from the base into the thick end of the tongue. {570}By rapidly filling the
apparatus with blood, and by the action of certain hyoid muscles, the
spring is, so to speak, released, and the momentum gained by the thick and
heavy club-shaped tongue proper projects it far out of the mouth. The
sticky end of the club shapes itself into an upper and a lower flap, which
partly envelop the prey, and the elastic bands of the far-stretched stalk
withdraw the whole. The detailed working of this ingenious shooting
apparatus is not easy to follow. An ordinary full-grown Chameleon can shoot
a fly at the distance of 7 or 8 inches. The whole performance is very
quick, lasting less than one second. When the desired object is very near,
only 2 or 3 inches off, the Chameleon has a certain difficulty in shooting
its prey. The tongue is at first put out slowly, tentatively, the following
jerk is feeble, and it seems as if the apparatus refuses to work unless it
is allowed to shoot out with full force.
Another remarkable and quite proverbial feature of Chameleons is their
changing of colour. This is by no means restricted to Chameleons, which
indeed are rivalled in this respect by various other lizards, for instance
by the Indian Agamoid _Calotes_ and by the American _Ameiva_.
The microscopical structure and mechanism of the colour-changing apparatus
is, in _Chamaeleon vulgaris_, as follows:–
The epidermis is colourless, and the Malpighian layer is not particularly
modified except that in it are imbedded some iridescent cells, with very
minute wavy striation on their surface. The cutis contains in its leathery
tissue a great number of small and closely packed cells, filled with
strongly refractive granules, chiefly guanine-crystals. These cause the
white colour by diffuse reflection of direct light. The cells nearer the
surface are charged with oil-drops and appear yellow. Large chromatophores
are imbedded in the white granular mass, most of them with blackish-brown,
others with reddish pigment, the granules of which are shifted up and down,
towards and away from the surface of the cutis, in ramified branches of the
chromatophores. When these branches are contracted the pigment is conveyed
back into the bulbous basal portion of the chromatophores and the skin
appears yellow or white. When all the pigment is shifted towards the
surface of the cutis, the animal looks dark, sometimes black. In
intermediate conditions the light is changed into green by diffraction
through the yellowish upper strata and by the finely {571}striated
iridescent cells of the Malpighian layer. Those parts into which the
chromatophores do not send pigment appear as yellow spots. The
chromatophores are to a great extent under control of the will of the
Chameleon, but external stimuli, as heat and cold and other reflex actions,
also play a great part in their movements.
For further information on this subject see Brücke,[168] P. Bert,[169]
Pouchet,[170] Thilenius,[171] and lastly Keller,[172] who has written a
very long but rather confused account.
The process of moulting is curious. When the Chameleon is in good health
the whole process is accomplished within a few hours. The skin to be cast
off becomes loose and assumes a blistered appearance. Sometimes the
creature looks as if it were wrapped up in white, semi-transparent tissue
paper. By rubbing against stones, or between the twigs of trees, the skin
comes off in large flakes, first on the lips, then on the contorted body,
and last on the under surface of the hands and feet. During a rapid and
successful moult the changes of colour go on as usual in the new skin.
Sometimes large flakes of the old skin remain adherent for days, especially
on the top of the head. The moulting takes place several times in one year.
One of my _Ch. vulgaris_ moulted in January and September, and then not
until June of the next following year. A _Ch. pumilus_ moulted in the
months of May, October, and March.
[Illustration: FIG. 150.–Diagrammatic section through the skin of a
Chameleon. Highly magnified. _C_, deeper portion of the cutis; _Ch_, three
chromatophores, in various stages of contraction, filled with black, brown,
or reddish pigment; _E_, epidermis; _W_, white layer of granules; _Y_,
yellow layer of cells.]
When they know themselves to be discovered, Chameleons make themselves as
thin as possible by compressing the body or rather the belly. This is done
by means of the peculiarly elongated abdominal ribs described above. The
whole body is then put into such a position that, by presenting only its
narrow edge to the enemy, it has become as little visible as {572}possible.
At the same time the Chameleon turns round upon its twig, so that the
latter comes to stand between the observer and its own body, which may
thereby be completely hidden. When angry, the creature either presents its
broadest surface, swaying to the right and left, or it blows itself up and
hisses. The lungs are very capacious, and, instead of being bag-shaped, end
in several narrow blind sacs which extend far down into the body-cavity, so
that not only the chest but the whole body can be blown up.
The usual mode of propagation is by means of eggs, but a few species allied
to _Ch. pumilus_ are viviparous. The time of incubation and of gestation is
long. For instance, the pairing of _Ch. vulgaris_ takes place in the month
of August. The eggs are laid in the last week of October, about fifty to
sixty days later. Sometimes, however, the eggs are retained much longer,
since I have received specimens with ripening eggs in July which did not
lay until the end of October. The eggs are deposited in the ground and are
not hatched until the following February or March, _i.e._ about 130 days
later. The new-born little creatures are snowy white, and cannot change or
rather assume colour until after the second week.
All Chameleons are insectivorous and require enormous quantities of food,
which must be alive to be taken. Most of them prefer Orthoptera, _e.g._
Locusts and Grasshoppers, and Lepidoptera. They also eat flies, meal-worms,
and cockroaches, but their tastes differ not only individually but also
temporarily. They require change of diet. One individual will take
cockroaches greedily, whilst another of the same kind will rather starve
itself than touch one. The same applies to meal-worms. It is a great but
common mistake to suppose that Chameleons do not require water. On the
contrary they drink regularly and often, generally by licking up drops of
water or by scooping them up with their lips, shoving the snout along the
edges of wet leaves. It is not too much to say that most Chameleons are
short-lived in captivity on account of the want of water. Those which are
sold by the dealers are generally in a parched condition. Sprinkling the
twigs or leaves of their cage with water works a wonderful change in them;
the dull, apathetic-looking creatures drink and drink, revive, assume
brighter colours, and will soon take food, which they have until then
refused {573}obstinately. Once I have even seen a Chameleon, when put into
the greenhouse, make straight for a tank and actually drink in gulps.
After they have fattened themselves in the autumn, Chameleons, at least
those of North Africa, withdraw to hibernate in the ground. But nothing is
known about how, when, and where they do this, nor is it known if tropical
species aestivate during the dry season.
Chameleons are notoriously difficult to keep successfully, whereby we do
not mean the keeping for three to six months. This is easy enough, since it
takes them several months to die of starvation. The difficulty is to keep
them through the winter. To enable them to do this, it is absolutely
necessary to fatten them up during the summer and autumn. Otherwise,
although kept in a warm place, they are liable to lose their appetite in
the autumn, when they become restless, probably with the desire to
hibernate. Those few individuals which get over this critical period, say
during the month of October, and do not refuse food, are probably safe. But
those are doomed which refuse to eat meal-worms or cockroaches or such food
as can be procured easily during the winter.
The origin of the Chameleons is unknown. They form only one family,
CHAMAELEONTIDAE, with between fifty and sixty species, which, with a few
exceptions, belong to the genus _Chamaeleon_.
_Ch. vulgaris_ is the Common Chameleon of North Africa, Syria, and Asia
Minor. It occurs also in a few parts of Southern Andalucia, for instance
near Jerez, and near Nerja, to the east of Malaga, where it has possibly
been introduced. A series of conical, slightly enlarged granules forms a
little crest on the median line of the throat. A whitish line, which does
not change colour, extends from the chin to the vent. The rest of the skin,
with the exception of a median dorsal series of slightly enlarged tubercles
on part of the back, is composed of small granules. A small but distinct
lobe of leathery skin extends along either side of the occiput towards the
posterior end of the median parietal crest. Dead or spirit-specimens are
usually pale yellow; living ones are greenish, usually with differently
coloured patches on the sides. Exceptionally large males reach a total
length of about 9 inches, females reach the length of perhaps a foot, but
about half of the total length belongs to the tail.
{574}It is impossible to say what is the colour of this Chameleon, since
the same specimen may within a few days appear in half-a-dozen different
garbs, not counting minor combinations of colour. After it has been watched
for several months, when all its possibilities seem to be exhausted, it
will probably surprise us by a totally new combination. Not every specimen
changes alike: some keep the same appearance for a long time, others change
often; some are partial to specks, others to large patches. In the group of
Chameleons shown in Fig. 152 several of the more usual arrangements of
colour have been indicated by stippling and various kinds of
cross-hatching.
[Illustration: FIG. 151.–_Chamaeleon vulgaris._ × ⅔.]
A represents the usual coloration at night. The whole animal, which has
just been stirred up from its sleep in the dark, is cream-coloured, with
irregular patches of yellow on the head, the back, the sides of the body,
the legs, and the tail.
B has the usual coloration: grey-green, with innumerable small darker
specks, with two series of pale brown patches on the sides of the body, and
with one patch on the region of the ear.
{575}[Illustration: FIG. 152.–Showing changes of colour in Chameleons. A to
D, _Chamaeleon vulgaris_ (see p. 574). _Chamaeleon pumilus_ in the right
upper corner.]
{576}C is the same specimen in an excited frame of mind; it is represented
in the act of shooting a fly. The light brown patches have changed to
maroon brown; and many round golden yellow spots have appeared on the green
parts.
D shows a specimen, coloured like C, within a few seconds after it has been
put into an angry mood, in the present case by having its tail squeezed.
The whole body is blown out, the thick tongue causes the throat to bulge
out, and all the yellow spots have become blackish green.
