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Richard Lydekker.

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Extinct Python- In this place may be noticed certain gigantic snakes from the
like Snakes, lower and middle Eocene rocks of Europe, described under the name
of Palcuophis, and represented by closely allied, if not generically identical forms
in the corresponding strata of North America. Equal in size to those of the largest
pythons, the vertebrae differ from the latter (shown in the figure on p. 18) by the
much greater height of the upper or neural spine, which has not the backwardly-
directed process at its summit characterising the pythons. From the shape of
these vertebrae, it is pretty certain that these snakes had compressed bodies like
the modern sea-snakes, while from the nature of the deposits in which their remains
occur, there can be little doubt that they were marine in their habits. Whether
they were really allied to the pythons and boas may be doubtful, but in any case
is probable that they indicate a separate family.



THE CYLINDER-SNAKES.
Family IL YSIIDsK

Agreeing with the pythons and boas in the retention of vestiges of the hind-
nbs, the small group of cylinder-snakes appears to form a connecting link
stween the two former and the under-mentioned family of shield-tailed snakes ;
their essential point of distinction from the preceding being that the supra-
temporal bone of the skull is of small size, and included in the walls of the brain-
case, instead of standing out as a support for the quadrate-bone, which is much
shorter than in the boas and pythons. Teeth are present on the palate as well as
in the jaws; and the vestiges of the hind-limb usually take the form of a spur on
each side of the vent. In general appearance, and in the arrangement of the
scaling, these snakes approximate to the boas ; while as regards the structure of the
skull they are intermediate between them and the next family. The distribution
of the group is remarkable, being restricted to Ceylon and South-Eastern Asia in
the Eastern, and to Tropical America in the Western Hemisphere. Three genera,
of which two have one species, while the third has three, represent the family.
Coral Cylinder- The single representative of the typical genus of the family is

Snake. ^] R1 beautiful coral cylinder-snake (Ilyxia wytale), inhabiting the
Guianas and Upper Amazonia, and attaining a length of something over 2i- feet.



196



SNAKES.



The distinctive features of the genus are the presence of two teeth in the anterior
upper jawbones, or premaxillse, and the eye being situated in the middle of an
ocular shield. The colour is a splendid coral-red, ornamented with black rings, or
incomplete ring-like black bands. From the little that is known concerning its
habits, it appears that this snake is sluggish in its movements, and never wanders
far from its retreat, which is situated under the roots of a tree or in a hole or cleft
in the ground. It feeds on insects and blind-snakes, and produces living young.

The true cylinder-snakes, as typically represented by the red
snake (Oylindropkis rufus), differ from the preceding by the absence
of teeth in the anterior upper jawbones, and likewise by the eye not being
included in any of the head-shields. This genus has three representatives, and is
distributed over Ceylon and South-Eastern Asia to the eastwards of the Bay of



Red Snake.




CORAL CYLINDER- SNAKE (| nat. size).

Bengal; the common red snake ranging from Burma and Cochin-China to Hie
Malayan region. This snake, which attains a length of about 2| feet, is either brown
or black above, with or without light alternating crossbars; the under-parts being
either white with black transverse bars or spots, or black with white bands : while
the under surface of the tail is of a brilliant vermilion hue. All the snakes of
this genus are burrowing reptiles, seldom showing themselves above the surface of
the ground, and feeding on insects, worms, and the smaller mammals. In common
with their allies, they have the body covered with polished, rounded scales, which
(in conformity with their burrowing habits) are scarcely larger on the upper
than on the lower aspect, although becoming wider on the inferior surface of
the tail.

The iliinl genus of the group (Anomalockilus), represented by a single species
from Sumatra, differs from the preceding in the absence of a groove on the chin.



SHIELD-TAILS.



197



THE SHIELD-TAILS.
Family UROPELTW^E.

