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Title: The Snakes of Europe
Author: G. A. Boulenger
Release Date: August 15, 2014 [EBook #46590]
Language: English
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When italics were used in the original book, the corresponding text has
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match the main text.
THE SNAKES OF EUROPE
------------------------------------------------------------------------
UNIFORM WITH THIS VOLUME
THE LIFE OF CRUSTACEA
BRITISH FRESHWATER FISHES
THE OX AND ITS KINDRED
THE LIFE OF THE MOLLUSCA
------------------------------------------------------------------------
THE
SNAKES OF EUROPE
BY
G. A. BOULENGER
LL.D., D.SC., PH.D., F.R.S., F.Z.S.
WITH FOURTEEN PLATES AND FORTY-TWO FIGURES IN THE TEXT
METHUEN & CO. LTD.
36 ESSEX STREET W.C.
LONDON
------------------------------------------------------------------------
_First Published in 1913_
------------------------------------------------------------------------
PREFACE
There is no work in the English language dealing with the Reptiles of
Europe. I have therefore endeavoured to supply this desideratum, so far
as the Snakes are concerned, by drawing up in a concise form an account
of what is known of their characters, their distribution, and their
life-histories. Professor Sordelli, of Milan, having kindly acceded to
my request to reproduce some of the beautiful figures drawn by him for
the work published in collaboration with the late Professor Jan under
the title of "Iconographie Générale des Ophidiens," I have been able to
supplement my descriptions with illustrations which leave nothing to be
desired from the point of view of accuracy. A few drawings have been
made specially for this book by Mr. J. Green. I have further to
acknowledge the permission given by the Trustees of the British Museum,
the India Office, and the Zoological Society, to reproduce a few figures
from previous publications of which I am the author.
In order to render this little book more useful, the account of the
Snakes of Europe has been preceded by an Introduction summarizing what
is known of Snakes generally.
I have purposely avoided overburdening a work of this kind, which aims
at concision, with bibliographical references and synonymic lists. I am
sure my readers will be thankful for being spared this display of
erudition. Whenever I have had to compile, and to trespass on ground
that is not my own, I have been careful to draw only from the writings
of the most trustworthy authorities. The descriptions of the species are
based on the collection in the British Museum, which has been
considerably increased since the publication of the Catalogue of Snakes
(1893-1896). I have also had access to Monsieur F. Lataste's rich
private collection, now under my care, and Dr. R. Gestro has kindly
entrusted to me for study the collection of Italian Snakes in the Genoa
Museum. I am indebted to Dr. L. W. Sambon for the chapter on Parasites,
which he has written at my request.
To all who have helped me I beg to tender my hearty thanks.
G. A. B.
CONTENTS
INTRODUCTION
CHAPTER PAGE
I. Definition and Classification 1
II. External Characters--Integument 8
III. Coloration 29
IV. Skeleton 40
V. Dentition 53
VI. Poison Apparatus--Different Kinds of Poisons 62
VII. Nervous System-Sense Organs 73
VIII. Viscera 77
IX. Organs of Reproduction; Pairing; Oviposition; Development 82
X. Habits 91
XI. Parasites 107
XII. Distribution 118
XIII. Snakes in Relation to Man 133
SYSTEMATIC ACCOUNT OF THE SNAKES
OF EUROPE
First Family: TYPHLOPIDÆ
Genus TYPHLOPS, Schneider 144
1. Typhlops vermicularis, Merrem--The Greek Blind-Snake 144
Second Family: BOIDÆ
Genus ERYX, Daudin 147
2. Eryx jaculus, Linnæus--The Javelin Sand-Boa 147
Third Family: COLUBRIDÆ
Genus TROPIDONOTUS, Kuhl 152
3. Tropidonotus natrix, Linnæus--The Grass-Snake,
or Ring-Snake 152
4. Tropidonotus tessellatus, Laurenti--The Tessellated
Water-Snake 160
5. Tropidonotus viperinus, Latreille--The Viperine
Water-Snake 165
Genus ZAMENIS, Wagler 170
6. Zamenis gemonensis, Laurenti--The European Whip-Snake 170
7. Zamenis dahlii, Fitzinger--Dahl's Whip-Snake 177
8. Zamenis hippocrepis, Linnæus--The Horseshoe Whip-Snake 179
Genus COLUBER, Linnæus 181
9. Coluber quatuorlineatus, Lacepède--Aldrovandi's Snake 182
10. Coluber dione, Pallas--The Dione Snake 185
11. Coluber longissimus, Laurenti--The Æsculapian Snake 187
12. Coluber leopardinus, Bonaparte--The Leopard Snake 191
13. Coluber scalaris, Schinz--The Ladder Snake 194
Genus CORONELLA, Laurenti 196
14. Coronella austriaca, Laurenti--The Smooth Snake 197
15. Coronella girondica, Daudin--The Southern Smooth Snake 202
Genus CONTIA, Baird and Girard 205
16. Contia modesta, Martin--The Dwarf Snake 205
Genus COELOPELTIS, Wagler 207
17. Coelopeltis monspessulana, Hermann--The Montpellier Snake 208
Genus MACROPROTODON, Guichenot 212
18. Macroprotodon cucullatus, I. Geoffroy--The False
Smooth Snake 213
Genus TARBOPHIS, Fleischmann 216
19. Tarbophis fallax, Fleischmann--The Cat-Snake 217
20. Tarbophis iberus, Eichwald--The Caucasian Cat-Snake 219
Fourth Family: VIPERIDÆ
Genus VIPERA, Laurenti 221
21. Vipera ursinii, Bonaparte--Orsini's Viper 221
22. Vipera renardi, Christoph--Renard's Viper 227
23. Vipera berus, Linnæus--The Northern Viper, or Adder 230
24. Vipera aspis, Linnæus--The Asp Viper 239
25. Vipera latastii, Bosca--Lataste's Viper 247
26. Vipera ammodytes, Linnæus--The Sand-Viper, or
Long-Nosed Viper 249
27. Vipera lebetina, Linnæus--The Blunt-Nosed Viper, or Kufi 257
Genus ANCISTRODON, Palisot de Beauvois 261
28. Ancistrodon halys, Pallas--Pallas's Pit-Viper 262
Index 265
LIST OF PLATES
PLATE FACING PAGE
I. Typhlops vermicularis, Eryx jaculus 144
II. Tropidonotus natrix and Vars. cettii and persa 152
III. Tropidonotus tessellatus, T. viperinus and
var. aurolineatus 160
IV. Zamenis gemonensis and vars. persica and
viridiflavus 170
V. Zamenis gemonensis, var. caspius, Z. dahlii,
Z. hippocrepis 176
VI. Coluber quatuorlineatus and var. sauromates,
C. dione 182
VII. Coluber longissimus, C. leopardinus and
var. quadrilineatus 188
VIII. Coluber scalaris 194
IX. Coronella austriaca 196
X. Coronella girondica, Contia modesta 202
XI. Coelopeltis monspessulana, Macroprotodon
cucullatus, Tarbophis iberus, T. fallax 208
XII. Vipera ursinii, V. renardi, V. berus 220
XIII. Vipera aspis, V. latastii 240
XIV. Vipera lebetina, V. ammodytes, Ancistrodon halys 250
------------------------------------------------------------------------
THE SNAKES OF EUROPE
INTRODUCTION
CHAPTER I
DEFINITION AND CLASSIFICATION
Snakes, _Ophidia_--regarded by some authorities as an order of the class
_Reptilia_, by the author as a sub-order of the order _Squamata_, which
includes besides the Lizards, _Lacertilia_, the Chameleons,
_Rhiptoglossa_, and the extinct _Dolichosauria_ and _Mosasauria_--may be
defined as greatly elongate scaly Reptiles without limbs, or with mere
vestiges of the hind pair, without movable eyelids, without ear-opening,
with elongate, deeply forked tongue retractile into a basal sheath, with
transverse vent and paired copulatory organs, and with the two halves of
the lower jaw independently movable, connected at the symphysis by an
elastic ligament.
The latter character alone distinguishes them from all Lizards, but no
single Lizard possesses all the others in combination.
In their most highly developed form these Reptiles are adapted for rapid
reptation and for swallowing prey much exceeding their own calibre;
hence the bones of the skull, on which a prehensile function devolves,
are loosely attached to the cranium by ligamentous elastic tissue, or
articulated in such a manner as to permit a wide buccal expansion;
whilst the absence of a sternum and the mobile attachment of the ribs
allow a corresponding dilatation of the body as the prey descends into
the digestive canal.
The fatal venom which many of these Reptiles possess has so impressed
the mind of men, even the scientific, that for a long time snakes were
primarily divided into poisonous and non-poisonous, a classification in
which the more important characters, derived from the general structure,
and especially from the skull, were subordinated to the physiological.
Such a system was far from reflecting natural relationships. Besides, as
our knowledge progressed, drawing a distinction between poisonous and
harmless snakes became more and more difficult, so many snakes
previously regarded as harmless proving to be poisonous in various
degrees--at least enough to paralyze the small prey on which they
subsist, if not to be of serious danger to man.
In the division into families, as followed in this work, the presence or
absence of a poison organ is left out of consideration. Further, in this
as in many other groups of the animal kingdom, external characters do
not furnish trustworthy indications for higher divisions, and the
definitions of the families are therefore based exclusively on
osteological characters. For those who wish to name snakes with
facility, the key which concludes the chapter on External Characters
will, however, remedy this defect, and suffice for the identification of
all the European species without any reference to their anatomy. Many
attempts have been made to furnish an easy criterion for the distinction
of harmless from poisonous snakes, but the characters hitherto suggested
with this object can only be applied successfully to the small number of
representatives in a limited area. Thus, in Southern Australia it might
be stated that all snakes showing the regular nine large shields on the
upper surface of the head are dangerous to man, whilst those with small
shields or scales are harmless; but in most parts of Europe this
criterion would have to be reversed. In some countries the shape of the
pupil might be used for the purpose, in others the size of the ventral
shields, or the presence or absence of a loreal shield, between the
nasal and the preocular, and so on. But when we have to deal with the
snakes of the whole world, about 2,000 species, of which nearly
one-third are poisonous to a greater or less degree, every attempt at a
definition of the two categories without regard to the dentition breaks
down. Only those who have made a study of the snakes of the world can
make a guess from the general appearance as to an unknown form being
poisonous or not, and even they may sometimes feel embarrassed, unless
the dentition be examined; the mistakes which have occasionally been
made by some experienced herpetologists are proof sufficient of the
fallacy of external characters for this purpose.
The Ophidia are divided into nine families, the first, third, seventh,
and ninth of which have representatives in Europe:
I. No transverse (ectopterygoid) bone; pterygoid not extending to
quadrate or mandible; no supratemporal; nasals in contact with
prefrontals; coronoid present; vestiges of pelvis.
Maxillary loosely attached to lower surface of cranium, toothed; lower
jaw edentulous; a single pelvic bone
1. TYPHLOPIDÆ.
Maxillary bordering mouth, forming a suture with premaxillary,
prefrontal, and frontal, toothless; pubis and ischium present, latter
forming a symphysis
2. GLAUCONIIDÆ.
II. Transverse bone present; both jaws toothed.
_A._ Coronoid present; nasals in contact with prefrontals.
1. Vestiges of pelvis; supratemporal present.
Supratemporal large, suspending quadrate
3. BOIDÆ.
(Subfamilies: _Pythoninæ_, _Boinæ_.)
Supratemporal small, intercalated in the cranial wall
4. ILYSIIDÆ.
2. No vestiges of pelvis; supratemporal absent
5. UROPELTIDÆ.
_B._ Coronoid absent; supratemporal present.
1. Maxillary horizontal; pterygoids reaching quadrate or mandible.
Nasals in contact with prefrontals
6. XENOPELTIDÆ.
Nasals not in contact with prefrontals
7. COLUBRIDÆ.
Three series: A. _Aglypha_ (subfamilies: _Acrochordinæ_, _Colubrinæ_,
_Dasypeltinæ_); B. _Opisthoglypha_ (_Homalopsinæ_, _Dipsadomorphinæ_,
_Elachistodontinæ_); C. _Proteroglypha_ (_Hydrophiinæ_, _Elapinæ_).
2. Maxillary horizontal, converging posteriorly towards palatine;
pterygoid not reaching quadrate or mandible
8. AMBLYCEPHALIDÆ.
3. Maxillary vertically erectile perpendicularly to transverse bone;
pterygoid reaching quadrate or mandible
9. VIPERIDÆ.
(Subfamilies: _Viperinæ_, _Crotalinæ_.)
The technical terms employed in the above synopsis will be found
explained and illustrated by figures in the chapter on the Skeleton.
No serial arrangement can express the affinities of the various groups
as conceived by the classificator; a diagram therefore follows to show
the author's views as to their interrelationships, and possibly their
phylogeny. Leaving aside the Typhlopidæ and Glauconiidæ, which should be
regarded as burrowing types independently derived from some Ophidian
form less specialized than any with which we are at present acquainted,
and probably without direct relationship to the Lizards, the family
Boidæ, and more especially the Pythons, claim the position of ancestral
group, from which all other snakes may have been derived.
Viperidæ Amblycephalidæ
| |
Colubridæ opisthoglyphæ Colubridæ proteroglyphæ |
| | |
+---------------------------+-----+--------------+
|
Uropeltidæ |
| |
Ilysiidæ Xenopeltidæ Colubridæ aglyphæ
| | |
+------------+--------------+
|
Boidæ
Further remarks on this subject in the chapter on Dentition.
It is to be regretted that paleontology cannot help us at present as
concerns the lines of evolution, the comparatively few fossil Ophidians
known, from the Lower Eocene upwards, the remains of which can be
identified with some measure of certainty, being either non-poisonous
types (_Boidæ_, _Ilysiidæ_, _Palæophiidæ_, _Colubridæ_) or _Viperidæ_
(Viperines from the Miocene of France and Germany, Crotalines from the
Miocene of North America). The vertebræ from the Puerco Eocene of
America, on the limit between the Cretaceous and Eocene periods,
described as the oldest snake remains, _Helagras_, Cope, are stated to
approach the Lacertilian type.
Whether the vertebræ named _Symoliophis_, Sauvage, from the chalk of
France, and _Coniophis_, Marsh, from the Laramie Cretaceous of North
America, are Ophidian, as claimed by their describers, or
Dolichosaurian, cannot be decided without further material.
CHAPTER II
EXTERNAL CHARACTERS--INTEGUMENT
The form varies enormously, worm-like in some, comparatively short and
heavy, elongate and more or less slender, or extremely gracile and
almost filiform, in others. In this respect our common Grass-snake
occupies a central position, and for this reason is termed a moderately
slender form, anything above or below this standard being described as
comparatively short or elongate. Our shortest and stoutest European
Snakes are the Vipers, especially _Vipera ursinii_; our longest and
slenderest, the _Coluber_ and _Zamenis_, especially _Zamenis dahlii_.
These extremes in both directions are, however, far surpassed by many
exotic snakes, as we find on comparing, for instance, one of the African
Puff-adders (_Bitis_), with certain _Oxybelis_ and _Leptognathus_ from
Tropical America. The body may be somewhat rigid, as in some burrowing
and ground snakes, not unlike in appearance to our Slow-worm and other
limbless Lizards; or extremely flexible, as in many Pythons and Boas and
in the Tree-snakes generally. This flexibility may be accompanied by a
vertical compression of the body in relation with an arboreal existence,
whilst sluggish snakes, such as most of the Viperidæ, may be remarkable
for the flattening of the body, which they may further increase when
basking in the sun or in order to assume a more formidable appearance on
the approach of an enemy. This power of flattening out the whole or the
anterior part of the body is possessed by many snakes, poisonous as well
as harmless, and reaches its highest degree in the Cobras of India and
Africa, the expanded anterior part being known as the "hood," from the
Portuguese name "Cobra di capello."
Thoroughly aquatic snakes are often short and heavy, but some of the
marine forms, or Hydrophids, may be extremely slender, with the
posterior part of the body compressed. In some of these Sea-snakes the
gracility of the anterior part, or "neck," as it has been called,
contrasts very strikingly with the great girth of the body towards the
tail, and suggests a limbless Plesiosaur.
The tail, the part of the body behind the transversely cleft vent, is
most frequently about one-fourth or one-fifth of the total length; but
it may be much shorter, even reduced to a mere stump, as in the
_Typhlops_, or, at the opposite extreme, enter for one half in the
length of the snake, as in the African _Xenurophis_. This organ may
taper gradually to a fine point; or end abruptly, as if mutilated; or
terminate in a horny spine, such as we see in some of the _Typhlops_ or
in the Australian Death-adder, _Acanthophis_, or in a series of horny
segments which are vibrated like a rattle, as in the well-known
_Crotalus_ of America, to which we shall refer again at the end of this
chapter. In some of the burrowing Uropeltidæ, the very short tail is
obliquely truncated, with indurated shields above, and acts as a trowel.
And, finally, the marine snakes of the subfamily Hydrophiinæ are
distinguished by a strongly compressed, oar-shaped tail, with rounded
vertical outline. In a few forms, arboreal or aquatic, the tail is more
or less prehensile.
Males generally have a longer tail than females, and the genital organs,
which are lodged in its base, cause a swelling of that region which
contrasts with the more gradually tapering extremity of the female, thus
affording a means of distinguishing the sexes externally in the majority
of snakes.
The rudimentary hind limbs of Boid snakes, to be mentioned further on in
the description of the skeleton, terminate in a claw-like horny spur,
which appears on each side of the vent in the male, and sometimes also,
though less distinctly, in the female. These spurs are probably of use
in facilitating the pairing, an explanation which appears the more
plausible from the fact that the snakes provided with them have the
copulatory intromittent organs destitute of the erectile spines which
are present in most others.
The head varies in shape as much as the body. Although never actually
compressed, except in the rostral region, it may be very narrow and
elongate, whilst in the opposite extreme it may be strongly depressed,
and so broad behind as to be abruptly defined from the anterior part of
the body, or "neck." This feature is very marked in some of the
Viperidæ, and this has given rise to the incorrect generalization that
poisonous snakes are distinguished from the harmless by a broad and flat
head, notwithstanding the fact that some of the most dangerous, such as
the Mambas, Cobras, and Kraits, have a comparatively narrow or small
head, not or but slightly defined behind, whilst, on the other hand, the
very opposite condition obtains in not a few of the harmless Colubrids.
Leaving the Typhlopidæ and Glauconiidæ aside for the present, snakes
have a wide gape, cleft far beyond the vertical of the eyes, with, when
closed, one or two notches in front for the passage of the protrusible,
bifid tongue. In most snakes this chink is in the lower border of the
rostral shield, capping the tip of the snout, and allows free passage to
the whole tongue; in the Hydrophids, or Sea-snakes, there are two
notches in the lower border of the rostral shield, through which only
the bifid end of the tongue can be protruded. The eyes, varying from
minute to enormous, are usually free from the surrounding shields, and
may move under a transparent cap like a watch-glass, which appears to
represent the lower eyelid of Lizards. The view as to this homology is
derived from our knowledge of various conditions in certain series of
Lizards of the families Lacertidæ and Scincidæ, where we find a
transparent disc appearing like a small window in the movable lower
eyelid, gradually increasing in size so as to occupy the whole of the
lower eyelid, which finally becomes fused with the rudimentary upper lid
and loses its mobility. In _Ilysia_ and in most of the Uropeltidæ, the
transparent disc over the eye is confluent with a thick horny shield of
which it occupies the middle.
The pupil is usually circular or vertical, rarely horizontal. In some
forms it is difficult to decide whether it is round or vertically
elliptic; in others, like the Boas and Vipers, for instance, it is
decidedly vertical, and contracts to the same extent as a cat's. In some
Water-snakes, and in Sea-snakes generally, the round pupil may contract
to a mere dot. The contraction of the pupil is independent on the two
sides.
The snout, or the part of the head anterior to the eyes, may be short or
long, rounded or pointed, depressed or compressed, sometimes projecting
strongly beyond the mouth, turned up at the end, or terminating in one
(_Langaha_) or two (_Herpeton_) long scaly dermal appendages. In some
burrowing forms it is provided with a more or less trenchant horizontal
or vertical edge. When the sides of the snout (loreal region) form an
angle with the upper surface, the angle is termed the "canthus
rostralis," which may be intensified by the loreal region being concave.
The deep pits which are sometimes present on the lips or between the
nostril and the eye (loreal pit) will be alluded to further on under
Sensory Organs.
The nostrils are either lateral, or, in the aquatic forms, directed
upwards, sometimes entirely on the upper surface of the snout.
Most snakes have a longitudinal groove on the chin (mental groove) to
allow for the distension caused by the lateral movements of the rami of
the lower jaw.
In the Typhlopidæ, the head passes gradually into the vermiform body,
and the small mouth is situated on the under surface of the projecting
snout; the head so resembles the extremely short tail, and the mouth is
so similar in shape and position to the vent, which is close to the
posterior extremity of the snake, that such creatures are often believed
by non-critical observers to have a head at each end. The eyes are very
small, and covered over by the semi-transparent head-shields, or they
may be completely concealed. There is no mental groove. It is much the
same with the Glauconiidæ, which have, however, a somewhat less
abbreviated tail. In both, the nostrils often open on the lower side of
the snout, which may be excavated so as to appear hooked in profile, or
may be provided with a sharp cutting horizontal edge.
Snakes are covered with epidermal folds in the form of scales and
shields, the shape and arrangement of which affords important characters
for their classification. Dermal ossifications are absent.
The scales on the body are usually elliptic or lanceolate and imbricate,
forming straight longitudinal and oblique transverse series, and they
are replaced on the belly and under the tail by transverse shields
mostly corresponding in number with the series of scales, and also with
the vertebræ. The body of the Typhlopidæ and Glauconiidæ is uniformly
covered with polished, closely adherent, rounded, overlapping, sub-equal
scales, without even an indication of ventral shields. In some of the
Acrochordinæ, aberrant aquatic Colubrids, the scaling consists, above
and beneath, of small juxtaposed, sometimes spinose granules, the skin
being suggestive of the shagreen of sharks. In the marine snakes of the
subfamily Hydrophiinæ, the ventral shields are often absent or merely
indicated, and the scales are mostly juxtaposed or feebly imbricate,
sometimes tetragonal or hexagonal, and occasionally studded with spinose
tubercles. In the more typical Ophidia the imbricate scales may be long
and narrow or short and broad, with every intermediate step between the
two extremes; smooth or furnished with a longitudinal ridge or keel, or
even several keels; nearly equal in size or with the median or outer
series more or less enlarged, the longitudinal series in odd, rarely in
even number; instead of running in longitudinal series parallel with the
axis of the body, as is the rule, they are sometimes disposed obliquely,
and among those in which we meet with this peculiarity several genera
are further remarkable in having some of the oblique lateral scales
furnished with a serrated keel, to which we shall again allude in the
chapter on Habits, when dealing with the rustling sounds produced by
certain snakes. The number of longitudinal series of scales on the body
varies from 10 (_Herpetodryas_) to nearly 100 (_Python_, _Boa_); in the
European species from 17 (_Contia modesta_) to 50 (_Eryx jaculus_). The
scales are sometimes furnished near the end with one or two shallow
impressions, termed "apical pits," which afford indications for the
distinction of genera and species; unless of a lighter or darker colour,
as is often the case, these pits are not always easy to see, except in a
strong light and with the aid of a powerful magnifying glass.
The ventral shields, also called "gastrosteges," usually occupy the
whole width of the belly; but they may be much narrower--in _Eryx_, for
instance. They are sometimes bent at an angle on the sides, and this
angle may even form a sharp keel, accompanied by a notch in the
posterior border, corresponding to the keel, as in several of the more
arboreal genera of Colubrids. The shields under the tail, termed
subcaudals or "urosteges," are sometimes similar to the ventrals, but
more often disposed in pairs; in certain species or individuals some of
the subcaudals are single, and the others paired. When the number of
subcaudals is given in the descriptions, each pair is reckoned as one,
and the conical or spine-like shield which caps the end of the tail is
not included. These numbers afford important characters for the
definition of species, and sometimes also for the distinction of sexes.
The subcaudals are nearly always much fewer than the ventrals, but the
difference is often not so great in the males as in the females, the
tail of which is usually shorter in proportion to the body. It is
noteworthy that in many species, if the number of subcaudals (C.) be
added to that of the ventrals (V.), the total is nearly the same in the
male as in the female, however much the respective numbers may differ
when taken separately. The following figures may be given by way of
example, taken from British specimens:
_Coronella austriaca_: [M] _V._ 154; _C._ 58 = 212
_Coronella austriaca_: [F] _V._ 165; _C._ 48 = 213
_Vipera berus_: [M] _V._ 138; _C._ 35 = 173
_Vipera berus_: [F] _V._ 144; _C._ 29 = 173
Although this rule is by no means universal, and does not apply at all
to some species, it will be found to hold good in many cases, and is of
interest in showing that the changes that have taken place in the
vertebral column (the vertebræ corresponding in number to the shields),
according to the sexes, have been by a modification of the character of
the segments about the anal region, a conversion of trunk vertebræ into
caudals, or _vice versa_. In dealing with certain species--of Vipers,
for instance--it is important, for systematic purposes, to keep the
counts of shields distinct for the two sexes.
The shield which covers the vent, the anal shield, is either single or
divided into two.
Some snakes have the head covered with scales or small tubercles similar
to those on the body, but in the great majority the lepidosis is in the
form of large symmetrical juxtaposed shields, the shape, proportions,
and number of which furnish some of the most important characters for
the distinction of genera and species. These head-shields belong to two
primarily different types, from each of which all further modifications
may be regarded as derived by alteration in shape or by disintegration.
The first type is that shown by the Typhlopidæ and Glauconiidæ, which is
explained by the figure on the next page.
The rostral, which is usually the largest of the head-shields, extends
to the upper surface of the head, of which it may occupy the greater
part. In the Glauconiidæ, the ocular usually borders the mouth.
As may be seen by a comparison of the first figure with the second, the
arrangement of the head-shields is essentially different from that which
prevails in the Colubrids and the majority of other snakes.
The second type is exemplified by the head of a member of the genus
_Zamenis_.
In the descriptions, temporals 2 + 3 means two superposed temporals in
the first row, three in the second. The internasals and the temporals,
and the loreal and the preocular, are sometimes absent, and the
prefrontal or the internasal may be single. One or two large shields are
in rare cases present behind the parietals, and are called occipital.
[Illustration: FIG. 1--HEAD OF _Typhlops braminus_. (From "Fauna of
British India")
_f_, Frontal; _ip_, interparietal; _l_, labial; _n_, nasal; _o_,
ocular; _p_, parietal; _po_, preocular; _prf_, prefrontal; _r_,
rostral; _so_, supraocular.]
A breaking up into smaller shields takes place in many snakes. In the
Pythons, for instance, the frontal may be divided into two by a
longitudinal cleft, and separated from the prefrontals by small shields.
In some Vipers, such as _V. berus_ and _V. ursinii_, in which the
frontal and parietals, though reduced in size, usually preserve their
primitive condition, the former is normally separated from the
supraocular by a series of small shields, and the internasals and
prefrontals are broken up; in these snakes the small shield or shields
behind the rostral are termed "apical," and those on the upper edge of
the snout are termed "canthals." The shield which, in Vipers, separates
the rostral from the nasal is called "naso-rostral." Allusion has been
made above to the scaly dermal appendages which terminate the snout in
certain genera. Some Viperidæ are furnished with horn-like erect spines
above the eyes or at the end of the snout, which add greatly to their
sinistral appearance.
[Illustration: FIG. 2--HEAD OF _Zamenis ventrimaculatus_. (From "Fauna
of British India")
_cs_, Chin-shields (anterior); _cs´_, chin-shields (posterior); _f_,
frontal; _in_, internasal; _l_, loreal; _la_, labial (upper); _la´_,
labial (lower); _m_, mental; _n_, nasal; _p_, parietal; _pf_,
prefrontal; _pro_, preocular; _pto_, postocular; _r_, rostral;
_sbo_, subocular; _so_, supraocular; _t_, temporals (first row);
_t´_, temporals (second row); _v_, first ventral.]
The periodical shedding of the outer layer of the epidermis in a single
piece, including even the covering of the eye, is one of the most
striking peculiarities of snakes, although paralleled in the Lizards of
the family Anguidæ, to which our British Slow-worm belongs. The skin
becomes detached at the lips, and is turned inside out from head to
tail, without any sort of laceration when the snake is in good health.
These exuviæ are transparent, but often carry a certain amount of
pigment, especially those of the Vipers, in which the characteristic
dark markings are perfectly visible; they usually exceed the length of
the reptile, owing to stretching. In Sea-snakes the epidermis is cast
piecemeal, and sloughing is a longer operation than in ordinary snakes.
In Rattlesnakes each piece of the rattle, or "crotalon," in which the
tail terminates, represents a retained portion of the sloughed
epidermis. This remarkable appendage looks like a number of horny rings,
but it consists in reality of hollow, bell-like pieces, similar to the
terminal one, or "button," each with a circular constriction, in which
the incurved free edge of the following piece fits, thus keeping the
pieces together without impairing the mobility necessary to produce the
rattling sound for which the apparatus is intended. At each exuviation
one bell-shaped horny piece is added. The number of segments in the
rattle is, therefore, not an index to age, as formerly believed; nor is
it to the number of exuviations, for whilst segments are being added at
the base of the apparatus the terminal ones break off and are lost. A
_Crotalus_ sixteen months old may have six pieces to the rattle if there
have been six exuviations and no loss. No rattle appears ever to
comprise more than about twenty pieces, even in old specimens. The size
of the terminal button shows whether it was formed at birth or at any
later period, no growth taking place in the horny tissue.
So far as trustworthy records are concerned, the largest snakes known,
the Malay _Python reticulatus_ and the South American Anaconda,
_Eunectes murinus_, reach a length of 25 to 30 feet. Measurements of
skins must be accepted with caution, as a skin may easily be stretched
to once and a half its real length; in estimating the exact length from
such a stretched skin, it is necessary to deduct the interstitial spaces
showing between the scales, and about one-fourth of the scale to allow
for the overlap. The smallest snake known is 4 inches long (_Glauconia
dissimilis_). The largest European snake (_Coluber quatuorlineatus_) is
reported to reach a length of 8 feet; the smallest (_Typhlops
vermicularis_) does not exceed 14 inches.
KEY TO THE IDENTIFICATION OF THE EUROPEAN SNAKES FROM EXTERNAL
CHARACTERS ONLY
I. Eyes minute, under the head-shields; mouth small, inferior; body
vermiform, covered with uniform scales above and beneath; vent close
to the end of the body, the extremely short tail ending in a small
spine
_Typhlops vermicularis._
II. Eyes very small, with vertical pupil; upper surface of head covered
with small scales; ventral shields much narrower than the body; tail
short, ending obtusely; subcaudals single, or mostly single; scales
smooth or feebly keeled, in 40 to 50 rows
_Eryx jaculus._
III. Eyes small, moderate, or large; ventral shields at least nearly as
broad as the body; tail tapering to a point; subcaudals paired.
_A._ Pupil round; upper surface of head with nine large shields; no
upper labial in contact with the parietal; anal shield usually
divided.
1. Dorsal scales strongly keeled, with paired apical pits; a single
anterior temporal.
_a._ Nostrils lateral; internasals broadly truncate in front.
Scales in 19 rows; normally 1 pre- and 3 postoculars; usually 7 upper
labials, third and fourth entering the eye; ventrals 157-181;
subcaudals 50-88
_Tropidonotus natrix._
_b._ Nostrils directed upwards; internasals much narrowed in
front.
Scales in 19 rows; normally 2 pre- and 3 or 4 postoculars; suboculars
sometimes present; usually 8 upper labials, fourth or fourth and fifth
entering the eye; ventrals 160-187; subcaudals 48-79
_Tropidonotus tessellatus._
Scales in 21 (rarely 19 or 23) rows; normally 1 or 2 pre- and 2
postoculars; usually 7 upper labials, third and fourth entering the
eye; ventrals 147-164; subcaudals 46-72
_Tropidonotus viperinus._
2. Dorsal scales smooth or feebly keeled; normally a single loreal.
_a._ Two or three superposed anterior temporals (very rarely
one); nostril usually between two nasals.
[alpha]. A subocular below the preocular.
* Scales smooth, in 17 or 19 rows.
Two upper labials entering the eye; preocular not in contact with the
frontal; scales with two apical pits; ventrals more or less distinctly
angulate laterally, 160-230; subcaudals 87-131
_Zamenis gemonensis._
Two upper labials entering the eye; preocular usually in contact with
the frontal; scales with a single apical pit; ventrals very distinctly
angulate laterally, 205-218; subcaudals 98-132
_Zamenis dahlii._
** Scales in 23 to 29 rows (usually 25 or 27), with two
apical pits.
Upper labials usually separated from the eye by a series of suboculars;
preocular in contact with the frontal; scales smooth; ventrals very
distinctly angulate laterally, 222-258; subcaudals 77-107
_Zamenis hippocrepis._
Two upper labials entering the eye; preocular not in contact with the
frontal; scales feebly but distinctly keeled; ventrals not angulate
laterally, 195-234; subcaudals 56-90
_Coluber quatuorlineatus._
Two upper labials entering the eye; preocular not in contact with the
frontal; scales smooth or faintly keeled; ventrals not or but very
obtusely angulate laterally, 172-214; subcaudals 50-80
_Coluber dione._
[beta]. No subocular; scales smooth, or faintly keeled on the
posterior part of the body.
* Ventrals more than 200; scales with two apical pits.
Snout obtuse; rostral broader than deep; scales in 21 or 23 rows;
ventrals distinctly angulate laterally, 212-248; subcaudals 60-91
_Coluber longissimus._
Snout obtuse; rostral broader than deep; scales in 25 or 27 rows;
ventrals not angulate laterally, 222-260; subcaudals 68-90
_Coluber leopardinus._
Snout pointed, strongly projecting; rostral deeper than broad, wedged
in between the internasals; scales in 25 to 29 rows; ventrals not
angulate laterally, 201-220; subcaudals 48-68
_Coluber scalaris._
** Ventrals not more than 200; scales mostly with a single
apical pit.
Rostral at least as deep as broad, often wedged in between the
internasals; usually 7 upper labials, third and fourth entering the
eye; scales in 19 (rarely 21) rows; ventrals 153-199; subcaudals 41-70
_Coronella austriaca._
Rostral broader than deep; usually 8 upper labials, fourth and fifth
entering the eye; scales in 21 (rarely 19 or 23) rows; ventrals
170-200; subcaudals 49-72
_Coronella girondica._
_b._ A single anterior temporal; nostril in a single nasal;
scales smooth, with single apical pits, in 17 rows; ventrals
150-191; subcaudals 53-78
_Contia modesta._
3. Scales longitudinally grooved in the adult, in 17 or 19 rows;
two loreals; canthus rostralis strongly marked; frontal very
narrow, in contact with the preocular; ventrals 160-189;
subcaudals 68-102
_Coelopeltis monspessulana._
_B._ Pupil vertical or vertically subelliptic (sometimes appearing
round in _Macroprotodon_).
1. Scales smooth, mostly with single apical pits; upper surface of
head with nine large shields.
Frontal 1-1/2 to 2 times as long as broad; loreal separated from the
eye by the preocular; one upper labial usually in contact with the
parietal; scales in 19 to 23 (rarely 25) rows; ventrals 153-192; anal
divided; subcaudals 40-54
_Macroprotodon cucullatus._
Frontal 1-1/4 to 1-1/2 times as long as broad, much shorter than the
parietals; loreal entering the eye; scales oblique, in 19 or 21 rows;
ventrals 186-222; anal divided; subcaudals 48-73
_Tarbophis fallax._
Frontal 1-1/4 to 1-1/2 times as long as broad, nearly as long as the
parietals; loreal entering the eye; scales oblique, in 19 or 21 rows;
ventrals 203-235; anal entire; subcaudals 54-70
_Tarbophis iberus._
2. Scales keeled, with two apical pits; anal shield entire.
_a._ No pit between the nostril and the eye; upper head-shields
small, if present; nasal separated from the rostral by a
naso-rostral; eye separated from the upper labials by
suboculars.
[alpha]. Snout not turned up at the end; supraocular usually
extending posteriorly beyond the vertical of the posterior
border of the eye; frontal and parietal shields usually well
developed; usually a single series of scales between the eye
and the upper labials.
Snout obtusely pointed, flat above, or with the canthus slightly
raised; rostral usually in contact with a single apical shield, rarely
with two; 6 to 9 upper labials, usually 7 or 8; scales in 19 rows,
rarely 21; ventrals: [M] 120-135, [F] 125-142
_Vipera ursinii._
Snout pointed, with raised canthus; rostral in contact with a single
apical shield; 8 or 9 upper labials; scales in 21 rows, rarely 19;
ventrals: [M] 130-148, [F] 130-150
_Vipera renardi._
Snout truncate or broadly rounded, flat above or with slightly raised
canthus; rostral in contact with two apical shields, rarely with one;
8 or 9 upper labials; scales in 21 rows, rarely 19 or 23; ventrals:
[M] 132-150, [F] 132-158
_Vipera berus._
[beta]. Snout usually more or less turned up at the end or
produced into a scaly dermal appendage; supraocular not
extending posteriorly beyond the vertical of the posterior
border of the eye; frontal and parietals often absent or very
small; 2 or 3 series of scales between the eye and the upper
labials; 9 to 13 upper labials; scales in 21 or 23 rows,
rarely 19 or 25.
Snout simply turned up, the raised portion bearing 2 or 3 scales;
rostral not more than once and a half as deep as broad; ventrals: [M]
134-158, [F] 141-169
_Vipera aspis._
Snout simply turned up or produced into a small appendage, the raised
portion with 5 or 6 (rarely 3) scales; rostral 1-1/2 to 2 times as
deep as broad; ventrals: [M] 125-146, [F] 135-147
_Vipera latastii._
Snout produced into an appendage covered with 10 to 20 scales; rostral
not reaching the summit of the rostral appendage; ventrals: [M]
133-161, [F] 135-163
_Vipera ammodytes._
[gamma]. Snout not turned up at the end; supraocular narrow or
broken up into several small shields; upper surface of head
with small, usually keeled scales; two or three series of
scales between the eye and the upper labials; scales in 23 to
27 rows, usually 25; ventrals: [M] 151-177, [F] 153-180
_Vipera lebetina._
_b._ A pit between the nostril and the eye; upper surface of head
with 9 large shields; nasal in contact with the rostral; third
upper labial entering the eye; scales in 23 rows; ventrals
149-174; subcaudals 31-44
_Ancistrodon halys._
------------------------------------------------------------------------
CHAPTER III
COLORATION
In dealing with the coloration, we have first to distinguish between the
colour and the markings. The former is very often highly variable among
snakes of the same species, to say nothing of the changes which may take
place with age or with the condition of the individuals, whether before
or after exuviation; it is not unusual to find among specimens from the
same locality a great range of variation, from greyish-white to brown,
or red, or black, as, for instance, in our Common Viper. The latter
afford more important characters, and often furnish valuable indications
for the distinction of species; but even the disposition of the markings
is subject to great individual variations, more likely to mislead than
to help the inexperienced student in the discrimination of species. It
is therefore always advisable to resort in the first instance to
structural characters for the purpose of specific identification, and to
fall back on coloration only as a means of confirmation. If we were to
be guided by colour and markings alone, how could we believe that an
adult four-lined _Coluber quatuorlineatus_ is of the same species as the
handsomely spotted _Coluber sauromates_; and yet, if we compare the
young of these two snakes we find them to be absolutely identical in
their markings, and, in the absence of any structural differences, we
are forced to conclude that they only represent two forms of the same
species, of which the latter is the more primitive.
It is nevertheless a fact that, with a few exceptions, the markings,
however variable they may be, are reducible to certain fundamental
patterns to which the innumerable variations may be traced back, and
their derivation followed and scientifically explained. Let us consider,
for instance, another species of _Coluber_, highly variable in its
markings: _C. leopardinus_, of which the typical form, so called from
having been the first described and named, is not by any means to be
regarded as the most primitive.