Many small spots scattered over the body are usually a sign of anger. One
of the specimens described above was, when fast asleep in a dark room,
dirty white, with about two dozen large and small round spots of a rich
yellow on each side of its body. Then a lighted lamp was brought into the
room without in any way disturbing the animal. Within sixteen minutes the
yellow spots had vanished completely; the whole body and tail had become
suffused with greenish yellow, which gradually turned to pale yellowish
green, and those parts which in Fig. B are pale brown, were just
distinguishable as pale yellowish-white regions. The Chameleon was found to
be fast asleep, and it kept this coloration during the rest of the evening.
Other specimens behaved on similar occasions in the same way, but the
greatest interest is attached to the fact that frequently only that side of
the body "greened up" which happened to be exposed to the light, whilst the
opposite side remained whitish. These changes are not absolutely
unconscious; they are, after all, under the control of the creature. In
order to test the possibility of direct action of the light, I have taken
the precaution of throwing the light of a candle only upon the body, whilst
the head was kept in darkness. No changes of colour took place whilst the
animal was asleep, but when a little light was allowed to sweep across the
closed eye, this soon began to twitch, and although the creature did not
open the eye, the usual changes of colour began to take place. When the
light was removed, the animal soon re-assumed its whitish appearance.
Artificially coloured light, for instance green, red, or blue glass or
paper, has apparently no influence upon the changes of colour. The
Chameleons behave as they would behave under ordinary conditions. Direct
and hot sunshine however causes them to darken, sometimes to turn uniform
dull black, except for the white median ventral {577}line. Occasionally I
found one of the specimens described above deep maroon brown, with dozens
of round orange spots. Blue and red do not seem to be within the range of
_Ch. vulgaris_, but the combinations of green, yellow, brown, black, and
white, with their various shades, are almost endless. Sometimes the
Chameleons do not turn pale during the night, but remain more or less dull
green, with or without brownish patches. Adaptation to their immediate
surroundings takes place to a very moderate degree only, but as a rule they
are brightest, especially in their green tints, when they are allowed to
sit amongst green foliage. The introduction of a branch with fresh leaves
generally has a brightening effect upon those which have previously been
confined in a cage with dry twigs only. Cold does not necessarily make them
pale, but they appear duller, and the changes take place more slowly. After
all, Linnaeus has summed up the little we really know about the causes of
these changes, in the following terse sentence: "Vivus varios colores
assumit secundum animi passiones, calorem et frigus."
Chameleons are not very amiable. When taken up they blow themselves out or
they bite painfully, and it is a long time before they are tame enough not
to go through various antics of anger when one approaches them. When taken
in the hand they produce a peculiar faint grunting noise, which, however,
can be better felt than heard. They quarrel much amongst each other; and
the males, during the pairing season, are particularly ill-tempered. Each
individual selects its own particular branch to sleep on, if possible a
horizontal one, upon which it crouches down lengthwise, with the head and
belly resting upon the branch. The tail generally makes a turn round
another branch, and the four legs, grasping some supporting branch, are put
into any, sometimes into an almost incredibly, awkward position. Although
they climb about a good deal during the daytime, they generally resort to
their accustomed sleeping branch, and they defend this vigorously against
would-be intruders.
Chameleons are most deliberate in their movements, sometimes provokingly
slow. Each arm and foot leaves the firmly grasped branch with great
hesitation, and makes with equal deliberation for some other foothold. It
does not matter if the thigh appears almost twisted out of its joint. The
creature will {578}remain in the most uncomfortable position, forgetting,
one might think, to put one or more of its limbs down, but keeping them
instead in the air.
It is most interesting to watch them stalking their prey. Suppose we have
introduced some butterflies into their roomy cage, which is furnished with
living plants and with plenty of twigs. The Chameleons, hitherto quite
motionless, perhaps basking with flattened-out bodies so as to catch as
many of the sun's rays as possible, become at once lively. One of them
makes for a butterfly which has settled in the farther upper corner of the
cage. With unusually fast motions the Chameleon stilts along and across the
branches and all seems to go well, until he discovers that the end of the
branch is still 8 inches from the prey, and he knows perfectly well that 7
inches are the utmost limit to a shot with his tongue. He pauses to think,
perhaps with two limbs in the air, but stability is secured by a judicious
turn of the tail. After he has solved the puzzle, he retraces his steps to
the base of the branch, climbs up the main stem, creeps along the next
branch above, and when arrived at the 7 inch distance, he shoots the
butterfly with unerring aim. The capacity of the mouth and throat is
astonishing. A full-grown Chameleon will catch, chew, and swallow the
largest moth, for instance a _Sphinx ligustri_. When large, the prey is
chewed, but the wings and legs are swallowed with the rest. Occasionally
these parts are bitten off, especially the prickly long legs of large
locusts.
In water Chameleons are quite helpless. Sometimes they inflate themselves,
but they always topple over on to the side, and the movements of their
limbs are absolutely without any definite purpose.
When the eggs are ripe, and this happens with the Common Chameleon about
the end of October, the female refuses to take food, and becomes restless.
One of my specimens searched about probing the ground for about a week
before she dug a hole in some more solid soil. This took two days. In the
evening I found her sitting in the hole to the middle of her body. On the
following morning she was still there, but busy filling the hole with soil
and covering it with dry leaves. A few eggs were lying about outside, two
of which at least I saw her taking up by the hand and putting them on the
{579}nest, which was found to contain some thirty soft-shelled eggs closely
packed upon each other. During the whole process she was very snappy, and
hissed much when approached. After that she crept into the twigs as usual,
but refused to eat, vomited at once the artificially introduced food,
became restless on the sixth day, crawling about at the bottom of the cage,
and died on the following day. This is the usual fate, almost without
exception, of females after they have deposited their eggs in captivity.
The great number of eggs and their deposition naturally exhausts them, and
they probably want to hibernate at once. The eggs, which are yellowish,
long-oval, about half an inch long and covered with a parchment-like shell,
are very difficult to rear, chiefly on account of the difficulty of
regulating the moisture. They shrink up when too dry, and they are very
liable to become mouldy. According to Fischer[173] the eggs can be hatched
in a large flower-pot with a layer of horse-droppings at the bottom, then a
layer of 6 inches of slightly moist soil, then the eggs, then another 6
inches of loose soil, with a glass plate covering the top, securing at the
same time ventilation. In this way he succeeded in hatching several sets of
eggs after 125 and 133 days respectively.
_Ch. calcaratus_, the Indian Chameleon, is found in the southern half of
the Peninsula and in Ceylon, but it is far from common. It much resembles
_Ch. vulgaris_, but the male is distinguished by a tarsal process or
"spur," covered with skin, on the inner side of the foot.
_Ch. pumilus_, the Dwarf Chameleon of South Africa, reaches a total length
of 5 to 6 inches. It has a well-marked, serrated gular crest, which extends
from the chin to the end of the neck. The chest and belly are without a
toothed line, but a strongly serrated series extends from the occiput over
the back and tail (see the right upper corner of Fig. 152 on p. 575). A row
of enlarged tubercles or scales extends along the sides of the body. The
general colour is green, with a large and long patch of brick-red on the
sides; small dots and spots of intense red are scattered over various parts
of the body. The changes of colour are rather limited. At night the Dwarf
Chameleon does not turn pale, but generally keeps its colour. When they are
very well the green is quite saturated, and the large red patch on the side
is {580}interrupted by several blue spots. When they are angry or unhappy
the red turns into dirty brown, and the green becomes quite dull. Sometimes
the whole animal turns dull black.
This pretty little species is relatively hardy, being, as a native of South
Africa, accustomed to cold nights. It does well in an ordinary temperate
greenhouse, where it will live for several years, provided it has an ample
supply of flies and meal-worms. It is viviparous, the young being probably
born in the month of March or April.
_Ch. bifidus_, of Madagascar, shows an extraordinary difference between the
sexes. The male reaches the great length of 16 inches, and develops two
long rostral processes, which extend forwards beyond the snout; these
processes are formed of dense connective tissue, which ossifies in the
adult, and they are covered with scaly skin.
_Ch. parsoni_, likewise of Madagascar, is the giant amongst Chameleons,
reaching a total length of 2 feet. The male has two large rostral processes
which diverge upwards and outwards.
_Brookesia_, with several species in Madagascar, may be mentioned on
account of its stunted appearance. The tail is much shorter than the body
and scarcely prehensile; the scales on the soles are spinous. Total length
only about 3 inches.
_Rhampholeon_, of tropical continental Africa, with several species, is
likewise remarkable for the stunted and dwarfed appearance, and for the
peculiar claws, each of which is furnished with a second cusp which is
directed downwards. The tail is much shorter than the body. The total
length of _Rh. spectrum_ of the Camaroons is about 3 inches.
{581}CHAPTER XIII
SAURIA, _continued_–OPHIDIA–SNAKES
ORDER II. OPHIDIA–_SNAKES_.
_Saurians which have the right and left halves of the lower jaw connected
by an elastic band._
The Snakes are the most highly specialised branch of the Sauria, from which
they do not differ in any fundamental characters. The chief modifications
consist in the absence of the limbs and limb-girdles (a feature intimately
correlated with the much-elongated body), and in the swallowing apparatus.
The reduction of the limbs and the elongation of the body also occurs in
many Lacertilia; in several of the older families of Snakes (_e.g._
Typhlopidae and Boidae) vestiges of the hind-limbs and even of the pelvis
are still in existence. Even the peculiar suspensorial apparatus of the
lower jaw approaches that of the Lacertilia in the burrowing Ilysiidae and
in _Xenopeltis_.
