable form accessible by the widest
array of equipment including outdated equipment. Many small donations
($1 to $5,000) are particularly important to maintaining tax exempt
status with the IRS.
The Foundation is committed to complying with the laws regulating
charities and charitable donations in all 50 states of the United
States. Compliance requirements are not uniform and it takes a
considerable effort, much paperwork and many fees to meet and keep up
with these requirements. We do not solicit donations in locations
where we have not received written confirmation of compliance. To SEND
DONATIONS or determine the status of compliance for any particular state
visit www.gutenberg.org/donate.
While we cannot and do not solicit contributions from states where we
have not met the solicitation requirements, we know of no prohibition
against accepting unsolicited donations from donors in such states who
approach us with offers to donate.
International donations are gratefully accepted, but we cannot make
any statements concerning tax treatment of donations received from
outside the United States. U.S. laws alone swamp our small staff.
Please check the Project Gutenberg web pages for current donation
methods and addresses. Donations are accepted in a number of other
ways including checks, online payments and credit card donations. To
donate, please visit: www.gutenberg.org/donate.
Section 5. General Information About Project Gutenberg™ electronic works
Professor Michael S. Hart was the originator of the Project
Gutenberg™ concept of a library of electronic works that could be
freely shared with anyone. For forty years, he produced and
distributed Project Gutenberg™ eBooks with only a loose network of
volunteer support.
Project Gutenberg™ eBooks are often created from several printed
editions, all of which are confirmed as not protected by copyright in
the U.S. unless a copyright notice is included. Thus, we do not
necessarily keep eBooks in compliance with any particular paper
edition.
Most people start at our website which has the main PG search
facility: www.gutenberg.org.
This website includes information about Project Gutenberg™,
including how to make donations to the Project Gutenberg Literary
Archive Foundation, how to help produce our new eBooks, and how to
subscribe to our email newsletter to hear about new eBooks.