First, we must take for granted that the markings of all such snakes,
whether consisting of spots, stripes, or bars, start from a regular
arrangement, which may be theoretically represented by four paired
longitudinal series on the head and body: (1) Dorsal series (D); (2)
Dorso-lateral (DL); (3) Lateral (L); (4) Ventro-lateral (VL). The first
starts from the middle line of the head, and is continued along the
spine; the second occupies the space between the first and third, which
originates at the tip of the snout, passes through the eye, and is
continued on the temple and along the side of the body; the fourth
follows the lower lip, and extends along each side of the belly. Bearing
this in mind, we find that the variety of _C. leopardinus_ named
_schwoederi_, with a vertebral series of paired spots, is to be regarded
as the most primitive, from which we can derive, on the one hand, the
true _leopardinus_ by imagining a transverse fusion of the spots of
series D into a single row, some of the spots often actually revealing,
in their biscuit shape, their dual origin; whilst, on the other hand,
confluence of the paired spots of the same series into two longitudinal
stripes produces the variety named _quadrilineatus_ (see Plate VII.). In
this particular instance, the paired series D has fused into a single
streak on the head, and the series L appears to have departed from its
primitive course to extend on the upper surface of the head, both in
front of and behind the eye.
Many snakes show an interocular band extending from lip to lip, through
the eyes, across the interorbital region. In others the lateral stripe L
may bifurcate in front of the eye, an upper branch extending across the
snout, through transverse fusion of series D and DL, and it may also
bifurcate in like manner on the temporal region, fusing with the
corresponding marking on the other side to form a W-shaped figure. The
pattern of markings on the upper surface of the head is, however, often
very complicated, and hence difficult of explanation.
As a second example of the derivation of patterns, we may mention
_Vipera aspis_, which varies enormously as to its mid-dorsal markings,
forming, in different individuals or even on different parts of the
body, single or paired spots, a zigzag band, or transverse bars; all
these are derived from the paired spots of series D. Each pair of spots
may fuse and form transversely oval or elliptical spots or bars, or the
spots may assume an alternate disposition from which, through
confluence, the zigzag or sinuous band results. Thus, spotted and
striped patterns may be traced to a common origin, however fundamental
the difference between them appears at first sight. If the elements of
the four series, D, DL, L, and VL, unite transversely with each other,
and also with the spots on the ventral surface, we obtain ringed forms
such as the Coral-snakes. That the black nuchal collar of our common
Grass-snake is actually formed by the fusion of the spots of three
originally distinct series has been proved by tracing the development of
the markings in the embryo.
In various species a pair of light streaks extends along the back,
bordering the D area, without interfering with the other markings, as we
see, among European snakes, in some specimens of _Tropidonotus natrix_
and _viperinus_, and _Vipera berus_.
Although it sometimes happens that a definite system of markings
prevails throughout a genus, such as the annulate form in the South
American _Elaps_, this is far from being universally the case; many
closely allied species, or individuals of the same species, may be
distinguished by very different patterns. Even on the same individual we
may find two opposite types of markings without any transition, as in
two Central American species of widely different genera, _Polyodontophis
annulatus_ and _Zamenis mexicanus_, in which the anterior part of the
body is annulate or barred, and the rest longitudinally striped.
It is also a remarkable fact that very often the two sides of the body
are not alike in their markings, appearing as if formed of the union, on
the median line, of the right and left halves of two individuals. Thus
it may happen, in annulate forms, that some of the annuli are broken
exactly in the mid-dorsal and mid-ventral lines, and that the halves do
not correspond in number on the two sides. In the handsome South
American _Lachesis alternatus_, which derives its specific name from the
two series of large C-shaped, dark, light-edged markings which adorn its
back, these markings are not always alternating, as is the rule; but
some may lie opposite to each other and back to back, this being due to
the fact that the numbers of the markings do not correspond on the two
sides. In one specimen I count twenty-four of these markings on the left
side, and twenty-seven on the right. This shows that great importance
cannot be attached to the number of the markings, for systematic
purposes. In fact, in some Coral-snakes, _Elaps fulvius_ for instance,
the number of annuli may vary from twelve to fifty-two, with every
gradation between the extremes. The bilateral asymmetry to which we have
alluded produces the chess-board arrangement of the ventral spots in
many snakes.
Among the markings which call for investigation as to their meaning, we
must allude to the presence, in some Colubrids, of a small, light,
dark-edged spot, or of a pair of light dots close together, in the
middle of the parietal shields or on each side of the suture between
these shields, which correspond in their position to the parietal organ
of many Lizards. May not this marking be in some way correlated with
sensory organs, like the apical pits on the scales of the body? And what
is the explanation of such bizarre signs as the spectacle or the
eye-spot on the hood of the Indian Cobra? At present it is as
inexplicable as the lugubrious emblem on the thorax of the Death's-head
Moth. It cannot be suggested that it is a warning mark intended to
terrify intruders, for when the Cobra is at rest the hood is folded, and
the characteristic marking is not displayed; whilst as soon as it is
aroused, and the hood expanded, it faces its enemy in such a way that
the spectacle, or ocellus, is not to be seen.
First among the most brilliantly coloured snakes, of which there are
many, stand the Coral-snakes, _Elaps_, of America, mostly annulate with
red, yellow or white, and black. This striking coloration obtains also
in diverse harmless snakes inhabiting the same part of the world, and
this coincidence has been adduced in favour of the theory of mimicry,
correlated with that of natural selection, which accounts for the
resemblance as being of advantage to a harmless species, which is thus
mistaken for one notorious for its deadly poison, and advertised as such
by its brilliant colours (warning coloration). But other poisonous and
much more dangerous snakes are not, as a rule, endowed with brilliant
colours. It is true that these also may have their mimics: the Krait,
_Bungarus cæruleus_, and _Lycodon aulicus_, in India, the Pit-viper,
_Ancistrodon himalayanus_, and _Psammodynastes pulverulentus_, in the
Himalayas and Assam, are good examples of such cases. On the other hand,
there are equally striking instances of what one would regard as mimics
if they only occurred together; thus, there is no better case of general
resemblance between a poisonous and a harmless snake than we find in the
Indian Cobra and the _Coluber corais_ of tropical America, where Cobras
are absent, or between a Viper and the Boid _Enygrus asper_, from New
Guinea, where no Vipers exist.
Without attempting to offer any suggestion to account for the similarity
of markings which prevails in certain parts of the world, attention may
be drawn to the predominance of longitudinal dark and light stripes in
the Indo-Malayan representatives of the American _Elaps_, shared by many
innocuous snakes of similar form inhabiting the same region, and to the
striped tails common to various Colubrids of Madagascar, as if the
snakes of a district had agreed to conform to certain fashions in dress.
It is further noteworthy, in relation to the theory of warning
coloration, that many Uropeltids, innocent burrowing creatures living
underground or concealed under stones or rotting tree-trunks in the
forests of Southern India and Ceylon, hardly ever showing themselves in
daylight, are among the most striking for their bright yellow or red and
black markings. We may point out at the same time the very marked
resemblance in form and coloration between the Uropeltid _Melanophidium
bilineatum_, and the Apodal Batrachian _Ichthyophis glutinosus_, both
occurring together in Southern India.
The colour of snakes often harmonizes with their surroundings. Thus,
many Tree-snakes, Boid, Colubrid, or Viperid, are of a bright green,
like the foliage in which they are concealed. On the other hand, other
Tree-snakes are not green, or only some specimens are green, as in the
genera _Dendraspis_ and _Dispholidus_. Desert-snakes are of the
yellowish or reddish colour of the sand or rock on which they live, and
in species whose range extends over different districts the desert
individuals are paler, without or with less distinct markings, as
compared to their fellows among other surroundings. In addition to their
markings, some snakes are adorned with a metallic iridescent gloss, due
to a fine striation of the scales.
The iris is often metallic, gold, bronze, or copper-red, and the black
streaks of the head sometimes extend over it.
Although, unlike many lizards, snakes are unable to rapidly alter their
colours, some produce a semblance of this phenomenon when inflating
their neck or body; this is due to the presence of dark and light
markings or of a bright pigment in the interstitial skin, which is not
seen when the scales overlap. Thus, in the Indian Tree-snake _Dryophis
mycterizans_ the skin between the green or brown scales in the anterior
part of the body is black and white, producing a striped pattern when
the neck is inflated; the skin of the same region is bright vermilion in
the Malay _Tropidonotus subminiatus_; many more examples could be
quoted. The spectacle marking on the hood of the Indian Cobra involves
the scales as well as the interstitial skin.
As a rule there are no sexual differences in colour. Yet these are so
marked in our Common Adder that the sex of a specimen can nearly always
be recognized by the coloration. This is, however, the exception, even
in the genus to which the Adder belongs. A nuptial dress is unknown in
snakes.
A special livery for the young is rather exceptional, but very often the
new-born is more vividly coloured than its parents, and in many black
varieties the young is similar to the typical form. Some green
Tree-Boids (_Chondropython_ and _Corallus caninus_) are not green, but
yellowish, cream-colour, or pinkish, when young, the green appearing
around the white spots, which are the remains of the ground colour, and
gradually spreading over the whole body. Conversely, the young of a
variety of the Pit-viper _Lachesis wagleri_, common in the Malay
Peninsula, is green, and the adult black and yellow. In the young of
_Grayia ornata_, a West African Water-snake, the markings of the young
are to those of the adult like positive and negative in photography, the
white bars, forked on the sides, which extend across the black back of
the former being gradually transformed into black bars on a light ground
in the latter; in such a case it is impossible to decide whether the
dark or the light parts are to be considered as the ground colour.
That the skin of many snakes contains soluble colouring matter of a
special kind is well known, green snakes, such as _Dryophis prasinus_
and _Lachesis gramineus_ staining the spirit in which they are
preserved. Chemists have not yet paid attention to this question, which
requires investigation.
Melanism is frequent in snakes, and sometimes affects all individuals in
the same locality. It seems undesirable to bestow varietal names on such
aberrations, as is so frequently done by systematists, any more than we
should in the case of albinos. Melanism may be produced in two ways: by
an extension of the black markings, which invade the whole surface, as
in the males of _Vipera berus_; or by a general darkening of the ground
colour and of the markings, as in the females of the same species. In
the latter case, the markings reappear under certain lights or after a
prolonged sojourn in spirits. Sometimes, as in _Zamenis gemonensis_, the
uniform black colour appears only as the snake approaches the adult
condition, the young having the normal livery.
Partial albinism is rare; perfect albinism, characterized by absence of
black pigment in the eye, rarer still. Cases have been observed, among
European species, in _Tropidonotus natrix_ and _tessellatus_, in
_Coluber longissimus_, and in _Coronella austriaca_.
------------------------------------------------------------------------
CHAPTER IV
SKELETON
The typical Ophidian skull is characterized by a solidly ossified
brain-case, with the distinct frontals and the united parietals
extending downwards to the basisphenoid, which is large and produced
forward into a rostrum extending to the ethmoidal region. The nasal
region is less completely ossified, and the paired nasals are often
attached only at their base. The occipital condyle is either trilobate
and formed by the basioccipital and the exoccipitals, or a simple knob
formed by the basioccipital; the supraoccipital is excluded from the
foramen magnum. The basioccipital may bear a strong, curved ventral
process or hypapophysis (in the Vipers).
The prefrontal is situated, on each side, between the frontal and the
maxillary, and may or may not be in contact with the nasal; the
postfrontal, usually present, borders the orbit behind, rarely also
above, and in the Pythons a supraorbital is intercalated between it and
the prefrontal.
[Illustration: FIG. 3--SKULL OF _Python amethystinus_. (From British
Museum Catalogue of Snakes)
_an_, Angular; _ar_, articular; _bo_, basioccipital; _bs_,
basisphenoid; _cor_, coronoid; _c.a_, columella auris (stapes); _d_,
dentary; _eo_, exoccipital; _epg_, ectopterygoid (transverse); _f_,
frontal; _m_, maxillary; _n_, nasal; _p_, parietal; _pl_, palatine;
_pm_, premaxillary; _prf_, prefrontal; _pro_, proötic; _pg_,
pterygoid; _ptf_, postfrontal; _q_, quadrate; _so_, supraoccipital;
_sor_, supraorbital; _sp_, splenial; _ste_, supratemporal; _tu_,
turbinal; _v_, vomer.]
The premaxillary is single and small, and as a rule connected with the
maxillary only by ligament. The paired vomer is narrow. The palatine and
pterygoid are elongate and parallel to the axis of the skull, the latter
diverging behind and extending to the quadrate or to the articular
extremity of the mandible; the pterygoid is connected with the maxillary
by the ectopterygoid or transverse bone, which may be very elongate, and
the maxillary often emits a process towards the palatine, the latter
bone being usually produced inwards and upwards towards the anterior
extremity of the basisphenoid. The quadrate is usually large and
elongate, and attached to the cranium through the supratemporal (often
regarded as the squamosal). In rare cases (_Miodon_, _Polemon_) the
transverse bone is forked, and articulates with two branches of the
maxilla. The quadrate and the maxillary and palatopterygoid arches are
more or less movable to allow for the distension required by the passage
of prey, often much exceeding the calibre of the mouth. For the same
reason, the rami of the lower jaw, which consist of dentary, splenial,
angular, and articular elements, with the addition of a coronoid in the
Boidæ and a few other small families, are connected at the symphysis by
a very extensible elastic ligament.
The hyoid apparatus is reduced to a pair of cartilaginous filaments
situated below the trachea, and united in front.
There are various modifications according to the genera. A large vacuity
may be present between the frontal bones and the basisphenoid
(_Psammophis_, _Coelopeltis_); the maxillary may be much abbreviated and
movable vertically, as in the Viperidæ; the pterygoids may taper and
converge posteriorly, without any connexion with the quadrate, as in the
Amblycephalidæ; the supratemporal may be much reduced, and wedged in
between the adjacent bones of the cranium; the quadrate may be short or
extremely large; the prefrontals may join in a median suture in front of
the frontals; the dentary may be freely movable, and detached from the
articular posteriorly.
[Illustration: FIG. 4--SKULL OF _Typhlops lumbricalis_. (From British
Museum Catalogue of Snakes)
Lettering of the bones as in Fig. 3]
[Illustration: FIG. 5--SKULL OF _Glauconia macrolepis_. (From British
Museum Catalogue of Snakes)
Lettering of the bones as in Fig. 3]
The deviation from the normal type is much greater still when we
consider the degraded, worm-like members of the families Typhlopidæ
(Fig. 4, p. 43) and Glauconiidæ (Fig. 5), in which the skull is very
compact and the maxillary much reduced. In the former this bone is
loosely attached to the lower aspect of the cranium; in the latter it
borders the mouth, and is suturally joined to the premaxillary and the
prefrontal. In both the tranverse bone and the supratemporal are absent,
but the coronoid element is present in the mandible.
[Illustration: FIG. 6--SKULL OF _Tropidonotus natrix_. (From British
Museum Catalogue of Snakes)
Lettering of the bones as in Fig. 3]
The principal modifications of the skull in the European genera may be
contrasted as in the following synopsis:
I. Quadrate articulating with the cranium, supratemporal absent;
mandible much shorter than the skull, with coronoid bone; maxillary
small, on lower aspect of cranium; pterygoids not extending to
quadrate; nasals forming long sutures with the premaxillary,
prefrontals, and frontal
_Typhlops._
II. Quadrate suspended from the supratemporal; mandible at least as
long as the skull; pterygoids extending to quadrate or mandible.
_A._ Mandible with coronoid bone; nasals in sutural contact with
frontals and prefrontals; transverse bone short, not projecting much
beyond cranium; maxillary not half as long as mandible, which is not
longer than skull (to occiput)
_Eryx._
[Illustration: FIG. 7--SKULL OF _Zamenis gemonensis_. (From British
Museum Catalogue of Snakes)]
_B._ No coronoid bone; nasals isolated.
1. Maxillary elongate, not movable vertically.
_a._ Maxillary half as long as mandible.
Supratemporal half as long as skull, projecting far beyond cranium;
mandible much longer than skull
_Tropidonotus._
Supratemporal not half as long as skull, projecting far beyond cranium;
mandible much longer than skull
_Zamenis._
[Illustration: FIG. 8--SKULL OF _Coluber longissimus_. (From British
Museum Catalogue of Snakes)]
Supratemporal not half as long as skull, projecting but slightly
beyond cranium; mandible much longer than skull
_Coluber._
Supratemporal not half as long as skull, not projecting beyond
cranium; mandible not longer than skull
_Coronella_, _Contia_.
_b._ Maxillary not half as long as mandible, which is longer
than skull; supratemporal not half as long as skull,
projecting beyond cranium.
[Illustration: FIG. 9--SKULL OF _Coronella austriaca_. (From British
Museum Catalogue of Snakes)]
Quadrate longer than supratemporal; maxillary much longer than
quadrate, nearly straight in front of prefrontal; a large vacuity
between the frontal bones and the basisphenoid
_Coelopeltis._
Quadrate not longer than supratemporal; maxillary little longer than
quadrate, strongly curved in front of prefrontal
_Macroprotodon._
Quadrate longer than supratemporal; maxillary little longer than
quadrate, nearly straight in front of prefrontal
_Tarbophis._
[Illustration: FIG. 10--SKULL OF _Vipera lebetina_. (From British
Museum Catalogue of Snakes)
Lettering of the bones as in Fig. 3]
2. Maxillary much abbreviated and erectile; supratemporal not half
as long as skull; mandible much longer than skull; basioccipital
with a strong process.
Maxillary bone solid
_Vipera._
Maxillary bone hollowed out
_Ancistrodon._
The vertebræ number 130 to 500--in the European forms 147 (_Vipera
ursinii_) to 330 (_Coluber leopardinus_).
The vertebral column consists of an atlas (composed of two vertebræ)
without ribs; numerous precaudal vertebræ, all of which, except the
first or first three, bear long, movable, curved ribs with a small
posterior tubercle at the base, the last of these ribs sometimes forked;
two to ten so-called "lumbar vertebræ" without ribs, but with bifurcate
transverse processes (lymphapophyses) enclosing the lymphatic vessels;
and a number of ribless caudal vertebræ with simple transverse
processes. When bifid, the ribs or transverse processes have the
branches regularly superposed.
The centra have the usual cup-and-ball articulation, with the nearly
hemispherical or transversely elliptic condyle at the back (procoelous
vertebræ), whilst the neural arch is provided with additional articular
surfaces in the form of pre- and post-zygapophyses, broad, flattened,
and overlapping, and of a pair of anterior wedge-shaped processes called
zygosphene, fitting into a pair of corresponding concavities, zygantrum,
just below the base of the neural spine. Thus the vertebræ of snakes
articulate with each other by eight joints in addition to the
cup-and-ball on the centrum, and interlock by parts reciprocally
receiving and entering one another, like the joints called
"tenon-and-mortice" in carpentry. The precaudal vertebræ have a more or
less high neural spine which, as a rare exception (_Xenopholis_), may be
expanded and plate-like above, and short or moderately long transverse
processes to which the ribs are attached by a single facet. The centra
of the anterior vertebræ emit more or less developed descending
processes, or hæmapophyses, which are sometimes continued throughout
(Fig. 11, A), as in _Tropidonotus_, _Vipera_, and _Ancistrodon_, among
European genera.
[Illustration: FIG. 11--POSTERIOR PRECAUDAL VERTEBRÆ OF _Lioheterodon_
(A) AND _Heterodon_ (B). (From British Museum Catalogue of Snakes)
_a_, Back view; _b_, lower view; _c_, side view.]
In the caudal region, elongate transverse processes take the place of
ribs, and the hæmapophyses are paired, one on each side of the hæmal
canal. In the Rattlesnakes the seven or eight last vertebræ are enlarged
and fused into one.
No snake shows any rudiments of the pectoral arch, but remains of the
pelvic are found in the _Typhlopidæ_, the _Glauconiidæ_, the _Boidæ_,
and the _Ilysiidæ_. In the first these vestiges are reduced to a single
bone (ilium?) on each side; in the second they consist of ilium, pubis,
and ischium, the latter forming a ventral symphysis, and a rudimentary
femur; whilst in the third there is a long ilium, attached to the lower
branch of the first bifurcate transverse process of the lumbar vertebræ,
bearing three short bones, the longest of which, regarded as the femur,
terminates in a claw-like spur which, in males at least, usually appears
externally on each side of the vent.
------------------------------------------------------------------------
CHAPTER V
DENTITION
In the most generalized snakes--those which show the nearest approach to
lizards--teeth are present not only on the rami of both jaws, but also
on the premaxillary bone, on the palatines, and on the pterygoids. A
reduction of the dentition takes place in various genera, in which the
teeth of either the upper or the lower jaw, and of the palatines or
pterygoids, or both, may be absent, and the premaxillary is devoid of
teeth in the great majority, including all European representatives, of
the Ophidia.
In the egg-eating snakes of the genera _Dasypeltis_ and _Elachistodon_
the dentition is very much reduced, in accordance with the peculiar
régime, and this deficiency is compensated by the development on some of
the anterior thoracic vertebræ of long, tooth-like processes
(hypapophyses) directed forwards, and capped with a remarkably dense,
vitreous tissue simulating enamel, the function of these tooth-like
processes being to break the shell of the egg within the gullet, where
none of its contents are lost, the shell being afterwards rejected
through the mouth in the form of a pellet.
With the exception of the worm-like Typhlopidæ, which are provided with
a few teeth in the upper jaw only, European snakes have teeth on the
maxillary, palatine, pterygoid, and dentary bones. Unless the maxillary
be strongly abbreviated and modified in connexion with the poison
apparatus, as in the Viperidæ, the teeth in the jaws as well as on the
palate form single longitudinal series; they are elongate, conical, with
or without a sharp posterior edge, more or less recurved, acutely
pointed, sometimes needle-like, and directed backwards, as behoves their
function, which, in addition to attack and defence, is to prevent the
retrogression of the prey in the act of prehension and deglutition. A
notable exception occurs in the genus _Iguanognathus_, from Sumatra, all
the teeth having spatulate crowns ribbed along the outer side.
Unfortunately, nothing is known as to the food of this remarkable snake.
The teeth are coated with a thin layer of enamel. It was held, for a
time, that the glossy outer coating was only due to a denser structure
of the dentine. As in all living Reptiles with the exception of the
Crocodiles, the teeth are not implanted in true sockets, but simply
ankylosed to the bone on which, when detached, their slightly enlarged
base, or rather the bony tissue on which it rests, leaves a shallow
impression, or pseudo-socket. In the process of biting or feeding, some
of the teeth are frequently lost, and are readily replaced by others
lying in reserve in the gum at the inner side, and becoming fixed to the
bone soon after a vacancy occurs. Such replacement teeth, of different
grades of development, form several series, so that in a snake like our
common _Tropidonotus_ the mouth may contain four times as many teeth as
are functional, without reckoning different earlier stages of tooth
germs which escape ordinary observation, being placed vertically one
above the other.
Three types of teeth, connected by every intermediate step, are
distinguished: the solid, the grooved, and the canaliculated or tubular,
so-called "perforated"; the third, as we shall explain, being only a
further modification of the second. In the grooved tooth, a sulcus runs
along the anterior or outer surface, its object being to convey into the
wound the secretion of a poison gland. It varies in depth according to
the species, and may be so slight as to escape detection without a very
strong magnifying glass. In some the sulcus may be very deep and wide,
forming a canal round which the tooth folds to the extent of its borders
nearly meeting; from this condition the so-called "perforated" fang is
derived through the complete fusion of the borders of the tooth, and the
obliteration of the line of union except at each extremity. The
structure of such a fang may be best understood by imagining a tooth,
lined all round with the same layer of dentine and enamel, being
flattened out in a vertical plane and then folded over, the outer edges
coalescing on the front median line in such a way that the inner wall of
the tooth is in reality the anterior surface, and the outer wall the
posterior surface, of the ordinary tooth.
Grooved teeth, with open canal, are situated either at the anterior
extremity (Proteroglyphs) or at the posterior extremity (Opisthoglyphs)
of the maxillary bone, usually followed or preceded by a series of solid
teeth, which in some cases may likewise show a more or less distinct
groove. Such may also be present on the teeth of the lower jaw, as in
the European _Coelopeltis_, in some specimens of which a faint groove is
visible on the outer side with the aid of a strong lens.
The tubular fangs of the Viperidæ are inserted on the posterior
extremity of the much abbreviated and erectile maxillary bone, which
bears no other teeth. The Proteroglyphs (Cobras, Coral-snakes,
Sea-snakes) and the Solenoglyphs (Vipers, Pit-vipers, Rattlesnakes) may
be regarded as the diverging extremes in the development of the poison
apparatus, both culminating in forms with tubular fangs, the former as
derived directly from the Aglyphs (harmless snakes), the latter from the
Opisthoglyphs, likewise evolved out of the Aglyphs. That the insertion
of the poison fangs of the Viperidæ is really on the posterior extremity
of the maxillary bone is evident from the condition of the bone in its
recumbent position, especially in the African Viper, _Causus_, which in
several respects departs less markedly from the Colubrid type than our
European Vipers.
The poison fangs of the Viperidæ appear to be movable, folding in the
mouth when at rest, and erected, or even thrust forward, when ready to
act. This, however, is simply due to the mobility of the maxillary bone,
to which they are ankylosed as in all other snakes. There are normally
two equally-developed fangs, close together and side by side, to each
maxillary, followed by several replacement fangs loosely attached behind
them, usually in two series of four. When the two fangs are _in situ_,
they of course both function in the act of biting, although only one is
in relation with the single poison duct; often, however, there is only
one fang in position, either the right or the left, the place of the
other being indicated by a shallow socket which will soon be filled by
one of the posterior reserve fangs moving forward and becoming ankylosed
to the bone. Snake-charmers who extract the poison fangs of the snakes
they use for their performances have therefore to renew the operation
frequently, unless they amputate the bone on which the fangs are
inserted, an injury which the creature does not long survive.
The dentition of the snakes in which the maxillary bone is not movable
vertically falls under three divisions: the Aglyphs, in which the teeth
are all solid; the Opisthoglyphs, in which one or more (usually two) of
the hindermost teeth are provided with a groove; and the Proteroglyphs,
in which grooved or canaliculated teeth are situated in front, followed
or not by solid teeth. Beyond these three principal divisions, the
dentition furnishes important characters for the classification,
although that importance has sometimes been over-estimated. The
maxillary teeth may be equal in length (Isodonts), or the anterior the
longer (Lycodonts), or the posterior the longer, increasing gradually in
size (Coryphodonts) or abruptly, without (Syncranterians) or with a
diastema, or break, in front of them (Diacranterians). These categories
are, however, so completely connected as to preclude their use in
taxonomy beyond helping to define genera. The number of maxillary teeth
and the relative proportions and disposition of the mandibular teeth
also afford useful generic characters.
The European genera may be arranged as follows, according to the
dentition:
I. Teeth few, disposed in a transverse series in the upper jaw only
_Typhlops._
II. Teeth in both jaws and on the palatines and pterygoids.
_A._ A series of solid teeth along the maxillary; no grooved teeth.
1. Anterior maxillary and mandibular teeth longest; 9 or 10
maxillary teeth
_Eryx._
2. Maxillary teeth equal, or increasing in size posteriorly.
_a._ Mandibular teeth 17 to 30; maxillary teeth 15 to 22.
Posterior maxillary teeth longest; mandibular teeth subequal, more than
20
_Tropidonotus._
Posterior maxillary teeth longest; mandibular teeth not more than 20,
posterior smallest
_Zamenis._
Maxillary teeth subequal; mandibular teeth 20 to 25, posterior smallest
_Coluber._
_b._ Mandibular teeth 14 or 15, subequal; maxillary teeth 12 to
15.
Maxillary teeth increasing in size
_Coronella._
Maxillary teeth subequal
_Contia._
_B._ One or two enlarged grooved fangs behind the series of solid
maxillary teeth.
14 to 17 subequal solid maxillary teeth, forming a continuous series;
21 to 23 mandibular teeth, anterior strongly enlarged
_Coelopeltis._
9 to 11 solid maxillary teeth, fourth and fifth or fifth and sixth
enlarged, followed by an interspace; sixth mandibular tooth fang-like,
followed by an interspace
_Macroprotodon._
9 or 10 solid maxillary teeth, forming a continuous series, decreasing
in length posteriorly; anterior mandibular teeth strongly enlarged
_Tarbophis._
_C._ Maxillary with only two large canaliculated fangs side by side,
one of which may be missing; anterior mandibular teeth longest
_Vipera_, _Ancistrodon_.
[Illustration: FIG. 12--MAXILLARY AND MANDIBLE OF--(_a_) _Tarbophis
fallax_; (_b_) _Coelopeltis monspessulana_; (_c_) _Macroprotodon
cucullatus_. (From British Museum Catalogue of Snakes)]
In counting the teeth for the purpose of using this key, care must be
taken to ascertain the full number, as it frequently happens that one or
more are missing; but their place is indicated by the shallow pits in
which their base was implanted, the overlooking of which might convey
the impression of a hiatus such as is characteristic of certain
genera--_Macroprotodon_, for instance. Needless to say, the loose teeth
which are in reserve on the inner side of the jaws or behind the tubular
fangs are not taken into consideration, the numbers given being those of
functional teeth only. Although as a rule the teeth can be counted
easily, on a specimen preserved in spirit, by simply pushing aside the
lips and gums with the finger, it is sometimes necessary to remove and
clean the bones of the jaws, an operation which does not require much
skill.
------------------------------------------------------------------------
CHAPTER VI
POISON APPARATUS--DIFFERENT KINDS OF POISONS
The gland which secretes the poison is a modification of the parotid
salivary gland of other Vertebrates, and is usually situated on each
side of the head below and behind the eye, invested in a muscular
sheath. It is provided with large alveoli in which the venom is stored
before being conveyed by a duct to the base of the channelled or tubular
fang through which it is ejected.
In the Vipers, which furnish examples of the most highly developed
poison apparatus, although inferior to some in its toxic effects, the
poison gland is very large and in intimate relation with the masseter or
temporal muscle, consisting of two bands, the superior arising from
behind the eye, the inferior extending from the gland to the mandible.
When the snake bites, the jaws close up, causing the gland to be
powerfully wrung, and the poison pressed out into the duct. From the
anterior extremity of the gland the duct passes, below the eye and above
the maxillary bone, where it makes a bend, to the basal orifice of the
poison fang, described above (p. 55), which is ensheathed in a thick
fold of mucous membrane, the _vagina dentis_. By means of the movable
maxillary bone (_supra_, p. 49) hinged to the prefrontal, and connected
with the tranverse bone which is pushed forward by muscles set in action
by the opening of the mouth, the tubular fang is erected and the poison
discharged through the distal orifice in which it terminates.
[Illustration: FIG. 13--POISON APPARATUS OF RATTLESNAKE: VENOM GLAND
AND MUSCLES (LATERAL VIEW). (After Duvernoy)
_a_, Venom gland; _a´_, venom duct; _b_, anterior temporal muscle;
_b´_, mandibular portion of same; _c_, posterior temporal muscle;
_d_, digastricus muscle; _e_, posterior ligament of gland; _f_,
sheath of fang; _g_, middle temporal muscle; _h_, external pterygoid
muscle; _i_, maxillary salivary gland; _j_, mandibulary salivary
gland.]
In some of the Proteroglyphous Colubrids, as we have seen, the poison
fangs are not tubular, but only channelled and open along the anterior
surface; and as the maxillary bone in these snakes is more or less
elongate, and not or but slightly movable vertically, the poison duct
runs above the latter, making a bend only at its anterior extremity, and
the tranverse bone has not the same action on the erection of the fangs.
Otherwise the mechanism is the same.
In the Opisthoglyphous Colubrids, with grooved teeth situated at the
posterior extremity of the maxilla, a small posterior portion of the
upper labial or salivary gland is converted into a poison-secreting
organ, distinguished by a light yellow colour, provided with a duct
larger than any of those of the labial gland, and proceeding inward and
downward to the base of the grooved fang; the duct is not in direct
connexion with the groove, but the two communicate through the mediation
of the cavity enclosed by the folds of mucous membrane surrounding the
tooth, and united in front.
The reserve or successional teeth, which are always present just behind
or on the side of the functional fang of all venomous snakes, are in no
way connected with the duct until called upon to replace a fang that has
been lost. It could not be otherwise, since the duct would require a new
terminal portion for each new fang; and as the replacement takes place
alternately from two parallel series, the new poison-conveying tooth
does not occupy exactly the same position as its predecessor.
Two genera, _Doliophis_ among the Elapine Colubrids, and _Causus_ among
the Viperids, are highly remarkable for having the poison gland and its
duct of a great length, extending along each side of the body and
terminating in front of the heart. Instead of the muscles of the
temporal region serving to press out the poison into the duct, this
action is performed by those of the side of the body.
When biting, a Viperid snake merely strikes, discharging the venom the
moment the fangs penetrate the skin, and then immediately leaves go. A
Proteroglyph or Opisthoglyph, on the contrary, closes its jaws like a
dog on the part bitten, often holding on firmly for a considerable time.
The poison, which is mostly a clear limpid fluid of a pale straw or
amber colour, more rarely greenish, sometimes with a certain amount of
suspended matter, is exhausted after several bites, and the glands have
to recuperate.
It must be added that the poison can be ejected otherwise than by a
bite, as in the so-called Spitting Snakes of the genera _Naia_ and
_Sepedon_. The fact that some of these deadly snakes when irritated are
in the habit of shooting poison from the mouth, at a distance of 4 to 8
feet, even apparently aiming at a man's face, has been too often
witnessed in India and Malaya, and especially in Africa, from the days
of the ancient Egyptians, for any doubt to subsist as to their being
endowed with this faculty, but the mechanism by which this action is
produced has not been satisfactorily explained. In all probability, the
poison escapes from the sheath of mucous membrane surrounding the base
of the fangs, and is mixed with ordinary saliva, the membranes of the
mouth perhaps acting as lips, in which case the term "spitting" would
not be incorrect. The spitting, which may take place three or four times
in succession, has been observed to be preceded by some chewing
movements of the jaws. If reaching the eye, the poisonous fluid causes
severe inflammation of the cornea and conjunctiva, but no more serious
results if washed away at once.
Snake poisons is a subject which has always attracted much attention,
and which has made great progress within the last quarter of a century,
especially as regards the defensive reaction by which the blood may be
rendered proof against their effect by processes similar to
vaccination--antipoisonous serotherapy. The studies to which we allude
have not only conduced to a method of treatment against snake-bites, but
have thrown a new light on the great problem of immunity. They have
shown that the antitoxic serums do not act as chemical antidotes in
destroying the venom, but as physiological antidotes; that, in addition
to the poison glands, snakes possess other glands supplying their blood
with substances antagonistic to the poison, such as also exist in
various animals refractory to snake poison, the hedgehog and the
mungoose for instance. Unfortunately, the specificity of the different
snake poisons is such that, even when the physiological action appears
identical, serum injections or graduated direct inoculations confer
immunity towards one species or a few allied species only. Thus, a
European in Australia who had become immune to the poison of the deadly
_Notechis scutatus_, manipulating these snakes with impunity, and was
under the impression that his immunity extended also to other species,
when bitten by a _Denisonia superba_, an allied Elapine, died the
following day. In India, the serum prepared with the venom of _Naia
tripudians_ has been found to be without effect on the poison of _Naia
bungarus_, the two species of _Bungarus_, and the Vipers _Vipera
russelli_, _Echis carinatus_, and _Lachesis gramineus_. _Vipera
russelli_ serum is without effect on Colubrine venoms, and on those of
_Echis_ and _Lachesis_. In Brazil, serum prepared with the venom of
_Lachesis lanceolatus_ has proved to be without action on _Crotalus_
poison. These examples, and others which could be given, show that the
hopes which were at first entertained as to the benefits to be conferred
on mankind by the serum treatment were somewhat over-sanguine--at least
as regards countries like India, where, different kinds of poisonous
snakes occurring together, it is sometimes impossible to know by which
the bite has been inflicted.
Chemistry teaches that snake venoms consist for the most part of
solutions of modified proteids, and all attempts to separate the toxic
principles from such proteids have hitherto been unsuccessful.
Accordingly, at the present time we must regard such toxic principles as
residing in some special grouping of a portion of the atoms in the
complex venom proteid molecule. The analysis of their physiological
actions has proved them to be made up of a great many more constituents
than would be imagined from their chemical composition.
The effect of the poison of Proteroglyphous Colubrids (Hydrophids,
Cobras, _Bungarus_, _Elaps_, _Pseudechis_, _Notechis_, _Acanthophis_) is
mainly on the nervous system, respiratory paralysis being quickly
produced by bringing the poison into contact with the central nervous
mechanism which controls respiration; the pain and local swelling which
follow a bite are not usually severe.
Viper poison (_Vipera_, _Echis_, _Lachesis_, _Crotalus_) acts more on
the vascular system, bringing about coagulation of the blood and
clotting of the pulmonary arteries; its action on the nervous system is
not great, no individual group of nerve cells appears to be picked out,
and the effect upon respiration is not so direct; the influence upon the
circulation explains the great depression which is a symptom of Viperine
poisoning. The pain of the wound is severe, and is speedily followed by
swelling and discoloration. The symptoms produced by the bite of the
European Vipers are thus described by the best authorities on snake
poison (Martin and Lamb): The bite is immediately followed by local pain
of a burning character; the limb soon swells and becomes discoloured,
and within one to three hours great prostration, accompanied by
vomiting, and often diarrhoea, sets in. Cold, clammy perspiration is
usual. The pulse becomes extremely feeble, and slight dyspnoea and
restlessness may be seen. In severe cases, which occur mostly in
children, the pulse may become imperceptible and the extremities cold;
the patient may pass into coma. In from twelve to twenty-four hours
these severe constitutional symptoms usually pass off; but in the
meantime the swelling and discoloration have spread enormously. The limb
becomes phlegmonous, and occasionally suppurates. Within a few days
recovery usually occurs somewhat suddenly, but death may result from the
severe depression or from the secondary effects of suppuration. That
cases of death, in adults as well as in children, are not infrequent in
some parts of the Continent is mentioned in the last chapter of this
Introduction.
The bite of all the Proteroglyphous Colubrids, even of the smallest and
gentlest, such as the _Elaps_ or Coral-snakes, is, so far as known,
deadly to man. The Viperidæ differ much among themselves in the toxicity
of their venom. Some, such as the Indian _Vipera russelli_ and _Echis
carinatus_, the American _Ancistrodon_, _Crotalus_, _Lachesis mutus_ and
_lanceolatus_, the African _Causus_, _Bitis_, and _Cerastes_, cause
fatal results unless a remedy be speedily applied. On the other hand,
the Indian and Malay _Lachesis_ seldom cause the death of man, their
bite in some instances being no worse than the sting of a hornet. The
bite of the larger European Vipers may be very dangerous, and followed
by fatal results, especially in children, at least in the hotter parts
of the Continent; whilst the small _Vipera ursinii_, which hardly ever
bites unless roughly handled, does not seem to be possessed of a very
virulent poison, and, although very common in some parts of
Austria-Hungary, is not known to have ever caused a serious accident.
It is noteworthy that the size of the poison fangs is in no relation to
the virulence of the venom. The comparatively innocent Indo-Malay
_Lachesis_ alluded to above have enormous fangs, whilst the smallest
fangs are found in the most justly dreaded of all snakes, the
Hydrophids.
Little is known of the physiology of the poison of the Opisthoglyphous
Colubrids, except that in most cases it approximates to that of the
Proteroglyphs. Experiments on _Coelopeltis_, _Psammophis_,
_Trimerorhinus_, _Dipsadomorphus_, _Trimorphodon_, _Dryophis_,
_Tarbophis_, _Hypsirhina_, and _Cerberus_, have shown these snakes to be
possessed of a specific poison, small mammals, lizards, or fish, being
rapidly paralyzed and succumbing in a very short time, whilst others
(_Eteirodipsas_, _Ithycyphus_) do not seem to be appreciably venomous.