In the majority of the Snakes the quadrate is very loosely suspended from
the squamosal (by some authorities homologised with the supratemporal bone
of other reptiles), and this again is loosely attached to the lateral
parietal region of the skull, placed horizontally, and elongated so far
backwards that the vertically placed quadrate lies in a plane behind the
skull. In most Snakes the elongated pterygoids are loosely attached to the
inner side of the distal end of the quadrates, and they also often touch
the mandibles. The whole palatal apparatus is movably attached to the
skull, except in some burrowing families. The right and left pterygoids and
palatines are widely separated from each other. The pterygoids and
maxillaries, connected by the ectopterygoids, are absent, owing to
reduction, in the {582}Typhlopidae and Glauconiidae only. The premaxilla is
unpaired and small, and is rarely furnished with teeth. The latter are
always sharp and recurved, and are lodged in sockets upon the edge of the
supporting bone, with which they become firmly ankylosed. There is a
perpetual succession of teeth. In the majority of Snakes teeth are carried
by the maxillaries, palatines, pterygoids, and dentaries, rarely by the
premaxillaries. The palatal teeth are restricted to the palatines in
_Oligodon_, _Dasypeltis_, and _Atractaspis_ only.
Peculiar modifications prevail in the poisonous Snakes. Those maxillary
teeth which are at their base in connexion with the openings of
poison-glands (modified upper labial glands), either have a furrow on the
anterior side (Proteroglypha if the anterior teeth are grooved, _e.g._ the
Cobras; Opisthoglypha if some of the posterior teeth are grooved), or the
groove is converted into a canal, as in the Solenoglypha or Viperidae. The
special modification of the maxillaries of the vipers with their long
poison-fangs is described on pp. 587 and 637.
The orbit is generally closed behind by the postfrontal. Quadrato-jugal,
postfronto-squamosal, and other arches are absent, so that the temporal
fossa is quite open (see Fig. 156, p. 597, and Fig. 155, p. 596). The
occipital condyle is distinctly triple. The mandibles are composed of
several bones, but the coronoid is absent in the Xenopeltidae, Colubridae,
Amblycephalidae, and Viperidae; it is large in the Boidae, reduced to a
nodule in the Ilysiidae.
The parietals are always fused into a large unpaired bone, which generally
forms a sharp crest and partly overlaps the occipitals; there is no
interparietal or pineal foramen.
The vertebral column consists of many, often nearly three hundred
vertebrae, and these skeletal segments correspond in number with those of
the ventral and transverse scales of the skin. The vertebrae are
procoelous; in addition to the anterior and posterior zygapophyses they
have a pair of accessory articulations on the neural arches, dorsally to
the zygapophyses;–the "zygantrum" carried by the posterior end of the
neural arches, its articular surfaces looking upwards; and the "zygosphene"
carried by the anterior end and looking downwards. Such accessory
articulations occur also in a few Lizards, _e.g._ Iguanidae. The vertebrae
of many Snakes have unpaired vertical, blade-like {583}haemapophyses on
their centra for the more effective attachment of the muscles. All the
vertebrae, except the atlas, carry ribs. These articulate by their
capitular portions only, and are very movable in a head- and tail-ward
direction. The ribs being long, and fitting with their ventral ends into
the connective tissue of the sides of the ventral transverse scales, are
the principal agents in pushing the body forwards, the posterior edges of
these scales being sharp and imbricating.
The skin is covered with scales, absolutely devoid of osteoderms. When the
scales are enlarged they are called shields. The keel, a common feature, is
caused by a slight ridge of the cutaneous part of the scale. The whole skin
is covered with a thin layer of horny epidermis, which is shed frequently,
at least several times in one year; the shedding begins at the lips, and
the whole outer skin is turned inside out from head to tail, retaining
every minute detail of the cutaneous scales; even the watch-glass-like
covering of the eyes is preserved.
The eyes are peculiar in so far as they possess no lids. The latter are
still present in a vestigial condition in the embryo, but their place is
taken by what is probably a modification of the nictitating membrane, which
is drawn over the eye and covered with a single transparent scale of the
horny skin, like a watch-glass. The eyes themselves are quite movable. The
"tears," which of course cannot appear on the outside, are drained off into
the nasal cavities by the naso-lacrymal ducts.
The ear is likewise peculiar. There is a long columellar rod with a fibrous
or cartilaginous pad at the outer end, which plays against the middle of
the shaft of the quadrate, an arrangement which, we must assume, produces a
thundering noise in the internal ear, since every motion of the quadrate
during the act of swallowing conveys the vibrations directly to the
fenestra ovalis. The tympanic cavity, the Eustachian tubes, and the
tympanum are abolished, and no external traces of the ear are visible.
However, in spite of all this, Snakes can hear very well.
The nose is well developed, and many Snakes, for instance the Grass-Snake,
are guided to their prey as much by the sense of smell as by the eyes and
ears. The tongue is slender, very protractile and bifid, always moist, and
furnished with many sensory corpuscles. It acts entirely as an additional
sense-organ, hence the incessant play of the tongue of a snake which wants
{584}to investigate anything. In spite of the protractility of the tongue,
the hyoid apparatus is very small; the hyoid arches themselves are reduced
to mere vestiges near the base of the first and only branchial arches,
which are thread-like and extend backwards down the throat.
The trachea is very long, and opens far forwards in the mouth; it can be
slightly protruded between the two halves of the lower jaw so as not to be
blocked during the act of swallowing. This is a laborious process. The
snake, having got hold of its prey with its teeth, generally shifts it into
the most convenient position, in order to swallow the head first. One half
of the mandible is then pushed forwards, then the other half; the recurved
teeth afford the necessary hold, and the snake, little by little, draws its
mouth-cavity, and later on itself, over the prey. In fact, it literally
gets outside it. Sometimes with a large victim this process may last for
hours; the whole mouth and head become painfully distended and the veins
swollen almost to bursting. The snake pushes the prey against a stone or
other obstacle, rests awhile quite exhausted, and begins afresh. At last
the bulk of the prey has passed the mouth, the skin of the neck is
stretched to the utmost, the scales being separated by wide interstices,
the ribs work spasmodically, the victim is pressed into the shape of a
sausage, and the deed is done. In order to assist deglutition there is a
great amount of salivation, but the often-heard story that Snakes cover
their prey with saliva before they swallow it, is a fable, or based upon
faulty observation, snakes sometimes being forced to disgorge the
half-swallowed prey, which, in such a case, is covered with slime. One of
my tame snakes had swallowed a frog on my table when a friend entered the
room. The snake was frightened, jumped on to the ground, striking it with
its full belly, and thereby hurting the frog, which squeaked loudly,
whereupon the snake reversed its mechanism and the frog hopped away, none
the worse for its terrible experience.
In correlation with the elongated narrow space of the body-cavity the lungs
are not equally developed, the right being much smaller than the left. The
latter is a very thin-walled, hollow bag, and the posterior half or third
scarcely contains any of the honey-comb-like respiratory "cells," but acts
merely as a reservoir of air.
{585}The cloacal arrangement is essentially the same as that of the
Lacertilia, but Snakes possess no urinary bladder. The copulatory organs
are stowed away beneath the skin in recesses of the posterior lateral
corners of the shallow cloacal vestibulum. Each organ is generally
bifurcated at the free end, and furnished with little spike-shaped, but
scarcely horny, excrescences. On each side of the outer cloacal chamber, in
both sexes, lies a roundish gland with an offensive, strongly-scented
secretion; that of various Boas smells disagreeably sweet and musky. The
majority of Snakes lay eggs, but most of the Viperidae and the thoroughly
aquatic kinds, besides a few terrestrial forms, are viviparous. The
egg-shells are like parchment, with very little or no calcareous deposit,
so that they are always soft; many embryos are, however, provided with a
little "egg-tooth" on the tip of the snout.
[Illustration: FIG. 153.–Map showing the distribution of dangerously
poisonous snakes.]
Snakes are intelligent creatures; some become quite affectionate in
captivity, but most of them are of a morose disposition, and do not care
for company.
The GEOGRAPHICAL DISTRIBUTION of Snakes has been dealt with in detail in
connexion with the various families. Unfortunately very few fossils are
known. One of the oldest is _Palaeophis_, of the London clay (Lower
Eocene). Remains of Elapine and of innocuous Colubrine snakes have been
found in the Lower Miocene of Germany; Crotaline forms are known from the
Miocene of Turkey and North America. All the Plistocene {586}remains belong
to recent genera. There are indications that the Ophidia are a relatively
young branch of Reptilia, essentially of Tertiary date, but the foundations
of the distribution of most of the older families were laid in Miocene
times. The older families, notably those which still possess vestiges of
hind-limbs or of the pelvis, are circumtropical, _e.g._ Typhlopidae,
Boidae. The few survivors of the Glauconiidae are likewise circumtropical,
with the exception of Australia. The Ilysiidae occur in South-Eastern Asia
and in tropical South America; their offshoot the Uropeltidae are
restricted to India and Ceylon. The Colubridae and even many of their
sub-families are cosmopolitan. It is quite possible that the Opisthoglypha
and Proteroglypha are not natural groups, but that their respective
conditions have been developed on various occasions and in different
countries. The same applies more strongly to the Viperidae, a further
development of the Opisthoglyphous type. To judge from their distribution,
the Crotaline snakes were possibly developed in the Palaearctic sub-region;
they spread all over America, but they were debarred from entering either
Australia or Africa. The Viperidae, on the other hand, are restricted
entirely to the Palaeotropical region and to the Palaearctic sub-region.