The snakes of this family, while agreeing with the boas and pythons in the
structure of the lower jaw, are sharply distinguished by the loss of all traces of the
limbs, and likewise by the complete disappearance of the supratemporal bone in
the skull. By Mr. Boulenger they are regarded as directly descended from the
preceding family of the suborder. The skull is remarkable for the firm union of
its constituent bones; and although both jaws are toothed, the teeth are small and
feeble, and very rarely present on the palate. Externally these snakes -are charac-
terised by their cylindrical bodies ; short, narrow heads, which pass imperceptibly
into the neck ; and by the
extremely short, truncated, or
slightly tapering tail, which
generally ends in a rough,
naked disc, although in one
genus it is covered with keeled
scales. On the body the scales
are small and polished, those
on the lower surface being
always somewhat larger than
those above; the eye is minute,
and the cleft of the mouth
comparatively small, and in-
capable of much dilatation.

These snakes are repre-
mted by upwards of seven
genera, some of which com-
prise a large number of species,

and are restricted to Ceylon and the mountains of Peninsular India. They are
purely burrowing creatures, generally living in soft earth, at a depth of several
feet, and consequently but seldom seen unless specially searched for. They are
frequently dug up in the cultivation of tea and coffee plantations, and may be
found beneath logs and stones. On the mountains these earth -snakes, as they
are frequently called, may be met with in the open grass-lands ; and during the
rainy season they not unfrequently leave their burrows to travel some distance
on the surface. Of relatively small size, many of them are beautifully coloured
with red and yellow, while those that are black display an iridescence like that
of some of the smooth -scaled skinks among the lizards. The food of these reptiles
appears to consist solely of earth-worms ; and the eggs are hatched before quitting
the body of the parent. There is a legend current among the natives of India to
the effect that every time a cobra bites it loses a joint of its tail, and eventually
acquires a head like that of a toad ; and Sir J. E. Tennent was of opinion that
this fable was based on the shield-tailed snakes, in which the jaws have lost the
great power of dilatation so characteristic of serpents in general.




A SHIELD-TAILED SNAKE.



198 SNAKES.

THE COLUBIMNK SXAKKS.

Family CoLUBiintj-:.

The skulls of the remaining .snakes are markedly distinguished from those
of the foregoing by the total absence in the lower jaw of the bone known as the
coronoid ; while in all cases a supratemporal is present on the upper surface of the
skull. The present family, which includes by far the great majority of the species
of the suborder, and comprises both harmless and noxious kinds, is specially
distinguished from those to be mentioned later on by the circumstance that in
the skull the upper jawbone, or maxilla, is fixed in a horizontal position, and
also that the pterygoids reach either to the quadrate-bone or the lower jaw.

Before coming to the Colubrine family it should, however, be mentioned
that there is one remarkable snake (Xenopeltis unicolor), from South-Eastern
Asia, retaining in the structure of its skull traces of affinities with the boas and
pythons. This affinity is displayed by the fact that the prefrontal bone, which
lies immediately behind the nasal aperture of each side, is of large sixe, and
extends forwards and inwards to articulate with the nasal bone in the same
manner as the boas. Accordingly, this snake is regarded as the representative of
a distinct family (Xenopeltidcv), which is considered to have originated from the
BoidcG quite independently of the Colubrines.

From Xenopeltis the Colubrines are distinguished by the small sixe of the
prefrontal bone of each side, which articulates merely to the outer front angle of
the frontal bone without any contact with the nasal bone. In such a large group
it is highly important to have some means of division into subgroups of higher
value than genera; and, according to the modern classification, three such serial
divisions may be indicated by the characters of the teeth. The first and most
primitive of these series, which may be termed the solid-toothed colubrines
(Aglypha), is characterised by the whole of the teeth being solid, without any
trace of grooves, all its representatives being harmless, On the other hand, in the
second series or hind-fanged colubrines (Opisthoglypha), one or more of the hinder
teeth of the upper jaw are grooved; while in the third series or front-fanged
colubrines (Proteroglypha) the front teeth of the upper jaw are grooved or tubular.
Of the last series the whole of the members are poisonous, while many of those
of the second are noxious in a minor degree. All these three sections contain
species adapted to particular modes of life, so that we may have two or three
snakes which, while externally very similar, are only distantly allied to one another.