Man, it is true, is not easily affected by the bite of these snakes,
since, at least in most of those which have a long maxillary bone, the
grooved fangs are placed too far back to inflict a wound under ordinary
circumstances. There are, however, exceptions. A case was reported a few
years ago of a man in South Africa nearly dying as a result of the bite
of the Boomslang, _Dispholidus typus_, the symptoms, carefully recorded,
being those characteristic of Viperine poisoning, an important fact to
oppose to the conclusions, based on the physiological experiments on
_Coelopeltis_, which appeared to disprove the theory that the Viperidæ
may have been derived from Opisthoglyphous Colubrids.
Experiments made with the secretion of the parotid gland of
_Tropidonotus_ and _Zamenis_ have shown that even Aglyphous snakes are
not entirely devoid of venom, and point to the conclusion that the
physiological difference between so-called harmless and poisonous snakes
is only one of degree, just as there are various steps in the
transformation of an ordinary parotid gland into a poison gland or of a
solid tooth into a tubular fang.
The question whether all snakes are immune to their own poison is not
yet definitely settled. Most snakes certainly are, and it is a
remarkable fact that certain harmless species, such as the North
American _Coronella getula_ and the Brazilian _Rhachidelus brazili_, are
proof against the poison of the Crotalines which frequent the same
districts, and which they are able to overpower and feed upon. The
Cribo, _Spilotes variabilis_, is the enemy of the Fer-de-lance in St.
Lucia, and it is said that in their encounters the Cribo is invariably
the victor. Repeated experiments have shown our Common Snake,
_Tropidonotus natrix_, not to be affected by the bite of _Vipera berus_
and _V. aspis_, this being due to the presence, in the blood of the
harmless snake, of toxic principles secreted by the parotid and labial
glands, and analogous to those of the venom of these Vipers.
The Hedgehog, the Mungoose, the Secretary Bird, and a few other birds
feeding on snakes, are known to be immune to an ordinary dose of snake
poison; whether the pig may be considered so is still uncertain,
although it is well known that, owing to its subcutaneous layer of fat,
it is often bitten with impunity. The Garden Dormouse (_Myoxus
quercinus_) has recently been added to the list of animals refractory to
Viper poison.
------------------------------------------------------------------------
CHAPTER VII
NERVOUS SYSTEM--SENSE ORGANS
The brain is small and of very oblong shape. It consists of smooth
cerebral hemispheres, small optic lobes, a still smaller cerebellum, and
long olfactory lobes; the pineal body is not accompanied by a parietal
organ. The spinal accessory cranial nerve is absent, and the sympathetic
system is but feebly developed.
The eyes have been noticed above (p. 12). When normally developed they
are susceptible of a slight movement under the transparent disc, quite
independent from the cornea, which covers them, and from which they are
separated by the so-called "lacrymal chamber." There are two lacrymal
glands, one in front and one behind; the lacrymal duct opens into the
posterior nares. A sclerotic bony ring is absent.
The olfactory organ proper is little developed, but is accompanied by an
accessory organ, Jacobson's organ, consisting of a pair of pediculate,
cup-shaped sacs, between the nasal sacs and the roof of the mouth,
encapsuled by the vomers and the turbinal bones, lined by olfactory
epithelium, and opening in the mouth just in front of the choanæ. As
this organ, richly provided with nerves, communicates with the inside of
the mouth, its function may be to smell the prey as it passes through
previous to deglutition. Snakes cannot be credited with a keen sense of
smell, although undoubtedly guided by it during the nuptial period.
In the more thoroughly aquatic snakes, the nostril may be closed, when
respiration is suspended, by a spongy tissue, which acts as a stopper,
and such nostrils are called "valvular," although a valve is not, in the
strict sense, present; when the animal breathes, the nostril is opened
by a compression, through special muscles, of the cavernous tissue. In
some Sand-snakes the narial opening may be reduced to a crescentic slit.
The sense of hearing is not much developed. Tympanum, tympanic cavity,
and Eustachian tubes are absent. In the typical snakes a long columellar
rod (the stapes), with a fibrous or cartilaginous pad at the outer end,
extends from the fenestra ovalis in the cranium to the quadrate, but in
the degraded burrowing forms the stapes is a small bony plate closing
the fenestra ovalis.
With one exception (_Eryx jaculus_, which is said by Schreiber to lap
like a lizard), the tongue is not used for drinking or for the
prehension or gustation of food, nor for hissing, but is a tactile organ
protruded on any object the snake wishes to probe. It is slender and
deeply bifid at the end, smooth, very protractile, often quite to the
length of the head, and furnished with many sensory corpuscules. It is
darted and vibrated on the least excitement, and is usually looked upon
by the ignorant as a "sting." In most snakes it is much pigmented, dark
brown or black; in a few it is flesh-coloured or bright red. The tongue
is entirely retractile into a sheath below the glottis and opening in
front of it; it is always withdrawn into the sheath when the snake bites
or feeds.
Other organs, which, in the absence of a satisfactory explanation of
their use, have been termed "organs of a sixth sense," reside in the
head-shields and scales of many snakes, and in the deep pits on the
sides of the head which are characteristic of various Boidæ and a few
Colubridæ.
Scales often show, near their posterior extremity, one or two small
light spots or impressions, caused by a thinning of the epidermis, which
have been called "apical pits"; they appear to coincide with the
terminations of nerve fibres extending along the epidermal folds of the
skin. Similar organs sometimes form series on the borders of some of the
head-shields, this being particularly noticeable in the Typhlopidæ.
The large and deep pit situated between the nostril and the eye (loreal
pit) in the Crotaline Viperidæ--whence the name Pit-vipers, or that of
"cuatro naricas" which is bestowed on them by the Spaniards of
Mexico--is divided into two chambers: an outer with large external
orifice, and an inner, rather more posterior in position and occupying
an excavation on the outer face of the maxillary bone. The inner walls
of these chambers are very thin and membranous, and form a partition
separating the two, except for the presence of a minute opening; this
partition is stretched across the hollow of the maxillary bone like the
membrane of a drum, and is supplied with blood-vessels and nerves, the
latter terminating in cells of variable form. The use of the organ, thus
situated at the base of the poison fang, and therefore in close
proximity to the sphincter of the poison duct, is still unknown.
Several of the Boidæ, such as _Python_ and _Corallus_, have deep pits in
some of the upper and lower labial shields, or also on each side of the
rostral shield; these problematic organs are in all probability also
sensory.
------------------------------------------------------------------------
CHAPTER VIII
VISCERA
In most snakes there is a very marked asymmetry of the viscera and their
blood-supply, the organs of the right side being anterior to, as well as
larger than, those of the left.
The heart in most cases is situated between the anterior seventh and the
anterior fourth of the body; it may be much farther back, beyond the
anterior third, in _Doliophis_, _Platurus_, and some Viperidæ and
Amblycephalidæ, in the middle in _Chersydrus_. It is of rather elongate
form, enclosed in a pericardium in which it lies freely, and has a sinus
venosus, two auricles, and a single ventricle divided by a septum. Three
arteries leave the ventricle, the pulmonary and two systemic arches. The
right systemic arch gives off the carotid artery, which in many snakes,
the common Grass-snake for instance, may branch into two, or in others
be double from its origin. The anterior abdominal vein is single in most
snakes, double in some Boidæ, and conveys blood from the ventral
body-wall to the liver. The caudal vein is continued as the renal
portal. Veins which have been regarded as remains of the two posterior
cardinal of lower Vertebrates have been found in some of the Boidæ.
The bifurcate transverse processes of the vertebræ at the limit between
the body and tail enclose the lymph-hearts, which are large and more or
less elongate, metamerically divided into several chambers, the right
often more developed than the left. The thymus gland lies on each side
of the trachea, near the heart, and the thyroid gland is in the middle
line, close to the base of the carotid artery.
The trachea is long, and the tracheal rings may be complete in front and
incomplete behind, or incomplete throughout. The bronchus opens at once
into the more or less elongate, usually single lung, with or without a
rudiment of a second, which seems to be constantly the left; in some
snakes the lung extends nearly to the cloacal region. In most of the
Boidæ there are two well-developed lungs, the left shorter than the
right. The lung has highly cellular walls in front, and becomes
thin-walled, smooth, or but little vascular, behind, where it may
receive its blood from the systemic and not from the pulmonary
circulation. In the Typhlopidæ and Viperidæ, as well as in some of the
Boidæ, Colubridæ, and Amblycephalidæ, the posterior end or the greater
part of the trachea may have its wall enlarged and provided with air
cells, resembling the normal lung, with which it is usually continuous;
this has been called the "tracheal lung," but, although serving as an
accessory breathing organ, it is not a prolongation of the true lung,
nor does it represent the missing left lung, as has been believed by
some authors.
The glottis has a longitudinal slit, and can be projected forwards when
the pharynx is obstructed by a voluminous prey. An epiglottis is usually
absent, or represented by a rudiment. It is, however, present in some
large American species of _Coluber_ (_Pityophis_), said to produce, when
hissing, a loud and hoarse sound which has been compared to the bellow
of the bull--hence the popular name of Bull-snakes by which they are
known. It has also been found in a few allied species from Mexico, for
which the genus _Epiglottophis_ has been proposed. This epiglottis is a
narrow, thin flap, erect in front of the glottis; it is not hinged, and
therefore not capable of falling down to cover the opening of the
windpipe during the process of swallowing, its function evidently being
to increase the sound produced by the escape of the air from the
windpipe.
The larynx is represented by two longitudinal bands of cartilage, united
by transverse bands; it is extremely long in some snakes
(_Leptognathus_).
The oesophagus, which may be extremely elongate, sometimes measuring
almost one-third of the digestive canal, passes into the tubular or
sac-like stomach, often with thickened walls, which itself gradually or
abruptly merges into the narrower intestine. The windings of the small
intestine are connected by ligamentous tissue, and enclosed in a common
sheath of peritoneum. In several of the Glyphodont Water-snakes
(Homalopsinæ and Hydrophiinæ), the intestine is much convoluted; in
_Herpeton_ it is even longer than the body, although when coiled
occupying only one-fourth of that length. The rectum is sometimes very
short, sometimes rather long, and its anterior portion may have a short
cæcum; it may be divided by transverse septa, with median or lateral
perforation.
In snakes which swallow hard-shelled snails, the anterior part of the
intestine has its inner wall furnished with zigzag muscular folds
producing a reticulate appearance, followed farther down by transverse
and then longitudinal folds. In these snakes the intestine is abruptly
constricted behind the stomach, at which point the shells are broken or
crushed after their contents have been digested; whilst in the
egg-eating snakes, in which the eggshell has to be broken previous to
its contents reaching the stomach, the oesophagus is narrowed in front
of the latter, at the point where the tooth-like ventral processes of
the vertebræ project and pierce the wall of the oesophagus in order to
aid in this function, after which the broken shell is rejected through
the mouth.
The more or less elongate, feebly-lobed kidneys are placed in the
posterior part of the body, often extending nearly to the cloaca; the
right is usually a little longer than the left, or extends a little
farther forward, or even may commence where the other ends. The
suprarenal bodies are narrow and elongate, placed on the renal veins or
on the vena cava inferior.
The ureters leave the hind ends of the kidneys, and open through the
side-walls of the cloaca on a papilla which in the males contains also
the opening of the vas deferens. There is no urinary bladder. The
genital organs will be mentioned in the next chapter. The liver is
usually long and narrow, measuring one-fifth to one-fourth the length of
the body, on the right side of the alimentary canal, commencing just
behind the heart or farther back. It is exceptionally short in
_Chersydrus_. It is sometimes divided by transverse furrows. Its
posterior extremity is bilobate, and the left lobe usually extends
beyond the right, although the reverse has been observed in some snakes.
The gall-bladder, which may be absent, is remarkable for its distance
from the liver. The pancreas, elongate but comparatively small, is
located near the spleen, on the left side of the alimentary canal, at a
considerable distance from the liver.
The peritoneal part of the body-cavity is subdivided into a number of
spaces or coelomic compartments enclosed in serous capsules--viz., a
posterior or intestino-genital, a gastric on the left side, and a pair
round the liver, corresponding to its two lobes.
Fat-bodies are much developed, either in the form of small separate
lobes, or as a continuous, much folded band, on each side of the body.
------------------------------------------------------------------------
CHAPTER IX
ORGANS OF REPRODUCTION; PAIRING; OVIPOSITION; DEVELOPMENT
The genital glands are situated anterior to the kidneys, the right
extending farther forward and often larger than the left. The testes are
elongate. The vas deferens is closely folded proximally, and runs along
the outer side of the kidney into the cloaca close to the ureter. The
ovaries are elongate, and consist of two lamellæ, with a lymph-space
between them. The oviduct extends from near the anterior extremity of
the ovary to a common chamber, or vagina, which is above the rectum and
opens into the cloaca; this vaginal chamber may be more or less
completely divided into two.
The males are provided with a pair of intromittent organs, or hemipenes,
each connected with one of the caudal vertebræ by a muscle (_retractor
penis_) which often exceeds it in length. These organs are cylindrical
or club-shaped and hollow, with the inner surface divided into numerous
cavities and beset with papillæ, and usually also with hard spines, of
which those towards the apex may be greatly developed, folded against
the walls, and directed towards the extremity. Such spines are absent in
the snakes provided with claw-like rudiments of hind limbs. The cavities
of the hemipenis are connected by a branch with the dorsal artery, and
it is by a flow of blood into them that erection of the organ is
accomplished. Each hemipenis is lodged in a cavity on each side of the
base of the tail; when protruded it turns inside out, and the inner
surface becomes the outer, the papillæ and erected spines serving to
maintain a firm hold in the vagina, from which the organ cannot be
withdrawn except by invagination. It has been observed that the presence
of spines on the hemipenis is associated with much tougher vaginal
walls. The organ is grooved along its entire length, the groove being
the _sulcus spermaticus_, which, when the edges of the two hemipenes
meet, forms with its fellow a canal to convey the semen into the
oviduct; this sulcus may be bifurcate, as in the Viperids and some
Colubrids.
Anal pockets, secretory organs on each side of the vent and lodged in
the base of the tail, seem, in females, to be the homologues of the
hemipenes; but this view cannot be held, since the same organs are
present, though smaller, in males also, situated dorsally to the
hemipenes. The glands with which they are provided produce the strong
and offensive odour which appears to be a means of defence in our
Grass-snake and other species, and which also serves to bring the sexes
together, the glands being more active during the breeding season. A
Viper-catcher in France is said to obtain good results by rubbing his
boots with these glands, as a means of attracting the snakes in the
spring.
In European species pairing takes place in spring, sometimes again at
the end of summer or in autumn. After hibernation the testes of the
males are rather voluminous, and the sperm-ducts are often full of
spermatozoa. The male gets alongside the female, sometimes seizing her
round the neck with his jaws, and remains stretched out against her or
twists the posterior part of his body in a few coils around hers. In the
Vipers the bodies of the pairing individuals are completely entwined.
The male then endeavours to bring the two anal orifices together, and
when he has succeeded in getting the female to distend her cloacal
opening, the intromittent organs are suddenly everted into the vagina.
The union of the sexes sometimes lasts only a few minutes, but usually
an hour or more; it has even been observed to last a whole day. Several
copulations may take place at intervals of a few days. Many snakes are
gregarious during the breeding season, and great numbers of males have
been seen wriggling round the females, forming with their coils huge
lumps or an entangled mass like a ball. The more or less prehensile tail
with which thoroughly aquatic snakes, such as _Hydrophis_ and
_Acrochordus_, are provided, is no doubt of use in facilitating the
pairing, when it has to take place in the water. Our European
Water-snakes pair on land.
During the rutting season a slight pressure on the base of the male's
tail may cause the protrusion of the hemipenes, and so may a violent
blow on the spine of the reptile. Thus, recently killed specimens of our
Adder, with the organs everted, have more than once been taken by the
ignorant for snakes with hind limbs, a mistake which must be pardoned
when we remember that male embryos of the slow-worm and of snakes, in
which the hemipenes are normally everted, have been described by
zoologists, who should have known better, as examples showing external
vestiges of limbs.
The spermatozoa soon make their way up the oviducts, in which the ripe
ova have previously descended, or which gradually descend shortly after,
these ducts becoming dilated in consequence. There are usually more eggs
in the right than in the left oviduct, although the reverse has
occasionally been observed.
Some snakes lay eggs shortly after impregnation, or a few weeks later;
in others the young undergo their development within the oviducts, each
enveloped in a thin, transparent, membranous capsule, which is torn
immediately before or immediately after parturition, such species being
termed "ovoviviparous." Just before oviposition the female curves the
base of the tail upwards, in order to extend the cloacal opening. The
eggs are all produced together, usually at intervals of a few minutes,
and generally adhere to one another by means of a sticky fluid secreted
by the oviducts, thus forming a clump. In ovoviviparous snakes the young
are born in succession, in the course of a few hours or of a few days.
In many oviparous species it is the rule for freshly-laid eggs to
contain more or less developed embryos, and _Coronella punctata_ is said
to produce thin-shelled eggs which hatch in less than half the time
required for the eggs of its American congeners under the most
favourable circumstances. There is thus almost every degree between
oviparity and ovoviviparity.
These two modes of parturition bear no relation to the natural
affinities of snakes. Thus, the European _Coronella austriaca_ is
ovoviviparous, and its North American congeners are oviparous; whilst,
curiously, it is the inverse in the genus _Tropidonotus_. It was long
believed to be an invariable rule for the Viperidæ to bring forth live
young, the name Viper being derived from this well-known peculiarity,
but it has now been ascertained that the South American _Lachesis
mutus_, the Indo-Malay _Lachesis monticola_, and the African _Causus_
and _Atractaspis_, lay eggs. All exclusively aquatic snakes, such as the
Hydrophiinæ, are ovoviviparous, and thus dispensed from going on land
for parturition.
The yolk entirely fills the eggshell; there is no albumen, or, if any
exists, it is so much reduced as to easily escape observation. The
eggshell in oviparous species contains a small amount of lime, and is
not hard, but tough and parchment-like, white or yellowish; it is
usually smooth, but in Pythons its surface is studded with minute pores,
and in the American _Zamenis constrictor_ it is rough, as if sprinkled
over with loose grains of salt. The shape varies from a short oval to a
long ellipse. It has been observed in some snakes that the eggs, on
leaving the cloaca, are of an elongate shape, suggestive of a short
cigar, and immediately after assume a more oval form. After they have
been laid, the eggs absorb moisture and thus increase in size,
especially in width; eggs which are at first twice as long as broad may
be almost globular just before the birth of the young.
The number of eggs or young of one brood varies much according to the
species, and also according to the age of the mother, large females
usually producing a higher number and of a larger size than smaller
specimens of the same species. Our European _Zamenis_, _Coluber_, and
_Coronella_ produce only 2 to 15; our _Tropidonotus_, 15 to 48; our
Vipers, 3 to 22. Among exotics we may mention, as the most prolific,
_Bitis nasicornis_, up to 47 young; _Tropidonotus fasciatus_, _Abastor
erythrogrammus_, and _Farancia abacura_, 50; _Lachesis lanceolatus_, 60;
_Vipera russelli_, 63; _Boa constrictor_, 64; _Tropidonotus ordinatus_,
78; _Pseudaspis cana_, 80; _Python molurus_, nearly 100 eggs.
The eggs are deposited in holes without any sort of nest, under moss or
decomposing leaves, in accumulations of saw-dust, or in manure-heaps. In
many cases it has been observed that the female remains for some time
with her eggs or young, and in the large Pythons a sort of incubation
takes place, the female remaining coiled in a spiral over the mass of
eggs for six to eight weeks; an increase of several degrees in her
temperature at that period has been ascertained by experiments conducted
with every possible care, a remarkable fact in the case of a so-called
"cold-blooded" animal.
The numerous reports of young snakes seeking refuge in their mother's
gullet have not been substantiated by satisfactory scientific evidence,
and, although it is perhaps wise to say that the question remains an
open one, it may be mentioned that, in Europe at least, trained
observers who have devoted special attention to the habits of Vipers, in
districts where these reptiles are exceedingly abundant, have never come
across an instance of the form of maternal solicitude with which these
snakes in particular have been credited. Not a single reported case of a
female snake swallowing her young for protection rests on satisfactory
evidence.
The embryo is closely coiled up in a spiral. Just before birth it is
distinguished by a large, convex head, with large, prominent eyes, and a
comparatively short body, the scales and ventral shields being much
shorter than later in life. The umbilicus is situated in the posterior
part of the body, from six to ten times as far from the head as from the
vent. Long after birth the umbilical slit remains visible, and affords a
means of distinguishing very young snakes from older examples of smaller
species. In oviparous species the embryo is provided with a very
conspicuous egg-tooth, pointing forwards and projecting from the notch
in the lower border of the rostral shield; this egg-tooth is much
reduced, and sometimes very indistinct, in the ovoviviparous species.
The function of the egg-tooth is to cut through the tough eggshell.
This, after the young has left it, shows one or several slits in its
anterior extremity, cut as clean as if with a sharp knife. The egg-tooth
becomes loose soon after birth, and is shed within a few hours or a few
days, sometimes even before birth in ovoviviparous species.
Frequent cases have been observed of dicephalous embryos or young, which
may live for a short time; there are even records of a three-headed
snake, stated to have been seen at Lake Ontario, and of snakes with two
heads and two tails.
Unless prematurely born with a considerable mass of vitellus attached to
the umbilicus, the young immediately after birth resent all
interference, hissing, snapping, or puffing themselves up, after the
manner of their parents. The first shedding of the outer coating of the
epidermis follows soon after birth; not before then does the young take
to food.
No snake appears to be able to breed before it is four years old.
Well-authenticated instances of different species interbreeding are
unknown, but specimens intermediate between _Vipera berus_ and _V.
aspis_, and between _V. berus_ and _V. ammodytes_, have been assumed,
with much probability, to be hybrids.
------------------------------------------------------------------------
CHAPTER X
HABITS
Snakes may be grouped, according to their mode of life, in five
principal categories, gradually merging into each other, or two of them
not infrequently found combined in one and the same species. These
categories are:--Ground-snakes, Sand-snakes, Burrowing-snakes,
Tree-snakes, and Water-snakes.
Ground-snakes may be defined as living above ground, and only
occasionally climbing bushes or entering the water. Among European
genera, _Coronella_ and _Vipera_ are perfect examples of this type,
whilst _Coluber_ and _Zamenis_ approach the Tree-snakes in often
ascending bushes, or even trees.
Sand-snakes are adapted for living on loose sand, in which they seek
concealment. Such are _Lytorhynchus_ and some _Psammophis_ among the
Colubridæ, _Cerastes_ among the Viperidæ. _Eryx_ connects this category
with the next.
Burrowing-snakes live chiefly underground, and often have the visual
organ atrophied in consequence, as in _Typhlops_; all the Typhlopidæ,
Glauconiidæ, and Uropeltidæ, belong to this category; the Viperid
_Atractaspis_ is also a burrowing type.
Tree-snakes spend the greater part of their life on bushes or trees.
_Corallus_ among the Boidæ, _Dendrophis_ and _Dendraspis_ among the
Colubridæ, _Atheris_ and various species of _Lachesis_ among the
Viperidæ, may be quoted as examples.
Of Water-snakes, some are exclusively aquatic, like the marine
Hydrophiinæ and the typical Acrochordinæ (_Acrochordus_, _Chersydrus_)
and Homalopsinæ (_Hipistes_, _Herpeton_). _Chersydrus_ and _Hipistes_
occur in the sea as well as in fresh water. Many species of
_Tropidonotus_ (_T. tessellatus_ and _T. viperinus_ in Europe), as well
as the genera _Helicops_, _Grayia_, _Boulengerina_, etc., among the
Colubridæ, _Eunectes_ among the Boidæ, _Ancistrodon piscivorus_ among
the Viperidæ, are chiefly but not exclusively aquatic.
Our _Tropidonotus natrix_ stands between the Ground-snakes and the
Water-snakes; Boas and Pythons are as much Water-snakes as Tree-snakes.
As shown by these and many other examples which might be given, a
division into categories cannot always be applied with precision, nor
does it convey an expression of the natural relationships of the
species, as was believed by many systematists of the last century, who
appealed to such adaptations for the definition of families.
A vertical pupil denotes more or less nocturnal habits. Nevertheless our
European Vipers, which are provided with such a contractile pupil, are
far from exclusively nocturnal, delighting to bask in the sun, and
pairing and feeding in the day-time. The Boidæ appear to be more
nocturnal, but no snake is known to be absolutely so, and the two
species of _Coluber_ which have been found living in perfect darkness in
limestone caves in the Malay Peninsula and China, where they feed
chiefly on bats, occur also outside the caves, and probably never breed
in them.
It is often stated in books that the organs of locomotion for the
exceedingly elongate body of snakes are the ribs, and these creatures
have even been compared to Centipedes. This statement is no doubt true
to a certain extent for slow locomotion on uneven ground, when the ribs
and the corresponding ventral shields afford a point of support; but it
does not account for the rapid movements, as when a snake darts like an
arrow in pursuit of its prey or to escape from an enemy. Besides, the
winding motions are not different from those of a Slow-worm or
Glass-snake, in which, encased as they are in a bony armour, the ribs
cannot come into play at all. The action of the muscles alone is quite
sufficient to account for the reptation of snakes, without the ribs
having to play an essential part.
Not only the Cobras, but several harmless snakes, are able to raise the
anterior third of the body vertically, when taking up a threatening
attitude in the presence of an enemy, at the same time widening or
inflating the region behind the head.
Most snakes can climb, and in this case the ribs and ventral shields are
of great assistance. The Tree-snakes, usually characterized by a very
slender, sometimes compressed, body, or by a prehensile tail, are
specially adapted for twining themselves round branches, and in several
of them the presence of a keel on each side of the ventral and subcaudal
shields, accompanied by a notch corresponding to the keel, affords an
additional help for climbing on vertical uneven surfaces, such as the
trunks of trees. This condition of the ventral shields has a bearing on
the extraordinary mode of locomotion with which some Tree-snakes
(_Chrysopelea_, and probably also _Dendrophis_) have long been credited
by the Malays. We allude to the so-called Flying-snakes, remarkable for
their habit of shooting down from trees and descending to the ground at
an oblique angle, the body being kept rigid the whole time of the
"flight." It has been observed in _Chrysopelea_ that the ventral surface
between the lateral keels, which may be compared to hinges, can be drawn
in and become deeply concave, whilst at the same time a slight
dorso-ventral flattening of the body takes place. During this muscular
contraction the snake is like a piece of bamboo bisected longitudinally,
and is buoyed up in such a way as to explain its parachute-like descent.
All snakes are able to swim, and the more aquatic kinds may spend a few
hours under the water. A _Python molurus_ is known to have remained
alive in a basket sunk for thirty-six hours in a river. The best adapted
for aquatic life are the Hydrophiinæ, or Sea-snakes, most of which never
leave the water, and are quite helpless and soon die when brought on
shore; their body is more or less compressed posteriorly, and the tail
oar-shaped. Sea-weeds and barnacles sometimes settle on them. Algæ have
also been observed growing on the fresh-water snake _Herpeton
tentaculatum_.
As regards food, Burrowing-snakes, as well as a few small Ground-snakes,
subsist mostly on worms, insects, and myriopods; Tree-snakes on lizards,
frogs, birds and their eggs; Water-snakes on fishes and batrachians.
Among the other types, some show a predilection for mammals, others for
lizards or snakes, whilst not a few feed indiscriminately upon mammals,
birds, reptiles and batrachians, even on slugs, insects, and worms, in
addition. However surprising, it is a fact that spiny mammals are
occasionally eaten, spines of the Madagascar Hedgehog (_Ericulus_)
having been found in the excrements of a _Boa madagascariensis_. Even
hard-shelled eggs and molluscs may constitute the principal or exclusive
food of certain snakes.
Thus, _Dasypeltis_ eats nothing but birds' eggs, the shells of which are
crushed in the gullet, by a special contrivance mentioned above (p. 80),
and are soon after rejected through the mouth as a pellet. Other snakes,
such as _Coluber_ and _Lioheterodon_ show themselves partial to eggs in
addition to live prey, but their alimentary canal does not depart from
the normal, the eggs being broken in the stomach and the remains of the
shells passed with the excrements.
The Amblycephalidæ subsist almost entirely on snails and slugs, the
shells of the former being crushed in the anterior part of the intestine
after their contents have been digested, and the débris are rejected
through the vent. A small land tortoise has been found in the stomach of
a Cobra (_Naia haie_) from Algeria.
Snakes which take large prey secure it according to three methods: By
catching it simply with the jaws, and immediately proceeding to swallow
it, as in _Tropidonotus_ and in some of the Constrictors when dealing
with small animals; by constriction, after having seized it with the
jaws, crushing it in the coils of their body and thus killing it
previous to feeding, as in the Boidæ and _Coluber_; or by poisoning, by
a mere stroke with the fangs, the result being awaited before the meal
is begun, as in most of the Viperidæ. Other poisonous snakes proceed
according to the first method, the use of the venom being to reduce the
struggles of the victim and to relax its muscles. Such snakes as are in
the habit of previously killing their prey show little reluctance to
accept dead food in confinement, a thing which others usually refuse to
do; they may, however, be deceived by the dead animal being agitated
before them, and the system now adopted in our Zoological Gardens, of
offering all snakes previously-killed animals, has been attended with
comparative success.
Some species feed almost exclusively on other snakes, and often manage
to swallow individuals as large as, or even a little larger than,
themselves. Examples are known of harmless snakes showing a predilection
for dangerous species, to whose poison they are immune (see p. 71).
As a rule snakes that eat fish will also eat batrachians, but nothing
higher in the scale, although exceptions have been reported, such as the
Anaconda feeding on mammals, birds, reptiles, and fish, and our
Grass-snake having taken mice and birds. Some that feed chiefly on
lizards and snakes will occasionally eat also mammals, and _vice versa_,
but rarely frogs. On the other hand, European Vipers accommodate
themselves to a more varied bill of fare, being known to feed on
mammals, birds, reptiles, batrachians, insects, and slugs, and they have
even been observed to eat voles showing signs of putrefaction.
The enormous prey which some snakes are able to swallow is quite
astounding. Anacondas and Pythons, the largest snakes, have been known
to swallow calves and good-sized antelopes with their horns, animals
which, even after being somewhat crushed by constriction, very much
exceed the calibre of the snake. A _Python molurus_ 17 feet long is
reported on good evidence to have swallowed a gravid Axis deer. A
Grass-snake half an inch in diameter can manage a frog or toad three
times that width, and a _Dasypeltis_ of the same size a hen's egg. Such
feats are rendered possible by the mobility of the jaws and
palato-pterygoid arch on the cranium, and the elasticity of the
ligaments by which they are attached (see above, p. 42), as well as by
the mobility of the ribs and the absence of sternal apparatus, together
with the great distensibility of the skin. When a snake proceeds to
dispose of a large prey, which, if it be a mammal or bird, is usually
seized head-first, it pulls itself forward by alternate movements of the
jaws, the maxillary and the mandibular ramus of the one side, and then
of the other, being extended anteriorly and laterally, the snake at the
same time producing an abundant salivation which renders the prey very
slimy. Several repeated alternate movements of the jaws bring the head
of the prey to the gullet, where the muscles and ribs come into play,
and the two sides of the jaws work no longer alternately, but together.
When once in the oesophagus, the prey progresses with much greater
facility, and usually reaches the stomach in a few minutes, whilst the
previous process of deglutition may have lasted half an hour. While this
laborious operation is going on, the breathing of the snake is not
impaired owing to a remarkable contrivance: the trachea can be protruded
in such a manner as to bring its opening outside the mouth.
In cases where the victim is eaten alive, the snake has to contend with
its struggles, but retrogression is rendered impossible by the
backwardly-directed sharp teeth with which the jaws and palate are
beset. A frog is usually caught by one of the hind limbs and swallowed
back-first, the long hind limbs stretching forwards as they fold against
the body; its struggles are often still apparent when it has reached the
oesophagus. Snakes when caught immediately after a meal are in the habit
of disgorging their food, and it sometimes happens that a frog or toad
is thus vomited alive. An instance is known of a naturalist having
captured a Grass-snake and put it in a linen bag. On opening it a short
time after, great was his surprise to find the snake had escaped through
a small hole in the bag, leaving instead a living toad too big to pass
through the hole.
If not of too large a size, several animals will often be swallowed in
rapid succession, after which the gorged snake will allow its digestive
organs several days, or even weeks, of repose. A large Anaconda in the
Paris Jardin des Plantes fed only thirty-six times in the course of
seven years. Digestion is usually rapid in the small snakes, defecation
taking place twenty-four to forty-eight hours after the feeding; it
lasts much longer in the large Boas and Pythons. Thus, in the
above-mentioned Anaconda it has been observed to take from nine to
thirty-eight days. Even the hardest bones of birds are decomposed by the
gastric juices, but hairs, feathers, and horny productions, are passed
with the excrements, sometimes forming regular balls. It is in most
cases possible to tell, from an inspection of the dried fæces, what a
snake has been feeding on, hairs, feathers, beaks, claws, epidermal
horny shields, bits of tooth-enamel, being found mixed with the chalky
matter which represents the decomposed bones. As a rule there is but one
defecation after each meal, but there are in addition more frequent
renal dejections, consisting chiefly of uric acid.
In captivity snakes show themselves capricious in the choice of food,
one individual preferring mammals, whilst another, of the same species,
will only take birds; and many, although to all appearances perfectly
healthy, will persist in refusing all food, and allow themselves to die
of starvation--a suicide which may require months, or even years, to
accomplish. A Rattle-snake in the menagerie of the Jardin des Plantes in
Paris has lived two years and two months without taking any food, a
_Python sebæ_ nearly two years and a half, a _Boa madagascariensis_ four
years and a month. A _Viper aspis_ was kept for three years without food
and without losing its vicious temper. Specimens thus fasting do not, as
a rule, renew their epidermis, or do so but very rarely. Our Common
Adder can very seldom be induced to feed in captivity. Other snakes may
rid themselves of all shyness to the extent of taking food from the
hand, or show such appetite as to seize a prey immediately on being
released from the small box or bag in which they have travelled for a
considerable time.
Most snakes drink, and pretty often--not by lapping with the tongue, but
by drawing in water from the mouth and immersing the anterior part of
the head. Some are said to be fond of milk, but there is no foundation
for the belief held by peasants, that they enter sheds with the object
of sucking milk from the cows, which would be a material impossibility;
their real purpose in visiting such places being a search for suitable
dung-heaps in which to deposit their eggs.
Snakes cannot be credited with much intelligence or educability, nor do
they display any very marked instincts. The least stupid and most easily
tamed are the species of the genera _Coluber_ and _Coronella_. There is,
however, considerable difference in this respect between individuals of
the same species. Most snakes, when freshly caught, defend themselves by
biting, and some individuals retain their savage temper after months of
captivity; others hardly ever bite, even if molested. The Common
Grass-snake, for instance, hisses loudly and takes up a very threatening
attitude, or even pretends to snap with open mouth, but very seldom
bites; its principal defensive action when caught consists in voiding a
most repulsive secretion from its anal glands, which it evidently
controls, as it ceases doing so when accustomed to being handled. The
same snake also produces, during the spring, an oily exudation from the
skin which has the same repulsive smell. Mr. H. N. Ridley has observed a
Malay snake allied to _Tropidonotus_, _Macropisthodon rhodomelas_, to
exude drops of a white viscid liquid from the skin of its neck, which is
flattened out like that of a Cobra when in an attitude of defence, and
he noticed that his dog, seizing the snake to worry it, foamed at the
mouth as if he had been biting a toad.
The hissing is produced by the rapid expulsion of air from the lungs
through the trachea and the notch at the end of the mouth, which is kept
shut at the time. Snakes provided with an epiglottis (see p. 79) produce
a much louder hissing. Other sounds are produced by some snakes. Thus,
the Indian and African Vipers of the genera _Echis_ and _Cerastes_ make
a curious, prolonged, rustling noise, by rubbing the folds of the sides
of the body against one another. This sound is produced by friction
between the serrated keels of the lateral scales, which are disposed
obliquely with their tips directed downwards and backwards; the noise
can even be repeated after the death of the animal, by twisting the body
and thus rubbing or rasping these little saws against one another. The
same thing probably takes place in the African genus _Dasypeltis_, in
which we find a similar arrangement of the scales, though to a less
degree.
The best known sounding apparatus is that of the Rattlesnakes, described
on p. 20. When alarmed, these snakes gather the body in a few coils or
roll themselves up in a spiral, with the tail erect in the centre, and
vibrating with great rapidity, whilst the head is ready for attack.
Other snakes, such as the _Ancistrodon_ and some species of _Coluber_
and _Zamenis_, when excited, vibrate the tail in the same manner; but,
being deprived of the sound-producing apparatus, this expression of
their anger does not attract the same attention. It is from such a
habit, however, that the rattle must have been evolved and perfected,
not necessarily in a Lamarckian sense, but through the different steps
by which evolution or creation has proceeded; _Natura non fecit saltus_,
as Linnæus well said. Many suggestions have been made as to the use of
the rattle. One of them is that the rattling resembles the sound made by
locusts, and serves to decoy insect-eating birds; another, that it
serves to call the sexes together. Probably it is useful to the snake as
a warning to keep off disturbers which cannot serve as food, and thus
prevents useless expenditure of venom, or even the breaking of the
fangs. At any rate, it gives expression to the snake's excitement, as
does the voice in the case of many other animals, and it seems
reasonable to suppose that it may be applied to different purposes. With
the advent of man, this means of attracting attention must tend to the
more rapid extermination of the snakes which possess it.
Another curious behaviour is that of feigning death, as observed in a
harmless but vicious-looking snake, _Heterodon_, often called Puff-adder
in America. It looks more like a Viper than a harmless snake, and when
disturbed hisses loudly and flattens out the anterior part of the body,
much as does a Cobra, and pretends to strike, although it is one of the
few snakes that never bite man. If, however, this display proves of no
avail in frightening away the intruder, the snake rolls on its back and
opens its mouth, and then lies for a time, which may exceed a quarter of
an hour, absolutely motionless, as if dead. As soon as it thinks the
danger over, it awakens from its spasm and rapidly moves off. It is the
opinion of those who have most experience of this snake that this
extraordinary behaviour is not to be explained as a convulsion or faint
due to fright, but constitutes a deliberate trick to save its life.
Individuals of the South African Ringhals (_Sepedon hæmachates_) and of
the Common Grass-snake have also been observed to feign death.
The notion that snakes fascinate their prey, attracting it or reducing
it to immobility by a mysterious power in their glittering eyes, is pure
fable. Animals placed in a cage with a snake evince no particular
fright, and fly away when pursued, if not actually turning round to
defend themselves. It is even dangerous to offer a good-sized snake a
wild rat for food, as all keepers of menageries know.
In cold and temperate climates snakes hibernate, lying more or less
torpid in holes or hollow trees, sometimes assembled in numbers and
coiled together in a mass. The first thing they do in awakening in the
spring is to cast the outer coating of the epidermis, as described above
(p. 20). Several exuviations take place during the period of activity,
sometimes pretty regularly every month, sometimes at very irregular
intervals. A few days previous to this operation the snake is languid
and abstains from feeding; its skin is dull and the sight impaired by
the opaque condition of the lid; a day or two before moulting, the outer
stratum of the epidermis becomes again transparent and the eye clear,
through this stratum becoming detached from the subjacent tissue, until
it is pulled off in one piece, by the snake rubbing itself against
stones or bushes. The first exuviation takes place very shortly after
birth.
Snakes are long-lived, although the limit of duration of life is not
known in any of them. They grow slowly, and do not appear ever to reach
sexual maturity until the fourth year, when they continue increasing in
size for a long period. A _Python reticulatus_ and an _Ancistrodon
piscivorus_ are reported to have lived twenty-one years in captivity in
Paris. The young of many snakes are very secretive, and are not often
found in the open, those that are met with being as a rule either
new-born or approaching sexual maturity.
Snakes are tenacious of life, and remarkable for the reflex movements
which take place after they have been cut to pieces, the severed parts
of the body and tail wriggling for a considerable time, and the head
endeavouring to bite. Accounts of decapitated Rattlesnakes turning round
and striking with their bloody stumps are probably not snake stories.