The fact that no separating belt of water existed for them between Europe
and Africa, indicates their being the most recently developed of poisonous
snakes. Madagascar is the only large country which, besides snakeless New
Zealand, enjoys a total absence of poisonous snakes of any kind, while the
Oriental is the only sub-region which suffers from the presence of numerous
species of every sub-family of poisonous Elapine, Crotaline, and Viperine
snakes.
_Snake-Poison._–Many Snakes, belonging to different families, are
poisonous, and unfortunately there is no external character, easily
ascertained, by which every poisonous snake can be distinguished from a
harmless kind. If the head is very broad, this is probably due to the pair
of poison-glands on the sides of the head; but many harmless snakes can
flatten and broaden their heads in a suspicious way, and, what is much
worse, many of the most poisonous snakes, for instance the Cobras, have a
head as smooth and as sleek-looking as the Grass- or Ring-Snake, the most
harmless of species. It so happens that, with a few exceptions, for
instance among the Crotalines and Vipers, no {587}badly poisonous snake has
loreal shields, _i.e._ a pair of shields intercalated between the nasals
and the preoculars, but this character is obviously no good for any
practical purposes. Therefore, unless you know a snake well enough when you
see it, leave it alone, because a mistake may be fatal.
The poison is secreted in modified upper labial glands, or in a pair of
large glands which are the homologues of the parotid salivary glands of
other animals.[174] A duct passes from the gland forwards along the side of
the upper jaw. Just in front of the fang it doubles on itself, so as to
open by a small papilla on the anterior wall of the sheath of mucous
membrane which embraces the base of the tooth like a pocket. As mentioned
before (p. 582), the poison is conveyed either along a furrow on the
anterior side of the tooth, or the growing substance of the tooth partly
converts the furrow into a canal which opens only near the end of the
tooth. This is a perfectly devilish contrivance, ensuring the conveyance of
the poison into the very deepest part of the wound. The Elapinae have
relatively short fangs, while those of the Vipers, and especially those of
the Crotaline snakes, are much longer, sometimes measuring nearly an inch
in length. The most formidable apparatus is that of the Viperidae, since in
them the maxillaries, each provided with only one acting fang, and without
any other teeth behind, can be erected. The mechanism is explained in Fig.
154 and Fig. 179 (p. 647). The apparatus of the upper jaw is so constructed
that the pushing forwards of the horizontal pterygoid bar will, by acting
on the ectopterygoid, rotate and erect the short maxillary. The pulling
forwards is effected by contraction of the spheno-pterygoid muscle, which
arises far forwards from the basal orbito-sphenoid region, and is inserted
on to the inner dorsal surface of the pterygoid. The principal closing
muscles of the mouth are the temporo-masseteric muscles (Fig. 179, _T.a._
and _T.p._) and the inner and outer pterygoid muscles, which latter arise
from the outer surface of the pterygoid bone, or from the maxillary, and
are inserted on to the articular region of the mandible.
A strong ligament arises from the squamoso-quadrate junction, and spreads
fan-shaped upon the connective tissue {588}wall of the poison-gland; the
anterior and posterior ends of the gland are held by another strong band,
which stretches from the maxilla to the mandibular joint. The whole is so
arranged that the acts of opening the jaws (by the digastric muscles) and
the erection of the fang-bearing maxillaries are enough to mechanically
squeeze the contents out of the poison-gland. A portion of the anterior
temporal muscle is attached to the capsule of the poison-gland.
[Illustration: FIG. 154.–Explanation of the biting mechanism of a
rattlesnake. _Ia_ and _Ib_, position of the apparatus when the mouth is
shut. _IIa_ and _IIb_, position of the apparatus when the mouth is opened
widely; the spheno-pterygoid muscle (_P.e_) is contracted, the pterygoid
(_Pt_) is pulled forwards, the transverse bone or ectopterygoid (_Tr_)
pushes the maxillary (_M_), rotates it and thereby causes the poison-fang
(_J_) to assume an erect position. _Di_, Digastric muscle, contraction of
which lowers, or opens, the lower jaw; _G_, the groove or pit
characteristic of the Crotaline snakes; _J_, poison-fang; _M_, maxillary;
_P_, palatine; _P.e_, spheno-pterygoid muscle; _Pm_, premaxillary; _Pt_,
pterygoid; _Q_, quadrate; _Sq_, squamosal; _T.a_, insertion of the anterior
temporal muscle, by contraction of which the mouth is shut; cf. Fig. 179
(p. 647); _Tr_, transversum or ectopterygoid; X, origin and insertion of a
muscle and a strong ligament, contraction of which draws the maxillary and
its tooth back into the position of rest and assists in shutting the
mouth.]
An excellent account of the nature and of the effect of the venom of Snakes
has been written by Charles J. Martin.[175] The following condensed account
has been abstracted from it:–
"The poison is a clear, pale yellow, or straw-coloured fluid, {589}which
reacts acid, and contains about 30 per cent of solids, but this varies much
according to the state of concentration. Most venoms are tasteless, but
Cobra poison is said to be disagreeably bitter. Dried venom keeps
indefinitely, and dissolves readily in water. It keeps also in glycerine.
It contains albuminous bodies in solution. The venom is, in fact, a pure
solution of two or more poisonous proteids, which are the active agents,
with a small quantity of an organic acid or colouring matter. The venom is
destroyed by reagents which precipitate proteids in an insoluble form, or
which destroy them, _e.g._ silver nitrate or permanganate of potash.
Hypochlorites have the same effect. Carbolic acid and caustic potash
destroy it only after a day or two.
"The venom is generally introduced into the subcutaneous tissue, whence it
reaches the general circulation by absorption through the lymph and
blood-vessels. When introduced directly into a vein, the effects are
instantaneous. It is absorbed by the conjunctiva, but, excepting Cobra
poison, not by the mouth or alimentary canal, provided there be no hollow
teeth or no abrasions. The venom of the various kinds of Snakes acts
differently.
"The symptoms of Cobra poison. Burning pain, followed by sleepiness, and
weakness in the legs after half an hour. Then profuse salivation, paralysis
of the tongue and larynx, and inability to speak. Vomiting. Incapability of
movement. The patient seems to be conscious, but is unable to express
himself. The breathing becomes difficult. The heart's action is quickened.
The pupil remains contracted and reacts to light. At length breathing
ceases, with or without convulsions, and the heart slowly stops. Should the
patient survive, he returns rapidly to complete health.
"The symptoms of Rattle-snake poison. The painful wound is speedily
discoloured and swollen. Constitutional symptoms appear as a rule in less
than fifteen minutes: prostration, staggering, cold sweats, vomiting,
feeble and quick pulse, dilatation of the pupil, and slight mental
disturbance. In this state the patient may die in about twelve hours. If he
recovers from the depression, the local symptoms begin to play a much more
important part than in Cobra poisoning: great swelling and discoloration
extending up the limb and trunk, rise of {590}temperature and repeated
syncope, and laboured respiration. Death may occur in this stage. The local
haemorrhagic extravasation frequently suppurates, or becomes gangrenous,
and from this the patient may die even weeks afterwards. Recovery is
sudden, and within a few hours the patient becomes bright and intelligent.
"Symptoms of bite from the European Viper. Local burning pain; the bitten
limb soon swells and is discoloured. Great prostration, vomiting, and cold,
clammy perspiration follow within one to three hours. The pulse is very
feeble, with slight difficulty in breathing, and restlessness. In severe
cases the pulse may become imperceptible, the extremities may become cold,
and 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. Within a few days
recovery usually occurs somewhat suddenly, but death may occur from the
severe depression, or from the secondary effects of suppuration.
"Symptoms of bite from the Daboia or _Vipera russelli_. These resemble the
effects of Rattle-snake poison, but sanious discharges from the rectum,
etc., are an additional and prominent feature. The recovering patient
suffers from haemorrhagic extravasations in various organs, besides from
the lungs, nose, mouth, and bowels. Kidney haemorrhage and albuminuria is a
constant symptom. The pupil is always dilated and insensitive to light.
"Symptoms of bite of Australian Elapine snakes. Pain and local swelling.
The first constitutional symptoms appear in fifteen minutes to two hours.
First faintness, and an irresistible desire to sleep. Then alarming
prostration and vomiting. The pulse is extremely feeble and thread-like,
and uncountable. The limbs are cold, and the skin is blanched. Respiration
becomes shallow with the increasing coma. Sensation is blunted. The pupil
is widely dilated, and insensible to light. There is sometimes passing of
blood. If the patient survives the coma, recovery is complete and as a rule
rapid, without secondary symptoms. The Australian venom and that of all
viperine snakes, perhaps also that of the Cobra, if introduced rapidly into
the circulation, occasions extensive intravascular clotting. If the venom
is slowly absorbed, the blood loses its coagulability, {591}owing to the
breaking down of the red blood-corpuscles, most so with vipers, less with
Australian snakes, least so with the Cobra. The Cobra venom is supposed to
extinguish the functions of the various nerve-centres of the cerebro-spinal
system, the paralysation extending from below upwards, and it has a special
affinity for the respiratory centre. The toxicity or relative strength of
the Cobra venom has been calculated to be sixteen times that of the
European Viper. Snakes can poison each other, even those of the same kind.
"_Treatment._–Apply a ligature above, not on the top of the situation of
the bite; twist the string tightly with a stick. Then make a free incision
into the wound. Sucking out is dangerous! Then bandage the limb downwards,
progressing towards the wound; repeat this several times. Direct
application into the widened wound of calcium hypochlorite, i.e. bleaching
powder, is very good, or of a 1 per cent solution of permanganate of
potash, or Condy's fluid. Amputation of the finger is the best remedy of
all if a large snake has bitten it. Do not keep the ligature longer than
half an hour. Then let the circulation return, and apply the ligature
again. In any case, do not keep the ligature on for more than one hour for
fear of gangrene.