The Javan wart-snake (Acrochordus javanicus) may be taken
Wart- Snakes. .

as a well-known representative of the first, or acrochordine subfamily

of the solid-toothed colubrines, which includes only five genera, distributed over
South-Eastern Asia and Central America. Unfortunately, the characters distin-
guishing this subfamily from the next are connected with the bones of the skull,
and cannot therefore be verified without dissection, but in the study of snakes,
according to the modern system, the student must accustom himself to such
difficulties. The essential feature of the skull in the present group is the pro-
duction of the postfrontal bone above the cavity of the eye; while, as a secondary



COLUBRINE GROUP.



199



feature, the scales of the body overlap one another but very slightly, it' at all.
The Javan wart-snake, which is the sole representative of the genus, is characterised
by the absence of lower shields, by the head being covered with uniform granules,
and by the very slight compression of the body. The head is rather short and
broad, with the muzzle wider than long, and the small eyes directed forwards;
while the nostrils are placed close together on the tip of the muzzle. The nearly
cylindrical tail is short and prehensile. The colour is brown above and yellowish
on the sides ; the young having large irregular dark brown spots, which coalesce
into bands on the back, and gradually tend to disappear in the adult. In size
this snake may measure upwards of 8 feet. It is distributed over the Malay
Peninsula, Java, and New Guinea; and, although it has been stated to be
terrestrial, modern observations indicate that it is essentially aquatic, seldom




3ven leaving the water, and feeding upon fish and frogs. A female in the
possession of Cantor gave birth to twenty-seven young ones in less than half
an hour, which were active and bit fiercely as soon as they came into the world.

An allied genus, represented by a single species (Chersydrus granulatus),
ranging from Southern India to New Guinea, differs by the marked compression
of the body and tail, and thus closely resembles the sea-snakes of the front-fanged
series of the family, and likewise resembles them in habits, frequenting the
mouths of rivers and the coast from Southern India to New Guinea, and being
often found far out at sea. It produces living young, and subsists on fish. A
third Oriental genus, likewise known merely by one species (Xenodermus
javanicus), has large shields on the under surface. In the other two genera
Stoliczkaia from India, and Nothopsis from Central America not only are there
lower shields, but the granules on the head are replaced by large shields.



200 SNAKES.

The large group of water-snakes bring; us to the second and
by far the largest subfamily of the solid-toothed colubrines, which
is known as the Colubrince, and is distinguished from the preceding group by the
supratemporal bone not being produced over the region above the socket of the
eye ; while the scales are usually overlapping, and teeth are present throughout
the entire length of the upper and lower jaws. The water-snakes belong to a
large assemblage of genera of the subfamily characterised by the circumstance
that in the skeleton of the backbone inferior projections or spines are present
throughout its length, the vertebrae in the hinder region of the body having
these spines represented by a more or less well-developed crest or tubercle.
From their allies, the water-snakes are distinguished by having the hinder upper
teeth larger than those in front, the equality in the size of the lower teeth, the
rather large size of the eye, in which the pupil is round, the presence of a pair
of internasal shields between the nostrils, the regular longitudinal series formed
by the scales throughout the body, and by the teeth in each hinder upper jaw-
bone varying in number from eighteen to forty, and forming a continuous series.

Represented by over forty species, the water-snakes have an almost cosmo-
politan distribution, although they are unknown in South America, while in
Africa south of the Sahara they are less abundant than in other regions, and in
Australia they occur only in the northern districts. Dr. Giinther writes that tin-
typical water-snakes "are easily recognised by their Stoutish cylindrical body,
keeled scales, flat head covered with regular shields, wide cleft of the mouth, and
numerous teeth, the strongest of which are at the hinder end of the maxillary
bone. They frequent the neighbourhood of fresh water, and feed on aquatic
animals frogs, toads, and fishes. They do not overpower or kill their prey by
throwing a coil of the body round it, but, having seized it, they at once commence
to swallow it. They are excellent swimmers, but more frequently live near water
than in it, in agreement with which habit, the position of their nostrils is not on
the upper surface of the head, as in the true freshwater snakes, but on the side."