------------------------------------------------------------------------
CHAPTER XI
PARASITES
Like all other animals, snakes are infested with a multitude of
vegetable and animal parasites, both external and internal. About 300
species of Ophidian parasites have been recorded; yet our knowledge of
them is very imperfect. Although some 2,000 species of snakes are known,
parasites have not been recorded for more than 168 species, and in the
great majority of these (102) only a single parasite: a tick, a
hæmogregarine, or some intestinal worm. Owing to the more frequent
opportunity of dissecting them, the common menagerie snakes have yielded
better records, notwithstanding the fact that they usually lose most of
their parasites through constant handling, prolonged fasting, and
artificial surroundings. Thus, we have a list of thirteen species for
the Indian _Python molurus_, and one of twenty-two species for the _Boa
constrictor_. But no systematic search appears to have been attempted,
save, perhaps, in the case of a few European species.
It is interesting to notice that it was the finding of an Ophidian
parasite which prompted Francesco Redi to write his famous "Observations
on the Living Animals which are found within Living Animals." This work,
a veritable treatise of comparative parasitology, published in 1684,
caused the great naturalist, physician, and poet to be regarded as the
father of that science. He tells us that in dissecting a curious
dicephalous _Vipera aspis_, caught at Pisa, he found within the
intestines a number of roundworms (_Ascaris cephaloptera_), and on the
surface of one of the two lobes of the liver five cysts enclosing a
small worm, which he rightly ascribed to the same species.
The parasites of snakes are here enumerated by Dr. L. W. Sambon, in
systematic order.
ARTHROPODA.--Two families of the class Arachnida, the Ixodidæ and the
Linguatulidæ, furnish numerous species parasitic on snakes.
Of the Ticks (Ixodidæ) we find, as a rule, species of the genera
_Amblyomma_ and _Aponomma_, the latter genus being almost entirely
confined to Reptiles. A single species of the genus _Hæmaphysalis_ (_H.
punctata_, Can. and Franz, 1877) has been reported once from _Vipera
aspis_. A few larval forms found on various snakes have been reported
under the generic name _Ixodes_, but they probably belong either to
_Amblyomma_ or _Aponomma_.
The Ophidian Tick-parasites, like those of mammals, birds, lizards, and
tortoises, appear to be in many cases the means of transmission of
protozoal infections from snake to snake.
The Tongue-worms (Linguatulidæ) are, without doubt, of the greatest
possible interest. Their systematic position has ever been a puzzle to
zoologists, and even now is a matter of controversy. They have been
looked upon as Hirudinea by Winsberg (1765), Cestoda by Chabert (1787),
Acanthocephala by Humboldt (1808), Trematoda by Rudolphi (1809), and
Nematoda by Nordmann (1832). It was Van Beneden (1848) who first
recognized their Arthropod nature, but he placed them amongst the
Crustacea. Schubärt (1853) suggested that their proper position is
amongst the Mites (Acarina), and Leuckart (1860) adduced important
anatomical and embryological evidence in support of this view, which was
confirmed by Railliet in 1883 and by Sambon in 1910.
No less than three out of the four genera of Linguatulids so far
established are represented by species parasitic on snakes. They are the
genera _Porocephalus_, _Reighardia_, and _Raillietiella_.
The genus _Porocephalus_ is of special interest, because some of its
species, such as _Porocephalus armillatus_, a parasite of African
Pythons (_Python regius_, _P. sebæ_) and Puff-adders (_Bitis arietans_,
_B. nasicornis_, _B. gabonica_), and _Porocephalus moniliformis_, a
parasite of Oriental Pythons (_Python molurus_, _P. reticulatus_), are,
in their nymphal stage, deadly parasites of mammals, including man.
The genus _Reighardia_ was established by Professor H. B. Ward, in 1899,
for a Linguatulid of gulls and terns, first described, in 1861, by De
Filippi. In 1910 Sambon included in this genus other similarly
structured Linguatulids from crocodiles, monitors, and snakes.
The genus _Raillietiella_ was established by Sambon in 1910 for a
Linguatulid (_Raillietiella boulengeri_) of the African Puff-adders
(_Bitis arietans_, _B. gabonica_). Amongst the characters of this genus
is one of great structural and phylogenetic importance--viz., the
position of the female sexual orifice at the anterior end of the
abdomen, whilst in the other known genera it is at the posterior
extremity.
According to Prowazek, Sambon, and Laveran, the Ophidian Linguatulids,
which live as blood-suckers in the air-passages of their hosts, are able
to foster and transmit the hæmogregarines of these hosts.
ACANTHOCEPHALA.--The early encysted stages of several species of
Thorn-headed worms (_Acanthocephala_), belonging to the family
_Echinorhynchidæ_, have been reported from snakes belonging to very
different genera, such as _Boa_, _Tropidonotus_, _Zamenis_, _Drymobius_,
_Xenodon_, _Dipsadomorphus_, _Oxyrhopus_, _Erythrolamprus_, _Diemenia_,
_Naja_, _Elaps_, _Vipera_, _Lachesis_. Their further development
probably occurs in ophiophagous birds. Thus, _Echinorhynchus
oligacanthoides_, Rud., the immature stages of which occur encapsuled
within the body cavity of _Lachesis lanceolatus_ and other neotropical
snakes, when adult is found attached to the intestinal mucosa of _Milvus
bidentatus_.
NEMATODA.--The roundworms (_Nematoda_) so far described from snakes
belong to the families Ascaridæ, Strongylidæ, Trichotrachelidæ, and
Filariidæ. Some of the genera belonging to these families, such as
_Cucullanus_, _Nematoxys_, _Oxysoma,_ are as yet represented by a single
species in a single host; others, such as _Ascaris_, _Polydelphis_,
_Heterakis_, _Strongylus_, _Diaphanocephalus_, _Physaloptera_,
_Trichosoma_, number already several species more or less widely
distributed.
Eelworm infection (ascariasis) is very common in snakes, and not
infrequently the infection is a heavy one; Sambon twice found over fifty
specimens of _Polydelphis_ in Puff-adders (_Bitis arietans_). This
investigator has shown that the snake eelworms undergo an encysted stage
of development within the body cavity of their hosts before migrating
into the intestinal lumen for the purpose of fertilization and
oviposition. Thus, Redi was quite right in considering the immature,
encysted forms found in one of the livers of his double-headed Asp as
belonging to the same species of eelworm (_Ascaris cephaloptera_) as
that which the snake harboured in its intestine.
Professor A. Railliet, whilst examining specimens of _Polydelphis_ which
had been preserved for nearly two months in a 3 per cent. solution of
formalin, found that the ova within their uterine tubes had undergone
development, and still contained living embryos; indeed, some of these
hatched under the microscope, and moved very actively in the preserving
fluid. This is in no way surprising, because even after several years of
preservation in formalin solution the embryos of other species of
eelworms (_Ascaris equorum_, _A. marginata_) have been found in a living
condition.
TREMATODA.--The Flukes (_Trematoda_) of snakes, so far described, belong
to the following genera: _Agamodistomum_, _Astiotrema_, _Brachylaimus_,
_Cotylotretus_, _Dicrocoelium_, _Diplodiscus_, _Distoma_, _Halipegus_,
_Lecithodendrium_, _Metorchis_, _Opisthogonimus_, _Opisthorchis_,
_Plagiorchis_, _Saphedera_, _Telorchis_, _Tetracotyle_, _Zeugorchis_.
CESTODA.--Save a few larval forms (_Cysticercoides_, _Piestocystis_,
_Sparganum_), the known tapeworms (_Cestoda_) of the Ophidia belong to
the genera _Bothridium_ and _Proteocephalus_.
PROTOZOA.--Numerous species of Hæmogregarines have been described from
snakes. As a rule the forms seen in the peripheral blood are sporonts,
the schizogonic cycle occurring in the lungs. The sporonts do not
greatly alter their host cells; they are invariably doubled up within a
more or less thick capsule. Some species show a marked sexual
differentiation, others not. _Trypanosomes_, _Spiroechaudinniæ_, and
_Plasmodidæ_ have also been described from the blood of various snakes.
Within the alimentary tube have been found species of _Trichomonas_ and
_Caryospora_.
BACTERIA.--Acid-fast bacilli have been described in tubercular lesions
found in snakes by Sibley, Gibbs and Shurley, Shattock, Hausemann, and
Sambon.
The so-called "canker," which so frequently develops in the oral cavity
of captive snakes, is also a bacterial disease, due to a specific
bacterium of thick, rod-shaped form.
LIST OF PARASITES HITHERTO
RECORDED FROM EUROPEAN SNAKES
TROPIDONOTUS NATRIX, L.
ACANTHOCEPHALA.
_Echinorhynchus inæqualis_, Rudolphi.
_Echinorhynchus polyacanthus_, Creplin.
NEMATODA.
_Strongylus auricularis_, Zeder.
_Strongylus catanensis_, Rizzo.
_Trichosoma mingazzini_, Rizzo.
_Oxysoma brevicaudatum_, Zeder.
_Nematoxys commutatus_, Rudolphi.
_Ascaris cephaloptera_, Rudolphi.
TREMATODA.
_Opisthorchis caudatum_, Polonio.
_Dicrocoelium assula_, Dujardin.
_Diplodiscus conicum_, Polonio.
_Tetracotyle colubri_, v. Linstow.
_Distoma acervocalciferum_, Gastaldi.
_Distoma allostomum_, Diesing.
_Distoma nematoides_, Mühling.
_Saphedera naja_, Rudolphi.
_Brachylaimus signatum_, Dujardin.
_Telorchis ercolanii_, Monticelli.
_Lecithodendrium nigrovenosum_, Bellingham.
_Plagiorchis mentulatus_, Rudolphi.
CESTODA.
_Ligula panceri_, Polonio.
TROPIDONOTUS TESSELLATUS, LAUR.
NEMATODA.
_Strongylus denudatus_, Rudolphi.
_Physaloptera abbreviata_, Rudolphi.
_Physaloptera striata_, v. Linstow.
TREMATODA.
_Plagiorchis mentulatus_, Rudolphi.
TROPIDONOTUS VIPERINUS, LATR.
ACANTHOCEPHALA.
_Echinorhynchus lobianchii_, Monticelli.
TREMATODA.
_Distoma allostomum_, Diesing.
_Opisthorchis caudatum_, Polonio.
_Telorchis ercolanii_, Monticelli.
_Astiotrema monticellii_, Stossich.
CESTODA.
_Ligula pancerii_, Polonio.
PROTOZOA.
_Hæmogregarina viperina_, Billet.
ZAMENIS GEMONENSIS, LAUR.
ACANTHOCEPHALA.
_Echinorhynchus cinctus_, Rudolphi.
_Echinorhynchus polyacanthus_, Creplin.
_Echinorhynchus heterorhynchus_, Parona.
NEMATODA.
_Strongylus catanensis_, Rizzo.
_Filaria parvomucronata_, Rizzo.
_Trichosoma sonsinoi_, Parona.
TREMATODA.
_Distoma subflavum_, Sonsino.
_Brachylaimus baraldii_, Sonsino.
_Saphedera naja_, Rudolphi.
CESTODA.
_Cysticercus acanthotetra_, Parona.
_Cysticercoides rostratus_, Mingazzini.
COLUBER QUATUORLINEATUS, LACEP.
ACANTHOCEPHALA.
_Echinorhynchus oligacanthus_, Rudolphi.
NEMATODA.
_Ascaris cephaloptera_, Rudolphi.
TREMATODA.
_Plagiorchis sauromates_, Poirier.
PROTOZOA.
_Hæmogregarina_, sp.
COLUBER LONGISSIMUS, LAUR.
PROTOZOA.
_Hæmogregarina colubri_, Börner.
CORONELLA AUSTRIACA, LAUR.
NEMATODA.
_Tricheilonema megalochilum_, Diesing.
_Physaloptera colubri_, Rudolphi.
CESTODA.
_Piestocystis dithyridium_, Diesing.
PROTOZOA.
_Monocercomonas colubrorum_, Hammersch.
CORONELLA GIRONDICA, DAUD.
PROTOZOA.
_Hæmogregarina coronellæ_, França.
VIPERA BERUS, L.
NEMATODA.
_Physaloptera dentata_, v. Linstow.
TREMATODA.
_Agamodistomum viperæ_, v. Linstow.
_Tetracotyle colubri_, v. Linstow.
VIPERA ASPIS, L.
ARTHROPODA.
_Hæmaphysalis punctata_, Can. & Franz.
ACANTHOCEPHALA.
_Echinorhynchus cinctus_, Rudolphi.
NEMATODA.
_Ascaris cephaloptera_, Rudolphi.
_Diaphanocephalus viperæ_, Rudolphi.
PROTOZOA.
_Caryospora simplex_, Léger.
_Hæmogregarina samboni_, Giordano.
VIPERA AMMODYTES, L.
NEMATODA.
_Ascaris ammodytis_, Rudolphi.
_Ascaris cephaloptera_, Rudolphi.
------------------------------------------------------------------------
CHAPTER XII
DISTRIBUTION
Representatives of the order Ophidia are found over the whole world,
with the exception of Iceland, Ireland, and New Zealand, between the
Northern limit of 67° in Europe (_Vipera berus_), 60° in Asia (_Vipera
berus_), and 52° in America (_Tropidonotus ordinatus_), and the Southern
limit of 44° (_Philodryas schotti_). The highest altitudes reached by
them are 14,000 feet in the Himalayas (_Tropidonotus baileyi_), 9,700
feet in the Alps (_Vipera aspis_), and 9,000 feet in the Andes (_Liophis
albiventris_). They are most numerous between the tropics, and the
number of species gradually diminishes to the North and South.
For the purpose of showing the distribution of the principal groups, we
will follow the divisions into families and subfamilies enumerated above
(p. 4).
_Typhlopidæ._--S.E. Europe, S. Asia, Africa, Australia (exclusive of
Tasmania), C. and S. America, and W. Indies.
_Glauconiidæ._--S. Asia (as far E. as Sind), Africa (exclusive of
Madagascar), C. America (extending into the S. parts of N. America), S.
America.
_Pythoninæ._--S. Asia, Africa (exclusive of Madagascar), Australia
(exclusive of Tasmania), C. America.
_Boinæ._--S.E. Europe, C. and S. Asia, N. Africa, Madagascar, Mauritius,
W. Polynesia, S.W. of N. America, C. and S. America, and W. Indies.
_Ilysiidæ._--S.E. Asia, S. America.
_Uropeltidæ._--India and Ceylon.
_Xenopeltidæ._--S.E. Asia.
_Acrochordinæ._--S.E. Asia, C. America.
_Colubrinæ._--The whole range of Ophidia, except Tasmania.
_Dasypeltinæ._--Africa (exclusive of Madagascar).
_Homalopsinæ._--S.E. Asia, N. Australia.
_Dipsadomorphinæ._--S. Europe, C. and S. Asia, Africa, Australia
(exclusive of Tasmania), C. America (extending into the S. parts of N.
America), S. America.
_Elachistodontinæ._--India.
_Hydrophiinæ._--Indian and Pacific Oceans.
_Elapinæ._--S. Asia, Africa (exclusive of Madagascar), Australia and
Tasmania, Fiji Islands, C. America (extending into the S. parts of N.
America), S. America.
_Amblycephalidæ._--S.E. Asia, C. and S. America.
_Viperinæ._--Europe, Asia, Africa (exclusive of Madagascar).
_Crotalinæ._--S.E. Europe, Asia, America.
The Zoogeographical Regions into which the world is usually divided
(Palæarctic or Europo-Asiatic, Oriental or Indian, Ethiopian or African,
Australian, Nearctic or North American, Neotropical or South American)
do not lend themselves any better than the ordinary divisions of
physical geography to the study of the distribution of Snakes. Contrary
to what we find in dealing with the Tortoises, Australia does not show
any special affinity to South America, and, as in the case of the
Lizards, it must be regarded as an impoverished extension of the
Indo-Malay fauna; as with the Lizards, also, Europe and Africa hang
together, whilst Madagascar stands apart, distinguished by many negative
features and some points of agreement with South America (Boidæ). There
is a greater difference between the Snakes of Europe and those of
Eastern Asia than there is between the latter and those of North
America, whilst in Lizards a primary distinction must be made between
the Old World and the New. Southern Asia east of Persia (the Oriental
Region) is the great Ophidian centre, all the groups mentioned above,
with the exception of the Dasypeltinæ, having representatives within its
limits, and a large and very distinct family, the Uropeltidæ, being
confined to it. The Pythoninæ occur along with the Boinæ, the Viperinæ
with the Crotalinæ, and the Elapinæ are represented by varied forms, as
they are also in Africa and still more in Australia, where they form the
overwhelming majority, and in some parts, as well as in Tasmania, the
exclusive Ophidian population. The coasts of India and Malaya are also
the home of the great majority of the Hydrophiinæ. Large genera like
_Tropidonotus_, _Zamenis_, and _Coluber_, extend over the Europo-Asiatic
and North American regions, but they are equally well represented in the
Oriental. The great difference between Madagascar and Africa is, as we
have said, very striking. Madagascar possesses Boidæ generically
identical with those of South America, but otherwise only Typhlopidæ,
Colubrinæ, and Dipsadomorphinæ; whilst in the greater part of Africa the
Boinæ are replaced by the Pythoninæ, and the Glauconiidæ, Elapinæ, and
Viperinæ are generally distributed. North America agrees with Asia and
South America in its Crotalinæ, otherwise its Ophidian fauna is not very
different from that of Europe, although much richer, and South America
shares the Glauconiidæ with Africa and the Ilysiidæ with Southern Asia.
South America is rich in Colubrinæ and Dipsadomorphinæ, nearly all
generically different from those of other parts of the world, and the
Elapinæ are represented by the single genus _Elaps_, with many species,
two of which extend to the southern parts of North America.
This rapid sketch of the principal facts of Ophidian distribution
suffices to show how difficult it would be to frame geographical regions
that would give expression to these facts. Such regions would
necessarily be very different from those adopted in dealing with the
distribution of the other divisions of the class Reptilia. This is a
task which need not be attempted on the present occasion.
A few words as to the salient characters of the European fauna, which is
a poor one as compared with other parts of the world. The single species
of the genera _Typhlops_ and _Eryx_ must be regarded as outposts from
South-Western Asia; the single species of _Ancistrodon_, which extends
from Central Asia into a very small territory to the south-east, is also
an Asiatic type. The genera _Tropidonotus_, _Zamenis_, _Coluber_,
_Coronella_, and _Contia_, are characteristic of the Northern
Hemisphere, and the first three are, besides, equally well represented
in the Oriental region; a few species of _Tropidonotus_ are also found
in Africa and Madagascar. _Coelopeltis_, _Macroprotodon_, and _Tarbophis_
are the northern outposts of an Afro-Indian group, although, with the
exception of the third, exclusively confined to the circum-Mediterranean
district. The genus _Vipera_ is also represented in East Africa and in
Southern Asia, but the species _V. berus_ is essentially a northern
type, extending to the highest latitude reached by any snake, and
ranging all over Northern Asia to the Amur and Sachalien. The same
species reaches the greatest altitude at which any snake has been
observed on the northern side of the Alps--viz., 9,000 feet.
Of the twenty-eight species inhabiting Europe, only two are generally
distributed: _Tropidonotus natrix_ and _Coronella austriaca_. One is to
be regarded as a northern form, although occurring locally in the south:
_Vipera berus_. It is the reverse with _Coluber longissimus_. The others
may be described as southern forms, two only as ranging from west to
east: _Zamenis gemonensis_ and _Coelopeltis monspessulana_; one of more
central habitat: _Vipera ursinii_. The remainder may be divided into two
groups--those of more western, and those of more eastern distribution.
To the first group belong _Tropidonotus viperinus_, _Zamenis
hippocrepis_, _Coluber scalaris_, _Coronella girondica_, _Macroprotodon
cucullatus_, _Vipera aspis_ and _Vipera latastii_; to the second,
_Typhlops vermicularis_, _Eryx jaculus_, _Tropidonotus tessellatus_,
_Zamenis dahlii_, _Coluber quatuorlineatus_, _dione_, _leopardinus_,
_Contia modesta_, _Tarbophis fallax_ and _iberus_, _Vipera renardi_,
_ammodytes_, _lebetina_, and _Ancistrodon halys_.
A remarkable fact in the distribution of European Snakes is the
altitudinal range of _Vipera berus_, _V. aspis_, and _V. ursinii_. The
first being the northernmost snake, generally distributed in Northern
Europe and more locally in the south, should, one would expect, be a
mountain form in the south. This is so in Switzerland, where it occurs
chiefly between 2,500 and 9,000 feet, on the northern aspect of the
Alps, whilst _V. aspis_ lives at altitudes below 5,000 feet; but on the
southern aspect of the same chain things are reversed, and _V. berus_ is
replaced by _V. aspis_, which reaches an altitude of 9,700 feet, whilst
the former shows a tendency to abandon the mountains, and has
established itself in a few localities in the plain of North Italy.
Again, in France _V. berus_ is the northern and _V. aspis_ the southern
species, yet the latter is the only one found on the French side of the
Pyrenees (up to 7,250 feet), whilst the former reappears in
North-Western Spain and Portugal at very low altitudes, even at
sea-level. _V. ursinii_ is a mountain form in Italy (Abruzzi), in France
(Basses-Alpes), and in the Balkan Peninsula (up to 6,800 feet); but it
is restricted to the plain in Lower Austria and Hungary, where _V.
berus_ occurs only in the mountains.
Only three species are entirely confined to Europe:
_Coluber scalaris_, _Vipera ursinii_, and _V. aspis_.
Of the species which range outside Europe, the following occur both in
Western Asia and in North Africa:
_Eryx jaculus_, _Tropidonotus natrix_, _Coelopeltis monspessulana_,
_Vipera lebetina_.
In Western Asia and the North-East of Egypt:
_Tropidonotus tessellatus_, _Zamenis dahlii_.
In Western Asia:
_Typhlops vermicularis_, _Zamenis gemonensis_, _Coluber
quatuorlineatus_, _C. dione_, _C. longissimus_, _C. leopardinus_,
_Coronella austriaca_, _Contia modesta_, _Tarbophis fallax_, _T.
iberus_, _Vipera renardi_, _V. berus_, _V. ammodytes_, _Ancistrodon
halys_.
In North Africa:
_Macroprotodon cucullatus._
In North-West Africa:
_Tropidonotus viperinus_, _Zamenis hippocrepis_, _Coronella girondica_,
_Vipera latastii_.
The following lists will help to elucidate the distribution of the
snakes in the different parts of Europe:
I. SCANDINAVIA
1. _Tropidonotus natrix_ (as far north as 65°).
2. _Coronella austriaca_ (as far north as 63°).
3. _Vipera berus_ (as far north as 67°).
II. GREAT BRITAIN
1. _Tropidonotus natrix_ (England and Wales, extreme south-east of
Scotland).
2. _Coronella austriaca_ (Surrey, Berkshire, Hampshire, and
Dorsetshire).
3. _Vipera berus._
III. BELGIUM AND HOLLAND
1. _Tropidonotus natrix._
2. _Coronella austriaca._
3. _Vipera berus._
IV. GERMANY AND DENMARK
1. _Tropidonotus natrix._
2. _Tropidonotus tessellatus_ (Middle Rhine and Moselle, Saxony).
3. _Coluber longissimus_ (Denmark, Schlangenbad, Treves).
4. _Coronella austriaca._
5. _Vipera berus._
6. _Vipera aspis_ (Black Forest, Lorraine).
V. FRANCE AND SWITZERLAND, EXCLUSIVE OF TICINO
1. _Tropidonotus natrix._
2. _Tropidonotus viperinus_ (as far north as South Brittany and
Fontainebleau).
3. _Zamenis gemonensis_ (south, locally as far north as the Sarthe and
Aube).
4. _Coluber longissimus_ (locally as far north as South Brittany, South
Normandy, and Fontainebleau).
5. _Coluber scalaris_ (Mediterranean Littoral).
6. _Coronella austriaca._
7. _Coronella girondica_ (south and west as far north as the
Charente-Inférieure).
8. _Coelopeltis monspessulana_ (Mediterranean Littoral).
9. _Vipera ursinii_ (Basses-Alpes).
10. _Vipera berus_ (as far south as the Loire basin, the Central
Plateau, and the Alps).
11. _Vipera aspis_ (as far north as the Loire basin, Fontainebleau, and
Lorraine).
VI. SPAIN AND PORTUGAL
1. _Tropidonotus natrix._
2. _Tropidonotus viperinus._
3. _Zamenis gemonensis_ (Catalonia).
4. _Zamenis hippocrepis_ (absent from the north).
5. _Coluber longissimus_ (Andalucia).
6. _Coluber scalaris._
7. _Coronella austriaca_ (north and north-west).
8. _Coronella girondica._
9. _Coelopeltis monspessulana._
10. _Macroprotodon cucullatus_ (centre and south, Baleares).
11. _Vipera berus_ (north-west).
12. _Vipera aspis_ (Pyrenees).
13. _Vipera latastii_ (absent from the north).
VII. ITALY, WITH TICINO AND CORSICA
1. _Tropidonotus natrix._
2. _Tropidonotus tessellatus_ (as far south as Naples; absent from the
islands).
3. _Tropidonotus viperinus_ (Liguria, Piedmont, Ticino, Corsica,
Sardinia, Sicily).
4. _Zamenis gemonensis._
5. _Zamenis hippocrepis_ (Sardinia).
6. _Coluber quatuorlineatus_ (south and Sicily).
7. _Coluber longissimus_ (absent from Corsica).
8. _Coluber leopardinus_ (south and Sicily).
9. _Coronella austriaca_ (absent from Corsica and Sardinia).
10. _Coronella girondica_ (absent from Corsica and Sardinia).
11. _Coelopeltis monspessulana_ (Western Liguria, Sicily).
12. _Vipera ursinii_ (Abruzzi).
13. _Vipera berus_ (the Continental part only).
14. _Vipera aspis_ (absent from Corsica and Sardinia).
15. _Vipera ammodytes_ (Northern Venetia).
VIII. AUSTRIA-HUNGARY, WITHOUT BALKAN STATES
1. _Tropidonotus natrix._
2. _Tropidonotus tessellatus._
3. _Zamenis gemonensis_ (South Tyrol, Littoral, South Hungary).
4. _Coluber quatuorlineatus_ (Istria).
5. _Coluber longissimus._
6. _Coluber leopardinus_ (Istria).
7. _Coronella austriaca._
8. _Coronella girondica_ (South Tyrol).
9. _Coelopeltis monspessulana_ (Istria).
10. _Tarbophis fallax_ (Istria).
11. _Vipera ursinii_ (Lower Austria, Littoral, Hungary).
12. _Vipera berus._
13. _Vipera aspis_ (South Tyrol, Littoral).
14. _Vipera ammodytes_ (South Tyrol, Styria, Carinthia, Carniola,
Littoral, South Hungary).
IX. BALKAN PENINSULA AND ARCHIPELAGO
1. _Typhlops vermicularis_ (Greece, Turkey, Bulgaria).
2. _Eryx jaculus_ (Greece, Turkey, Roumania).
3. _Tropidonotus natrix._
4. _Tropidonotus tessellatus._
5. _Zamenis gemonensis._
6. _Zamenis dahlii_ (coast of the Adriatic, Greece).
7. _Coluber quatuorlineatus._
8. _Coluber longissimus._
9. _Coluber leopardinus._
10. _Coronella austriaca._
11. _Coelopeltis monspessulana_ (West Coast, Greece, and islands).
12. _Tarbophis fallax_ (West Coast, Greece and islands, Constantinople).
13. _Vipera ursinii_ (Bulgaria, Bosnia, Herzegovina, Montenegro).
14. _Vipera berus_ (Bosnia, Herzegovina, Roumania).
15. _Vipera aspis_ (Bosnia).
16. _Vipera ammodytes._
17. _Vipera lebetina_ (Cyclades).
X. RUSSIA
1. _Tropidonotus natrix_ (as far north as 60°).
2. _Tropidonotus tessellatus_ (south).
3. _Zamenis gemonensis_ (south).
4. _Zamenis dahlii_ (Caucasus).
5. _Coluber quatuorlineatus_ (south).
6. _Coluber dione_ (south, between Volga and Ural).
7. _Coluber longissimus_ (south, Poland).
8. _Coluber leopardinus_ (Crimea).
9. _Coronella austriaca_ (as far north as 57°).
10. _Contia modesta_ (Caucasus).
11. _Tarbophis iberus_ (Caucasus).
12. _Vipera renardi_ (south).
13. _Vipera berus_ (as far north as 64°).
14. _Ancistrodon halys_ (south, between Volga and Ural).
Without attempting anything like a complete bibliography, we have
compiled a list of faunistic works and papers dealing with the snakes of
Europe:
EUROPE IN GENERAL
SCHREIBER, E.: Herpetologia Europæa. Zweite Auflage, Jena, 1912, 8vo.
STEINHEIL, F.: Die Europaeischen Schlangen. Kupferdrucktafeln nach
Photographien der lebenden Tiere. Jena, 1913, 4to. (in progress).
GREAT BRITAIN
BELL, T.: A History of British Reptiles. 2nd edit., London, 1849, 8vo.
COOK, M. C.: Our Reptiles. London, 1865, 8vo.
LEIGHTON, G.: The Life-History of British Serpents. Edinburgh and
London, 1901, 8vo.
FRANCE
GADEAU DE KERVILLE, H.: Faune de la Normandie. IV. Reptiles. Paris,
1897, 8vo.
LATASTE, F.: Essai d'une Faune Herpétologique de la Gironde. Bordeaux,
1876, 8vo.
MARTIN, R., ET ROLLINAT, R.: Vertébrés sauvages du Département de
l'Indre. Paris, 1894, 8vo.
SWITZERLAND
FATIO, V.: Faune des Vertébrés de la Suisse. III. Reptiles et
Batraciens. Geneva and Basle, 1872, 8vo.
SPANISH PENINSULA
BOSCÁ, E.: Catalogue des Reptiles et Amphibies de la Péninsule Ibérique
et des Îles Baléares (Bull. Soc. Zool. France, 1880).
ITALY
BONAPARTE, C. L.: Iconografia della Fauna Italica. II. Anfibi. Rome,
1832-1841, fol.
CAMERANO, L.: Monografia degli Ofidi Italiani (Mem. Acc. Torin., [2]
xxxix., 1888, and xli., 1891).
GERMANY
DÜRIGEN, B.: Deutschlands Amphibien und Reptilien. Magdeburg, 1890-1897,
8vo.
LEYDIG, F.: Ueber die Einheimischen Schlangen (Abh. Senck. Ges., xiii.,
1883).
AUSTRIAN EMPIRE
WERNER, F.: Die Reptilien und Amphibien Oesterreich-Ungarns und der
Occupationsländer. Vienna, 1897, 8vo.
GREECE
BEDRIAGA, J. DE: Die Amphibien und Reptilien Griechenlands (Bull. Soc.
Nat. Mosc., 1881).
BORY DE ST. VINCENT, J. B.: Expédition Scientifique de Morée. Reptiles.
Paris, 1832-1835, 4to., fol. atlas.
BULGARIA
KOWATCHEFF, W. T.: Herpetological Fauna of Bulgaria. Philippopolis,
1912, 8vo. [Bulgarian text.]
ROUMANIA
KIRITZESCU, C.: Contribution à la Faune Herpétologique de Roumanie.
Sauriens et Ophidiens (Bull. Soc. Rom. Bucarest, x., 1901).
RUSSIA
NIKOLSKY, A.: Herpetologia Rossica. St. Petersburg, 1905, 4to. [Russian
text.]
STRAUCH, A.: Die Schlangen des Russischen Reichs. St. Petersburg, 1873,
4to.
------------------------------------------------------------------------
CHAPTER XIII
SNAKES IN RELATION TO MAN
Under this head, the question of poisonous snakes naturally occupies the
first place. In addition to what has been said above in Chapter VI.,
dealing with the anatomical and physiological aspects of the subject, we
have to allude to the accidents caused by these dangerous reptiles, and
the measures taken to combat them.
The enormous mortality for which snake-bite is responsible in India is
well known. Statistics establish the fact that an average of 20,000
human lives are thus lost annually: 24,264 is the official return for
1911. In Australia, where highly poisonous snakes of various genera and
species abound, the fatal cases are likewise very numerous, though less
in proportion than in South America, and no doubt also in Africa. In the
small island of Martinique, the Fer-de-Lance, _Lachesis lanceolatus_,
causes every year the death of about 100 human creatures. Though
numerous in species, the poisonous snakes of Ceylon cause a
comparatively small mortality--200 per annum.
Modern research has resulted in the discovery of the only effective
antidote for snake-venom intoxication: the serotherapic treatment. An
animal that has been treated over a length of time with the venom of a
poisonous snake, such as a Cobra, yields a serum which is antitoxic
towards that venom; but the great difficulty resides in the specificity
of the different poisons, which often renders the use of the serum
ineffective in countries like India and Australia, where several kinds
of poisonous snakes occur in the same district (see above, p. 67). In
India, where a special laboratory has been established for the supply of
antivenine, at the Central Institute of Kasauli, it has been found
impossible to obtain any venoms but those of the Cobra and Russell's
Viper in sufficient quantity to immunize animals, and thus produce the
serum necessary for dealing with the bite of the King Cobra, the Krait,
and the Echis Viper.
In Pondicherry the French Government places annually a sum of 200 rupees
at the disposal of the director of the hospital for obtaining Cobra
poison, the snakes, to be brought alive, being paid for to the natives
at the rate of half a rupee to one rupee each, according to size and
condition. Six hundred and fifty-three specimens were thus purchased in
less than two years (1901-1903). The poison is utilized for the
preparation of Calmette's antivenine, which, as we have said above, is
only effective against cobra poison, and, unfortunately, useless for the
cure of bites from other species.
In Brazil, where the number of accidents is estimated at 19,200 per
annum, and that of fatal cases at 4,800, over 2,000 snakes (_Lachesis_
and _Crotalus_) are brought annually to the Serotherapic Institute of
Batantan, in the province of S. Paolo, for the preparation of the
antitoxic serum, which is given in exchange for the snakes. According to
the latest report of the Institute (1911), two serums are distributed:
the anti-crotaline (for Rattlesnake bite) and the anti-bothropine (for
Lachesis bite); the third, the anti-elapine (for Coral-snake bite), is
in course of preparation.
In many countries a premium has for years been paid for the heads of
poisonous snakes, and has led to the destruction of enormous numbers of
them, without, however, resulting in a very appreciable diminution of
the dangerous reptiles. More than £12,000 has been spent for this
purpose in India alone; the numbers destroyed in 1885 and 1886
throughout British India amount to 420,044 and 417,596 respectively.
About forty years ago the Governor of St. Lucia offered a reward of 4d.
for every Fer-de-Lance's head. But the negroes caught them alive and
bred families of snakes for the sake of the reward, and thereby made
what was for them a little fortune, these snakes bringing forth up to
sixty young at a birth. The reward had to be abolished very soon.
Now about the Vipers of Europe, the only really dangerous snakes of this
part of the world.
Although the Adder, _Vipera berus_, is quite common in many parts of
England and Scotland, accidents caused by its bite are rarely heard of,
and cases of death are few and far between. It is not so, however, on
the Continent, where the same species, and especially its close ally,
the more southern _V. aspis_, are responsible for many fatalities, due
no doubt to the more virulent action of the venom in a warmer climate.
In the French Departments Loire-Inférieure and Vendée, where these
snakes are very plentiful, three or four cases of death are reported
annually. From 1860 to 1868, 370 serious accidents to man have been
carefully recorded, 53 ending in death, not only in the case of
children, but also of adults of all ages, in 10 cases within one to
twenty-four hours. In the Puy-de-Dôme cases of death are of frequent
occurrence. In Germany and in Switzerland, 12 or 13 per cent. of the
cases on record have ended fatally. Instances of death from the bite of
the south-eastern _V. ammodytes_ are also not infrequent. On the other
hand, the bite of _V. ursinii_, which is but seldom inflicted, is not
known to have ever resulted in death.
It must be borne in mind that accidents are much more frequent in
districts where the poorer classes are in the habit of going about
barefoot.
Anyhow, it is certain that Vipers are a serious danger in many parts of
Europe, not only to man, but also to horses, cattle, and dogs. And it is
not surprising that efforts have been made to reduce their numbers. The
most efficacious means, besides the protection of certain animals and
birds which feed on Vipers, appeared to be the institution of premiums
to be paid for the heads of the dangerous snakes. By offering 2-1/2d.
per head, 500,000 Vipers (_V. aspis_) were destroyed from 1864 to 1890
in three French departments, Haute-Saône, Doubs, and Jura, and in one
district (Chaumont) of the Haute-Marne 57,045 were killed from 1856 to
1861; this gives an idea of the extraordinary abundance of these snakes
in some parts of France. In the Puy-de-Dôme the premium was fixed for a
time at 5d., and one man managed to destroy in the course of seven years
9,175 Vipers (_V. berus_ and _V. aspis_). A woman in the Deux-Sèvres has
made a living for many years by catching Vipers, the heads of which were
paid to her at the rate of 5d. each. The average number of her captures
amounted to 2,062 per annum (mostly _V. aspis_). Around Oesnitz in
Saxony, 2,140 _V. berus_ were killed in 1889, and 3,335 in 1890. In a
single district in Southern Styria the heads of 4,197 _V. berus_ and
7,381 _V. ammodytes_ were sent in for the reward in the course of two
years (1892, 1893).
In spite of all this effort, the institution of the bounty has not
answered expectations, and, with the exception of a few districts,
Vipers remain as plentiful as ever, showing what little man can do in
altering the equilibrium of Nature, except by interfering with the
natural conditions under which animals live. Cultivation of the ground
or destruction by fire of the vegetation of the wilderness seems to be
the only efficacious means of getting rid of so abundant and prolific a
creature as the Viper.
A word may be said, however, in defence of Vipers: they do a great deal
of good to agriculture by the destruction of small rodents, on which
they feed chiefly, and whose multiplication they serve to keep in check.
It must be pointed out that, with the exception of the species of
_Coluber_ and _Zamenis_, other European snakes are to be regarded as
indirectly injurious to agriculture, feeding as they do mainly on
lizards or frogs and toads, which, as insectivores, deserve to be
protected.
Snakes are not of much economic value to man. Tanned skins of Boas and
Pythons are utilized for making shoes and fancy articles, such as
purses, pocket-books, blotters, etc., and the Siamese make the
drum-heads of native drums out of the skins of Pythons and
_Acrochordus_. To say nothing of savages, who seem to be partial to the
flesh of large snakes, the peasantry in some parts of France do not
disdain snakes as an article of food, the Grass-snake being occasionally
served in village inns under the name of _Anguilles de haies_, or
hedge-eels.
Viper fat has for a long time been in request as an ointment in the case
of various affections, and much used by quack doctors in the preparation
of their remedies. Some forty years ago a chemist in Challans (Vendée)
collected Vipers (_V. aspis_) for medicinal purposes, and was able to
send several thousands to Paris in the course of a few years, thus
realizing a considerable sum of money, but the demand has gradually
fallen off since.
Very frequent in the past, snake-worship is still prevalent in many
parts of India, where the Cobra is held in great veneration, and is
never willingly killed by the Hindoo. In pre-Buddhist days the gods were
represented with a canopy of five or seven Cobras over them. The North
African Cobra was sacred to the ancient Egyptians, and is profusely
represented on the monuments and tombs; it was also an emblem of the
physical sun, and, as a sign of royal power, along with the sun's disc,
formed part of the headdress of all solar deities. The Greeks and Romans
also worshipped snakes, and the god of medicine is represented holding a
snake, which is supposed to be _Coluber longissimus_, the so-called
"Æsculapian snake"; the occurrence at the present day of certain common
Italian species (_Zamenis gemonensis_, _Coluber longissimus_,
_Tropidonotus tessellatus_) in isolated localities of Central Europe,
formerly Roman settlements, has been attributed to their importation for
use in the temples.