"_Internal remedies._–The administration of enormous doses of alcohol is to
be condemned strongly; small stimulating doses are good, but stimulation
can be more effectively produced by ammonia or strychnia. Hypodermic
injection of strychnine, in some cases as much as one to two grains (but
not into a vein!) has in some cases had good results; but injection of
ammonia, instead of doing any good, has disastrous sloughing results. There
is only one fairly reliable treatment, that by serum therapeutics, the
injection of considerable quantities of serum of animals which have been
partially immunised by repeated doses of snake-venom. Unfortunately this
treatment will not often be available."
Several well-known Mammals and Birds are immune by nature against
snake-venom, but most of them avoid being bitten. Some birds induce the
snake to strike and bite frequently into their spread-out wings. Such more
or less immune creatures are the Mongoose, the Hedgehog, and the Pig, the
Secretary bird, the Honey Buzzard, the Stork and probably other
snake-eaters.
{592}CLASSIFICATION OF OPHIDIA.–Duméril and Bibron[176] divided Snakes
according to their teeth into Opotérodonts, Aglyphodonts, Solenoglypha,
Proteroglypha, and Opisthoglypha.
J. E. Gray[177] divided Snakes into two sub-orders: Viperina and
Colubrinia. Günther[178] distinguished between Ophidii colubriformes, O.
colubriformes venenosi (Elapidae and Hydrophidae) and O. viperiformes.
Cope[179] laid stress upon the modifications of the squamosal,
ectopterygoid, and ectopterygoid bones, and also upon the condition of the
vestigial limbs. He divided the snakes into Scolecophidia (Typhlopidae),
Catodonta, Tortricina, Asinea (the harmless snakes without limb-vestiges),
Proteroglypha, and Solenoglypha.
Boulenger[180] has accepted Cope's principles, and, mainly by combining the
Asinea with the Proteroglypha as Colubridae, has produced a logically
conceived system, by far the best hitherto proposed. It has been followed
in the present work. Boulenger's phylogenetic system stands as follows:–
9 Viperidae
5 Uropeltidae | 8 Amblycephalidae
| 7_a_ C. Opisthoglypha 7_b_ C. Proteroglypha |
| | | |
| +––––––––––––––––––––+––––––––––––+
| |
4 Ilysiidae 7 Colubridae Aglypha
| 6 Xenopeltidae |
| | |
+––––––––––––––––––+–––––––––-–––––––––––––+
|
1 Typhlopidae 3 Boidae 2 Glauconiidae
I. No ectopterygoid; pterygoid not extending to quadrate or to mandible;
no supratemporal (squamosal); prefrontal forming a suture with nasal;
coronoid present; vestiges of pelvis.
Maxillary vertical, loosely attached, toothed; mandible edentulous; a
single pelvic bone. .......... _Typhlopidae_, p. 593.
Maxillary bordering mouth, forming a suture with premaxillary,
prefrontal, and frontal, toothless; lower jaw toothed; pubis and
ischium present, latter forming a symphysis. .......... _Glauconiidae_,
p. 594.
II. Ectopterygoid present; both jaws toothed.
A. Coronoid present; prefrontal in contact with nasal.
1. Vestiges of hind-limbs; supratemporal (squamosal) present.
Squamosal large, suspending quadrate. .......... _Boidae_, p. 596.
Squamosal small, intercalated in the cranial wall. ..........
_Ilysiidae_, p. 594.
2. No vestiges of limbs; squamosal absent. .......... _Uropeltidae_,
p. 595.
{593}B. Coronoid absent; squamosal present.
1. Maxillary horizontal; pterygoid reaching quadrate or mandible.
Prefrontal bone in contact with nasal. .......... _Xenopeltidae_,
p. 605.
Prefrontal not in contact with nasal. .......... _Colubridae_,
p. 606.
2. Maxillary horizontal; pterygoid not reaching quadrate or mandible.
.......... _Amblycephalidae_, p. 637.
3. Maxillary vertically erectile, perpendicularly to ectopterygoid;
pterygoid reaching quadrate or mandible. .......... _Viperidae_,
p. 637.
For ordinary practical purposes this synopsis is useless, being based
entirely upon anatomical characters, not all easily ascertained. The
following characterisation of families may therefore be preferred:–
Eyes vestigial; no teeth in the lower jaw; without enlarged ventral
scales. .......... _Typhlopidae._
Eyes vestigial; teeth restricted to the lower jaw; without enlarged
ventral scales. .......... _Glauconiidae._
Eyes very small; head not distinct; ventral scales scarcely enlarged;
tail extremely short, ending obtusely and covered with peculiar scales.
.......... _Uropeltidae._
With vestiges of the hind-limbs appearing as claw-like spurs on each side
of the vent; ventral scales transversely enlarged; eyes functional, free.
Ventral scales scarcely enlarged. .......... _Ilysiidae._
Ventral scales transversely enlarged. .......... _Boidae._
With a pair of poison-fangs in the front part of the mouth, carried by
the otherwise toothless, much shortened, and vertically erectile
maxillaries; ventral scales transversely enlarged; eyes free. ..........
_Viperidae._
All the remaining Snakes combine the following characters: the
maxillaries are typical, not separately movable, horizontal, with a
series of teeth.[181] The mandible is toothed but has no coronoid bone.
There are no vestiges of limbs or of their girdles. The eyes are free.
Dentary movably attached to the tip of the articular bone of the
mandible; skin beautifully iridescent. .......... _Xenopeltidae._
Without a mental groove; the ends of the pterygoids are free, not
reaching the quadrates. .......... _Amblycephalidae._
With a median longitudinal groove between the shields of the chin; the
squamosal is horizontally elongated, movable; the pterygoid reaches the
quadrate. .......... _Colubridae._
FAM. 1. TYPHLOPIDAE.–Burrowing snakes which have the whole body covered
with uniform cycloid scales, and with the teeth restricted to the small and
transversely placed maxillary bones. The pterygoids do not extend backwards
to the quadrates, and there are no endopterygoids. The quadrates slant
obliquely forwards, and are attached directly to the pro-otics, {594}owing
to the absence of squamosal bones. The prefrontals are in lateral contact
with the nasals. There are vestiges of the pelvis, reduced to a single bone
on each side. The eyes are hidden by shields of the skin.
The Typhlopidae, mainly composed of the genus _Typhlops_, with about one
hundred species, are undoubtedly the last living descendants of formerly
cosmopolitan, rather archaic, snakes, which in adaptation to their
burrowing life and insectivorous diet have undergone degradation. They are
still widely distributed in all tropical and sub-tropical countries, some
on the solitary Christmas Island, but not in New Zealand. One species, _T.
vermicularis_, inhabits the Balkan Peninsula and South-West Asia. It is
brown above, yellowish below, and reaches a length of about 10 inches. The
tail is extremely short and ends in a horny spine. _T. braminus_ is widely
distributed in Southern Asia, the Malay Islands, the islands in the Indian
Ocean and in Southern Africa.
FAM. 2. GLAUCONIIDAE.–In most respects resembling the Typhlopidae, but the
maxillaries retain their normal position and are toothless, teeth being
restricted to the lower jaw, which is stout and short. The pelvic girdle
and the hind-limbs show the least reduction found in any recent Snakes; in
the pelvis the ilia, pubes, and ischia can still be distinguished, the last
even retaining their symphysis; there are also vestiges of femurs. About
thirty species, nearly all belonging to the genus _Glauconia_, are found in
South-Western Asia, Africa, and the warmer parts of America, including the
West Indies.
FAM. 3. ILYSIIDAE.–The scales of the cylindrical body are smooth and small,
those on the ventral side are scarcely larger. The tail is extremely short
and blunt. The head is very small, not distinct from the neck. The gape of
the mouth is very narrow. Teeth are carried by the mandibles, the
pterygoids, palatines, maxillaries, and one or two or more by the
premaxillae. The endopterygoids are short. An important cranial feature is
the short quadrates, which stand rather vertically and are connected with
the cranium by the squamosals; these are very small and are firmly wedged
in between the upper ends of the quadrates and the pro-otic, lateral, and
supra-occipital bones; now forming part of the cranial wall. Vestiges of
the pelvis and hind-limbs are very incomplete, and terminate in claw-like
spurs, {595}protruding between the scales on either side of the vent. The
eyes are very small, and are either free or covered by transparent shields.
The few, scarcely half-a-dozen, species are found in South America
(_Ilysia_) and in Ceylon, the Malay Islands, and Indo-China.
_Ilysia_ (_Tortrix_) _scytale_, the Coral-Snake of Tropical South America,
is a beautiful coral-red with black rings. On account of its beauty,
perfectly harmless nature, and for "cooling purposes," this snake, which
grows to nearly a yard in length, is sometimes worn as a necklace by native
ladies. All the Ilysiidae lead a partly burrowing life, live chiefly upon
worms, insects, and little Typhlopidae, and are viviparous.
FAM. 4. UROPELTIDAE.–Burrowing snakes of Ceylon and Southern India, with a
short and rigid cylindrical body and a very short tail, which ends in a
large peculiar shield, often obliquely truncated. The scales of the body
are smooth, and are little larger on the belly; the coloration is mostly
very beautiful. The eyes are very small.