The best known and at the same time the typical representative
Ringed Snake. . . i /m -j

or the group is the common ringed snake (1 ropiaonotus natmx),

inhabiting Europe, Algeria, and West and Central Asia, and attaining a maximum
length of 6 feet. Belonging to a group of the genus in which the number of
teeth in the hinder upper jawbone does not exceed thirty, this snake has a single
anterior temporal shield on the head, usually seven upper labial shields, of which
the third and fourth enter the aperture of the eye, and from one hundred and fifty-
seven to one hundred and ninety shields on the lower surface of the body. Tim
eye is of moderate size, and most of the scales are strongly keeled. The colour
is usually grey, olive, or brown above, with spots or narrow transverse bands ; the
labial shields being white or yellowish, with their dividing lines black ; while
the under-parts are mottled black-and-white or grey. There are, however, several
variations as regards the coloration of the neck. In the ordinary variety, for
instance, there is a white, yellow, or orange collar, usually divided in the middle,
behind which is a broad black collar ; the latter being sometimes alone present.
In another variety, mostly from the south of Europe, the collar is altogetl id-
wanting, or reduced to a small black patch on each side of the nape ; while in the



COLUBRINE GROUP.



201



south-eastern race the collar, although well marked, is divided in the middle, and
there is a yellowish streak along each side of the back.

In England the ringed snake is one of the most common reptiles, inhabiting
woods, heaths, and hedges, especially where water is abundant. Although its chief
food consists of frogs, it also preys upon voles, mice, young birds, and fish, and is
stated occasionally to consume eggs. When a frog is pursued by one of these
snakes, it seems paralysed with fear, and, instead of making any effort to escape,
sits still and gives vent to a shrill cry never heard at any other time. Generally
the frog is seized by the hind-leg, and gradually swallowed by the snake without
its position being changed. On this point Bell observes that " when a frog is in
the progress of being swallowed in this manner, as soon as the snake's jaws have
reached the body, the other hind-leg becomes turned forwards, and as the body




RINGED SNAKE SEIZING ITS PREY (A liat. size).

gradually disappears, the three legs and head are seen standing forwards out of
the snake's mouth in a very singular manner. Should the snake, however, have
taken the frog by the middle of the body, it invariably turns it by several
movements of the jaws, until the head is directed towards the throat of the snake,
and it is then swallowed head-foremost." As a rule, the frog remains alive during
the swallowing process, and it may sometimes be heard to croak 'when buried in
the stomach of its captor, while instances are on record where a frog has returned
after being thus entombed. When swimming, the ringed snake carries its head
and neck raised above the surface of the water. The skin, as in the case of other
serpents, is shed several times during the year, and is drawn off turned inside out,
so that the lenses covering the eye appear concave instead of convex. Previous
to changing its coat, the reptile becomes almost if not completely blind, and
evidently ill at ease, and the change is accomplished by the old skin bursting at



202



SNAKES.



tin- neck, and being pulled offby the owner wriggling its body between brushwood
or dense herbage. Some sixteen to twenty eggs are annually deposited by the
female of the ringed snake, these being attached together by a viscid substance.
Although they are sometimes hatched solely by the heat of the sun, at other times
the process of development is hastened by their being placed in a heap of decaying
vegetable matter or manure. When the cold of autumn makes itself felt, this
species retires for the winter, passing its time in a state of torpor ensconced in
some hole in a hedge-bank, under the roots of trees, or some such place, w r here it




VIPERINE AND TESSELATED SNAKES ( nat. size)



remains till awakened by the returning warmth of spring. Not unfrequently
several snakes occupy the same hole for the winter, and occasionally a considerable
number have been found coiled up together in a mass.

Tesseiated and The preceding species, as already said, belongs to the typical

viperine Snakes, section of the genus, in which the teeth of the hinder upper jawbone
do not exceed thirty in number, and are gradually enlarged towards the hinder
end of the series, while the eyes and nostrils are lateral, and the internasal shields
broadly truncated in front. As examples of the second section, in which, while the
number and characters of the teeth are similar, the small eyes and nostrils are
directed upwards and outwards, and the internasal shields usually much narrowed



CO LU BRINE GROUP.