Snake-charmers have existed from the remotest antiquity, and are still
to be found among all races of men, from the accomplished Indian juggler
down to the more commonplace European snake-catcher, who boasts of his
immunity, and of his art of attracting snakes by devices of which he has
the secret. The Libyan Psillii of the ancient Romans have handed down
their art to the present day, and their performances are to be witnessed
in most of the towns of Egypt and Tunisia. But India above all lands is
reputed for its snake-charmers, and the favourite species used by them
is the Cobra, which, by the way in which it raises the anterior part of
the body and expands the region behind the head, lends itself better
than any other to the display. Constantly facing the man before him, and
swaying the raised anterior part of the body, it seems to dance to the
music performed by the snake-man, people believing it to be charmed by
the sounds of the instrument. However, anyone sitting on the ground in
front of a Cobra, and swaying the body from side to side as does the
man, can obtain the same result without the aid of any sort of music.
The most puzzling thing about these performances is how the man can thus
play with impunity with so deadly a snake. It is a mistake to think that
the snake is rendered harmless through the poison fangs having been
extracted, although this subterfuge is frequently resorted to by the
less accomplished jugglers. The immunity of the snake-charmer is to be
explained by the fact that the man has submitted himself to a series of
successive and graduated inoculations of the venom, a process similar to
vaccination, which renders his blood proof against the venom of the
particular species of snake, and that one only, used for his
performances.
Another deadly snake shown by the snake-charmers in North Africa is the
Horned Viper, _Cerastes cornutus_. The presence of an erect spike above
the eye is, however, not a constant character in this snake, and
hornless specimens are made to look more formidable by spines of the
hedgehog being inserted in the proper place; the illusion is such that
even naturalists have been deceived by this trick.
Indian snake-charmers profess to have a belief in the efficacy of
snake-stones, or bezoar stones, as a remedy to be applied on the part
bitten by a poisonous snake, a belief shared by the natives of many
tropical countries. These stones, extracted from various reptiles,
birds, and mammals, are calcareous concretions from the stomach or
bladder, sometimes composed of superphosphate of lime, sometimes of
phosphate of ammonia or magnesia. The value of a bezoar stone being
supposed to increase with its size, the larger are sold in India at very
high prices.
In many places a popular belief prevails that such stones are found in
the heads of snakes. Mr. J. A. Bucknill, now Attorney-General at
Hong-Kong, who spent five years in Cyprus, has informed the author that
the Viper of the latter island, _Vipera lebetina_, is commonly believed
to contain a stone which, when applied to the bite of a poisonous snake,
quickly nullifies the effect; it is also believed that, when this stone
is allowed to stand in a glass of water and the water is drunk, it
endows the drinker with surprising virility. Indeed, there was an action
tried by the English judge at Larnaka in which the plaintiff claimed the
return, or damages for the non-return, of one of these "Viper-stones"
which he had lent for a monetary consideration to the defendant for the
promotion of his manly vigour, and Mr. Bucknill's recollection is that
the plaintiff recovered £10 for the loss.
------------------------------------------------------------------------
SYSTEMATIC ACCOUNT OF THE SNAKES OF EUROPE[A]
FIRST FAMILY: TYPHLOPIDÆ
Skull compact, with short, toothless lower jaw, without transverse bone;
palatine and pterygoid reduced and toothless; maxillary small, loosely
attached to lower surface of cranium and bearing a few small teeth; no
supratemporal, the quadrate articulated to the proötic; a coronoid
element in the lower jaw. Rudiments of a pelvic arch, reduced to a
single bone. Body vermiform, covered with uniform cycloid scales; head
small, not distinct from the body; mouth small, crescentic, inferior;
eyes under the more or less transparent head-shields, sometimes entirely
hidden. Worm-like, smooth, shiny snakes, of small or very small size,
the largest measuring little over 2 feet, of subterranean habits, or
found in rotten trees, under stones, or in the saw-dust of sawmills;
rarely appearing on the surface except when the ground is soaked by
heavy rains.
Inhabit the intertropical parts of the whole world, as well as South
Africa, Southern Asia, and Southern Australia. One species occurs in
South-Eastern Europe. About 120 species are known.
GENUS TYPHLOPS, SCHNEIDER
Head with large shields; nostril in a single or divided nasal. Tail
extremely short.
1. TYPHLOPS VERMICULARIS, Merrem
The Greek Blind-Snake
[Illustration: FIG. 14 (after Sordelli)]
_Form._--Slender, worm-like, the greatest diameter of the body 40 to 52
times in the total length. Tail about as long as broad, ending in a
short spine. Snout depressed, rounded, strongly projecting. Eyes
distinguishable, appearing as a small black spot surrounded by an
unpigmented circle; nostrils lateral.
_Head-Shields._--Rostral about one-third, or a little less than
one-third, the width of the head, extending on its upper surface nearly
to the level of the eyes. Nasal incompletely divided, the cleft
proceeding from the second labial. Preocular present, about as broad as
the ocular, in contact with the second and third labials. Upper
head-scales feebly enlarged and subequal. Four upper labials.
_PLATE I_
[Illustration: TYPHLOPS VERMICULARIS
_After Sordelli_]
[Illustration: ERYX JACULUS
_After Sordelli_]
_Scales._--Equal, 22 or 24 round the body.
_Coloration._--Brown or yellowish-brown above, yellowish beneath.
_Total Length._--10 inches. A specimen from Cyprus is reported to
measure 14 inches.
_Distribution._--This species has long been known from Greece, the
Ionian Islands, and the Grecian Archipelago. It is on record from the
Eli-Deren Pass, in Bulgaria. A specimen stated to come from
Constantinople is preserved in the British Museum. The range further
extends over a considerable part of South-Western Asia, viz., Asia
Minor, Syria, Cyprus, Transcaucasia, Persia, Turkestan, and Afghanistan.
_Habits._--Pretty alert in its movements, this little snake has
considerable constricting powers, and coils itself fast round the
fingers when handled. It lives much after the manner of earth-worms, and
if dug out of loam or sand a specimen must be instantly grasped, as it
draws back with extraordinary quickness. Its food probably consists
mainly of earthworms and small insects. Some exotic species of the genus
are known to feed on termites, and are often dug out of their nests.
_Reproduction._--No observations have been made that I am aware of, but,
as some of the exotic species of which we know something more lay large,
elongate eggs, it is probable that this species also is oviparous.
SECOND FAMILY: BOIDÆ
Maxillary, palatine, and pterygoid bones movable; transverse bone
present; pterygoid extending to quadrate or mandible; supratemporal
present, attached scale-like to cranium, suspending quadrate; prefrontal
in contact with nasal; a coronoid element in the lower jaw. Teeth in
both jaws. Vestiges of pelvis and hind limbs, usually terminating, at
least in males, in a claw-like horny spur on each side of the vent.
This family contains, besides the gigantic Boas and Pythons, several
small more or less burrowing forms, among which the genus _Eryx_, its
only European representative, belonging to the subfamily Boinæ,
characterized by the absence of a supratemporal bone and of premaxillary
teeth. This subfamily, the largest members of which inhabit tropical
America, is distributed over the hotter parts of America, Asia west of
the Bay of Bengal, Madagascar, the Mascarene Islands, Africa north of
the equator, Papuasia, and some islands of the South Pacific. The
habitat of the European species is confined to the eastern and southern
countries of the Mediterranean district.
This very varied family, including terrestrial, arboreal, aquatic, and
burrowing forms, is a comparatively small one as regards the number of
species, viz., about sixty, of which one-third pertain to the Pythoninæ,
which inhabit tropical and South Africa, Southern Asia, Papuasia,
Australia, and Mexico.
GENUS ERYX, DAUDIN
Anterior maxillary and mandibular teeth longer than the posterior. Head
small, not distinct from neck, covered with small scales; a large
rostral shield. Eye very small, with vertical pupil. Body cylindrical;
scales small; ventral shields narrow. Tail very short; subcaudal shields
mostly single.
The range of this genus, embracing eight species, extends from
South-Eastern Europe and Africa north of the equator to Central Asia and
India.
2. ERYX JACULUS, Linnæus
The Javelin Sand-Boa
_Form._--Stout. Head small, not distinct from neck; snout projecting
beyond the mouth; eye directed upwards and outwards; a feeble mental
groove. Tail, ending very obtusely, one-tenth to one-sixteenth of the
total length. Anal spurs more or less developed, often absent in the
female.
_Head-Shields._--Rostral very large and broad, with angular horizontal
edge, followed by a pair of internasals and a second row of two or three
small shields, the rest of the upper surface of the head covered with
scale-like shields, 5 to 8 from eye to eye across the vertex, 7 to 11
round the eye; 9 to 12 upper labials, second or third deepest, separated
from the eye by one or two series of scales. Nostril between the
internasal and two nasals, the anterior of which sometimes fuses with
the former. Two or three series of scales between the nasals and the
eye.
[Illustration: FIG. 15 (after Sordelli)]
_Scales._--Smooth, feebly keeled on the posterior part of the body and
on the tail, in 40 to 51 rows. Ventrals narrow, occupying about
one-third of the ventral surface, 163 to 200; anal small, entire;
subcaudals all or greater part single, 15 to 29.
_Coloration._--Pale greyish, reddish, or yellowish-brown above, with
brown, purplish-brown, or blackish markings, which may be very irregular
or form a single or alternating series of large blotches or cross-bands
on the back; the sides with smaller spots; these markings may be
confluent and so large as to reduce the ground colour to small yellowish
spots; one, two, or three short, dark stripes often present on the nape;
a dark streak from the eye to the angle of the mouth; sometimes a dark
curved band from eye to eye across the upper surface of the snout. Lower
parts yellowish-white, uniform or with small blackish spots.
_Size._--2-1/4 feet is the greatest length which this snake is known to
attain.
_Distribution._--Originally described from Lower Egypt, and extending
westwards to Algeria, this _Eryx_ has been found in Greece, in Corfu, in
the Cyclades, in Turkey, and in Roumania. It occurs also in Asia Minor,
in Transcaucasia, in Transcaspia, in Northern Persia, and in Syria. It
has been found at an altitude of 5,000 feet in Persia, to the west of
Lake Urmia. A closely allied form (_E. miliaris_, Pallas), which has
been confounded with this species, extends from Transcaspia to Turkestan
and Afghanistan.
The reported occurrence of this snake in Bulgaria is based on a specimen
labelled "Bulgaria (?)" in the Sofia University Museum. The species is
omitted from Kovatscheff's latest list of Bulgarian Reptiles.
_Habits._--This diminutive Boid is a burrower in arid, sandy districts,
appearing only early in the morning or towards dusk; it is as a rule
more crepuscular than nocturnal. Notwithstanding its rather heavy form,
it is capable of very quick movements, darting like an arrow upon its
prey, which consists chiefly of small mammals and lizards. A
constrictor, like all the members of the family to which it pertains, it
crushes its prey before swallowing it. If given several mice at a time,
it will catch and kill them all in succession before proceeding to feed.
Specimens recently discovered in the Danube Valley in Roumania were
found to live in the sand at the bottom of small limestone caves, going
about at night and feeding principally on slugs. Unlike other snakes, it
is said to lap dewdrops with its tongue. It is a gentle snake, seldom
attempting to bite.
Egyptian jugglers are in the habit of implanting the claw of a bird or
small mammal in the skin of the head of this snake, above each eye, in
order to give it a more formidable appearance.
_Reproduction._--Like the other species of _Eryx_, this snake is
ovoviviparous, but, beyond this fact, nothing appears to have been
observed concerning the breeding habits, although many examples have
been kept in captivity.
THIRD FAMILY: COLUBRIDÆ
Maxillary, palatine, and pterygoid bones movable; transverse bone
present; pterygoid extending to quadrate or mandible; supratemporal
present, attached scale-like to cranium, suspending quadrate; prefrontal
not in contact with nasal; maxillary horizontal, not movable
perpendicularly to the transverse bone; no coronoid bone. Teeth in both
jaws. No vestiges of pelvic arch.
An enormous group, comprising the great majority of snakes. Divided into
three parallel series:
_A._ Aglypha, with all the teeth solid.
_B._ Opisthoglypha, with one or more of the posterior maxillary teeth
grooved.
_C._ Proteroglypha, with the anterior maxillary teeth grooved or
canaliculated.
The third, which is not represented in Europe, includes some of the most
deadly snakes, such as the Cobras, Kraits, Death-adders, etc.
The European genera are thus distributed in the two other series:
AGLYPHA (COLUBRINÆ): _Tropidonotus_, _Zamenis_, _Coluber_, _Coronella_,
_Contia_.
OPISTHOGLYPHA (DIPSADOMORPHINÆ): _Coelopeltis_, _Macroprotodon_,
_Tarbophis_.
These genera give but a feeble idea of the variety of forms included in
this family, which comprises adaptations to every mode of life for which
snakes are fitted.
The distribution of the family coincides with that of the order,
extending over the whole world with the exception of the Arctic and
Antarctic regions, and Ireland and New Zealand, as well as most of the
smaller islands of the Pacific Ocean.
GENUS TROPIDONOTUS, KUHL
Maxillary teeth increasing in size posteriorly. Head more or less
distinct from neck; eye moderate or rather small, with round pupil. Body
more or less elongate; scales keeled, with apical pits. Tail moderate.
This large genus, comprising about ninety species, and of almost
cosmopolitan distribution, with the exception of South America and the
greater part of Australia, may be divided into several subgenera, two of
which are represented in Europe--_Tropidonotus_ proper, with the common
_T. natrix_, and _Nerodia_, Baird and Girard, with two closely related
species of more thoroughly aquatic habits, _T. tessellatus_ and _T.
viperinus_.
3. TROPIDONOTUS NATRIX, Linnæus
(_Natrix vulgaris_, Laurenti; _Coluber torquatus_, Lacepède)
The Grass-Snake, or Ring-Snake
_Form._--Moderately slender; snout short, obtuse, not prominent; eyes
and nostrils lateral, the former moderately large. Tail four to six and
a half times in the total length.
_Head-Shields._--Rostral broader than deep, visible from above. Nasal
divided, very rarely semidivided. Internasals at least as broad as long,
trapezoid, shorter than the prefrontals. Frontal broader than the
supraocular, once and one-third to once and a half as long as broad, as
long as or a little shorter than its distance from the end of the snout,
shorter than the parietals, not in contact with the preocular. Loreal
deeper than long. One (rarely two) pre- and three (rarely two or four)
postoculars. Temporals 1 + 2. Upper labials seven (rarely six or eight),
third and fourth (or fourth and fifth) entering the eye. Four or five
lower labials in contact with the anterior chin-shields, which are
shorter than the posterior.
_Scales_ with two apical pits, in nineteen rows, strongly keeled on the
body, of outer row smooth or faintly keeled. Ventral shields 157 to 181;
anal divided; subcaudals 50 to 88.
[Illustration: FIG. 16 (after Sordelli)]
_Coloration._--Very variable. We shall first describe the typical form,
and then allude to the principal varieties and individual variations
with which we are acquainted.
Grey, bluish-grey, olive, or brown, above, usually with black spots or
narrow bars on the back, and vertical bars on the sides; upper lip
whitish or yellowish, with the sutures between the shields black; the
preocular, and sometimes the postoculars, yellow in the young; a white,
yellow, or orange collar on the nape, sometimes uninterrupted, more
often divided in the middle, bordered behind by two black subtriangular
or crescentic blotches, which usually meet on the median line; the
bright collar often becomes faint, or even entirely disappears, in large
females (Plate II., first figure); belly usually checkered black and
grey or white, more rarely grey with small black spots, or entirely
black. Iris dark brown or reddish-brown, with a golden circle round the
pupil. This is the form found in England and Central Europe and in some
parts of Southern Europe.
In Jersey, in the Spanish Peninsula, and in Cyprus, the white or yellow
collar, which is always present in the very young, soon disappears, and
so does usually the black collar, which is either much reduced or
entirely absent (var. _astreptophorus_, Seoane). Some large specimens
from the Spanish Peninsula are uniform olive, without any markings.
Another variation (Plate II., third figure), rare in France, but common
in Italy, South-Eastern Europe, and Asia Minor (var. _persa_, Pallas;
_bilineatus_, Bibr.; _murorum_, Bonap.) has the collar well marked,
though widely interrupted in the middle, and a white, yellow, or orange
streak extends along each side of the back, which may bear the usual
black markings in addition.
In some specimens from Austria and Corfu (var. _subfasciatus_, Werner)
the belly is white, with black bars occupying the free edge of each
ventral shield.
A very remarkable variety (var. _cettii_, Gené) from Corsica and
Sardinia (Plate II., second figure) is grey or olive above, with the
black markings confluent into more or less regular annuli, which are
nearly as wide as the spaces between them; these annuli are often broken
up on the middle line of the back, and alternating; the collar is
absent, or is transformed into the first annulus, and the upper surface
of the head is more or less spotted or blotched with black. This pattern
is most distinct in young and half-grown specimens; in large examples
the annuli may break up into spots, disposed with great symmetry in
transverse series. The belly is black, spotted with white.
A specimen 20 inches long, from Bona, Algeria (Lataste collection), has
the posterior half of the head, from between the eyes and behind the
postocular shields, of an intense black, followed by the usual yellow
and black collar; two light dots close together on the parietal shields.
Some specimens are entirely or nearly entirely black. In the var.
_picturatus_, Jan, from the Caucasus, the upper parts are sprinkled all
over with light dots, and the yellow collar is present; the belly is
grey, dotted with black, and with white spots on the sides. In others
the body is black above, and checkered black and white beneath (var.
_scutatus_, Pall.), or entirely black (var. _ater_, Eichw.). This
melanism never appears until the second or third year of life, the young
being marked like the typical form.
Albinos have occasionally been met with, yellowish flesh-colour with
reddish markings, and a white or yellow collar, the eye and the tongue
red. Such an albino, from Horsted Keynes, Sussex, is preserved in the
British Museum. A remarkable aberration, to be regarded as an imperfect
albino, has been found in Dorsetshire, and described as uniform whitish,
with a well-defined broad longitudinal central dorsal pale yellow-brown
band.
_Size._--May reach a length of 6 feet 8 inches. Such giants, females,
known from Sardinia, Sicily, and Istria, are, however, very exceptional,
individuals of this species seldom exceeding a length of 4 feet. The
largest British specimen on record, from Wales, is stated to measure 5
feet 10 inches. Males rarely exceed 3 feet.
_Monstrosity._--A dicephalous young, with the two well-formed heads side
by side, is preserved in the British Museum, and several others have
been described, one being reported to have lived for about a month.
_PLATE II_
[Illustration: TROPIDONOTUS NATRIX
_After Sordelli_]
[Illustration: T. NATRIX, VAR. CETTII
_After Sordelli_]
[Illustration: T. NATRIX, VAR. PERSA]
_Distribution._--_Tropidonotus natrix_ occurs all over Europe, with, of
course, the exception of Ireland, as far north as the extreme south-east
of Scotland, and the sixty-fifth degree in Scandinavia and Finland, and
as high up as 7,450 feet in the Italian Alps. With the exception of a
few districts in England and in Central Europe, as well as in the
extreme north, it is common everywhere, in the north as well as in the
south. On the Mediterranean islands it is absent from the Baleares and
Malta. In North Africa it is known from Algeria and Tunisia, north of
the Atlas, where it does not seem, however, to be at all common. It has
a wide range in Asia, extending eastwards to Lake Baikal, and southwards
to Cyprus, Asia Minor, and Northern Persia. In the south-east of its
range, the bilineated variety predominates over the typical form. The
melanistic so-called varieties are not geographically restricted, but
occur all over the habitat of the species, though not recorded from
England.
_Habits._--Although fond of water, and often seen swimming in ponds or
streams or creeping by the water's edge, this snake is far less aquatic
than its two congeners described hereafter; it often occurs on dry chalk
hills or in woods far from any water. It is moderately agile in its
movements, and easily caught, on which occasions it hisses loudly and
emits a nauseous smell from its anal glands, together with the renal
dejections, but makes no attempt to bite; exceptionally an individual
may go so far as to strike with open mouth, but cases of this snake
really biting are extremely rare. However, Gené says of the male of his
_Natrix cettii_, "iracundum et mordacissimum animal." Dr. Gadow relates
his experience with aggressive specimens which inhabited a swamp with a
little stream to the north of Oporto, close to the coast. To his utter
surprise, some of them actually made for him, swimming along rapidly
with the head erect, about 6 inches above the water, and darting
forwards with widely opened jaws; but they did not bite. According to
Professor Kathariner, this snake when caught has been observed to sham
death, lying rigid and motionless, with open gape. Some specimens do
well in captivity, and are known to have lived for many years; others
refuse all food and die of starvation. After a time they become
tolerably tame, and cease to produce the offensive odour when handled.
The food consists of frogs and toads--the latter being preferred
notwithstanding their poisonous secretion, which protects them from the
attacks of most animals--occasionally of newts, seldom of fish; these
snakes are reported to have a predilection for tree-frogs, and to feed
occasionally on mice and birds, but most observers agree that they will
not take anything higher in the zoological scale than frogs. The prey is
swallowed alive, and, if not very large, four or five frogs or toads are
often taken in succession; a case is known of a snake having swallowed
twenty very small frogs at one meal. The young feed on worms and
batrachian larvæ, in addition to very small frogs and toads.
The Grass-snake gets on very well with the Adder, to whose venom it is
immune.
It has more than once been met with swimming in the sea, and a case is
reported of one having been captured in the open sea twenty-five miles
from the nearest land, no doubt carried away by the current, but still
perfectly lively.
The hibernating season is spent in holes in walls or at the root of
trees, often under manure-heaps, and the awakening occurs in March or
April, soon to be followed by the first exuviation and the pairing.
_Reproduction._--Pairing takes place in April or in May, according to
the climate, and the eggs are laid between June and August, the young
emerging six to ten weeks later. It is probable that a second pairing
occasionally takes place in the autumn, as eggs have sometimes been
found in manure-heaps at the end of winter. Females do not breed until
about 2 feet long, males a little sooner. The eggs number 11 to 48,
according to the size of the female, and, after being produced in a
string, stick together in a mass, without any regularity.
The eggs measure 1 to 1-1/2 inches in length, and when newly laid are
about once and a half as long as broad. They often contain at the time
they are produced a more or less developed embryo. They are sometimes
laid in recesses in walls, in heaps of sawdust near sawmills, under dead
leaves, but preferably in manure, for which purpose females often
approach farms during the period of oviposition. Holes near baking ovens
at the back of village houses are sometimes selected as breeding
resorts. The female rolls herself up, and by violent contortions makes a
sort of chamber in the manure, in which she may remain for some days
after the eggs have been produced. It is not very unusual for several
females to congregate for the purpose of laying, and as many as 1,200
eggs have been found in the same hole. The young on emerging has lost
the umbilical cord, and measures 6 to 8-1/2 inches. It often remains for
a considerable time, sometimes until the following spring, in the hole
or manure-heap in which it was born, feeding principally on worms. Very
young specimens are never found in the water.
4. TROPIDONOTUS TESSELLATUS, Laurenti
(_Coluber hydrus_, Pallas)
The Tessellated Water-Snake
_Form._--Rather slender; head rather long and narrow; snout obtuse, not
prominent; eyes and nostrils directed upwards and outwards, the former
rather small, the latter somewhat valvular. Tail four to six times in
the total length.
_PLATE III_
[Illustration: TROPIDONOTUS TESSELLATUS]
[Illustration: TROPIDONOTUS VIPERINUS
_After Sordelli_]
[Illustration: T. VIPERINUS, VAR. AUROLINEATUS
_After Sordelli_]
_Head-Shields._--Rostral broader than deep, visible from above. Nasal
often semidivided. Internasals usually as long as broad or longer,
subtriangular, truncate in front, as long or nearly as long as the
prefrontals. Frontal a little broader than the supraocular, once and a
half to twice as long as broad, as long as or a little shorter than its
distance from the end of the snout, shorter than the parietals, not in
contact with the preocular. Loreal as deep as or deeper than long. Two
(rarely one or three) preoculars, with or without a small subocular
below; three postoculars, often with one or two suboculars below.
Temporals 1 + 2. Upper labials eight (rarely seven, nine, or ten),
fourth or fourth and fifth (rarely third or fifth) entering the eye.
Five (rarely four) lower labials in contact with the anterior
chin-shields, which are shorter than the posterior.
[Illustration: FIG. 17]
_Scales_ with two apical pits, in nineteen rows, strongly keeled, of
outer row smooth or feebly keeled. Ventrals 160 to 187; anal divided;
subcaudals 48 to 79.
_Coloration._--Olive, olive-grey, or brown above, with dark spots
usually arranged quincuncially or forming narrow bars on the back (Plate
III.); sides often with lighter vertical bars; a more or less distinct
[V]-shaped dark band on the nape, sometimes produced as a median streak
to the frontal shield; upper lip yellowish, with dark bars on the
sutures between the shields. Lower parts whitish, yellow, orange, or
red, marbled or checkered with black, or nearly entirely black. Iris
golden, bronzy, or coppery red.
Some specimens depart very strikingly from the coloration thus briefly
defined. We will now mention the principal variations which have been
described: Sides of body checkered with black and yellow or black and
red (var. _rubro-maculosus_, Dürigen). With four dark stripes along the
anterior part of the back (var. _lineaticollis_, Werner). Above with
four light streaks in addition to the dark markings. Uniform grey or
light brown above (var. _concolor_, Jan, _hagenbecki_, Werner). Uniform
black or blackish (var. _nigrescens_, De Betta). The most remarkable
variety is the var. _vosseleri_, Werner, from Asia Minor: above with
small black and yellowish spots, beneath yellowish with three blackish
stripes beginning at some distance from the head, the median much weaker
than the outer; the scales are less strongly keeled than in the typical
form. There are also specimens with two very regular black stripes along
the belly.
A case of chlorochroism, in a specimen from Dalmatia, has been observed
by Peracca. The snake was sulphur yellow with black markings; a black
band along the belly; iris golden.
An imperfect albino, which has been met with several times in Dalmatia,
has been described as var. _flavescens_, Werner. Yellowish-white or
brownish-yellow above, with small blackish spots; belly whitish in the
middle, with a series of black spots, bright yellow on the sides; eye
and tongue red.
_Size._--This snake occasionally reaches a length of 4 feet, but
specimens over 3 feet are rare. The largest specimen in the British
Museum measures 3 feet 10 inches.
_Distribution._--The Tessellated Snake has a wide range in Europe and
Asia. It is found south of the Alps, from Liguria to Naples, and
eastwards, extending northwards over the greater part of
Austria-Hungary, and even as far as Saxony, and again reappears to the
west in various localities of the Middle Rhine district (from Bingen to
Coblenz and Kreuznach, from Nassau to Lahnstein) and of the Moselle.
From Southern Russia it extends into Siberia as far as the Altai, the
extreme west of China, and the extreme north-west of India; it is also
found in Asia Minor, Transcaucasia, Persia, Mesopotamia, Syria, and the
neighbouring parts of Egypt. Italy and the Rhine constitute the western
limit of its range in Europe. It does not ascend to any considerable
altitude in the mountains of Europe, but it is on record from 6,000 feet
elevation in Chitral.
_Habits._--This is a far more aquatic species than the preceding, being
seldom found in summer away from the water, in which it swims and dives
to perfection; which does not prevent it from being equally agile on
land. In accordance with these thoroughly aquatic habits, it feeds
mostly on fish, although occasionally taking frogs and toads and their
tadpoles. Small fish are swallowed in the water, but large ones are
landed. This snake does not object to salt water, and it has been
observed on the seashore near Odessa, chasing small fish, mostly gobies,
in shallow water. Hibernation and pairing take place on land, and it is
not until the latter function is accomplished that the snakes of this
species resort to the water, which the females leave again for
oviposition. Like the Grass-snake, the Tessellated Snake seldom bites.
_Reproduction._--Pairing takes place in spring, when large numbers have
been observed to congregate for the purpose. As in the Viperine Snake, a
second pairing may occur in the autumn, Dr. Werner having found a pair
in copula on September 14, at Trebinje, Herzegovina, the female laying
her eggs in the following July, which with the beginning of August is
the time for oviposition. The eggs measure a little over an inch in
length and two-thirds of an inch in width, and number 5 to 25; they are
deposited under stones, in the fissures of walls and rocks, or under the
refuse of tanneries.
5. TROPIDONOTUS VIPERINUS, Latreille
The Viperine Water-Snake
_Form._--Moderately slender; head shorter than in the preceding species;
snout obtuse, not prominent; eyes and nostrils directed upwards and
outwards, the former rather small, the latter somewhat valvular; tail
four to six times in the total length.
[Illustration: FIG. 18 (after Sordelli)]
_Head-Shields._--Rostral broader than deep, visible from above. Nasal
usually semi-divided. Internasals as long as broad or longer,
subtriangular, truncate in front, as long as the prefrontals. Frontal
usually broader than the supraocular, once and a half to twice as long
as broad, as long as or slightly longer than its distance from the end
of the snout, shorter than the parietals, not in contact with the
preocular. Loreal as deep as or a little deeper than long. One or two
preoculars and two (rarely three) postoculars. Temporals 1 + 2 or 1 + 3.
Upper labials seven (rarely eight), third and fourth (or third, fourth,
or fourth and fifth) entering the eye. Four (rarely five) lower labials
in contact with the anterior chin-shields, which are usually shorter
than the posterior.
_Scales_ with two apical pits, in twenty-one (rarely nineteen or
twenty-three) rows, strongly keeled, of outer row smooth or feebly
keeled. Ventrals 147 to 164; anal divided; subcaudals 46 to 72.
_Coloration._--Grey, brown, or reddish above with two alternating series
of dark brown or black spots on the back, or with a black zigzag dorsal
band (Plate III., second figure), rarely with a single series of black
vertebral spots; a lateral series of black spots, usually ocellar, with
yellow centres; upper surface of head with dark symmetrical markings; a
more or less distinct dark band on the temple, and another on each side
of the nape, often edged with yellow in front; upper lip yellow, with
dark bars on the sutures between the shields, or dark with a yellow spot
on each shield. Lower parts yellow or red, checkered with black, or
entirely black; the black of the belly may be connected with the ocellar
lateral spots by black vertical bars. Iris golden, often mixed with
brown.
A specimen from Ponte Carrega, near Genoa, preserved in the Genoa
Museum, is remarkable as being of a dark olive-grey, with three series
of black and yellow ocellar spots. It is further exceptional in having
the scales in nineteen rows. A second specimen, from the same locality,
with the normal number of scales, has some of the vertebral spots
ocellar. Specimens with ocellar vertebral spots are found also in
Sardinia and in Spain.
As in _T. natrix_, there occur, in the South of France, in Sardinia, in
the Spanish Peninsula, and in North Africa, specimens with two light
yellow or reddish lines along the back (Plate III., third figure), in
addition to the usual markings (_C. aurolineatus_, Gervais, _T.
chersoides_, Duméril and Bibron).
Melanism is rare in this species, only one specimen being known, from
Nantes in Southern Brittany; uniform black, with the exception of a few
white spots on the belly. A remarkable variety (var. _incertus_, Fatio),
connecting this species with the preceding, occurs in Switzerland near
Geneva. Not only is its coloration sometimes very similar to that of _T.
tessellatus_, but it agrees with it in the scales being often disposed
in nineteen rows instead of twenty-one, and in the presence of eight
upper labials, fourth or third and fourth entering the eye; however, the
frequent presence of ocellar spots on the sides, and the low number of
ventral shields (147 to 151), show that it should be referred to _T.
viperinus_.
_Size._--Rarely reaches a length of 3 feet in Europe, the largest
specimens being from Sardinia. An Algerian specimen 3 feet 3 inches long
is on record.
_Distribution._--France as far north as Southern Brittany, the Forest of
Fontainebleau, and the Department Aube, the whole of the Spanish
Peninsula and the Balearic Islands, Southern Switzerland, north and
south of the Alps, Liguria, Piedmont, Corsica, Sardinia, and Sicily. In
Africa in Morocco, Algeria, and Tunisia, penetrating into the northern
parts of the Sahara.
In Liguria, Piedmont, and Ticino, _T. viperinus_ occurs alongside with
_T. tessellatus_. It reaches an altitude of nearly 4,000 feet in the
Alps.
_Habits._--Very much the same as in the preceding species, although
slightly less thoroughly aquatic, large individuals being sometimes met
with at some distance from water. Ponds and marshes are the favourite
abode of the Viperine Snake, huge numbers being often found on the
borders, diving into the water when disturbed. Frogs and toads,
tadpoles, newts, fishes, and large earthworms, are its principal food
when adult, the young feeding chiefly on batrachian larvæ, young fishes,
and earthworms. A case is known of this snake having eaten a water-shrew
(_Crossopus fodiens_). When a fish has been caught, it is usually eaten
on land; in captivity dead fish are rather readily accepted, provided
they be quite fresh. Some specimens bite when handled; others are as
gentle as the Grass-snake.
For hibernation, hollow trees, fissures in rocks, holes in the ground or
in railway embankments, are selected, and numerous individuals sometimes
congregate in the same retreat. In the mild winters of the South of
Europe they remain quiet, without being torpid, and resume activity very
early in the spring.
In the Alemtejo, according to Gadow, when during the rainless and hot
summer the small rivers have nearly dried up, these snakes collect in
great quantities in the remaining stagnant and muddy pools, and, as the
stock of suitable fish gets exhausted, are often reduced to a deplorably
emaciated condition. By the month of August they have become so
thoroughly aquatic that they cannot be kept alive in dry surroundings
for twenty-four hours, apparently dying from some kind of cutaneous
suffocation. The same observer once caught a Viperine Snake in a ditch
whilst it was swallowing an eel of nearly its own length.
Some specimens show so great a superficial resemblance to the Common
Adder, _Vipera berus_, which, however, being a more northern reptile,
very seldom occurs in the same localities--that this snake well deserves
its name _Viperinus_. A celebrated herpetologist, Constant Duméril, was
once himself deceived by this resemblance and bitten by a _Vipera berus_
which he had picked up in the Forest of Senart, near Paris, believing it
to be a _Tropidonotus viperinus_; whilst, conversely, a specimen of the
harmless snake was killed in mistake for a Viper by no less an expert
than Dr. Viaud-Grandmarais.
_Breeding._--This snake pairs in March and April, and sometimes again in
the autumn; but the eggs are only laid at one season, in June or July,
and hatch in August, September, or October. The eggs, numbering four to
twenty, are deposited in holes not far from water, often in abandoned
galleries of voles or moles. The young at birth measure 4 to 6-1/2
inches, and soon resort to the water, where, unlike those of the
Grass-snake, they are frequently met with.
GENUS ZAMENIS, WAGLER
Maxillary teeth increasing in size posteriorly, the two last often
separated from the others by a narrow interspace. Head elongate,
distinct from neck; eye rather large, with round pupil. One or more
subocular shields. Body much elongate; scales smooth, with apical pits.
Tail long.
The species of this genus, about thirty in number, are distributed over
Europe, North Africa, Asia, and North and Central America. Three inhabit
Europe.
6. ZAMENIS GEMONENSIS, Laurenti
(_Coluber viridiflavus_, Lacepède; _C. atrovirens_, Shaw)
The European Whip-Snake
_Form._--Slender; snout rounded, with distinct canthus, moderately
prominent, concave on each side in front of the eye. Tail three and
one-third to four and one-third times in the total length.
_PLATE IV_
[Illustration: ZAMENIS GEMONENSIS
_Young, after Sordelli_]
[Illustration: Z. GEMONENSIS, VAR. PERSICUS
_After Sordelli_]
[Illustration: Z. GEMONENSIS, VAR. VIRIDIFLAVUS]
_Head-Shields._--Rostral a little broader than deep, the portion visible
from above measuring one-fourth to two-fifths its distance from the
frontal. Frontal more or less bell-shaped, not or but little broader
than the supraocular, once and two-thirds to twice as long as broad, as
long as or a little longer than its distance from the end of the snout,
a little shorter than the parietals. Loreal as long as deep or longer.
One preocular (rarely two), extending to the upper surface of the head,
but never in contact with the frontal; a small subocular below the
preocular; two postoculars (rarely three). Temporals 2 + 2 or 2 + 3
(rarely 1 + 2). Upper labials eight, fourth and fifth entering the eye,
fifth and seventh deepest. Five lower labials (rarely four) in contact
with the anterior chin-shields, which are usually shorter than the
posterior.
[Illustration: FIG. 19 (after Sordelli)]
_Scales_ with two apical pits, in nineteen (rarely seventeen or
twenty-one) rows. Ventral shields more or less distinctly angulate
laterally, 160 to 230 (usually under 200 in the typical form and the
var. _caspius_, 190 or more in the vars. _viridiflavus_ and _asianus_);
anal divided; subcaudals 87 to 131.
_Coloration._--In the typical _Z. gemonensis_ the upper parts are
yellowish-brown or pale olive, anteriorly with blackish cross-bars or
numerous small black spots, the black scales with a yellowish shaft, the
lower parts yellowish-white or pale yellow, rarely more orange; the
sides of the head are yellow, the shields edged with blackish. A female,
3-1/4 feet long, from Levico, Trentino, preserved in the Genoa Museum,
is uniform reddish-brown above, with mere traces of darker markings on
the head and nape. There is every gradation between this form and the
var. _viridiflavus_ or _atrovirens_ (Plate IV., third figure), which is
dark green or black above, with yellow spots forming transverse series
or bars on the anterior part of the body, and longitudinal streaks,
following the series of scales, on the posterior part and on the tail;
the yellow sometimes predominates over the black, or may appear as a
shaft along each dark scale; the preocular and postocular shields are
yellow, the labials likewise yellow, with black spots or bars. The lower
parts are yellow or greenish-white, with or without black dots, and
usually with a series of large black spots on each side.
Some specimens of both the typical form and the var. _viridiflavus_ are
entirely black or nearly black. (_Z. carbonarius_, Bonaparte; _Z.
sardus_, Suckow). In some localities and islands only black specimens
occur.
In the var. _caspius_, Iwan (_trabalis_, Pallas, Plate V., first figure;
_persicus_, Jan, Plate IV., second figure), from Hungary, Bosnia,
Herzegovina, Corfu, Bulgaria, Roumania, Greece, Turkey, Southern Russia,
Northern Asia Minor, and North-West Persia, the upper parts are pale
olive or reddish-brown, with or without brown or black spots, and each
scale bears a yellowish or pale brown longitudinal streak; there is
often a dark longitudinal streak on the nape; the belly is uniform
orange or red.
Another variety, var. _asianus_, Boettger, from Asia Minor, Rhodes,
Cyprus, and Syria, has the upper parts brown or olive, each scale with a
longitudinal light streak, and there are usually large black spots
relieved by yellowish shafts; the belly is red, spotted or dotted with
black. Melanism is frequent in this form, such specimens being entirely
black except on the chin and throat, which are yellow variegated with
red.
The very young of the typical form, as well as that of the var.
_viridiflavus_, has a striking livery (Plate IV., first figure), the
head and nape black with yellow markings, or olive with black-edged
yellow markings, contrasting sharply with the pale olive-grey of the
body; the most conspicuous and constant of the yellow markings consist
of a bar between the eyes, interrupted on the frontal shield, but
sometimes continuous with the yellow of the postoculars, five or six
small round spots on the parietal shields, and a V- or W-shaped line
just behind the parietals, followed by one or two others separating the
dark cross-bars which may be present on the nape, and occasionally even
continue some way down the anterior part of the body. This livery
persists in some half-grown specimens.
In young individuals from Syria (var. _asianus_) the head is not
differently coloured from the olive-brown body, and the markings
described above appear as mere traces; on the other hand, the whole body
has black and yellow spots or cross-bars above, and the belly is
profusely marked with round black spots.
In the new-born of the var. _caspius_, of which I have examined only one
specimen, 11 inches long, from the Crimea, the head is olive-brown like
the body, which bears dark brown spots and narrow cross-bars; and there
is a dark brown streak along the middle of the nape, as is sometimes the
case in the typical form. The belly is unspotted. A young from Malta is
intermediate in its markings between the typical form and this variety.
The young of the so-called black variety are not black at birth, but
similar to the normal young of the races to which they belong.