The Uropeltidae are somewhat intermediate between the Ilysiidae,
Glauconiidae, and Boidae. The pterygoids do not reach the quadrates; but
ectopterygoids are present; the quadrates are very small and directly
attached to the skull, squamosals being absent. Teeth are carried by the
mandibles and by the maxillaries, which are normal in their position. There
are no vestiges of hind-limbs or of the pelvis. The Uropeltidae, of which
about forty species are known, are viviparous, burrow in the ground, and
frequent damp localities, preferring mountain-forests. The use of the
characteristic tail-shield is not clear; perhaps it assists these rather
rigid creatures in digging, by being pressed against the ground.
_Uropeltis._–The tail is obliquely truncated, ending in a roundish, flat
shield.
_U. grandis_ s. _philippinus_.–The latter name seems to have misled W.
Marshall[182] into including the Philippine Islands in the range of the
family, a mistake which is sure to be propagated. The species, the only one
of the genus, is confined to Ceylon; it is blackish above, yellow below,
frequently with small yellow spots above and brown spots on the under
surface. It grows to about 18 inches in length.
{596}_Rhinophis._–The tail-shield is convex and the snout is pointed. _Rh.
sanguineus_ of Southern India is black above with a bluish gloss, sometimes
with small pale specks; the belly and several of the lateral series of
scales are bright red, spotted with black. The tail-shield is black and
red.
[Illustration: FIG. 155.–Skull of _Eunectes murinus_. × 1. The teeth on the
maxillary, palatine, and pterygoid have been omitted. _Col_, Columella
auris; _Cond_, occipital condyle; _E.P._ and _E.Ptg_, ectopterygoid or
transverse bone; _F_, frontal; _Mand_, mandible; _Max_, maxillary; _Na_,
nasal; _Pal_, palatine; _Par_, parietal; _Pmx_, premaxillary; _Pr.f_,
prefrontal; _Pt.f_, postfrontal; _Ptg_, pterygoid; _Q_, quadrate; _Sq_,
squamosal; _Tb_, turbinal.]
FAM. 5. BOIDAE.–Typical Snakes, usually large, and with vestiges of pelvis
and hind-limbs, appearing externally as claw-like spurs on each side of the
vent. The scales of the upper surface are usually small and smooth, while
those of the ventral surface form one broad series on the belly, and one or
two rows on the tail. The quadrate is carried by the horizontally elongated
squamosal, which rests loosely upon the lateral occipital region. The
prefrontal is in contact with the nasal. Teeth are carried by the
mandibles, the pterygoids, palatines, maxillaries, and, in the Pythoninae,
by the premaxillaries also. For further details see Figs. 155, 156.
{597}[Illustration: FIG. 156.–A, Ventral, B, dorsal, view of the skull of
_Eunectes murinus_. Lettering as in Fig. 155. × 1.]
The Boidae comprise between sixty and seventy species, which have been
grouped into many genera, on unimportant characters, referring to the
scales and shields of the head. It is doubtful if they are natural groups,
a consideration which detracts much from their value in the study of
geographical distribution. Even the two sub-families are not free from this
reproach. The range of the family is world-wide, Boidae occurring in all
tropical and sub-tropical countries, including islands, except New Zealand.
A few species live in South-Eastern Europe (_Eryx_) and in North-Western
America. They mostly prefer wooded districts, especially forests; climbing
trees, assisted by the short and partly prehensile tail. Others are
semi-aquatic, and a few live in sandy localities. They are all rapacious,
and by preference feed on warm-blooded creatures, which they constrict by
coils of the body in order to hold, kill, and crush the victim before
swallowing it. Exaggerated notions are entertained about their swallowing
capacity. It is obvious that a large snake, 20 feet long, half a foot
thick, and weighing several hundred pounds, can crush a tiger, a stag, or
even a {598}cow; but common sense tells us where to draw the line when it
comes to the swallowing of the prey. Small game, although of a bulk
apparently far too big for the snake, is so crushed and mangled that it is
turned into the shape of a sausage preparatory to the long process of
swallowing. The Boidae lay eggs, and some species incubate them, or rather
the female coils herself round them for the sake of protection. No
appreciable amount of extra warmth is developed. Unfortunately the
observations of one of the best cases on record[183] were conducted so
imperfectly that they are of little value.
SUB-FAM. 1. PYTHONINAE.–With a pair of supra-orbital bones, intercalated
between the prefrontal, frontal, and postfrontal bones. The sub-caudal
scales are mostly in two rows. The premaxilla often carries a few small
teeth.
The Pythoninae, comprising about twenty species, are restricted to the
Palaeotropical and Australian regions, with the sole exception of
_Loxocemus bicolor_ in Southern Mexico.
_Python_, the principal genus, has teeth on the premaxilla. The rostral,
each of the anterior upper labials, and some of the lower labial shields,
contain a deep, probably sensory, pit. The maxillary and mandibular teeth
are long, but decrease from before backwards. The head is distinct from the
neck, and is covered with symmetrical shields or with small scales. The
scales of the body are small and smooth. The tail is short and prehensile;
below with two rows of scales. The pupil of the eye is vertical. The range
of the genus extends over the whole of the Palaeotropical and Australian
regions, excepting Madagascar and New Zealand.
_P. spilotes_, the "Carpet Snake" of Australia and New Guinea, is mostly
beautifully marked, but is subject to much variation in colour. The more
typical specimens are black above, each scale with a yellowish dot, with
yellow spots or combinations of dots, more or less arranged in rows. The
under parts are yellow. It reaches a length of about two yards, and spends
a great part of its time in trees.
_P. reticulatus_ is the commonest species in Indo-China and in the Malay
Islands. Four upper labial shields of each side are pitted. The specific
name refers to the bold, dark, lozenge-shaped markings upon the lighter
yellowish or brown ground. A black {599}line extends over the head from the
nose to the neck, and another on each side from the eye to the angle of the
mouth. The under parts are mostly yellowish, with small brown spots on the
sides.
This is one of the largest species of Python, some specimens being known
which measured about 30 feet in length.
[Illustration: FIG. 157.–_Python spilotes_ (the Carpet Snake). × ⅛.]
As a sample of folk-lore connected with this monstrous snake the following
Burmese fable has been recorded by Mason:–[184]
"According to a Karen legend all the poisonous serpents derive their
virulence from the Python, which, though innocuous now, was originally the
only one that was venomous. In those days he was perfectly white, but
having seduced away a man's wife, Aunt Eu (Eve), he made her, while she was
in his den, weave figures on his skin in the forms which are now seen. At
that time, if he bit the footstep of a man in the road, such was the
virulence of his poison that the man died, how far soever that man might
have passed from the bitten track. The Python had not, however, an ocular
demonstration of the fact, so he said to the Crow: 'Crow, go and see
whether people die or not when I bite the foot-track.' The Crow went to the
neighbourhood of a Karen cabin, and found the people, as is their custom at
funerals, laughing, singing, dancing, jumping, and beating drums. He
therefore returned to the Python, and told him that so far from {600}his
efforts producing death, on the contrary they produced joy. The Python was
so angry when he heard this that he ascended a tree and spit up all his
venom, but other creeping things came and swallowed it, and people die of
their malignancy to this day. The tree, therefore, from which the Python
spat up his venom became deadly, and its juice is used to this day for the
purpose of poisoning arrows. The Python made the other creatures promise
not to bite without provocation. The Cobra said: 'If there be transgression
so as to dazzle my eyes, to make my tears fall seven times in one day, I
will bite.' So said the Tiger (whose bite the Karens esteem as virulent as
a serpent's) and others, and they were allowed to retain their poison. But
the Water Snake and Frog said they would bite with or without cause as they
liked; so the Python drove them into the water, where their poison melted
away and their bite became harmless."
[Illustration: FIG. 158.–_Python molurus._ × ⅒.]
_P. molurus_ is the species of India and Ceylon, ranging, however, also
into Indo-China. Boulenger quotes W. Elliot[185] {601}as the authority for
the statement that this species grows to the length of 30 feet. Only two
pairs of upper labials are pitted. The general colour above is greyish or
yellowish brown with a dorsal series of large reddish-brown, black-edged
patches, and on the sides of the body with a series of smaller spots with
light centres. On the head is a lance-shaped marking; a brown stripe passes
from the eye backwards. The under parts are yellowish.
_P. sebae_ and _P. regius_ are African species. The former has two pairs of
upper labials pitted, the latter four pairs. _P. sebae_ is generally pale
brown above with dark brown, black-edged cross-bars, which are usually
connected by a sinuous dark stripe along each side of the back. The upper
surface of the tail has a light stripe between two black stripes. The belly
is spotted and dotted with dark brown. _P. sebae_ ranges over the whole of
Tropical and Southern Africa, perhaps with the exception of Eastern Africa.
_P. regius_ of West Africa is beautifully marked, and may be recognised by
the dark brown, black-edged band along the back, sending down triangular or
Y-shaped processes on the sides, which are pale brown. This dorsal band
encloses a light streak on the neck and another on the tail. The belly is
yellowish.
These African Pythons grow to a length of about 15 feet, but specimens so
large as this are not often met with. The negroes of certain parts of the
coast of Guinea are said to worship them and to keep them in special
temples, where they are regularly attended to. Their food consists chiefly
of small Mammals, notably rats, and of Birds. A couple of these snakes
paired in the Zoological Gardens of London in the month of June. The female
laid nearly one hundred eggs in the following January, and incubated them
until April, when the embryos were found to be still unripe.