203



in front, wo select the tesselated snake (T. tesselatus) and the nearly allied viperine
snake (T. viperinus), both of which are found in Europe, the former being a more
southerly type than the latter, and extending eastwards into South- Western and
Central Asia. The tesselated snake, which never grows quite so large as the
common ringed species, is olive or olive-grey above, and may be either uniformly
coloured, or market I with dark spots, usually arranged quiiicuncially, 011 the back.
The nape of the neck is ornamented with a dark chevron ; the upper labial shields
are yellowish, with dark lines of division between them ; and the under-parts are
either yellow or red mottled and marbled with black, or almost wholly black.
The viperine snake is rather smaller, having the upper surface grey, brown, or
reddish, with a zigzag black band down the back, and a row of yellow-centred



r




KEEL-TAILED SNAKE (i liat. Size).

}lack spots down each side. There is a more or less distinctly marked oblique
dark band on each side of the top of the head, and another on the nape of the neck ;
while the labials and under-parts are coloured like those of the tesselated snake.
The general habits of both these species are very similar to those of the ringed
snake ; but in spring they are more generally found concealed in pairs beneath
stones, and only take to the water in the summer. As other well-known North
American representatives of the genus, we may refer to the garter-snake (T.
ordinatus) and moccasin-snake (T. fasciatus) ; the former belonging to the first,
and the latter to the second section. As an example of the third section, in which
the last two or third upper teeth are suddenly enlarged, the Indian long-banded
snake may be mentioned.

Oblique-Eyed Among the genera belonging to this section the only other that

Snake. our .space admits of even mentioning is the one containing the



204



SNAKES.



numerous species of oblique-eyed snakes. Generally having a smaller eye than the
water-snakes, the members of this genus are distinguished by having only a single
inter-nasal shield; the nostril being placed in a half-divided nasal shield, while the
teeth of the lower jaw are of nearly equal size, and the scales lack the pits
characterising those of an allied genus. There are from eighteen to twenty-rive
teeth in the hinder upper jawbone ; the head is, at most, but slightly distinct from
the neck; the body is cylindrical; and the tail, which has two rows of shields
beneath, is of moderate length, the scales being usually striated and keeled. The
genus is represented by eleven species, some of which are found in the New World,
while others inhabit South-Eastern Asia, and others Tropical Africa.

The keel-tailed snake (Helicops carinicauda), inhabits Brazil. It attains a




JAVAN PIGMY SNAKE (nat. size).

length of between 3 and 4 feet ; and is characterised by having the scales on the
back of the head smooth, and those on the body keeled and arranged in nineteen
rows, the frontal shields being nearly or quite as long as the parietals, while there
are from one hundred and twenty-six to one hundred and fifty-five shields on the
lower surface of the body. The general colour is dark olive-brown above, with four
more or less distinctly defined blackish stripes, and a yellow stripe along the two
lower rows of scales; on the under-parts the ground-colour is yellow or red, with
black spots or stripes on the body, and a black stripe on the tail. In the neighbour-
hood of the Rio Grande do Sul this species is one of the commonest of snakes ; and
while its general habits appear to be very similar to those of the water-snakes,
like all the other members of its genus, it produces living young.

The snakes we have now to consider, while still belonging to the
Pigmy Snakes.

typical subfamily of the solid-toothed series, differ from the foregoing



CO LU BRINE GROUP.



205



that inferior spines are developed only in the vertebrae of the anterior half of
the backbone, and are further characterised by the nasal bones being fully as large
as the prefrontals. The preceding group are more or less aquatic in their habits,
but those of the present assemblage are terrestrial or arboreal. The pigmy snakes
have the hinder borders of the shields on the lower surface of the body entire,
the front lower teeth larger than the hinder ones, the eyes relatively small, and
no internasal or temporal shields on the head. The head is not distinct from the
neck, each nostril is pierced in a very small nasal shield, the body is cylindrical
with the smooth scales arranged in thirteen rows, and there are two rows of shields
on the lower aspect of the tail.

These snakes are represented by some thirty species, their headquarters being
the islands of Java, Sumatra, and Borneo. The figured species (Calamaria linncei)
is from Java. They are all of small size, frequently not exceeding a foot in length ;
and they are in the habit of hiding themselves among stones, beneath fallen tree-
trunks, or in grass. Their small dimensions, together with the relatively narrow
cleft of the mouth, and a want of dilatibility in the throat and body, indicate that they



Online LibraryRichard LydekkerThe new natural history (Volume 5) → online text (page 22 of 62)