The four principal forms--_viridiflavus_, _gemonensis_, _caspius_, and
_asianus_--are so completely connected that I cannot regard them as more
than geographical races or varieties.
_Size._--This handsome snake grows to a length of 6 feet, the var.
_caspius_ even to 8 feet. I have seen a specimen of this variety, from
Salonica, which measures 7-2/3 feet.
_Distribution._--From the Atlantic coast of Europe to South-Western
Asia. The typical form, in its narrowest sense, inhabits the Southern
Tyrol, the north-eastern corner of Italy, and the countries to the east
of the Adriatic, as far as Greece and Crete. The specimens from France,
Switzerland, Italy, Giglio, Montecristo, Elba, Corsica, Sardinia,
Sicily, and Malta, are mostly referable to the form known as _Z.
viridiflavus_. Farther to the east the species is represented by the
vars. _caspius_ and _asianus_, of which the distribution has been
mentioned above. From Spain, this snake is only on record from
Catalonia, not far from the French frontier.
Rare or local in the north of its range (Maine-et-Loire, Vienne, Indre,
Sarthe, Haute-Saône, Yonne, Aube, in France, Switzerland north of the
Alps), it is one of the commonest snakes in Italy and on the borders and
islands of the Adriatic, as well as on practically all the islands of
the Mediterranean east of the Baleares. The highest altitudes at which
it has been met with are 3,900 feet in the Alps, 4,500 feet in the
Balkan Peninsula.
_Habits._--The name "Whip-snake," under which an American representative
of this genus (_Z. flagelliformis_) is known, like that of "Fouet" and
"Loucinglant," which have been bestowed on it in some parts of France,
expresses the quick movements with which, when captured, this snake
lashes its long, slender tail, at the same time furiously biting the
hand that has seized it. The generic term _Zamenis_, of Greek
derivation, alludes to its viciousness, which also accounts for its
German name, "Zornnatter." This snake, occurring in Malta, may well have
been the "Viper" which fastened on the hand of St. Paul. Some specimens
have been kept for months in captivity without losing their savage
temper, hissing and flying with open mouth at anyone approaching the
glass walls of their prison; others, on the other hand, become quite
tame in a very short time, such as one which I kept for nearly two
years. Except when sunning itself on a cold early morning in the spring,
this snake is always on the alert, and difficult to capture, uncoiling
itself and darting away like an arrow at the least disturbance. It lives
in preference among shrubs or on the edges of woods, avoiding damp
localities, and females at least appear to have sedentary tastes.
Lataste tells us of one, near Bordeaux, which he repeatedly met for over
two years within 20 yards of the same spot, a bush between a wood and a
meadow, without ever being able to capture it.
_PLATE V_
[Illustration: ZAMENIS GEMONENSIS, VAR. CASPIUS
_After Sordelli_]
[Illustration: ZAMENIS DAHLII
_After Sordelli_]
[Illustration: ZAMENIS HIPPOCREPIS
_After Sordelli_]
The food of this snake is very varied, consisting of voles and mice,
young birds which it takes from the nests, being a good climber on
bushes and low trees, occasionally of frogs, but above all of other
reptiles: lizards, slow-worms, and snakes, which it does not attempt to
crush before deglutition. It has even been observed in Istria to eat
locusts (_Acridium ægyptium_) and sphyngid moths.
_Reproduction._--Eggs, laid at the end of June or beginning of July in a
well-sheltered hole, are a little over twice as long as broad, and
measure 1·2 to 1·4 inches in length. The number of eggs is eight to
fifteen according to Fatio, about a dozen according to Tomasini, five
according to Werner. The pairing was observed by Schreiber at the end of
May, the male and female seizing each other reciprocally by the neck
with their jaws; this mode of pairing must not, however, be regarded as
the rule in this species, for in other cases observed by Schreiber and
by Honnorat the pairs were simply entwined by their coils.
7. ZAMENIS DAHLII, Fitzinger
Dahl's Whip-Snake
_Form._--Very slender; head narrow, snout moderately prominent, obtuse.
Tail about one-third of the total length.
_Head-Shields._--Rostral a little broader than deep, just visible from
above. Frontal not or but little broader than the supraocular, once and
two-thirds to once and three-fourths as long as broad, as long as or
longer than its distance from the end of the snout, shorter than the
parietals. Loreal longer than deep. One preocular, usually in contact
with the frontal, with a subocular below it; two postoculars. Temporals
2 + 2 or 2 + 3 (rarely 1 + 2). Upper labials eight or nine, fourth and
fifth or fifth and sixth entering the eye. Four or five lower labials in
contact with the anterior chin-shields, which are shorter than the
posterior.
_Scales_ with a single apical pit, very narrow, in nineteen rows.
Ventral shields very distinctly angulate laterally, 205 to 218; anal
divided; subcaudals 98 to 132.
[Illustration: FIG. 20 (after Sordelli)]
_Coloration._--Olive in front, with a few large black, white- or
yellow-edged spots on each side, the anterior of which is sometimes
confluent with its fellow and forms a nuchal collar, as in the specimen
figured on Plate V.; the greater part of the body and tail uniform pale
olive, yellowish, or reddish above, yellowish-white beneath. Head
uniform olive-brown above, the labial, preocular, and postocular shields
yellowish-white.
_Total Length._--3 feet, rarely nearly 4 feet.
_Distribution._--Southern Europe east of the Adriatic, as far north as
Dalmatia, Asia Minor, Cis- and Trans-Caucasia, North-Western Persia,
Cyprus, and Syria. Has also been recorded from Lower Egypt.
_Habits._--This snake is even more lively than _Z. gemonensis_, and does
not stand captivity long. It seeks dry, bushy localities, and feeds on
small lizards, occasionally on locusts. It does not seem to be very
common anywhere in Europe, except perhaps in Dalmatia, whence most of
the specimens sold by dealers are imported.
_Reproduction._--The pairing has been observed at the end of May.
According to Werner, the eggs number usually three only, measuring 1-1/2
inches by 1/2 inch.
8. ZAMENIS HIPPOCREPIS, Linnæus
The Horseshoe Whip-Snake
_Form._--Slender; snout obtuse, feebly prominent. Tail one-fifth to
one-fourth of the total length.
[Illustration: FIG. 21 (after Sordelli)]
_Head-Shields._--Rostral once and one-third to once and a half as broad
as deep, the portion visible from above measuring about one-fourth to
one-third its distance from the frontal. Frontal bell-shaped,
considerably broader in front than the supraocular, once and one-fourth
to once and a half as long as broad, as long as or a little longer than
its distance from the end of the snout, shorter than the parietals.
Loreal longer than deep, sometimes divided into two. One preocular
(sometimes divided into two), in contact with the frontal; two
postoculars; a series of three or four suboculars, usually completely
separating the eye from the labials. Temporals 2 + 3 or 3 + 3. Eight or
nine (rarely ten) upper labials, fifth or sixth very rarely entering the
eye. Four lower labials in contact with the anterior chin-shields, which
are shorter than the posterior.
_Scales_ with two apical pits, in twenty-five to twenty-nine rows,
usually twenty-seven. Ventral shields very distinctly angulate
laterally, 222 to 258; anal divided (rarely entire); subcaudals 77 to
107.
_Coloration._--Brown, pale olive, reddish, yellow, or orange above, with
a dorsal series of large dark brown, black-edged rhomboidal spots, often
bordered with yellow, on each side of which is a series of smaller,
alternating spots (Plate V.); these spots may become entirely black in
the adult, and so large as to reduce the ground colour to a mere network
or series of X-shaped pale lines. A dark cross-band between the eyes,
and a [V]- or horseshoe-shaped band on the back of the head, which may
be confluent with an elongate spot on the nape; a light circle often
present in the middle between the parietal shields. The spots often more
or less confluent into three longitudinal streaks on the tail. Yellow,
orange, or red beneath, with or without black dots, but constantly with
a lateral series of black spots, which may be very large or unite with
the spots higher up on the sides to form vertical bars.
_Size._--Examples 5 feet long are on record; the largest examined by me
measures 4 feet 3 inches.
_Distribution._--Spain and Portugal, Sardinia, Pantellaria, Morocco,
Algeria, Tunisia. Does not reach the North of Spain nor penetrate into
the Sahara.
_Habits._--This very handsome snake is as a rule as irascible as its
European congeners. In Spain as well as in Algeria it is often found
about the dwellings of man, occasionally entering houses in search of
mice, on which it principally feeds; it is also fond of birds, and,
climbing with great facility, plunders the nests of sparrows in towns
and villages. It must be regarded as a useful commensal of man, and
deserving of protection.
_Reproduction._--F. Doumergue found in a hole in a rock near Oran, in
September, the recently-laid eggs, five in number and as large as
pigeons'.
GENUS COLUBER, LINNÆUS
Maxillary teeth equal or nearly equal in length. Head elongate, distinct
from neck; eye moderately large, with round pupil. Body more or less
elongate; scales smooth or feebly keeled, with apical pits. Tail
moderate or long.
This large genus, embracing close upon fifty species, is represented in
Europe, Asia, and North and tropical America. Five species in Europe.
Very nearly allied to _Zamenis_, but distinguished principally by the
posterior teeth of the upper jaw not being at all enlarged, and,
further, in being, like _Coronella_, constrictors.
9. COLUBER QUATUORLINEATUS, Lacepède
(_Elaphis cervone_, Aldrovandi; _Coluber quatuorradiatus_,
Gmelin)
Aldrovandi's Snake
_Form._--Moderately slender. Snout obtuse, scarcely prominent. Tail
one-sixth to one-fourth of the total length.
[Illustration: FIG. 22 (after Sordelli)]
_Head-Shields._--Rostral broader than deep, just visible from above.
Frontal once and one-fourth to once and a half as long as broad, as long
as its distance from the rostral, shorter than the parietals. Loreal
nearly as long as deep, with one or two small shields below it. One
preocular, rarely divided, with a subocular below it; two or three
postoculars. Temporals 2 + 3 or 3 + 4. Upper labials eight
(exceptionally nine), fourth and fifth (or fifth and sixth) entering the
eye. Four or five (rarely three) lower labials in contact with the
anterior chin-shields, which are longer than the posterior.
_PLATE VI_
[Illustration: COLUBER QUATUORLINEATUS
_Young, after Sordelli_]
[Illustration: COLUBER QUATUORLINEATUS
_After Werner_]
[Illustration: COLUBER QUATUORLINEATUS, VAR. SAUROMATES
_After Sordelli_]
[Illustration: COLUBER DIONE
_After Sordelli_]
_Scales_ feebly but distinctly keeled, except on the outer rows, with
two apical pits, in twenty-five (rarely twenty-three or twenty-seven)
rows. Ventral shields not or but very obtusely angulate laterally, 195
to 234; anal divided; subcaudals 56 to 90.
_Coloration._--Young (Plate VI., top) with three or five alternating
longitudinal series of dark brown, black-edged spots on a yellowish,
grey, or pale brown ground, the spots of the median series largest,
transversely elliptical or rhomboidal; a dark streak across the
forehead, black bars on the labial shields, and a black oblique streak
from the eye to the angle of the mouth. In specimens from Italy and the
countries bordering the Adriatic (the typical _C. quatuorlineatus_) the
markings very gradually disappear with age, with the exception of the
temporal streak, whilst a pair of black streaks appear along each side
of the body, at a short distance from the head, the lower corresponding
to the postocular streak, the adult being brown without spots, but
four-lined (Plate VI., second figure). In more eastern specimens (_C.
sauromates_, Pallas), which may be regarded as representing the original
form, the markings of the young persist throughout life, or, if they
disappear, they are not replaced by dark streaks (Plate VI., third
figure). Lower parts pale yellow, closely spotted or marbled with brown,
these markings usually disappearing in the adult, except on the tail.
Iris dark brown.
_Size._--The largest European snake, stated to reach a length of 8 feet.
The largest specimen examined by me measures, however, only 4-1/2 feet.
_Distribution._--Aldrovandi's Snake inhabits Southern Italy and Sicily,
Istria, Croatia, Dalmatia, Herzegovina, Greece, and eastwards to
Southern Russia, Transcaucasia, Asia Minor, and Persia. It has been
observed at an altitude of 2,600 feet in Herzegovina.
All the specimens from Roumania, Bulgaria, Turkey, and eastwards, belong
to the var. _sauromates_, which is regarded by some authors as worthy of
specific rank. The reported occurrence of _C. quatuorlineatus_ in
various parts of France is certainly due to confusion with _C. scalaris_
and _C. longissimus_.
_Habits._--Dry as well as marshy localities are the abode of this large
and handsome snake, which often approaches the dwellings of man,
attracted by the poultry. Comparatively slow in its movements, it is
more easily captured than any of the other large Colubrids of Europe,
and does well in captivity, where it should be provided with a tank, in
which it will remain for hours under water. It is as good at swimming as
at climbing. Biting readily when captured, it becomes of gentle
disposition after a short period of captivity. In consequence of its
slow, phlegmatic temperament, it often allows itself to be picked up
when surprised in liberty, but as soon as it feels the grasp it turns
round and defends itself. It appears to feed exclusively on mammals and
birds, up to the size of a rat or dove, and will readily take dead food.
It has a predilection for eggs, and has often been observed to swallow
hens' eggs.
_Reproduction._--In Herzegovina pairing takes place from the middle of
June to the middle of July, and the eggs are laid soon after, to hatch
in September or beginning of October. The eggs number six to sixteen,
and measure 2 inches by 1-1/3 inches. The young measure 8 to 14 inches
at birth.
10. COLUBER DIONE, Pallas
The Dione Snake
_Form._--Similar to the preceding. Head more convex, a little narrower;
snout obtuse, scarcely prominent. Tail about one-fifth of the total
length.
_Head-Shields._--Rostral broader than deep, just visible from above.
Frontal once and one-fourth to once and a half as long as broad, as long
as its distance from the end of the snout, shorter than the parietals.
Loreal as long as deep, or a little longer than deep. A large preocular,
with a subocular below it, the latter very exceptionally absent; two or
three postoculars. Temporals 2 + 3 or 3 + 3. Upper labials eight or nine
(very rarely seven), fourth and fifth or fifth and sixth entering the
eye. Four or five lower labials in contact with the anterior
chin-shields, which are nearly as long as the posterior.
_Scales_ smooth or faintly keeled, with two apical pits, in twenty-five
or twenty-seven (rarely twenty-three) rows. Ventral shields not or but
very obtusely angulate laterally, 172 to 214; anal divided; subcaudals
50 to 80.
[Illustration: FIG. 23 (after Sordelli)]
_Coloration._--Pale brown or greyish-olive above, with blackish
cross-lines or dark brown or reddish, black-edged spots, and usually two
or three more or less distinct pale longitudinal bands; two dark
longitudinal stripes on the nape, usually united on the head and
terminating on the frontal shield; a curved dark cross-band from eye to
eye, and another, oblique, from the eye to the angle of the mouth. Lower
parts yellowish, usually dotted or spotted with blackish.
_Size._--Seldom exceeds a length of 3 feet. The largest specimen
examined by me measures 37 inches.
_Distribution._--Across temperate Asia from Asia Minor, Transcaucasia,
and the southern border of the Caspian Sea, to the Amur, Corea, and
China. In Europe the habitat of this snake is restricted to the steppes
of Southern Russia, between the Caucasus and the Lower Ural. The
specimen figured on Plate VI. is from Sarepta, on the Volga.
_Habits._--This snake frequents arid, sandy localities, and is only
exceptionally found in small woods. Nothing more is known of its habits.
11. COLUBER LONGISSIMUS, Laurenti
(_Coluber æsculapii_, Lacepède; _C. flavescens_, Gmelin)
The Æsculapian Snake
_Form._--Slender. Snout obtuse, scarcely prominent; head narrow. Tail
about one-fifth to one-fourth of the total length.
[Illustration: FIG. 24]
_Head-Shields._--Rostral broader than deep, just visible from above.
Frontal once and one-fourth to once and one-third as long as broad, as
long as its distance from the rostral or the end of the snout, shorter
than the parietals. Loreal as long as deep or longer than deep. One pre-
and two postoculars. Temporals 2 + 3. Upper labials eight or nine,
fourth and fifth or fifth and sixth entering the eye. Four or five lower
labials in contact with the anterior chin-shields, which are as long as
or a little longer than the posterior.
_Scales_ smooth or feebly keeled on the posterior part of the body, with
two apical pits, in twenty-three (rarely twenty-one) rows. Ventral
shields distinctly angulate laterally, 212 to 248; anal divided;
subcaudals 60 to 91.
_Coloration._--Yellowish-grey to dark olive-brown above, some of the
scales with whitish lines on the margins occasionally forming a network;
sometimes with a yellowish vertebral stripe or with four darker stripes
along the body (var. _romanus_, Suckow); upper lip, and often also a
triangular patch on each side behind the temple, pale yellow; a more or
less distinct dark band on the temple, and a vertical dark bar below the
eye (Plate VII., first figure). Lower parts uniform pale yellow. Young
(second figure) with dark brown dorsal spots, forming four to seven
longitudinal series, a [V]-shaped black marking on the nape behind the
yellow nuchal blotches, which are brighter than in the adult, a dark
brown bar across the forehead, and a black vertical line below the eye;
belly greyish or yellowish-olive. Iris dark grey or brown. Tongue
pinkish-brown.
_PLATE VII_
[Illustration: COLUBER LONGISSIMUS]
[Illustration: COLUBER LONGISSIMUS
_Young, after Sordelli_]
[Illustration: COLUBER LEOPARDINUS
_After Sordelli_]
[Illustration: C. LEOPARDINUS, VAR. QUADRILINEATUS
_After Sordelli_]
Melanism is rare in this snake. Such specimens are entirely black above
and beneath (var. _niger_, Nikolsky), or blackish-grey to black above,
dark grey beneath (var. _subgriseus_, Werner), the angular line on each
side of the belly often remaining light. An albino found near Vienna has
been described as pale orange-yellow above, with small white spots;
pupil and tongue red.
_Size._--Grows to 6 feet. Specimens over 4-1/2 feet are, however, very
rarely met with.
_Distribution._--Generally distributed over the greater part of Austria,
Italy, with Sardinia and Sicily, and the whole of South-Eastern Europe,
this snake has a very broken range in France, Switzerland, Germany, and
is found, quite isolated, as far north as Denmark and Poland. According
to Segerus, quoted by Lacepède, it used to be quite common near
Copenhagen at the end of the eighteenth century, but it is now much
rarer. Its northern limit in France is in Southern Brittany, the
Department Orne, and the Forest of Fontainebleau; in Germany,
Schlangenbad, near Wiesbaden, perhaps also Baden-Baden and Treves. It is
on record from Southern Spain. Its discontinuous distribution in Central
Europe, and its presence in various localities near former Roman thermal
stations, has been ascribed to its introduction from Italy as an inmate
of the temples erected to Æsculapius; but I am more inclined to look
upon its sporadic occurrence in the North as the indication of a once
more widely distributed species now in process of extinction over part
of its range.
In Asia the Æsculapian Snake is only found in Transcaucasia. It occurs
in the mountains as well as in the plain, being recorded from 5,200 feet
altitude in the Tyrol, 3,200 feet in the Apennines.
_Habits._--The Æsculapian Snake lives in woods; among shrubby
vegetation; in meadows, where it is often found under haystacks;
occasionally about old walls. It climbs well, and often ascends trees.
Although a good swimmer, it seldom enters the water of its own accord.
It feeds chiefly on small mammals, occasionally on birds and their eggs,
and lizards. Specimens which I kept in confinement fed on mice only,
refusing sparrows and lizards. Very savage when fresh caught, most
individuals soon become tame, and like being handled by people to whom
they are accustomed, although still resenting the intrusion of
strangers. However, this snake never becomes so thoroughly domesticated
as the Smooth Snake, and cannot be trained to take food from the hand,
according to R. Rollinat, who has devoted many years to experiments on
the taming of reptiles. This observer had no difficulty in feeding his
Æsculapian Snakes on mice and voles placed dead in their cage.
This snake is particularly sensitive to cold, and does not emerge until
late in the spring from the vole galleries and hollow trees which
constitute its winter-quarters. It also avoids excessive heat, never
showing itself in the daytime during the hotter months in the South of
Europe.
_Reproduction._--Pairing takes place between the middle of May and the
middle of June. The eggs are laid towards the end of June or in July, in
holes in walls or hollow trees, under moss, sometimes even in the
dung-heaps of farms, and hatch in September. According to trustworthy
observers, the eggs, which measure 1-1/2 to 2 inches in length, and less
than 1 inch in width, number only five or six, rarely up to eight.
The young on emerging are highly suggestive of young Grass-snakes in
colour and markings, as well as in their much less slender shape as
compared with the adult. They measure about 5 inches, and are at once
most ready to bite.
12. COLUBER LEOPARDINUS, Bonaparte
(_Coluber quadrilineatus_, Pallas)
The Leopard Snake
_Form._--Slender. Snout obtuse, scarcely prominent. Tail about one-fifth
of the total length.
_Head-Shields._--Rostral broader than deep, just visible from above.
Frontal once and one-third to once and a half as long as broad, as long
as its distance from the end of the snout, shorter than the parietals.
Loreal longer than deep. One pre- and two postoculars. Temporals 1 + 2
or 2 + 3. Upper labials eight (rarely seven), fourth and fifth (rarely
third and fourth) entering the eye. Four or five lower labials in
contact with the anterior chin-shields, which are longer than the
posterior.
_Scales_ smooth, with two apical pits, in twenty-five or twenty-seven
rows. Ventral shields rounded, not angulate laterally, 222 to 260; anal
divided; subcaudals 68-90.
[Illustration: FIG. 25 (after Sordelli)]
_Coloration._--Typical form (Plate VII., third figure) greyish or pale
brown above, with one dorsal series of dark brown, reddish-brown, or
bright red, black-edged transverse spots and a lateral alternating
series of smaller black spots with or without lighter centres; usually a
[Y]-shaped dark marking on the occiput and nape; a crescentic black band
from eye to eye across the prefrontal shields, an oblique black band
from behind the eye to the angle of the mouth, and a black spot or
vertical bar below the eye. Lower parts white, checkered with black, or
nearly entirely black. Iris reddish-golden.
In some specimens (var. _quadrilineatus_) the dorsal spots are replaced
by two brown or red, black-edged stripes bordering a pale greyish or
yellowish vertebral stripe (Plate VII., fourth figure); such specimens
are so coloured from birth. This colour variety, which is so strikingly
different from the typical form, is connected with the latter by the
var. _schwoederi_, Werner, in which the spots form two vertebral series,
and the var. _elsneri_, Werner, in which the light vertebral band is
broken up by dark transverse bars, producing a ladder-like pattern.
_Size._--Rarely exceeding a length of 3 feet.
_Distribution._--Southern Italy, Sicily, Malta, Istria, Dalmatia, and
other parts of the Balkan Peninsula, Grecian islands, Crimea, Asia
Minor. The altitudinal range does not extend beyond 1,600 feet.
_Habits._--This is not only the prettiest European snake as regards its
markings, whether in the form of spots or of stripes, but also the most
graceful in its movements. Unless compelled to fly for safety, there is
something slow and deliberate in its behaviour which is more suggestive
of _Coronella_ than of most other species of _Coluber_. It is fond of
climbing, and if the terrarium in which it is kept be provided with a
bush or small tree, it will spend most of the time gracefully coiled
round the branches. Usually very savage when fresh caught, some
specimens become quite tame in captivity. In Dalmatia, where it is not
uncommon, this snake is found principally among prickly shrubs, in
hedges, or on old walls. It awakens from its winter slumber later than
other South European snakes. Although occasionally taking lizards, its
principal food consists of mammals and birds, which are killed before
being devoured, the Leopard Snake being, like the other members of the
genus _Coluber_, a constrictor.
_Reproduction._--According to Werner, the eggs, two to five in number,
are deposited in midsummer; they are remarkably elongate: 2-1/2 inches
long, 2/3 inch broad.
13. COLUBER SCALARIS, Schinz
The Ladder Snake
_Form._--Moderately slender. Snout pointed, strongly projecting beyond
the mouth. Tail one-sixth to one-fifth of the total length.
[Illustration: FIG. 26 (after Sordelli)]
_Head-Shields._--Rostral deeper than broad, forming an acute angle
above, wedged in between the internasals, the portion visible from above
nearly as long as its distance from the frontal. Frontal about once and
one-third to once and a half as long as broad, as long as or shorter
than its distance from the end of the snout, nearly as long as the
parietals. Loreal longer than deep. One pre- and two or three
post-oculars. Temporals 2 + 3 or 2 + 4. Upper labials seven or eight
(rarely nine), fourth or fourth and fifth (or fifth and sixth) entering
the eye. Four or five lower labials in contact with the anterior
chin-shields, which may be either longer or shorter than the posterior.
_PLATE VIII_
[Illustration: COLUBER SCALARIS
_After Sordelli_]
_Scales_ smooth, with two apical pits, in twenty-seven (rarely
twenty-five or twenty-nine) rows. Ventral shields not angulate
laterally, 201 to 220; anal divided, rarely entire; subcaudals 48 to 68.
_Coloration._--Young yellowish-grey, or pale brown, above, with a series
of regular H-shaped black or blackish-brown markings along the back,
forming a ladder-like pattern--whence the name _scalaris_--and small
black spots on the sides; a V-shaped black marking on the snout, a black
oblique streak from the eye to the angle of the mouth, and a black spot
below the eye; belly yellow, spotted or checkered with black or nearly
entirely black. These dorsal markings disappear in the adult, and are
replaced by a pair of brown stripes running along the back (Plate
VIII.); the belly loses the black markings, and becomes uniform yellow.
Iris dark brown.
_Size._--Grows to a length of 3-1/2 feet, exceptionally 4-1/2 feet.
_Distribution._--The Mediterranean coast of France, Spain and Portugal,
and Minorca. Its occurrence in Algeria is very doubtful.
_Habits._--Not uncommon near the coast in France, in hedges and
vineyards, often climbing on shrubs. In the Spanish Peninsula, according
to Boscá, it is common in forests and on the sheltered side of valleys,
under stones or in holes in the ground. A specimen I kept alive for a
short time showed a more furious temper than I have ever witnessed in
any snake, repeatedly flying with open mouth against the glass of its
cage whenever I entered the room in which it was kept. Other specimens
are reported to have become quite tame after a certain time. It is one
of the quickest of European snakes, one of the most difficult to catch;
it is a good climber. The food consists of mice, birds, and lizards; the
young are said to occasionally eat grasshoppers.
_Reproduction._--According to J. von Fischer, the eggs, nine in number,
are deposited twenty-five days after the pairing, which takes place in
May or June, and measure about 2 inches by 2/3 inch.
GENUS CORONELLA, LAURENTI
Maxillary teeth increasing in size posteriorly. Head not or but slightly
distinct from neck; eye rather small, with round pupil. No subocular
shields. Body moderately elongate; scales smooth, with apical pits. Tail
moderate.
_PLATE IX_
[Illustration: CORONELLA AUSTRIACA
_After Sordelli_]
This genus, embracing about twenty species, is represented in the
different parts of the Northern Hemisphere, extending a little beyond
the Equator in East Africa. Two species are European.
14. CORONELLA AUSTRIACA, Laurenti
(_Coluber lævis_, Lacepède)
The Smooth Snake
_Form._--Moderately slender; snout more or less prominent, sometimes
decidedly pointed; tail one-fourth (males) to one-sixth (females) of the
total length. The considerable differences to be observed in the shape
of the snout are merely individual, specimens with more prominent snout
and a corresponding development of the rostral shield (_C. italica_,
Fitz., _fitzingeri_, Bonap.) occurring over the greater part of the
range of the species.
[Illustration: FIG. 27 (after Sordelli)]
_Head-Shields._--Rostral at least as deep as broad, more or less
produced posteriorly between the internasals, the portion visible from
above at least half as long (in some specimens quite as long) as its
distance from the frontal, rarely separating the internasals. Frontal
once and one-fourth to once and a half as long as broad, much broader
than the supraocular, as long as or longer than its distance from the
end of the snout, shorter than the parietals, widely separated from the
preocular. Nasal rarely undivided; loreal longer than deep. One (very
rarely two) pre- and two postoculars. Temporals 2 + 2 or 2 + 3 (very
rarely 1 + 2). Upper labials seven (rarely eight), third and fourth (or
fourth and fifth) entering the eye. Four lower labials (rarely three) in
contact with the anterior chin-shields, which are as long as or longer
than the anterior.
_Scales_ with one or two apical pits, the pit usually single on the back
and paired on the sides, in nineteen (rarely twenty-one) rows.[B]
Ventral shields 153 to 199; anal divided (rarely entire); subcaudals 41
to 70.
_Coloration._--Grey, brown, or reddish above, with small blackish, dark
brown, or brick-red spots usually disposed in pairs, sometimes forming
cross-bars; sometimes with one or three lighter stripes; one or two
black dots precede on each scale the single or paired apical pit;
frequently two blackish, dark brown, or brick-red stripes on the nape,
usually confluent with a large dark blotch on the occiput; the top of
the head occasionally nearly entirely blackish, especially in the young;
a dark streak on each side of the head, from the nostril to the angle of
the mouth, passing through the eye, sometimes extending along the side
of the neck or even of the whole body. Lower parts red, orange, brown,
grey, or black, uniform or speckled or closely spotted with black and
white, the sides often lighter (Plate IX.).
A colour variety, of which I have examined a single specimen from near
Vienna, is pale brown above, with four black lines along the anterior
part of the body, and two small, yellowish, dark-edged spots close
together on the back of the head, separated by the suture between the
parietal shields.
Werner has described another variety, also from near Vienna, which
resembles _Coluber leopardinus_, having two series of large, brown,
dark-edged spots along the back, some of the spots alternating, others
uniting across the back. Apparently very similar to the last variety,
and also said to be suggestive of _Coluber leopardinus_, is the var.
_scalaris_, Sternfeld, from Lüneburg in Hanover, reddish-brown above,
with two rows of bright red, black-edged spots, partly confluent and
connected across the spine by transverse bars producing a ladder-like
pattern. Specimens of a uniform greyish-brown, without any markings, are
very rare. The var. _veithi_, Schreiber, established on a single
specimen from Carinthia, represents a case of melanism: bluish-black,
with the normal markings of an intense black. Two specimens of a "black
variety" are said to have been found in this country, near Poole.
_Size._--Seldom exceeds a length of 2 feet, and in many districts, in
England for instance, does not appear to often reach that size. The
largest specimen, from Austria, examined by me, measures 25 inches; one
from Hampshire measures 24 inches.
_Distribution._--The range of the Smooth Snake extends over nearly the
whole of Europe, as far north as 63° in Norway; it becomes rare and more
local in the south, being absent from part of Spain and the islands of
the Mediterranean, with the exception of Sardinia. It is common in the
hilly parts of Belgium, Northern and Central France, Germany, and
Austria. In Sweden it appears to be restricted to the oak region. In
Great Britain it has been found in four counties in the South of
England: Surrey, Hampshire, Dorsetshire, and Berkshire, in some parts of
which it is less uncommon than usually supposed. Its reported occurrence
in Dumfriesshire is the result of an error; the snake figured as
_Coluber dumfriesiensis_ represents an American species. In a very
interesting article written for _Science Gossip_ in 1888, Mr. A. L.
Beldy says that about 1868, when Bournemouth was but a very small
village, surrounded by large expanses of moorland, _Coronella austriaca_
was extraordinarily abundant, and during a hot summer examples were to
be seen literally in scores and great numbers were killed. Since then,
however, their numbers have gradually decreased. About 1880 the snake
was occasionally found near Wellington College, Berks, and as many as
five were captured by one person in the course of one year; it is
believed to be now extinct in that neighbourhood. From South-Eastern
Europe the range of this species extends to South-Western Asia. The
ascertained altitudinal range is 4,000 feet in the Alps, 6,000 feet in
Bosnia, and 6,500 feet in the Caucasus.
_Habits._--The Smooth Snake lives on heathland, stony wastes, and wooded
hills, showing a preference for dry localities. Although not infrequent
on the Dorsetshire and Hampshire heaths, where it was first discovered
in 1853, it was not recorded as a British reptile until 1859; it was
discovered much later on the sandy heaths between Haslemere and Farnham,
where it occurs in small numbers, and in Berkshire. These localities are
likewise inhabited by the rarer British lizard, the Sand Lizard.
Notwithstanding its gentle, timid appearance, this snake when fresh
caught is usually very ready to bite; either it snaps angrily, or,
without hissing or other warning, it suddenly fastens its jaws into the
finger of its captor, even if it be gently handled. The food consists
mostly of lizards, occasionally of slow-worms or small snakes, more
rarely of voles or mice, even shrews, which are seized,
constrictor-like, and crushed by the coils of the body. O. von Tomasini
has observed one swallowing a _Coluber longissimus_ as large as itself.
In Central Europe this snake becomes active towards the end of March or
beginning of April, and retires in September or October. It does well in
captivity, and becomes very tame. It is one of the most intelligent of
snakes, second to none in educability; it can be trained to feed in the
hand of its master.
_Reproduction._--The Smooth Snake pairs in early spring, and is
ovoviviparous. The young, two to fifteen in number, are born late in
August or in September, enveloped by a thin membrane which they tear
immediately; they measure 5 to 6 inches. Embryos 3-1/2 or 4 inches long
have the scaling and the characteristic markings fully developed, but
the scales and shields much abbreviated, the former broader than long. A
dicephalous young is preserved in the Bosnian Museum at Sarajev, and
another was caught near Karlsruhe, in Germany, in 1881, and kept alive
for some time. According to Rollinat, a second autumnal pairing
sometimes takes place in France.
15. CORONELLA GIRONDICA, Daudin
(_Coluber riccioli_, Metaxa)
The Southern Smooth Snake
Distinguished from the preceding by a somewhat more slender form, a more
obtuse, scarcely prominent snout, a much lower rostral shield, which is
considerably broader than deep and just visible from above, not
penetrating between the internasals, constantly eight upper labials,
fourth and fifth entering the eye, and the scales in twenty-one (rarely
nineteen or twenty-three) rows. Ventrals 170 to 200; anal divided;
subcaudals 49 to 72.
_PLATE X_
[Illustration: CONTIA MODESTA
_After Sordelli_]
[Illustration: CORONELLA GIRONDICA
_After Sordelli_]
_Coloration._--Brown, greyish, yellowish, or reddish above, with dark
brown or black spots or transverse bars, sometimes with four dark
stripes in addition; dark dots in front of the apical pits as in the
preceding species; a pair of elongate dark spots or a U-shaped marking
on the nape; a dark streak from the eye to the angle of the mouth, and a
dark cross-bar from eye to eye, across the prefrontal shields; a dark
line below the eye. Lower parts yellow, orange, or coral red, with
large, mostly quadrangular black spots, often arranged in chess-board
fashion, or with two series of black spots (Plate X.), which may be
confluent into two longitudinal bands.
[Illustration: FIG. 28 (after Sordelli)]
_Total Length._--26 inches.
_Distribution._--South of France (as far north as the
Charente-Inférieure to the west, the Dauphiné to the east), the whole of
Spain and Portugal, Southern Tyrol, Italy, and Sicily. It has not been
recorded from higher than 2,500 feet in the Alps. Rare in Northern
Morocco and Algeria. In many localities in Europe it occurs alongside
with _C. austriaca_.
_Habits._--All that is known to me of the habits of this close ally of
the preceding species is derived from the works of Bonaparte, Gené, and
Schreiber, and from a note by Gachet, who observed it near Bordeaux and
described it under the name of _Coluber rubens_. According to these
authors, it frequents dry and rocky localities as well as old walls, in
which it finds a refuge and a good supply of the lizards on which it
feeds. A large specimen from Albano, near Rome, preserved in the Genoa
Museum, had swallowed a full-grown _Chalcides tridactylus_. This
_Coronella_ is crepuscular, rarely showing itself in the daytime,
leaving its retreat only after sunset, and has been observed to crawl
about by moonlight. Its movements are slow, which accounts for crushed
specimens being often met with on paths or roads. Contrary to the rule
in _C. austriaca_, it is extremely gentle, seldom attempting to bite.
_Reproduction._--Whether this species is ovoviviparous, like its
European congener, has not, I think, been ascertained. All we know on
this matter is that a female found dead on a road near Bordeaux by M.
Lataste at the end of June contained eggs which showed no trace of
embryos. This does not, however, settle the question, as the young would
not be born until at least two months later. According to Gené, pairing
takes place in May, when specimens have been observed to congregate in
considerable numbers.
GENUS CONTIA, BAIRD AND GIRARD
Maxillary teeth subequal. Head not or but slightly distinct from neck;
eye moderate or rather small, with round pupil. Nasal single; no
subocular shields. Body moderately elongate; scales smooth, with apical
pits. Tail moderate.
This genus, with certain modifications in the above definition, is made
to embrace about twenty-five species from South-Western Asia and Sind
and North and Central America. One of the species inhabiting Asia
extends into a very small part of Europe.
16. CONTIA MODESTA, Martin
The Dwarf Snake
_Form._--Moderately slender. Head small, quite flat above; snout obtuse,
feebly prominent. Length of tail four to five times in the total length.
_Head-Shields._--Rostral a little broader than deep, visible from above.
Suture between the internasals as long as or a little shorter than that
between the prefrontals. Frontal once and a half to once and two-thirds
as long as broad, as long as or longer than its distance from the end of
the snout, shorter than the parietals, as broad as or a little broader
than the supraocular, widely separated from the preocular. Nostril in
the middle or upper part of the nasal. Loreal square or longer than
deep. One (rarely two) pre- and two (rarely one) postoculars. Temporals
1 + 2; parietal sometimes nearly touching the fifth upper labial. Upper
labials seven, third and fourth entering the eye. Four (rarely five)
lower labials in contact with the anterior chin-shield; posterior
chin-shields smaller than the anterior, and separated from each other by
one or two rows of scales.
[Illustration: FIG. 29 (after Sordelli)]
_Scales_ with a single apical pit, in seventeen rows. Ventral shields
150 to 191; anal divided; subcaudals 53 to 78.
_Coloration._--Not unlike that of a young _Zamenis gemonensis_.
Greyish-olive above, uniform or each scale lighter in the centre. The
greater part of the upper surface of the head behind the snout, together
with the nape, black in the young, with a yellow cross-bar or a pair of
yellow spots between the eyes, the bar sometimes confluent with the
yellow postoculars, and a horseshoe-shaped band of the same colour on
the temples and across the occiput (Plate X.); the black of the nape
again edged with yellow behind. More or less distinct traces of these
markings are preserved in adult specimens. Upper lip yellowish, with
black spots or bars on the sutures between the shields. Lower parts
uniform white or yellowish.
In the var. _semimaculata_, Boettger, from Chios, small dark spots are
scattered over the upper parts of the anterior half of the body.
_Size._--This snake rarely reaches a length of 19 inches. It is the
smallest Colubrid of Europe.
_Distribution._--The Caucasus up to about 5,000 feet, Asia Minor, Chios,
Cyprus, Syria, Mesopotamia, and North-Western Persia. The northern slope
of the Caucasus appears to be the only part of Europe included in its
habitat. The British Museum possesses two specimens labelled as from
Constantinople, but the presence of this species in European Turkey
requires confirmation.
A closely allied species, which has been confounded with _C. modesta_,
_C. collaris_ (Ménétriès), and which also inhabits the Caucasus without
having been recorded from the northern slope, is distinguished by having
the scales in fifteen rows (very rarely seventeen), and the posterior
chin-shields in contact with each other.
_Habits._--Nothing is known as regards this species, but the North
American members of the genus _Contia_ are chiefly insectivorous and
oviparous.
GENUS COELOPELTIS, WAGLER
Maxillary teeth small and subequal, followed after a short interspace by
one or two very large grooved fangs situated below the posterior border
of the eye; anterior mandibular teeth strongly enlarged. Head not very
distinct from neck, with angular canthus rostralis and projecting
supraocular; eye large, with round pupil; nostril a crescentic slit in a
single or divided nasal. Body elongate; scales smooth, more or less
distinctly grooved longitudinally in the adult, with apical pits. Tail
moderately long.