SUB-FAM. 2. BOINAE.–Without supra-orbital bones. The premaxilla is
toothless. The subcaudal scales form mostly a single row.
The Boinae comprise between forty and fifty species. Most of them are
American, but the genus _Eryx_ inhabits North Africa, Greece, and
South-Western Asia; the genus _Enygrus_ inhabits New Guinea and many of the
Pacific Islands, for instance New Britain (Neu Pommern), the Solomon,
Loyalty and Fiji Islands, {602}and the New Hebrides. _Casarea dussumieri_
is found on Round Island near Mauritius; and two species of _Boa_ and one
of _Corallus_ represent the Boidae in Madagascar, while all the others live
in Central and South America.
_Boa._–The maxillary and mandibular teeth gradually decrease in size. The
scales of the upper parts of the body and tail are smooth and very small.
The rostral shield is enlarged. The nostrils are placed between two or
three nasals, and these are separated from those of the other side by small
scales. The tail is short and prehensile. The pupil is vertical.
_B. constrictor_, of South America, has the head covered with small scales,
one of the pre-oculars being enlarged. The eye is separated from the
labials by several series of tiny scales. The general colour is a delicate
"pale brown above, with fifteen to twenty dark brown cross-bars widening on
each side, and, if connected by a dark dorso-lateral streak, enclosing
large elongate oval spots.... On each side is a series of large dark brown
spots with light centres, most of which alternate with the cross-bars. On
the tail the markings become much larger, brick-red, edged with black, and
separated by narrow, yellowish interspaces." Under parts yellowish with
black dots. _Boa constrictor_, a name applied in popular parlance to many
species, reaches a length of more than 10 feet; the largest specimen in the
British Museum measures exactly 11 feet. A few other species inhabit
Central America and the West Indies. _B. dumerili_ and _B.
madagascariensis_, both of Madagascar, cannot be separated from the genus
_Boa_.
A. D. Bartlett[186] has described the following incident:–
"In the evening of 5th October 1892 two pigeons were put into the cage in
which two fine specimens of _Boa constrictor_ had been living on friendly
terms since the beginning of the year. The larger snake seized one of the
pigeons and the keeper left the house. The next morning only one of the
snakes, the larger specimen, was visible, and from its enormously extended
body it was evident that it had swallowed its companion, which was about 9
feet in length. It had no longer the power of curling itself round, but
remained extended nearly to its full length in a straight line, and
appeared to be at least three times its normal circumference. It was almost
painful to see the distended skin, {603}which had separated the scales all
over the middle of the body. By 2nd November, twenty-eight days later, the
snake had not only digested its companion but had regained its appetite as
well as its normal size, and it immediately swallowed a pigeon put into its
den."
This peculiar case is not one of ordinary cannibalism. It is rather an
unintentional accident. When two snakes happen to get hold of the same
animal (in the present case a pigeon) and begin to swallow it, the action
of swallowing becomes almost mechanical, the snakes continuing to push
their jaws over the prey–which in the case of a bird or mammal they cannot
taste, nor can they see it–so long as they feel something in the mouth.
After the original prey has been mastered, it is the turn of the opposite
snake's head, and if the weaker snake does not give way it is swallowed by
its stronger mate. Grass-Snakes will swallow several frogs if these are
tied together in a string, and other snakes do the same with mice. There
are instances on record in which a _Python_ swallowed its blanket, which,
being absolutely indigestible, caused its death.
[Illustration: FIG. 159.–Head of _Eunectes murinus_. × 1.]
_Casarea_, the "Round-Island Snake," differs from _Boa_ chiefly by the
rough and strongly keeled scales, and by the relatively much longer tail.
_Eunectes murinus_, the "Anaconda," is an aquatic _Boa_. It differs from
this genus mainly by the inner of the three nasal shields being in contact
with that of the other side (see Fig. 159), and by the absence of the
little scales between the eye and the labials; the snout is, moreover,
covered with shields instead of small scales. The pupil of the eye is
normally vertical, but it had contracted into a round pinhole in the dead
but still fresh {604}specimen from which the figure was drawn. The general
colour is dark olive-brown, with large oval black spots arranged in two
more or less alternating rows along the back, and with smaller black,
white-eyed spots along the sides. The under parts are whitish, spotted with
black. The upper parts of this and of many other dark-coloured species of
Boidae are often shiny, with an iridescent lustre.
The Anaconda combines an arboreal with an aquatic life, a kind of existence
eminently in harmony with the well-watered, dense forests of Tropical South
America, which are the home of this, the largest of all modern Snakes. It
is said to attain a length of as much as 33 feet. There is no inherent
impossibility in such statements, but the giant specimens seem to have a
knack of keeping out of the naturalist's way.
The Anaconda feeds chiefly upon Birds and Mammals, which it catches either
on land, mostly during the night-time, or in the water. For the latter
purpose it lies submerged in the rivers or floats about leisurely, only the
head being above the surface, and anything suitable is attacked. In other
localities the snake, if so inclined, establishes itself upon the branches
of a tree which overhangs the water, or the track of the game. These
aquatic Snakes seem to be viviparous.
_Eryx_ has the head not distinct from the neck and covered entirely with
small scales. Those of the body are likewise small, and are either smooth
or keeled. The tail is very short. The anterior maxillary and mandibular
teeth are longer than the posterior teeth. These snakes, most of which are
less than 3 feet in length, inhabit the sandy districts of North Africa,
Arabia, and South-Western Asia, extending into Central Asia. One species,
_E. jaculus_, extends into Greece and the Ionian Islands. Like the other
species it is an ugly creature, pale grey or yellowish above, with darker
patches and spots. The under parts are whitish. The scales are smooth on
the front half of the body, becoming keeled further back and on the tail.
Total length under 2 feet. The pupil is vertical.
According to Zander[187] and Werner[188] this snake lives in sandy
localities, digging itself into the sand, or covering the body lightly with
sand and leaving only the eyes and nostrils free. The whole body is very
flabby, and presses itself into any irregularity of the {605}ground over
which the snake creeps. Some specimens live on lizards, others prefer mice.
The prey is caught by the head, and further secured by several turns of the
body of the captor, whose tail is then turned forwards, round the head of
the victim, so as to form a kind of knot.
Not less striking than their agility is their jealousy, which is so strong
that a snake will occasionally leave the mouse which it has just strangled
in order to seize another snake's mouse. Sometimes several snakes fight for
the same mouse, coiled together into one inextricable lump so that the
mouse itself is quite invisible. The snakes poke their heads about in
search of the hidden prey, and every attempt of one of the snakes to free
itself, causes the others to squeeze it firmer and firmer, thinking
apparently that the motion was caused by the lost prey.
Occasionally one of Werner's captives caught several mice in succession.
With these it crawled into a corner, dropped the mice, and then proceeded
quietly to swallow one after another. After a fortnight the whole repast
was digested, and the snake was ready for more.
FAM. 6. XENOPELTIDAE.–The single species, _Xenopeltis unicolor_, of
South-Eastern Asia, including the Malay Islands, has been raised to the
dignity of family-rank on account of the following combination of
characters. The prefrontal bones are still in contact with the nasals as in
the previous families, but the coronoid bones of the mandibles are absent
as in the remaining families. The whole suspensorial apparatus and the
lower jaw itself are peculiar. The dentary bone is movably attached to the
end of the much-elongated articular bone, the movability being enhanced by
the absence of the coronoid element.[189] The quadrate is short and thick,
and is carried by the short and broad squamosal, which lies flat against
the skull, resembling in this respect that of some of the Ilysiidae.
Boulenger rightly considers _Xenopeltis_ to be in various ways intermediate
between this family, the Boidae and the Colubridae. The head is small and
not distinct from the neck. The eyes are small and have a vertical pupil.
The body is cylindrical, covered above with {606}smooth black or brown and
highly iridescent scales, hence the generic name. The ventral scales are
white and transversely enlarged as in the majority of snakes. The tail is
short, but not stunted, measuring about 4 inches in full-grown specimens of
a total length of 3 feet.
FAM. 7. COLUBRIDAE.–This family comprises those snakes (about nine-tenths
of all recent species) which combine the following
characters:–ectopterygoids are present: the squamosals are loosely attached
to the skull, and carry the quadrates, which are not reached by the
pterygoids: the prefrontals are not in contact with the nasals: the
maxillaries are horizontal and form the greater portion of the upper jaws:
the mandibles lack the coronoid process or element: both jaws are toothed.
The best arrangement of this enormous cosmopolitan family with terrestrial,
arboreal, and aquatic forms, is that by Boulenger, who, adopting Duméril's
terms, has divided them into three parallel series.
A. _Aglypha._–All the teeth are solid and not grooved.
B. _Opisthoglypha._–One or more of the posterior maxillary teeth are
grooved.
C. _Proteroglypha._–The anterior maxillary teeth are grooved or
"perforated."
The Aglypha are harmless, non-poisonous. Most of the Opisthoglypha are
poisonous, although few of them are dangerously so. The Proteroglypha,
which comprise the "Cobras" and their allies, are deadly poisonous.
SERIES A. AGLYPHA.
SUB-FAM. 1. ACROCHORDINAE.–The postfrontal bones, besides bordering the
orbits posteriorly, are extended forwards so as to form the upper border of
the orbits, separating the latter from the frontals. The few genera and
species of this sub-family are mostly aquatic, inhabiting rivers, or
estuaries with brackish water, and they have been known to swim far out
into the sea. The body is covered with small, frequently granular scales;
in the typically aquatic forms the body is slightly compressed laterally,
and the ventral scales are scarcely larger than the others. Most of these
ugly snakes inhabit the rivers of coasts of South-Eastern Asia and
Papuasia; one, _Stoliczkaia_, is found in the Khasia Hills {607}of
North-Eastern India; another, _Nothopsis_, lives far from its supposed
allies, on the Isthmus of Darien, Central America.