The range of this genus, which comprises only two species, extends over
Southern Europe, South-Western Asia, and North Africa.
17. COELOPELTIS MONSPESSULANA, Hermann
(_Natrix lacertina_, Wagler; _Coluber insignitus_, I. Geoffroy)
The Montpellier Snake
_Form._--Slender; head elongate, narrow, concave above on the snout and
between the eyes; snout projecting, rounded, with raised canthus and
concave loreal region. Tail about one-fifth to one-fourth of the total
length.
_PLATE XI_
[Illustration: COELOPELTIS MONSPESSULANA
_After Sordelli_]
[Illustration: MACROPROTODON CUCULLATUS]
[Illustration: TARBOPHIS IBERUS
_After Sordelli_]
[Illustration: TARBOPHIS FALLAX]
_Head-Shields._--Rostral nearly as deep as broad, just visible from
above. Internasals much shorter than the prefrontals. Frontal very
narrow, twice to twice and a half as long as broad, its width in the
middle not more than half that of the supraocular, widening in front and
extending beyond the supraoculars to join the preoculars, longer than
its distance from the end of snout, as long as or a little longer than
the parietals. Two loreals. One preocular, the upper portion of which is
much enlarged, and encroaches upon the area occupied in other snakes by
the prefrontal and the supraocular; two (rarely three) postoculars.
Temporals 2 + 3 or 4. Upper labials eight (rarely nine), fourth and
fifth (or fifth and sixth) entering the eye. Four or five lower labials
in contact with the anterior chin-shields, which are as long as or
shorter than the posterior.
_Scales_ with single apical pits, in seventeen or nineteen rows,
longitudinally grooved in the adult, less distinctly in the young.
Ventral shields 160 to 189; anal divided; subcaudals 68 to 102.
[Illustration: FIG. 30]
_Coloration._--The young is elegantly marked with dark brown and
yellowish-white on a pale brown ground. On the head, the principal dark
markings usually are an oblique band on the posterior half of the
supraocular shield, and another, or a large spot, on the parietal,
sometimes produced backwards, and forming with its fellow a [V]-shaped
band, separated from a large occipital blotch by a yellowish space;
anterior half of the frontal shield and shields on the snout edged with
dark brown; a dark streak, sometimes broken up into small spots, on the
temporal region; yellow spots on the pre- and post-oculars; lips brown,
with large, yellow, black-edged spots, or yellow with brown spots; chin
with three brown longitudinal streaks. Back with a vertebral series of
large roundish dark spots or narrow cross-bars; small spots on the
sides, these sometimes forming longitudinal series or accompanied by
yellowish streaks or dots; these markings often confluent into three
longitudinal streaks on the tail. Belly pale brownish, greyish, or
reddish, with numerous pale spots, sometimes with a dark brown line on
each side. The adult is greyish, reddish-brown, or olive above. Some
specimens preserve more or less the markings of the young, and the dark
dorsal markings (Plate XI.) may be edged with yellowish and ocellar in
appearance (var. _insignitus_, Geoffroy); the belly is yellowish, with
small dark spots which usually form longitudinal series, and may be
confluent into streaks. A variety common in Dalmatia (_neumayeri_,
Fitzinger) is brown or olive above, without spots, sides with a
bluish-grey lateral band, the scales on which are edged with black, the
belly uniform yellow. Other specimens are brown or reddish, with light
edges to the scales on the sides, or with yellowish lateral lines, or
dark olive or dark brown above and black on the sides, each scale with a
yellowish central spot; in the last-mentioned the second third of the
back may be almost entirely black, and the belly dark olive-grey in the
middle and yellowish on the sides. Iris brown, with a golden or coppery
circle round the pupil.
_Size._--This handsome snake grows to a length of 6-1/2 feet. Specimens
5 to 6 feet long are not uncommon.
_Distribution._--Mediterranean coast of France and Western Liguria,
Spain and Portugal, Sicily, Lampedusa, eastern coast of the Adriatic,
Greece and eastern islands of the Mediterranean, Mediterranean coast of
Asia and Sinaitic Peninsula, eastwards to the Caucasus and Persia, North
Africa from Egypt to Rio de Oro. It is not known to occur above 2,300
feet altitude in Europe.
_Habits._--A lively, swift snake, living on land and on low bushes,
often found near human habitations. Some specimens are very vicious,
whilst others show a gentle disposition after a short period of
captivity. A specimen nearly 6 feet long, which I kept for some time,
never attempted to bite when handled, and some have become so tame as to
take food from the hand. The sense of sight appears to be better
developed than in any other European snake. The food consists chiefly of
mammals, even large rats and young rabbits, birds such as chickens,
partridges, and quails, lizards, and other snakes, which, if of
considerable size, are not swallowed until paralyzed or killed by the
effect of the poison. In Eastern Europe, _Vipera ammodytes_ is said to
be the principal enemy of _Coelopeltis_, and the two snakes are
consequently seldom found together in the same locality.
Many experiments have been made on the action of the poison of this
Opisthoglyph. Peracca and Deregibus, as well as, later, Phisalix, found
a striking similarity with the symptoms of Cobra poison in their
experiments on small animals, the suspension of the respiration
occurring in a few minutes, the blood being otherwise unaffected. It has
been stated by some authors that _Coelopeltis_ poison has little or no
action on man, but a French zoologist, E. Taton-Baulmont, having been
bitten in the index-finger by a four-foot-long specimen at Algiers, the
swelling extended within thirty hours up to the shoulder, and was
accompanied by fever and nervous troubles. As a rule, however, the bite
of this snake has no poisonous effect on man, from the fact that the
fangs conveying the venom are situated so far back in the mouth as not
to come into action.
_Reproduction._--According to Werner, the eggs, four to twelve in
number, are laid in July, and measure 2 inches in length and 1/2 inch in
width.
GENUS MACROPROTODON, GUICHENOT
Maxillary teeth few and very unequal in size, fourth and fifth or fifth
and sixth enlarged and followed by an interspace, the two last teeth
fang-like and grooved, situated just behind the eye; sixth mandibular
tooth fang-like, and separated from the remainder by an interspace. Head
slightly distinct from neck; eye rather small, the pupil vertically
elliptic or subelliptic when contracted. Body moderately elongate;
scales smooth, with apical pits. Tail moderate or rather short.
A single species.
18. MACROPROTODON CUCULLATUS, I. Geoffroy
The False Smooth Snake
_Form._--Very similar to the Smooth Snakes, with which it has been
confounded, but snout broader and very strongly depressed. Tail five and
a half to six and a half times in the total length.
[Illustration: FIG. 31]
_Head-Shields._--Rostral at least twice as broad as deep, not or but
scarcely visible from above. Internasals as long as or a little shorter
than the prefrontals. Frontal not much broader than the supraocular in
the adult, once and a half to twice as long as broad, as long as or
longer than its distance from the end of the snout, shorter than the
parietals. Nasal usually semidivided. Loreal once and a half to twice as
long as deep. One preocular, extending to the upper surface of the head,
but not reaching the frontal; two (rarely one or three) postoculars.
Temporals 1 + 2. Upper labials eight, fourth and fifth entering the eye,
sixth usually in contact with the parietal. Four or five lower labials
in contact with the anterior chin-shields, which are as long as or a
little shorter than the posterior.
_Scales_ with mostly single apical pits, the pits sometimes paired on
the sides of the body, in twenty-one or twenty-three rows (nineteen to
twenty-five in North African specimens). Ventral shields 153 to 192;
anal divided; subcaudals 40 to 54.
_Coloration._--Pale brown or greyish above, with small dark brown or
blackish spots or with more or less distinct darker and lighter
longitudinal streaks. Upper surface of head with dark brown
vermiculations; a dark brown or black, often light-edged occipito-nuchal
band, extending downwards to the gular region and produced forwards into
a point to between the parietal shields; a dark brown or black streak on
each side of the head from the end of the snout, through the eye, to the
last lower labial shield, traversing the four last upper labials, which
are yellowish above and below the streak (Plate XI.). Lower parts yellow
or coral red, with black spots, which may form a tessellated pattern,
two longitudinal series, or be so crowded as to fuse into a band along
the middle of the belly and tail.
The above description is taken from Spanish specimens (Badajos,
Algeciras, Andalucia), but the variations are very great when we take
North Africa into consideration. The nuchal band may be narrow or broken
up into spots, the median of which sometimes forms a longitudinal
streak, or so much enlarged as to fuse with the dark markings on the
upper surface of the head; in some specimens (from Morocco and Algeria)
the upper surface of the head and the nape may be entirely ink black, or
the whole head black above and beneath with the exception of a whitish
streak bordering the upper lip. The dark streak from the eye to the
angle of the mouth may be absent, or reduced to a short oblique streak
below the eye. Irrespective of the variations in the markings of the
upper parts, the lower parts may be more or less spotted with black, or
immaculate.
Some specimens of this small snake bear a general resemblance to
_Coronella girondica_, with which _Macroprotodon_ has sometimes been
confounded. But a careful examination of its whole structure shows it to
be more affine to _Coelopeltis_ and _Tarbophis_, the other European
representatives of the Opisthoglyphous Colubrids.
_Size._--The largest European specimen examined measures 17-1/2 inches.
Specimens up to 22 inches long occur in Algeria and Tunisia.
_Distribution._--In Europe this snake is only known from Spain
(Estremadura, New Castille, Andalucia), Portugal (Alemtejo), the
Balearic Islands (Majorca and Minorca), and the island of Lampedusa. In
North Africa it is generally distributed from the north coast of Egypt
to the Rio de Oro; in Algeria it penetrates into the northern parts of
the Sahara. The specimen figured on Plate XI. is from Algeciras.
_Habits._--Appear to be similar to those of _Coronella girondica_.
Crepuscular in its habits, it is usually found under stones or in
burrows in the ground. Unless pursued, when it darts off with great
rapidity, its movements are slow. It is very ready to bite, but no
experiments have been made on the effects of its poison. The food
consists chiefly of small lizards.
_Reproduction._--All that is known on this head is that, according to
Doumergue, eggs are laid in July in Algeria.
GENUS TARBOPHIS, FLEISCHMANN
Maxillary teeth few, anterior longest, gradually decreasing in size
posteriorly, and followed, after an interspace, by a pair of enlarged,
grooved fangs, situated below the posterior border of the eye; anterior
mandibular teeth strongly enlarged. Head distinct from neck; eye
moderate or rather small, with vertically elliptic pupil. Body
moderately elongate; scales smooth, oblique, with apical pits. Tail
moderate or rather short.
The eight species of this genus inhabit South-Eastern Europe,
South-Western Asia, and Africa. Two are dealt with here.
19. TARBOPHIS FALLAX, Fleischmann
(_Ailurophis vivax_, Bonaparte)
The Cat-Snake
_Form._--Moderately slender. Head much depressed. Tail five and a half
to seven times in the total length.
[Illustration: FIG. 32]
_Head-Shields._--Rostral broader than deep, just visible from above.
Internasals shorter than the prefrontals. Frontal much broader than the
supraocular, once and one-fourth to once and a half as long as broad, as
long as its distance from the end of the snout, shorter than the
parietals. Nasal divided or semidivided. Loreal twice and a half to
thrice as long as deep, entering the eye below the preocular, which is
in contact with the frontal. Two (rarely three) postoculars. Temporals
small, scale-like, 2 or 3 + 3 or 4. Upper labials eight (rarely seven or
nine), third, fourth, and fifth (rarely fourth and fifth, or fourth,
fifth, and sixth) entering the eye. Three or four lower labials in
contact with the anterior chin-shields; posterior chin-shields very
small and widely separated from each other by scales.
_Scales_ with single or paired apical pits, in nineteen or twenty-one
rows, usually nineteen in European specimens. Ventral shields 186 to
222; anal divided; subcaudals 48 to 73.
_Coloration._--Greyish above, with 40 to 57 brown or black spots or bars
on the body; a lateral series of smaller spots or vertical bars,
alternating with the dorsals; the first spot, on the nape, elongate,
usually with one or three linear processes in front, extending on the
head (Plate XI.); usually a dark streak on each side of the head, from
the eye to the angle of the mouth. Lower parts whitish, speckled,
spotted, or marbled with grey or brown. Iris brown, with a golden circle
round the pupil.
_Size._--This species grows to a length of 2 feet 10 inches.
_Distribution._--From Istria and Dalmatia to Greece, the Archipelago,
Constantinople, Asia Minor, Cyprus, and Northern Syria; 2,600 feet
appears to be its altitudinal limit.
_Habits._--Although to a certain extent crepuscular or nocturnal, the
Cat-snake is often seen hunting in the daytime, its food consisting
almost exclusively of lizards, rarely of small mammals. Its movements
are rather slow. The names Katzenschlange and _Ailurophis_, translated
Cat-snake, probably originated from the way in which this snake stalks
its prey, and suddenly pounces upon it. According to Eiffe, the poison
causes the death of a _Lacerta vivipara_ in one minute, and P. de Grijs
observed the larger _Lacerta agilis_ to die in two or three minutes. As
a rule even fresh-caught specimens allow themselves to be handled
without attempting to bite; some specimens, on the other hand, are very
savage. Stony localities, old walls, and ruins, are the favourite abodes
of this snake, which does well in captivity.
_Reproduction._--Seven or eight eggs are laid in July; they measure
about 1-1/4 inches in length and 1/2 inch in width.
20. TARBOPHIS IBERUS, Eichwald
The Caucasian Cat-Snake
Very closely allied to the preceding, and differing from it only in the
following points: Parietals shorter, slightly longer than the frontal,
and anal entire. Loreal twice to twice and a half as long as deep.
Fourth and fifth, or third, fourth, and fifth, labials entering the eye.
Scales in nineteen or twenty-one rows. Ventrals 203 to 235; subcaudals
54 to 70.
Grey above, with 35 to 40 blackish spots on the body, the anterior
largest and darkest; a lateral series of smaller spots or vertical bars.
Lower parts blackish, with small whitish spots and dots. Reaches a
length of 3-1/2 feet.
This species inhabits the Caucasus, and, being on record from the
northern slope (Kuban River), has to be included in the European fauna.
It occurs also in Mesopotamia, a specimen from Bagdad being preserved in
the British Museum. The young specimen figured on Plate XI. is stated to
be from Constantinople.
Nothing is known of its habits, which are probably the same as those of
_Tarbophis fallax_.
FOURTH FAMILY: VIPERIDÆ
Maxillary, palatine, and pterygoid bones movable, the first much
abbreviated, erectile perpendicularly to the large transverse bone, and
supporting a pair of large canaliculated poison fangs; mandible without
coronoid bone. No vestiges of pelvic arch.
All more or less poisonous, some being among the most dangerous of
snakes.
Divided into two subfamilies, each of which is represented by one genus
in Europe:
_Viperinæ._--No pit on the side of the snout; maxillary bone not
hollowed out.
_Crotalinæ._--A deep pit on each side of the snout, between the nostril
and the eye; maxillary bone hollowed out above.
_PLATE XII_
[Illustration: VIPERA URSINII
_From Zoological Society's Proceedings_]
[Illustration: VIPERA RENARDI
_From Zoological Society's Proceedings_]
[Illustration: VIPERA BERUS
_After Sordelli_]
The _Viperinæ_ inhabit nearly the whole of Europe, Asia, and Africa; the
_Crotalinæ_ are Asiatic (one species extending its range into a small
part of South-Eastern Europe) and American.
GENUS VIPERA, LAURENTI
Head distinct from neck, covered with small shields or scales, with or
without distinct frontal and parietal shields; eye moderate or small,
with vertical pupil, separated from the labial shields by scales; nasal
separated from the rostral by a naso-rostral. Body short. Scales keeled,
with apical pits. Tail short.
Of the eleven species of this genus, six are found in Europe; two
inhabit South-Western Asia, one the Indo-Malay region, and two Eastern
Africa.
The distinction of the European species is one of considerable
difficulty, owing to their close relationship and the presence of
intermediate forms connecting them. Matters being so, it seems curious
that the Common Adder should have been regarded by so many authors as
generically distinct from the Asp Viper, under the name of _Pelias
berus_. It is highly probable that hybrids are produced in those
districts where two species coexist, as in some parts of France, North
Italy, and Austria.
21. VIPERA URSINII, Bonaparte
Orsini's Viper
_Form._--Short and stout. Snout obtusely pointed, flat above or with the
canthus slightly raised. Eye very small, usually smaller than the nasal
shield, its horizontal diameter usually not exceeding its distance from
the posterior border of the nostril, its vertical diameter often less
than and rarely exceeding its distance from the mouth. Length of tail
seven to eight times in total length in males, nine and a half to twelve
times in females.
[Illustration: FIG. 33 (From Proceedings of the Zoological Society,
1893)]
_Head-Shields._--Rostral as deep as broad or slightly deeper than broad,
visible from above, in contact with one apical shield (rarely with two).
Distinct frontal and (usually) parietal shields, the former once and a
half to once and two-thirds (rarely once and one-third) as long as
broad, as long as its distance from the rostral or the end of the snout,
and nearly always longer than the parietals; the latter always in
contact with the former, rarely broken up into small shields. Four to
seven small shields on the snout between the canthals, of which there
are two on each side. Supraocular well developed, extending posteriorly
beyond the vertical of the eye, separated from the frontal by one to
three shields, very rarely in contact with it. Six to ten scales round
the eye, usually eight or nine, the upper preocular usually in contact
with the nasal; a single series of scales between the eye and the
labials. Nasal single. Temporal scales smooth. Upper labials six to
nine, usually seven or eight, usually third or third and fourth below
the eye. Three (rarely four) lower labials in contact with the
chin-shields, of which there is but one pair.
_Scales_ in nineteen (rarely twenty or twenty-one) rows, with two apical
pits, strongly keeled on the back, less strongly on the sides, outer row
smooth. Ventral shields 120 to 135 in males, 125 to 142 in females; anal
entire; subcaudals 30 to 37 in males, 20 to 28 in females. By adding the
subcaudals to the ventrals in a hundred specimens, the total numbers are
153 to 169 in males, 150 to 168 in females.
_Coloration._--Unlike its ally _V. berus_, _V. ursinii_ shows no sexual
differences in the coloration. The ground colour of the back is usually
yellowish or pale brown, sharply defined from the darker grey or brown
colour of the sides; some specimens, however, are of an almost uniform
brown ground colour. The light colour of the back is relieved by a
series of more or less regular transversely oval, elliptic, or
rhomboidal dark brown, black-edged spots, some or all of which may run
together to form a wavy or zigzag band (Plate XII.). Two or three
longitudinal series of dark brown or black spots extend along the sides,
the upper series, if present, occupying the space between the series of
spots continued from the postocular band and the large dorsal spots or
vertebral band, the lowermost following the outer row of scales. Small
dark spots and one or two [V]-shaped markings are present on the upper
surface of the head; an oblique dark band proceeds from the eye to the
angle of the mouth, and is not infrequently confluent with the branches
of the occipital [V]. The rostral and the labial shields are uniform
yellowish-white, rarely with a few small, blackish spots or with brown
borders. The chin and throat are yellowish-white, rarely with some
blackish spots. The ventral and subcaudal shields are black, with
transverse series of small white spots, or grey checkered with black and
white, or whitish with small round black spots; the tail is but rarely
(females) tipped with yellow.
The form recently described as _V. macrops_, Méhely, from Bosnia and
Herzegovina, is distinguished by a usually larger eye, the vertical
diameter of which equals or a little exceeds its distance from the
mouth, and the parietals are often broken up into small shields. The
postocular dark band is often reduced, originating at some distance from
the eye, and is not prolonged beyond the mouth. In this geographical
race melanic specimens occasionally occur, which are dark brown or
blackish above, the lower parts not differing from those of the typical
form.
_Size._--20 inches appears to be the usual maximum size reached by this
species, but, Dr. Werner informs me, a female 2 feet long has been found
in Lower Austria.
_Distribution._--First discovered in Italy in the Abruzzi, this species
has since been found in the Basses-Alpes, near Digne, in various parts
of Hungary, in Lower Austria, on the island of Veglia in Istria, and in
Bosnia, Bulgaria, Herzegovina, and Montenegro. A very broken and curious
distribution, the more so as _V. ursinii_ is essentially a form of the
plain in Lower Austria and Hungary, and an alpine form in Italy, in
France, and in the Balkan Peninsula, where it only occurs between 3,000
and 6,800 feet. In no part of its habitat does it appear ever to be
found in company with _V. berus_.
_Habits._--Only a few specimens have hitherto been found in Italy and in
France, but the species occurred up to a few years ago in extraordinary
numbers in Lower Austria, in the immediate vicinity of Laxenburg. The
intendant of the imperial castle pays a premium for the destruction of
Vipers, and in the course of one year (1892) more than 1,000 specimens
were brought to him. These snakes are found principally, though not
exclusively, in the marshy meadows around the park, where they may be
seen about in the daytime from May to September, feeding chiefly on
lizards (_Lacerta agilis_), and also on small rodents. The lizards are
swallowed as soon as seized, without the effect of the poison being
awaited as in other Viperid snakes. This Viper is as a rule of gentle
disposition, allowing itself to be handled without attempting to bite,
and village boys have been seen playing with them. Although occurring in
such enormous numbers at Laxenburg, no accident from snake-bite has ever
been heard of. The form from the Balkan Peninsula (_V. macrops_) is even
more pacific still, and is believed never to make use of its poison
apparatus, its food consisting of orthopterous insects. According to
Captain Veith, who has collected a large number of specimens of this
Southern form, the contents of the stomach as well as the excrements
show this snake to feed exclusively on grasshoppers. On one occasion a
big specimen showed such a swelling of the body as to lead to the
conclusion that it had swallowed a mouse, but it soon after disgorged
what proved to be a ball made up of the agglutinated remains of at least
a hundred grasshoppers. When handled, this Viper hisses or even pretends
to snap, but with closed mouth, never biting unless seriously hurt. The
poison appears to have little effect on man.
_Reproduction._--Nothing has been published on the breeding habits of
this species, but in a letter to the author, dated January 14, 1913,
Herr L. von Kirchroth, who has examined over 4,000 specimens since 1890,
says the young are born in July or August, exceptionally as early as
June. Young females bring forth from six to eight young, older females
from eight to eighteen; but a large female from Lower Austria is
reported to have contained as many as twenty-two. The length of the
new-born young is from 5 to 6 inches, and it grows rapidly within the
first week, probably through stretching out, without taking any food.
According to Captain Veith, the form described as _V. macrops_ brings
forth only from three to five young.
22. VIPERA RENARDI, Christoph
Renard's Viper
_Form._--Similar to the preceding species, but snout more pointed, the
raised canthi rostrales meeting at an acute angle. Eye usually as large
as in _V. berus_, nearly as large as the nasal shield; its horizontal
diameter equal to its distance from the posterior or anterior border of
the nostril, its vertical diameter equal to or a little less than its
distance from the mouth. Length of tail seven and a half to nine times
in total length in males, eight to ten times in females.
_Head-Shields._--Rostral as deep as broad or a little deeper than broad,
just visible from above, and in contact with a single apical shield.
Distinct frontal and (usually) parietal shields, the former once and
two-thirds to twice and one-third as long as broad, as long as or longer
than its distance from the end of the snout, usually longer than the
parietals; the latter always in contact with the former, unless broken
up into small shields. Two to six, usually three or four, small shields
on the snout between the canthals, of which there are two on each side,
the second broadly in contact with the supraocular. Supraocular well
developed, extending posteriorly beyond the vertical of the eye,
separated from the frontal by one to four shields. Nine to eleven,
usually ten, scales round the eye, the upper preocular usually in
contact with the nasal; either a single series of scales between the eye
and the labials, or two series except under the centre of the eye, which
is separated from the fourth labial by a single scale. Nasal single.
Temporal scales all smooth, or the upper faintly keeled. Upper labials,
eight or nine, fourth or fourth and fifth below the eye. Four (rarely
five) lower labials in contact with the chin-shields, of which there is
but one pair.
[Illustration: FIG. 34 (From Proceedings of the Zoological Society,
1893)]
_Scales_ in twenty-one (very rarely nineteen) rows, with two apical
pits, strongly keeled, outer row smooth or feebly keeled. Ventral
shields 130 to 148 in males, 130 to 150 in females; anal entire;
subcaudals 31 to 37 in males, 24 to 30 in females.
_Coloration._--As in _V. ursinii_, the sexes are alike in coloration.
European specimens (Plate XII.) are very similar to _V. ursinii_, except
that the labial shields are markedly dark-edged and speckled or spotted
with brown or black. The dorsal band or series of spots is dark brown,
edged with blackish; the ground colour of the middle of the back and of
the scales of the two outer rows on each side is yellowish, of the sides
(four rows of scales) greyish-brown with two or three series of dark
brown spots; two dark [V]-shaped markings on the head; a dark postocular
streak, extending or not to the side of the neck. The lower parts are
whitish or pale greyish, with blackish dots, of which there is a series
of larger ones along each side of the belly. The tip of the tail is
never yellow.
Central Asian specimens are of a pale yellowish sand-colour, with a
brown, dark-edged dorsal zigzag band or series of spots and two series
of small spots on the sides. Belly whitish, dotted or spotted with
black, or uniform blackish.
_Size._--23 inches is the length of the largest specimen examined.
_Distribution._--In Europe _V. renardi_, which has long been confounded
with _V. berus_, is abundant in the district of Uralsk, in the steppe
around Sarepta, in Crimea, and it is also found in Cis-Caucasia and in
Bessarabia. Its range extends far into Central Asia, being known from
the Khirghiz steppes, the Emba steppes, the steppes near the Alatau, on
the borders of the Urdshar, and in the Semipolatinsk district. Around
Sarepta it is common in the bare steppe, and only exceptionally occurs
in localities overgrown with willows and small shrubs.
_Habits._--Nothing has been published concerning the habits of this
snake, except that it is more sensitive to cold than _V. berus_ and does
not appear before the middle of April, retiring to its winter-quarters
in the beginning of October. The food consists of small mammals and
lizards.
_Reproduction._--Pairs in May, and brings forth five to seven young in
August, these young at birth measuring about 5-1/2 inches.
23. VIPERA BERUS, Linnæus
The Northern Viper, or Adder
_Form._--Short and stout. Snout flat above, rarely slightly concave, the
upper contour broadly rounded or truncate in front, the canthus well
marked, sometimes slightly raised, the loreal region nearly vertical.
Eye as a rule smaller in females than in males, as large or nearly as
large as the nasal shield; its vertical diameter equals or a little
exceeds its distance from the mouth. Length of tail five and a half to
nine times in total length in males, eight to ten and three-quarter
times in females.
[Illustration: FIG. 35 (after Sordelli)]
_Head-Shields._--Rostral as deep as broad or slightly broader than deep,
rarely once and one-third as deep as broad, not or but scarcely visible
from above. In addition to the supraoculars, three large shields, the
frontal and the parietals, are as a rule present on the top of the head.
Frontal as long as broad or a little longer than broad, rarely much
longer than broad, once and a half to twice and a half as broad as the
supraocular, from which it is as a rule separated by one to four
shields, as long as or a little shorter than its distance from the
rostral, as long as or a little shorter than the parietals. Parietals
usually in contact with the frontal and separated from the supraoculars
by small shields, but sometimes in contact with both, or separated from
the frontal. Exceptionally, in specimens from Great Britain, Germany,
and Austria, the parietals, or the frontal and the parietals, are broken
up into scales, and this is more frequently the case in specimens from
North-Western Spain (var. _seoanei_). Upper surface of snout bordered by
six (rarely by five or four) small shields, viz., two apicals (rarely
one), and on each side two canthals, the second of which is usually in
contact with the supraocular; canthals very rarely united into one
shield; the space between these shields covered by four to twenty flat
or convex, juxtaposed scales, which very exceptionally are fused into a
single large shield. Supraocular usually extending posteriorly beyond
the vertical of the eye. Six to thirteen scales round the eye, usually
eight to ten; two or three superposed scales, rarely two vertical series
of scales, separate the preoculars from the nasal, which is single. As a
rule a single series of scales intervenes between the eye and the
labials; specimens with two series are of very exceptional occurrence
(single specimens from Isle of Arran, Normandy, Southern Norway, and
Carniola, in the British Museum), but there are occasionally two series
except just below the centre of the eye. Upper labials six to ten,
usually eight or nine; fourth or fourth and fifth (rarely third and
fourth) below the eye. Temporal scales smooth, rarely feebly keeled.
Three or four (rarely five) lower labials in contact with the single
pair of chin-shields.
_Scales_ in twenty-one (rarely nineteen or twenty-three) rows, with two
apical pits, strongly keeled, those of the outer row smooth or feebly
keeled. Ventral shields 132 to 150 (usually 137 to 147) in males, 132 to
158 (usually 140 to 150) in females; anal entire; subcaudals 32 to 46
(usually 35 to 40) in males, 24 to 38 (usually 28 to 33) in females.
_Coloration._--It is characteristic of this species, contrary to the
rule in snakes, to present such marked differences of colour, according
to the sexes, that these can be distinguished in most cases from that
character alone.
Whitish or pale grey specimens, with black belly and jet black dorsal
markings (Plate XII.), are males. Brown and brick-red specimens, with
the markings of a more or less dark brown or red, are females. There are
also brown, reddish-brown or olive males with the markings of a deep
black, and grey males with brown markings. A very pretty colour variety,
which affects only females, is olive with brick-red band and spots. Some
males, just before exuviation, have the lower surface of a pale
greyish-blue (_Coluber cæruleus_, Sheppard), with the outer ends of the
shields black. Specimens with yellowish-white chin and throat, which may
be tinged with red, are females; males have the throat black, or whitish
with the scales spotted or edged with black. Exceptional females occur
(in Carniola) which in this respect resemble the males.
The markings vary considerably. Those on the back usually consist of a
wavy or zigzag longitudinal band, flanked on each side with a series of
spots corresponding to its sinuses; but this band may be partly or even
entirely broken up into rhomboidal or transversely oval spots, or,
losing its indentations, form a straight stripe edged on each side with
a yellowish streak (as in some specimens of the var. _seoanei_, from
North-Western Spain). The markings may be absent altogether (var.
_concolor_, Jan), or reduced to a narrow straight vertebral band
(_Pelias dorsalis_, Gray). In the var. _seoanei_ the zigzag band is
often replaced by a dark brown vertebral band, three to five scales
wide, bordered on each side by a series of subtriangular or crescentic
black spots opposite to each other, as in the Pyrenean specimens of _V.
aspis_. A pair of elongate dark markings are usually present on the back
of the head, affecting the following shapes: |\,)(,)(,)(; By uniting
together, this pair of markings may form a [V] or an X. An oblique dark
streak extends on each side from the eye to the last labial shields,
being sometimes prolonged a short way down the neck. The snout and
vertex may be uniform or bear some symmetrical dark spots, or in some
males be entirely black, the black involving the apex of the [V]-shaped
marking. The labial shields are whitish or yellowish, those at least
which are anterior to the eye being more or less broadly edged with
brown or black.
The belly and the lower surface of the tail vary from grey or brown to
bluish, blackish-grey, or black, the sides usually dotted or spotted
with whitish; sometimes, especially in females, the belly is dark grey,
each shield with a white posterior border which is broken up by a series
of small roundish black spots. The end of the tail is often yellowish,
bright yellow, or pale orange below, rarely coral red, more commonly in
females than in males.
The iris is usually coppery red, more rarely golden suffused with brown.
Black specimens occur, more or less frequently, all over the habitat of
this species, and are often referred to as _V. prester_, Linnæus. A
distinction has to be made between individuals which are black through
darkening of the ground colour, and such as are thus coloured through
expansion and confluence of the markings. The latter are males, and
among them we may find intermediate stages showing how this melanism is
brought about; in one case the black of the back is separated from the
black of the sides by a narrow light brown wavy stripe, the remains of
the ground colour. When, as in all females, and occasionally in males,
the black is the result of a gradual darkening of the ground colour, the
typical markings may still be detected under certain lights. Some
specimens (from Schneeberg, Lower Austria) are black, with scattered
golden dots, or of a dark mahogany brown speckled with yellowish. In
nearly all the black specimens at least a few dots of whitish are
visible on the lips, and of yellow under the end of the tail.
Most of the variations enumerated above occur irrespective of the
geographical distribution. Two forms, however, deserve to be regarded as
ill-defined local races: the var. _seoanei_, Lataste, from North-Western
Spain, in which, in addition to the peculiarities of coloration
mentioned in the description, the canthus rostralis is frequently more
distinctly raised, and the frontal and parietal shields are often
disintegrated into scales; and the var. _bosniensis_, Boettger, from
Bosnia, Carniola, and Carinthia, which is sometimes very suggestive of,
and has been taken for, the typical form of _V. aspis_, having like it,
though not at all constantly, two series of scales between the eye and
the labials, and the zigzag band replaced by a series of dark bars
across the back. The var. _pseudaspis_, Schreiber, from the plains of
Sclavonia, described as straw yellow above, with narrow dark cross-bars,
is hardly separable from the var. _bosniensis_.
_Size._--_Vipera berus_ is said to reach very exceptionally a length of
2 feet 11 inches. The largest specimen in the British Museum (from
Belgium) measures 2 feet 3-1/2 inches: the largest British specimen 2
feet 3 inches. Both these specimens are females. The largest male
measures 2 feet 2 inches.
_Distribution._--_Vipera berus_ ranges over the whole of Northern
Europe, to the extreme north of Scotland, and the sixty-seventh degree
in Scandinavia, and right across Northern Asia as far east as the island
of Saghalien. It is generally distributed in Great Britain, occurring
also on the Isles of Arran, Islay, Skye, Lewis, and Mull, rare or absent
in some districts, common in others. Its distribution in Central and
Southern Europe is irregular. In Western France it does not extend much
beyond the Loire to the south, only isolated captures being on record
from the departments Vendée, Deux-Sèvres, Vienne, and Indre. Of rare
occurrence south of Paris, in the departments Yonne and Allier and in
the mountains of Auvergne, it is again abundant in some parts of the
Central Plateau. To the east it is recorded from the departments Aude,
Haute-Marne, and Vosges. In Belgium, it is known from Flanders, Limburg,
the Meuse Valley, and the Ardennes; in Holland it is pretty generally
distributed in the uncultivated parts. It is spread over nearly the
whole of the German Empire with the exception of the vine districts,
where it is absent or extremely rare; it is also very scarce in the
mountains of the Black Forest; it is on record from only a few
localities in Lorraine, and has never been found in Alsatia. In South
Germany it is rarely found below 1,000 feet altitude. In Switzerland it
is absent from the Jura, but occurs in the Alps chiefly between 2,500
and 9,000 feet. To the East it extends to Russia, as far north as 64°,
Austria-Hungary, confined to the hills in the south, and Roumania. In
the Balkan Peninsula it occurs in the mountains of Bosnia, of
Herzegovina, and of Bulgaria, up to 7,000 feet. Absent from the South of
France, it curiously reappears in the hills of the north coast of Spain,
even at sea-level in Galicia, and in a few localities in North Portugal.
On the southern side of the Alps it is much rarer than _V. aspis_, but
it has established itself in a few low-lying districts in Lombardy,
Venetia, and the neighbouring part of Emilia.
_Habits._--As we see from the above sketch of its distribution, the
Adder generally avoids the hotter parts of Europe; when found in the
plain in the South, as in Italy, it dwells in marshy localities, and
Bonaparte called it _Marasso palustre_ (Marsh Viper) in opposition to
his _Marasso alpino_, _Vipera ursinii_. In the North, however, it
usually selects in preference dry moors, sandy heaths, and hills well
exposed to the sun, in which, although to a certain extent a nocturnal
reptile, it delights to bask. Its food is very varied: weasels, mice,
voles, shrews, moles, birds, lizards, slow-worms, frogs, salamanders,
large slugs, have been found in the stomach, and the very young feed
also on insects and worms. Of irascible temper as a rule, Adders are
very ready to bite when fresh caught, but instances are known of their
becoming quite tame in captivity, allowing themselves to be handled. As
a rule they refuse food in captivity, but some have been known to live
for as long as five years, being fed on lizards. Accidents from their
bite, although seldom heard of in this country, are of frequent
occurrence in France and in Germany, where many cases of fatal results
on people have been recorded.
_Reproduction._--Pairing takes place in April and May, and the young,
five to twenty in number, are born in August or September, exceptionally
as early as the end of July; the young, on releasing themselves from the
thin, transparent membrane in which they are enclosed at birth, measure
6 to 8 inches. According to J. Geithe, a black female from Saxony gave
birth to seventeen young, of which only one, a male, was black.
It is probable that exceptionally some individuals pair late in the
summer or in the autumn. There is a trustworthy record, by Eiffe, of
three pregnant females having been caught near Hamburg on March 12,
1882, one of them giving birth to young on the following day.
Dicephalous young have occasionally been observed. One 6 inches long was
found crawling in a field near Hornburg in Germany in October, 1895,
and, having been kept alive for some time, was observed to hiss and open
the two mouths alternately when taking up a defensive attitude. Another
similar monster, from Cornwall, is reported to have been sent alive to
the London Zoological Gardens in 1854.
24. VIPERA ASPIS, Linnæus
The Asp Viper
_Form._--Rather more elongate than in the preceding. Snout flat above,
more or less distinctly turned up at the end, with sharp, not or but
very slightly raised canthus, and vertical or nearly vertical loreal
region. Vertical diameter of the eye equal to or a little less than its
distance from the mouth. The raised upper border of the transversely
truncate or obtusely pointed extremity of the snout, coupled with the
downward slant of the supraocular region and canthus rostralis, gives
the head, seen from the side, a peculiar expression; the eye is so
oblique that a vertical line drawn from the posterior extremity of the
supraocular shield to the lip usually passes through the eye or down its
posterior border; but the extent to which the snout is turned up at the
end varies considerably, some specimens approaching _V. berus_ in this
respect, others _V. latastii_. Length of tail five and a half to eight
times in total length in males, seven to nine times in females.
[Illustration: FIG. 36 (after Sordelli)]
_Head-Shields._--Rostral deeper than broad, its width two-thirds to
seven-eighths its depth, extending to the upper edge of the snout. As a
rule, with the exception of the large supraocular, the upper surface of
the head is covered with small, subimbricate scales, which are smooth,
very rarely feebly keeled, between the eyes and on the snout; however,
an enlarged frontal shield, or even a frontal and a pair of parietals,
are sometimes present, though rarely so large as in a typical _V.
berus_; when present, the frontal is separated from the supraocular by
one or two series of scales; when the frontal is absent, four to seven
series of scales separate the supraoculars. Upper surface of snout
usually bordered by eight or nine small shields--viz., two or three
apicals, in contact with the tip of the rostral and raised to form the
turned-up nose, and, on each side, two canthals and the upper preocular,
which separates the supraocular from the canthals, or three canthals;
sometimes, however, the border is formed by six or seven small shields,
the second canthal being in contact with the supraocular, as in _V.
berus_. Supraocular usually with very convex outer border, not extending
posteriorly beyond the vertical of the eye. Eight to thirteen scales
round the eye, usually ten to twelve; one or two vertical series of
scales separate the preoculars from the nasal, which is single or
divided, and often rather deeply hollowed out. As a rule two series of
scales (very rarely three) separate the eye from the labials; sometimes,
however, there is but one scale between the eye and the fourth labial,
the second series being incomplete. Upper labials nine to thirteen,
usually nine to eleven, fourth and fifth, rarely fourth to sixth or
fifth and sixth, below the eye. Temporal scales smooth or feebly keeled.
Four (rarely five) lower labials in contact with the single pair of
chin-shields.
_PLATE XIII_
[Illustration: VIPERA ASPIS
_After Calmette_]
[Illustration: VIPERA LATASTII]
_Scales_ in twenty-one or twenty-three (rarely nineteen or twenty-five)
rows, with two apical pits, strongly keeled, those of the outer row more
or less distinctly keeled, rarely perfectly smooth. Ventral shields 134
to 158 (usually 143 to 153) in males, 141 to 169 (usually 145 to 157) in
females; anal entire; subcaudals 32 to 49 (usually 37 to 45) in males,
30 to 43 (usually 32 to 38) in females; the terminal caudal shield is
sometimes shorter and less spine-like than in _V. berus_, quite obtuse
in some specimens.
_Coloration._--Grey, greyish-brown, brown, reddish-brown, coppery red,
or orange, is the ground colour in individuals from the same district;
in this respect sexual differences are less marked than in the preceding
species, red or copper-coloured specimens being found in both sexes, and
silvery white specimens do not seem ever to occur. In rare cases
markings are entirely absent. In specimens from the greater part of
France, Italy, and the Southern Tyrol (see Plate XIII.), the dark brown
or black markings on the body are mostly in the form of narrow
cross-bars, continuous across the back or broken on the vertebral line
and often alternating with each other and with similar bars on the
sides, thus producing a pattern not unlike that frequently found in
_Tropidonotus natrix_; a narrow dark line running straight or zigzag
along the spine may connect these cross-bars, and in rare cases it is so
broad as to produce a zigzag band similar to that of _V. berus_. In
specimens from South-Western France and the Pyrenees, rarely in some
from other parts of France and Italy, there is a broad dark grey or
brown vertebral band between two series of black or blackish-brown
spots, opposite to each other or alternating; this band may be straight
or wavy, sometimes forming a regular zigzag; there is another series of
blackish spots or short bars lower down on the side, alternating with
those of the dorsal series.
The upper surface of the head may be devoid of any markings, or bear
merely the two oblique dark streaks forming the branches of a [V]; or a
dark cross-bar may be present on the snout, followed or not by smaller
spots or a pair of oblique streaks on the occiput; the [V] on the back
of the head may be united with the first cross-bar on the nape, and
enclose a cordiform figure of the lighter ground colour. A light line
sometimes borders the upper edge of the snout and the outer edge of the
supraocular shield. A blackish band or a mere line extends obliquely
from the eye to the first lateral spot; below this the upper lip is
whitish, yellowish, or pinkish, with or without dark vertical bars on
the sutures between the labial shields. The iris is golden or coppery
red.
The lower parts vary as much as the upper: sometimes black or steel
blue, with or without whitish or reddish dots or spots, sometimes
yellowish or pale reddish, with brown dots or marblings; in some young,
white with greyish dots. The throat is yellowish white or pale reddish,
uniform or speckled with blackish, sometimes (males) nearly entirely
black. The end of the tail is usually bright yellow or reddish, or at
least with a few bright spots. And finally we must mention black
specimens--some nearly black by darkening of the ground colour, others
intensely black by enlargement of the markings. A specimen from
Piedmont, in the Turin Museum, shows the ground colour reduced to mere
narrow light bars disposed in pairs. In most of these black specimens
the chin and throat remain entirely or partially yellowish or reddish,
and a few spots of the same colour are to be seen under the end of the
tail.
A remarkable form of _V. aspis_, which some herpetologists would perhaps
regard as entitled to rank as a species, is the var. _hugyi_, Schinz,
from Calabria and Sicily. It is in some respects intermediate between
_V. aspis_ and _V. latastii_. The snout is rather more pointed than
usual in the typical form, often, though not constantly, more strongly
turned up at the end, and the canthus rostralis may be distinctly
raised. Constantly two canthal shields, the second in contact with the
supraocular. Ventral shields 134 to 148; subcaudals 30 to 43. Pale
greyish, yellowish, brownish, or reddish, above, with a broad wavy dark
brown vertebral band, edged with darker; this band sometimes broken up
into transversely oval spots; a lateral series of blackish-brown spots,
each corresponding to the sinus of the dorsal band.
Specimens so completely intermediate between _Vipera aspis_ and _V.
berus_ as to render their naming arbitrary are known from parts of
France and Italy where the two species coexist, and are probably to be
regarded as hybrids.
_Size._--The largest specimen examined (St. Sever, Landes, in the
Lataste Collection) measures 2 feet 2-1/2 inches. It is a male. The
largest female in the British Museum is 2 inches shorter.
_Distribution._--_Vipera aspis_ is found over the whole of France south
of a line connecting the departments Loire-Inférieure, Orne,
Seine-et-Marne, and Meurthe-et-Moselle, and ascends the Pyrenees to the
altitude of 7,250 feet. In Germany it is known from Lorraine and the
Black Forest, in Switzerland from the western and southern parts, up to
5,000 feet on the northern side of the Alps. It occurs also in Austria,
in the Southern Tyrol and in the Karst, and is distributed over the
whole of Italy and Sicily, reaching an altitude of 9,700 feet in the
Alps. Most of the specimens from the western parts of the Balkan
Peninsula which have been referred to this species belong, apparently,
to _V. berus_, var. _bosniensis_, but one from Jahorin in Bosnia,
altitude 5,650 feet, preserved in the Bosnian Museum, is pronounced by
Werner to be an unquestionable _V. aspis_.
_Habits._--This Viper shows a predilection for hot and dry localities.
It is both diurnal and nocturnal, and does not seem to wander far from
its hole in a rock or in the earth. It is slow in its movements, but
very irascible, and innumerable accidents, in some cases fatal to man,
are caused yearly in many parts of France, where it is extremely
abundant. Its food consists principally of small mammals, young birds,
and lizards, but the very young eat insects and worms. In France it
retires into its winter-quarters at the end of October or in November,
and numerous specimens often congregate in the same hole; it resumes its
activity towards the end of March or the beginning of April, sometimes
as early as the end of February. In rare cases it will even leave its
retreat in the middle of winter, to bask in the sun. In captivity it
long retains its savage temper, and usually refuses all food.
_Reproduction._--_Vipera aspis_ pairs in April and May; the pair are
entwined in each other's coils. The young, four to eighteen in number,
but rarely more than ten, are born in August or September, and measure 7
or 8 inches.
Several cases of dicephaly in young specimens have been described.
25. VIPERA LATASTII, Bosca
Lataste's Viper
_Form._--Heavier than in the preceding. Head similar, but snout more
pointed and loreal region slanting towards the lip, well visible when
the head is viewed from above. The extent to which the snout is turned
up at the end varies considerably, sometimes similar to certain
specimens of _V. aspis_, sometimes forming an appendage which is only a
little less developed than in _V. ammodytes_. Length of tail six and a
half to seven and a half times in total length in males, seven and a
half to nine times in females.
[Illustration: FIG. 37]
_Head-Shields._--Rostral once and a half to twice as deep as broad,
nearly reaching the tip of the rostral wart. Upper surface of head
covered with small, smooth or feebly keeled, subimbricate scales, among
which a slightly enlarged frontal, or a frontal and a pair of parietals,
may sometimes be distinguished; four to seven longitudinal series of
scales between the supraoculars, which are large, and do not as a rule
extend posteriorly beyond the vertical of the eye. Five or six (rarely
three) scales on the posterior aspect of the raised part of the snout;
two canthal scales on each side, the second in contact with the
supraocular, or separated from it by the uppermost preocular. Eight to
thirteen (usually nine to twelve) scales round the eye; two or three
series of scales between the eye and the labials. Nasal hollowed out,
entire, separated from the preoculars by one or two vertical series of
scales; naso-rostral sometimes divided into two in North African
specimens. Temporal scales smooth or feebly keeled. Upper labials nine
to eleven (rarely eight), fourth and fifth (rarely third and fourth)
below the eye. Four or five lower labials in contact with the single
pair of chin-shields.
_Scales_ in twenty-one rows, with two apical pits, strongly keeled,
outer row smooth or feebly keeled. Ventral shields 125 to 146 in males,
135 to 147 in females; anal entire; subcaudals 35 to 45 in males, 32 to
38 in females.
_Coloration._--Grey or brown above, the back often paler than the sides,
with a broad darker, usually black-edged, wavy or zigzag band along the
spine, and a lateral series of spots (Plate XIII.); the band sometimes
replaced by large rhombic or transversely oval spots. Head with or
without dark markings above, sometimes with two oblique dark streaks on
the occiput; a dark streak from behind the eye to the first lateral
spot, sometimes originating at a considerable distance from the eye;
upper lip white or pale brown, more or less speckled or spotted with
black. Lower parts grey, spotted with black and white, or blackish
speckled with white, the end of the tail usually yellow or with yellow
spots.
_Size._--This Viper is not known to exceed a length of 2 feet.
_Distribution._--Locally distributed over the greater part of Spain and
Portugal, as far north as Burgos and Barcelona. Also found in Morocco
near Tangier, and in Algeria near Bona and Guyotville.
_Habits._--Lataste's Viper lives in stony and arid districts, and also
in forests. The food consists chiefly of small mammals, but remains of a
scorpion have been found in the stomach of an adult, and of a centipede
in that of a young. According to Graells, this Viper easily climbs low
trees in search of young birds, five of which have been found in the
stomach of one specimen. The bite is believed to be less dangerous than
that of _V. aspis_, and rarely causes the death of man and domestic
animals.
26. VIPERA AMMODYTES, Linnæus
The Sand-Viper, or Long-Nosed Viper
This species may be divided into several geographical forms. The typical
form will be described first.
_Form._--Short and heavy. Snout pointed, produced into an erect,
horn-like dermal appendage covered with scales; canthus rostralis
strong, sometimes slightly raised, loreal region slanting more or less
towards the lip. Vertical diameter of the eye less than its distance
from the mouth in the adult. Length of tail six to nine and a half times
in the total length in males, eight to eleven times in females.
[Illustration: FIG. 38 (after Sordelli)]
_Head-Shields._--Rostral usually broader than deep. Naso-rostral (rarely
divided into two) usually reaching the canthus rostralis, and extending
considerably higher up than the upper border of the rostral. Rostral
appendage covered with ten to seventeen scales, arranged in three
(rarely two or four) transverse series between the rostral shield and
the apex. Upper surface of head covered with small smooth or faintly
keeled, subimbricate scales, among which a feebly enlarged frontal
shield or a frontal and a pair of parietals are rarely distinguishable;
when present, the frontal is separated from the supraocular by two
series of scales; on the vertex five to eight series of scales separate
the supraoculars. Two (rarely three) canthal scales, the second
separated from the supraocular by the upper preocular. Supraocular with
very convex outer border, usually not extending posteriorly beyond the
vertical of the eye. Ten to thirteen scales round the eye; one or two
vertical series of scales separate the preoculars from the nasal, which
is single or rarely divided, and hollowed out. Two series of scales
between the eye and the labials. Upper labials eight to twelve, usually
nine or ten, usually fourth and fifth below the eye. Temporal scales
smooth or feebly keeled. Four or five lower labials in contact with the
single pair of chin-shields.
_PLATE XIV_
[Illustration: VIPERA LEBETINA
_After Sordelli_]
[Illustration: VIPERA AMMODYTES
_After Sordelli_]
[Illustration: ANCISTRODON HALYS
_After Sordelli_]
_Scales_ in twenty-one or twenty-three (rarely twenty-five) rows, with
two apical pits, strongly keeled, those of the outer row smooth or
feebly keeled. Ventral shields 143 to 161 in males, 147 to 160 in
females; anal entire; subcaudals 27 to 40 in males, 24 to 37 in females.
_Coloration._--Grey, pinkish-grey, brown, yellowish-brown, or brick red
above, with a more or less distinct wavy or zigzag black or brown,
usually black-edged, band along the back, or a series of large rhombs
connected on the median line, with or without a lateral series of dark
spots; specimens with the markings of an intense black are males (Plate
XIV.). Head with or without dark markings, very variable in disposition,
sometimes forming a [V] on the occiput, or a lyre-shaped figure
confluent with the dorsal band; a dark streak or broad band from the eye
to the angle of the mouth, sometimes continued along the neck; dark
vertical bars often present on the sides of the snout and under the eye;
on the lower lip, the dark shade, if present, broken up by light bars
separated by two to four labial shields. Belly greyish or pink, powdered
with brown or black, or dark bluish-grey, with or without black and
white spots; lower surface of end of tail orange or coral red, rarely
yellow. Iris golden. Specimens with a straight brown vertebral band
flanked with triangular black spots pointing outwards (var.
_steindachneri_, Werner) are known from Hungary, and resemble certain
colour varieties of _V. berus_ and _V. aspis_. Black specimens are very
rare.
The following varieties are important geographical forms occurring in
Europe:
Var. _montandoni_, Boulenger: Naso-rostral shield never reaching the
canthus rostralis nor the summit of the rostral shield, which is deeper
than broad (once and one-seventh to once and a half); rostral appendage
clad with ten to fourteen scales, in three (rarely two or four)
transverse series between the rostral shield and the apex. Scales in
twenty-one rows. Ventral shields 149 to 158; subcaudals 30 to 38. A more
or less distinct dark blotch on the lower lip, involving five to seven
labial shields without complete interruption. Lower surface of end of
tail yellow.
[Illustration: FIG. 39--SIDE VIEWS OF HEADS OF _V. ammodytes typica_
(_a_) AND VAR. _meridionalis_ (_b_)]
[Illustration: FIG. 40--FRONT VIEWS OF END OF SNOUT, SHOWING THE
LEPIDOSIS. (From Proceedings of the Zoological Society, 1903)
_a_, Form _typica_; _b_, var. _meridionalis_; _c_, var. _montandoni_]
Var. _meridionalis_, Boulenger: Naso-rostral shield never reaching the
canthus rostralis, and but rarely extending higher up than the upper
border of the rostral, which is often as deep as broad or a little
deeper than broad; rostral appendage clad with fourteen to twenty
scales, in four or five (rarely three) transverse series between the
rostral shield and the apex. Supraciliary edge usually more prominent
than in the typical form, sometimes slightly angular. Scales in
twenty-one rows (very rarely twenty-three). Ventral shields 133 to 147;
subcaudals 24 to 35. A more or less distinct dark blotch on the lower
lip, involving five or six labial shields without interruption. Lower
surface of end of tail yellow.
_Size._--This Viper exceptionally attains a length of 3 feet. The
largest male in the British Museum measures 2 feet 6 inches, the largest
female 2 feet 4 inches. In _V. berus_ females grow to a larger size than
males; in this species, as in _V. aspis_, the reverse appears to be the
rule.
_Hybrid._--A female specimen, presumed to be a hybrid between _V. berus_
and _V. ammodytes_, was obtained by Captain Veith in 1902 in Carinthia,
in a locality where both these species occur together. The shape of the
head is exactly that of a typical _V. aspis_, the snout distinctly
turned up at the end, but without wart or scaly appendage, the raised
portion being covered by the apex of the rostral shield and three apical
shields. The rostral shield, which is a little deeper than broad
(5 : 4), extends above the level of the slightly raised canthus
rostralis, which bears two shields, the second in contact with the
supraocular. The naso-rostral extends to the canthus rostralis, where it
joins the first canthal and the lateral apical shield; one series of
scales between the nasal shield and the preoculars. On the upper surface
of the head the snout is covered with fifteen subimbricate smooth
scales, in addition to the canthals and apicals. A frontal shield and a
pair of parietals are well developed, although smaller than in an
average _V. berus_; the parietals are in contact with the frontal,
between which and the supraoculars two series of scales intervene. The
supraocular, as in _V. berus_, extends backwards considerably beyond the
vertical of the eye. Eleven scales round the eye; two series of scales
between the eye and the labials. Temporal scales smooth. Upper labials
nine, fourth and fifth below the eye. Scales in twenty-one rows, outer
row smooth. Ventrals 159; subcaudals 31.
Grey-brown above, with a reddish-brown or mahogany-coloured zigzag
vertebral band and a lateral series of paler reddish-brown spots;
temporal band ill-defined in front; no markings on the upper surface of
the head; lips pinkish, with a few reddish-brown spots. Ventral shields
pale brownish, finely speckled or powdered with blackish, and with small
whitish spots on the free edge and reddish brown spots on the sides.
Tail orange red below. Iris fire red.
Total length 2 feet 2-1/3 inches; tail 2-2/3 inches.
_Distribution._--The typical form is known from Northern Venetia,
Austria-Hungary (Styria, Carinthia, Southern Tyrol, Carniola, Illyria,
Istria, Croatia, Slavonia, and eastward through Southern Hungary to
Transylvania), Dalmatia, Bosnia, Herzegovina, Montenegro, Albania, and
Servia. In the Alps up to 1,300 feet, in the Balkan Peninsula up to
7,500 feet. The var. _montandoni_ inhabits Roumania and Bulgaria. The
var. _meridionalis_ inhabits Greece, with the Archipelago, Asia Minor,
and Syria.
The specimens from Transcaucasia constitute a further variety (var.
_transcaucasiana_, Boulenger), agreeing with the var. _montandoni_ in
the rostral scutellation and in the number of ventral shields (150 to
156), but differing in the markings on the back; these consist of dark
bars or alternating paired dark spots, as in the typical form of _V.
aspis_. The dark and light markings on the lower lip are as in the
typical _V. ammodytes_, and the lower surface of the tail is pale yellow
or greenish towards the end.
_Habits._--Notwithstanding its name _ammodytes_, this Viper is by no
means restricted to sandy localities; on the contrary, it shows a
predilection for dry stony hills with low vegetation, and has often been
found climbing bushes. It avoids thick forest, but occurs on the edges
of woods and in clearings, as well as on the borders of roads through
woods. In the cooler regions of the mountains, which it ascends to a
considerable altitude, it is essentially diurnal, leaving its retreat
only when the sun shines; but in warm localities it is stated to be
principally nocturnal, appearing in numbers by moonlight. The length of
its period of hibernation depends entirely on the climate, but when the
winter is mild it may be seen about in midwinter whenever the sun
shines. The poison of this Viper is stated to be more active than that
of _V. berus_ and _V. aspis_, and, as the snake is very common in some
parts of Austria and the Balkan Peninsula, fatal accidents to man are
frequent.
The food consists of small mammals and birds, and also of lizards. _V.
ammodytes_ does much better in captivity than its European congeners,
and takes food more readily.
The hissing is louder than in _V. berus_ and _V. aspis_, and it is often
produced, on the approach of man, by specimens lying in such perfect
concealment that their presence would not otherwise be suspected; this
habit, like the rattling of the _Crotalus_, is evidently detrimental to
the species in its relation to man.
This species is extremely abundant in some parts of Austria, and over
7,000 specimens were killed in a district of Southern Styria in the
course of two years (1892, 1893). According to Werner, it is the
commonest of all snakes in Bosnia and Herzegovina.
_Reproduction._--Pairing takes place in the spring, sooner or later
according to altitudes, and the young, five to fourteen in number, are
born in August.
27. VIPERA LEBETINA, Linnæus
The Blunt-Nosed Viper, or Kufi
_Form._--Short and heavy. Snout rounded, obtuse, usually with
well-marked canthus, and the loreal region slanting towards the mouth.
Eye small, its vertical diameter less than its distance from the mouth
in the adult. Nostril large and directed backwards. Length of tail six
(males) to ten times (females) in the total length.
[Illustration: FIG. 41 (after Sordelli)]
_Head-Shields._--Rostral as deep as broad, a little broader than deep,
or slightly deeper than broad, reaching or nearly reaching the upper
surface of the snout, and in contact with two or three apical shields.
Upper surface of head covered with small subimbricate scales, which are
all more or less distinctly keeled, or, rarely, smooth on the snout and
forehead; seven to twelve longitudinal series of scales between the eyes
(supraoculars included); two to four canthal shields, of which the
anterior is the largest, and may be regarded as a supranasal.
Supraocular narrow, usually broken up into two or more small shields.
Twelve to eighteen scales round the eye; two or three series of scales
between the eye and the labials; two or three vertical series of scales
separate the preoculars from the nasal, which is single and often
strongly hollowed out, and usually partially fused with the
naso-rostral. Upper labials nine to twelve, usually fourth and fifth
below the eye. Temporal scales keeled. Four or five lower labials in
contact with the single pair of chin-shields.
_Scales_ in twenty-three to twenty-seven rows, usually twenty-five, with
two apical pits, strongly keeled, those of the outer row smooth or
feebly keeled. Ventral shields 151 to 177 in males, 153 to 180 in
females; anal entire; subcaudals 42 to 51 in males, 38 to 49 in females.
_Coloration._--Very variable. The typical form, which alone is
represented in Europe, and was originally described from Cyprus, is
grey, greyish-buff, or pale brown, above, with two dorsal series of
darker spots, which may stand in pairs, alternate, or unite to form
cross-bars, and a lateral series of large dark spots or bars. A more or
less distinct dark band on each side of the head, passing through the
eye and often extending to the neck; a dark bar or triangular spot below
the eye, and usually another below the nostril. Lower parts
pinkish-white, powdered with grey-brown, with or without dark brown
spots; end of tail yellow. The ground colour of the young is pink or
flesh-colour. In specimens from desert sandy regions in Asia and North
Africa the markings may be very indistinct, the snake being of a nearly
uniform pale buff.
In the var. _mauritanica_, Guichenot, from Morocco and Algeria, the back
has three series of very large dark brown or reddish-brown spots,
separated by a network of the yellowish ground colour, or the middle
series may be transformed into a wavy or zigzag band. The scales in this
variety are usually in twenty-seven rows, instead of twenty-five (rarely
twenty-three) as in the typical form.
_Size._--This species, the largest of European Vipers, grows to a length
of 4-1/2 feet.
_Distribution._--The European habitat of _V. lebetina_ is restricted to
the Cyclades, where it is not uncommon on the island of Tinos, and
appears to be found also on Kimoli. It is common on Cyprus, where it is
called _Kufi_, or Deaf Snake, and extends from Syria and Asia Minor
through Transcaucasia, Mesopotamia, Persia, Northern Baluchistan, to
Afghanistan and Cashmere. It is further found on the Atlas of Morocco
and Algeria, near Oran and Bona, and in Tunisia. Its reported occurrence
in Egypt has not been confirmed by recent investigations.
_Habits._--According to M. Doumergue--who has had ample opportunities of
observing this Viper near Oran, where it is common--it is a nocturnal
reptile, rarely moving about in the daytime. It inhabits rocky
localities, where there is brushwood, and vineyards. During the day it
remains sluggish under large stones. It is most frequently met with in
April and May.
On Milos, Dr. de Bedriaga observed this much-dreaded snake, the bite of
which is probably as bad as that of its Indian ally, the Daboia, _V.
russelli_, to occur frequently in gardens, and to crawl about near
houses in villages after sunset. The same observer has noted a sort of
valvular closing of the nostril through raising of the posterior part of
the nasal shield when the snake prepares to strike.
The food consists principally of mammals up to the size of a rabbit.
_Reproduction._--According to Doumergue's observations in Algeria, the
young, up to thirteen in number, are born in May and June.
GENUS ANCISTRODON, PALISOT DE BEAUVOIS
Head distinct from neck, its upper surface covered with large shields,
as in the normal _Colubridæ_; a loreal pit; eye moderate or small, with
vertical pupil. Body moderately elongate or short. Scales keeled (or
smooth), with apical pits. Tail moderate or short.
This genus is distributed over nearly the whole of Asia, the eastern
parts of the United States of America, and Mexico and Central America.
One of the Asiatic species just penetrates into South-Eastern Europe,
and is the sole representative of the Crotalinæ in this part of the
world.
28. ANCISTRODON HALYS, Pallas
Pallas's Pit-Viper
_Form._--Moderately elongate. Head subtriangular, flat or slightly
concave above, swollen in the temporal region, very distinct from neck;
snout rounded or obtusely pointed, slightly turned up at the end, with
obtuse canthus and vertical or slightly oblique loreal region; eye
rather small. Tail seven to eight and a half times in the total length.
[Illustration: FIG. 42]
_Head-Shields._--Rostral as deep as broad or slightly broader than deep,
just visible from above. A pair of internasals and a pair of larger
prefrontals. Frontal as broad as the supraocular, as long as or a little
longer than its distance from the end of the snout, as long as or a
little shorter than the rather short parietals. Supraocular extending
beyond the vertical of the posterior border of the eye. Loreal pit
between three shields, separated from the labials. Nostril between two
nasals, the posterior of which is separated from the upper preocular by
a loreal. Two preoculars, one or two postoculars, and a subocular. Three
large lower temporals, anterior largest. Upper labials seven or eight,
third and fourth largest, third entering the eye. A pair of small
chin-shields.
_Scales_ sharply keeled, with two apical pits, in twenty-three rows.
Ventral shields 149 to 174; anal entire; subcaudals 31 to 44 pairs.
_Coloration._--Pale yellowish-grey, greyish-brown, or reddish, sometimes
greenish in young specimens, with transverse series of darker spots or
with more or less regular dark bars with serrated edges across the back
(Plate XIV.); these bars may be narrower than the interspaces between
them, or so large as to cause the back to appear brown with light
cross-bars; the bars sometimes broken up on the vertebral line, and the
two halves alternating. The sides usually paler and bearing two
alternating longitudinal series of small spots, the lower of which are
usually darker, and sometimes extend on the outer ends of the ventral
shields. Head pale above, with a dark spot on the middle of the snout, a
cross-bar or a pair of spots between the eyes, a spot or short band on
each side of the parietal region, and a horseshoe-shaped band on the
occiput, the branches of which are more or less produced on the nape;
all these markings sometimes confluent. A broad, dark, light-edged band
on the temple. Lips whitish, speckled with brown. Lower parts whitish,
more or less profusely speckled with grey or brown. The horny shield
terminating the tail usually dark brown or black at the end.
_Size._--This species rarely reaches a length of 29 inches. The largest
specimen in the British Museum measures only 19 inches.
_Distribution._--From the north and east coasts of the Caspian Sea,
across Central Asia to the Upper Yenissei, as far north as 51°. In
Europe it is only known from two arid tracts between the Volga and the
Ural, near the Caspian Sea, viz., the Saltan-Murat desert and the
Induski hills.
_Habits._--Nothing has been published on the habits of this snake, but
they are probably similar to those of its near and more eastern
relative, _A. blomhoffi_, Schlegel, which inhabits China and Japan. _A.
blomhoffi_ is said to be more or less nocturnal, although showing a
predilection for localities well exposed to the sun. It is
ovoviviparous. The symptoms of its bite, which is rarely fatal to man,
are the same as in the Vipers.
All the species of _Ancistrodon_, so far as they have been observed, are
in the habit of raising and vibrating the tail, like the Rattlesnakes,
when coiling themselves up in a defensive attitude.
INDEX
Acanthocephala, 110
_Acrochordinæ_, 5
Adder, 230
Æsculapian Snake, 187
_æsculapii_ (_Coluber_), 187
_Aglypha_, 4, 151
_Ailurophis vivax_, 217
Albinism, 39
Aldrovandi's Snake, 182
Altitudinal range, 118, 123
_Amblycephalidæ_, 5
_ammodytes_ (_Vipera_), 249
Anal pockets, 83
Anal shield, 17
_Ancistrodon_, 261
_Ancistrodon halys_, 262
Antitoxic serums, 66
Apical pits, 15, 75
Arteries, 77
Ascariasis, 111
_asianus_ (_Zamenis gemonensis_, var.), 173
Asp Viper, 239
_aspis_ (_Vipera_), 239
_astreptophorus_ (_Tropidonotus natrix_, var.), 154
_ater_ (_Tropidonotus natrix_, var.), 156
_atrovirens_ (_Coluber_), 170
_aurolineatus_ (_Coluber_), 167
_austriaca_ (_Coronella_), 197
Bacteria, 113
_berus_ (_Pelias_), 221
_berus_ (_Vipera_), 230
Bezoar stones, 141
_bilineatus_ (_Tropidonotus natrix_, var.), 154
Blind Snake, 144
Blood-supply, 77
Blunt-nosed Viper, 257
Body, 8
_Boidæ_, 4, 146
_Boinæ_, 4, 146
_bosniensis_ (_Vipera berus_, var.), 236
Brain, 73
Burrowing Snakes, 91
_cæruleus_ (_Coluber_), 233
Canker, 113
Canthus rostralis, 13
Captivity, 100
_carbonarius_ (_Zamenis_), 172
_caspius_ (_Zamenis gemonensis_, var.), 172
Cat-Snake, 217
Caucasian Cat-Snake, 219
_cervone_ (_Elaphis_), 182
Cestoda, 112
_cettii_ (_Tropidonotus natrix_, var.), 155
_chersoides_ (_Tropidonotus_), 167
Classification, 2
Cobra di capello, 9
_Coelopeltis_, 207
_Coelopeltis monspessulana_, 208
_collaris_ (_Contia_), 207
Coloration, 29
Colour, 29
_Coluber_, 181
_Coluber æsculapii_, 187
_Coluber atrovirens_, 170
_Coluber aurolineatus_, 167
_Coluber cæruleus_, 233
_Coluber dione_, 185
_Coluber dumfriesiensis_, 200
_Coluber flavescens_, 187
_Coluber hydrus_, 160
_Coluber insignitus_, 208
_Coluber leopardinus_, 191
_Coluber longissimus_, 187
_Coluber quadrilineatus_, 191
_Coluber quatuorradiatus_, 182
_Coluber quatuorlineatus_, 182
_Coluber riccioli_, 202
_Coluber rubens_, 204
_Coluber sauromates_, 183
_Coluber scalaris_, 194
_Coluber torquatus_, 152
_Coluber viridiflavus_, 170
_Colubridæ_, 4, 150
_Colubrinæ_, 4, 151
_concolor_ (_Tropidonotus tessellatus_, var.), 162
_concolor_ (_Vipera berus_, var.), 234
_Coniophis_, 7
Constriction, 96
_Contia_, 205
_Contia modesta_, 205
Coral-Snakes, 32, 34, 35
_Coronella_, 196
_Coronella austriaca_, 197
_Coronella girondica_, 202
_Coronella italica_, 197
Coryphodonts, 58
_Crotalinæ_, 5, 220
Crotalon, 20
_Crotalus_, 21
_cucullatus_ (_Macroprotodon_), 213
Dahl's Whip-Snake, 177
_dahlii_ (_Zamenis_), 177
_Dasypeltinæ_, 5
Defecation, 99
Definition, 1
Deglutition, 98
Dentition, 53
Desert Snakes, 36
Development, 88
Diacranterians, 58
Dicephalous young, 89
Digestion, 99
_dione_ (_Coluber_), 185
Dione Snake, 185
_Dipsadomorphinæ_, 5, 151
Disgorging, 99
Distribution, 118
_Dolichosauria_, 1
_dorsalis_ (_Pelias_), 234
Drinking, 101
_dumfriesiensis_ (_Coluber_), 200
Dwarf Snake, 205
Economic value, 138
Eggs, 85
Egg-eating Snakes, 53, 80
Egg-tooth, 89
_Elachistodontinæ_, 5
_Elaphis cervone_, 182
_Elapinæ_, 5
_Elaps_, 35
_elsneri_ (_Coluber leopardinus_, var.), 193
Embryo, 88
Epiglottis, 79
_Eryx_, 147
_Eryx jaculus_, 147
European Whip-Snake, 170
External characters, 8
Exuviæ, 20
Exuviation, 105
Eyes, 11, 73
False Smooth Snake, 213
_fallax_ (_Tarbophis_), 217
Fangs, 55
Fascination, 104
Fat-bodies, 81
Faunistic works, 130
Feigning death, 104
_fitzingeri_ (_Coronella_), 197
_flavescens_ (_Coluber_), 187
_flavescens_ (_Tropidonotus tessellatus_, var.), 163
Flukes, 112
Flying Snakes, 94
Food, 95
Form, 8
Fossils, 6
Gape, 11
Gastrosteges, 15
_gemonensis_ (_Zamenis_), 170
Genital organs, 82
_girondica_ (_Coronella_), 202
_Glauconiidæ_, 4
Glottis, 79
Grass Snake, 152
Greek Blind Snake, 144
Ground Snakes, 91
Habits, 91
Hæmogregarines, 112
_hagenbecki_ (_Tropidonotus tessellatus_, var.), 162
_halys_ (_Ancistrodon_), 261
Head, 10
Head-shields, 17
Hearing, 74
Heart, 77
_Helagras_, 7
Hemipenes, 82
Hibernation, 105
Hind limbs, 10
_hippocrepis_ (_Zamenis_), 179
Hissing, 102
_Homalopsinæ_, 5
Hood, 9
Horseshoe Whip-Snake, 179
_hugyi_ (_Vipera aspis_, var.), 244
Hybrids, 90
_Hydrophiinæ_, 5
_hydrus_ (_Coluber_), 160
Hyoid apparatus, 42
_iberus_ (_Tarbophis_), 219
_Iguanognathus_, 54
_Ilysiidæ_, 4
Immunity, 66, 71
_incertus_ (_Tropidonotus viperinus_, var.), 167
Incubation, 88
Intelligence, 101
_insignitus_ (_Coluber_), 208
Integument, 8
Intestines, 79
Iris, 37
Isodonts, 58
_italica_ (_Coronella_), 197
Jacobson's organ, 73
_jaculus_ (_Eryx_), 147
Javelin Sand-Boa, 147
Key to the identification, 22
Kidneys, 80
Kufi, 257
Labial pits, 76
_Lacertilia_, 1
_lacertina_ (_Natrix_), 208
Ladder Snake, 194
Largest Snakes, 21
Larynx, 79
Lataste's Viper, 247
_latastii_ (_Vipera_), 247
_lebetina_ (_Vipera_), 257
Leopard Snake, 191
_leopardinus_ (_Coluber_), 191
_lineaticollis_ (_Tropidonotus tessellatus_, var.), 162
Liver, 81
Livery of the young, 38
Locomotion, 93
Long-nosed Viper, 249
_longissimus_ (_Coluber_), 187
Loreal pit, 75
Loreal region, 12
Lungs, 78
Lycodonts, 58
Lymph-hearts, 78
_Macroprotodon_, 212
_Macroprotodon cucullatus_, 213
_macrops_ (_Vipera_), 224
Marine Snakes, 92, 95
Markings, 29
_mauritanica_ (_Vipera lebetina_, var.), 259
Melanism, 39
Mental groove, 13
_meridionalis_ (_Vipera ammodytes_, var.), 253
Mimicry, 35
_modesta_ (_Contia_), 205
_monspessulana_ (_Coelopeltis_), 208
_montandoni_ (_Vipera ammodytes_, var.), 252
Montpellier Snake, 208
Mortality from Snake-bite, 133
_Mosasauria_, 1
_murorum_ (_Tropidonotus natrix_, var.), 154
_Natrix lacertina_, 208
_Natrix vulgaris_, 152
_natrix_ (_Tropidonotus_), 152
Neck, 9
Nematoda, 111
_Nerodia_, 152
Nervous system, 73
_neumayeri_ (_Coelopeltis monspessulana_, var.), 210
_niger_ (_Coluber longissimus_, var.), 188
_nigrescens_ (_Tropidonotus tessellatus_, var.), 162
Nocturnal Snakes, 93
Northern Viper, 230
Nostrils, 13, 74
Oesophagus, 79
Olfactory organ, 73
_Ophidia_, 1
_Opisthoglypha_, 4, 151
Organs of a sixth sense, 75
Orsini's Viper, 221
Oviparous Snakes, 86
Oviposition, 85
Ovoviviparous Snakes, 85
Pairing, 84
Pallas's Pit-Viper, 262
Parasites, 107
_Pelias berus_, 221
_Pelias dorsalis_, 234
Pelvic arch, 52
_persa_ (_Tropidonotus natrix_, var.), 154
_persicus_ (_Zamenis gemonensis_, var.), 172
_picturatus_ (_Tropidonotus natrix_, var.), 155
Pit-Vipers, 75, 262
Poison apparatus, 62
Poison fangs, 55, 62
Poison glands, 62
Poisons, 66
_prester_ (_Vipera_), 235
_Proteroglypha_, 4, 151
Protozoa, 112
_pseudaspis_ (_Vipera berus_, var.), 236
Pupil, 12
_Pythoninæ_, 4
_quadrilineatus_ (_Coluber_), 191
_quatuorradiatus_ (_Coluber_), 182
_quatuorlineatus_ (_Coluber_), 182
Rattle, 20
Rattlesnakes, 20, 103
Rattling, 103
Reflex movements, 106
Relation to man, 133
Renard's Viper, 227
_renardi_ (_Vipera_), 227
Replacement teeth, 55
Reproduction, 82
Reptation, 93
_Reptilia_, 1
_Rhiptoglossa_, 1
_riccioli_ (_Coluber_), 202
Ring-Snake, 152
_romanus_ (_Coluber longissimus_, var.), 188
_rubens_ (_Coluber_), 204
_rubro-maculosus_ (_Tropidonotus tessellatus_, var.), 162
Rustling, 102
Sand-Boa, 147
Sand-Snakes, 91
Sand-Viper, 249
_sardus_ (_Zamenis_), 172
_sauromates_ (_Coluber_), 183
_scalaris_ (_Coluber_), 194
_scalaris_ (_Coronella austriaca_, var.), 199
Scales, 14
_schwoederi_ (_Coluber leopardinus_, var.), 193
_scutatus_ (_Tropidonotus natrix_, var.), 155
_semimaculata_ (_Contia modesta_, var.), 207
Sense organs, 73
_seoanei_ (_Vipera berus_, var.), 235
Serotherapy, 66, 134
Serum treatment, 67
Shedding of the epidermis, 20
Shields, 14
Sixth sense, 75
Skeleton, 40
Skull, 40
Smallest Snakes, 21
Smooth Snake, 197
Snake-charmers, 139
Snake-stones, 141
Snake swallowing her young, 88
Snake-worship, 139
Snout, 12
Solenoglyphs, 56
Southern Smooth Snake, 202
_Squamata_, 1
_steindachneri_ (_Vipera ammodytes_, var.), 252
Stomach, 79
Subcaudal shields, 15
_subfasciatus_ (_Tropidonotus natrix_, var.), 155
_subgriseus_ (_Coluber longissimus_, var.), 189
_Symoliophis_, 7
Syncranterians, 58
Tail, 9
_Tarbophis_, 216
_Tarbophis fallax_, 217
_Tarbophis iberus_, 219
Teeth, 53
Tessellated Water-Snake, 160
_tessellatus_ (_Tropidonotus_), 160
Thymus gland, 78
Ticks, 108
Tongue, 74
Tongue-worms, 108
_torquatus_ (_Coluber_), 152
_trabalis_ (_Zamenis gemonensis_, var.), 172
Trachea, 78
_transcaucasiana_ (_Vipera ammodytes_, var.), 256
Tree-Snakes, 36, 92, 94
Trematoda, 112
_Tropidonotus_, 152
_Tropidonotus chersoides_, 167
_Tropidonotus natrix_, 152
_Tropidonotus tessellatus_, 160
_Tropidonotus viperinus_, 165
_Typhlopidæ_, 4, 143
_Typhlops_, 144
_Typhlops vermicularis_, 144
Ureters, 81
_Uropeltidæ_, 5
Urosteges, 15
_ursinii_ (_Vipera_), 221
Veins, 77
_veithi_ (_Coronella austriaca_, var.), 199
Ventral shields, 15
_vermicularis_ (_Typhlops_), 144
Vertebræ, 50
Vertebral column, 50
_Vipera_, 221
_Vipera ammodytes_, 249
_Vipera aspis_, 239
_Vipera berus_, 230
_Vipera latastii_, 247
_Vipera lebetina_, 257
_Vipera macrops_, 224
_Vipera prester_, 235
_Vipera renardi_, 227
_Vipera ursinii_, 221
_Viperidæ_, 5, 220
_Viperinæ_, 5, 220
Viperine Water-Snake, 165
_viperinus_ (_Tropidonotus_), 165
_viridiflavus_ (_Coluber_), 170
Viscera, 77
_vivax_ (_Ailurophis_), 217
_vosseleri_ (_Tropidonotus tessellatus_, var.), 162
_vulgaris_ (_Natrix_), 152
Warning coloration, 35, 36
Water-Snakes, 92, 94, 160
Whip-Snake, 170
Worms, 110
_Xenopeltidæ_, 5
_Zamenis_, 170
_Zamenis carbonarius_, 172
_Zamenis dahlii_, 177
_Zamenis gemonensis_, 170
_Zamenis hippocrepis_, 179
_Zamenis sardus_, 172
Zoogeographical Regions, 119
------------------------------------------------------------------------
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Footnote A:
For a key to the identification of the species, see above, p. 22.
Footnote B:
The only specimen with twenty-one rows I have examined is a male from
Albano, near Rome (Genoa Museum).
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