_Acrochordus javanicus_ has no ventral shields. The head is flat, covered
with small granules, with the eyes and nostrils on the upper surface. The
general colour is dull olive-brown, lighter and spotted beneath. The food
consists of fishes. Total length up to 4 feet.
_Chersydrus granulatus_ ranges from the coast of Madras to New Guinea. The
body and tail are compressed, and form a ventral fold, covered with tiny
scales like the rest of the body. General colour grey above, yellow below.
SUB-FAM. 2. COLUBRINAE.–The postfrontal bones are restricted to the
posterior border of the orbits. The maxillary and dentary bones carry teeth
on their whole length. The scales are usually imbricating. This sub-family
contains the overwhelming majority of snakes, about 1000 species, all of
them harmless so far as poison is concerned. None of them reach a great
size, species of 6 or 7 feet in length being rare, e.g. _Zamenis mucosus_,
but a few species of the Indian genus _Zaocys_ s. _Coryphodon_ grow to 10
feet. Most of the Colubrine snakes are oviparous, but some, e.g.
_Coronella_, are viviparous. Some are aquatic, or semi-aquatic, others are
absolutely arboreal, others again prefer dry, sandy, or rocky localities,
according to their food. The distribution of the sub-family is
cosmopolitan, finding its natural limits only in the permanently frozen
under-ground, a condition which makes hibernation impossible. Most of them
love warmth and like to bask, although many are not fond of the broiling
sun. In the temperate regions they hibernate. As a rule they are
intelligent and some of them become even affectionate.
_Tropidonotus._–The teeth form closely set series on the whole length of
the maxillaries, palatines, pterygoids, and the greater portion of the
dentaries. The premaxilla is toothless. The teeth of the maxillaries
gradually increase in length, the posterior teeth being the longest. The
pupil is round. There is a pair of internasal shields. The scales covering
the body have each an apical, sensory pit, are mostly keeled, and are
arranged in longitudinal series. The ventral shields are broad; the
sub-caudals form two rows. This genus, with more than seventy species, has
a wide range, practically over the whole world with the exception of New
Zealand and the southern half of Australia.
{608}_T. natrix_, the common Grass-Snake, has a divided, or double, anal
shield. The strongly keeled scales of the body form nineteen rows. There
are normally seven upper labials, the third and fourth of which border the
eye. The usual colour of the Grass-Snake is olive-grey or brown above, with
black spots and narrow cross-bands. The labials are white or yellowish,
with black sutures. The belly is checkered black and white, more or less
suffused with grey. There are several colour-varieties. The typical or
northern form has a white, yellow, or orange collar, bordered behind by a
black collar; the pale collar is sometimes faint or absent. The second
variety, rather common in Spain and Portugal, although not the only form in
the Peninsula, has no collar whatever, and these specimens are sometimes
almost uniformly grey-green above. The third variety, common in
South-Eastern Europe and in Asia Minor, has a well-marked collar and a
yellowish streak along each side of the back. But there are also almost
black specimens.
The usual length of an adult female Grass-Snake is about 3 feet, but very
exceptional cases of more than 6 feet are on record; the males are smaller
and more slenderly built. The range extends over the whole of Middle
Europe, Algeria, West and Central Asia. It does not, however, occur in
Ireland or Scotland. Its northern limit is the southern part of Sweden.
The Grass-Snake prefers moist, grassy localities, with the neighbourhood of
water, chiefly on account of the food, which consists entirely of fishes
and Amphibia, notably of frogs; tree-frogs are preferred to anything else;
toads are occasionally eaten, but mice are never taken.
The Grass-Snake can climb trees or rather shrubs and is an accomplished
swimmer, often spending much of its time in water for fishing purposes. The
fish is caught by the belly and then generally swallowed on land. The
Grass-Snakes appear in the spring and disappear in the autumn to hibernate
in the ground. They pair, in England, in the month of May or June, usually
on warm and sunny mornings. The eggs are laid from July to the end of
August, mostly in rich vegetable soil, in heaps of weeds or in
manure-heaps. Young snakes lay fewer eggs than old specimens, which
sometimes produce more than three dozen at a time. The eggs are soft,
whitish yellow, about one inch long, and soon stick together, so that the
whole clump {609}can be taken up at once. As a rule the new-laid eggs do
not contain any visible sign of the embryo, but it often happens that the
snake has to delay oviposition, and then the embryos are more or less
advanced. This is especially the case with recently caught specimens. The
young are hatched in the late summer or in the autumn, and seem to live at
first upon soft insects and worms. Curiously enough they are easily drowned
when they fall into the water, even in a shallow tank. My tame snakes have
often laid eggs between the stones in the greenhouse; the young throve well
upon unknown food, but most of them met their fate in the water. When they
are a few weeks old they are strong enough to take baby-frogs.
The Grass-Snake becomes very tame, learns to distinguish between different
people, allows itself to be handled without hissing or without voiding the
obnoxiously smelling contents of its cloaca and anal glands, will in time
take the offered food from the hand, and will even crawl up the arm or
sleeve and coil itself up contentedly. One of the finest specimens, quite
green, without a trace of a collar, and with brownish-red eyes, I caught in
the Guadiana, where it had been fishing in midstream. It swam towards the
bank, dived, and hid itself at the bottom between rocks. This snake, a
female, became very tame. It never hibernated, shed its skin regularly
every few months, and grew within nine years from 35 inches to 42 inches in
length.
The Grass-Snake is perfectly harmless: although hissing, and striking out
furiously with its head, it never bites, not even when it is severely
handled. Its only defence consists of the awful contents of the cloaca and
the anal glands, the secretion of which smells of concentrated essence of
garlic mixed with other indescribable odours. The wildest specimens I have
ever met with inhabited a swamp with a little stream to the north of Oporto
close to the coast. To my utter surprise some of them actually made for me,
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. These
and other kinds of allied snakes require to drink much and often.
Occasionally they drink milk when this is offered them, but that they suck
the udders of cows or the breasts of women is an idle fable.
{610}_T. viperinus._–The scales are strongly keeled and form twenty-one to
twenty-three longitudinal rows. The third and fourth labials border the
eye. The anal shield is divided. The eyes and nostrils are directed upwards
instead of sidewards, in adaptation to the essentially aquatic habits of
this species, which lives upon fishes and Amphibia. The general colour is
grey to reddish brown, with a black zigzag band along the back and a
lateral series of black, yellow-eyed spots. The belly is yellow or red,
checkered with black.
[Illustration: FIG. 160.–_Tropidonotus sirtalis._ × ½.]
The Viperine Snake bears a general resemblance to the common viper. It
inhabits France, Italy, Spain and Portugal, and Morocco. Very large
specimens attain a length of nearly 3 feet, but the ordinary size of adults
is 2 feet. This snake spends most of its time in the water, but it is often
found on land, basking on the top of a low wall or on a low shrub. It is
exceedingly common in Spain and Portugal, where it inhabits almost every
ditch, any standing water or slow river. In the Alemtejo, when during the
rainless and hot summer the small {611}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. Those which I collected generally died,
apparently from some kind of cutaneous suffocation, during the night
following their capture. Taken under other conditions they are very easily
kept and tamed.
I once caught a Viperine Snake in a ditch whilst it was swallowing an eel
of nearly its own length. Both were separated, and then put into a small
bag together with other creatures, and no more attention was paid to them
for several hours. When I opened the bag again, the snake, undisturbed by
my incessant walking about, was again busily engaged in trying to get
outside that same eel!
_T. sirtalis_ (Fig. 160) is one of the almost endless varieties of what is
now known by the name _T. ordinatus_, of North and Central America.
_T. tesselatus_ is closely allied to _T. viperinus_, which it represents in
South Germany, Italy, South-Eastern Europe, and Asia; but the scales form
only nineteen rows, and the fourth, or fourth and fifth labials, border the
eye. The usual colour is olive-grey with dark little spots, and with a dark
chevron-shaped band behind the occiput. The lower parts are yellow or red
checkered with black, hence the specific name.
_Zamenis._–The maxillary teeth are not closely packed; they increase
slightly in size backwards, and the last two are often a little larger and
separated from the rest by a diastema. The mandibular teeth rather decrease
in size from before backwards, inversely with the upper teeth. The scales
are smooth with apical pits; the sub-caudals form two rows. The eye is
large, and has a round pupil. The range of this genus, with about thirty
species, extends over the whole of the Periarctic region.
_Z._ (_Ptyas_) _mucosus_ (Fig. 161), the Rat Snake of India, extending from
Transcaspia to Java, is a very common species, often seen in menageries.
Its general colour is brown above, often with black cross-bands on the
hinder part of the body and tail. The under parts are yellowish. The fourth
and fifth labials border the eye. {612}The scales on the body form only
seventeen rows. Another feature of this species is the prominent ridge of
the back-bone, not only in half-starved but in well-conditioned specimens.
The Rat Snake grows to a length of more than 7 feet, and is as ill-tempered
as most species of this genus.
[Illustration: FIG. 161.–_Zamenis mucosus_ (Rat Snake). × ⅕.]
_Z. gemonensis_ s. _viridiflavus_ inhabits France, Italy, the Balkan
Peninsula, and Asia Minor. Its coloration is very variable. In general it
is either green above and yellow below, hence the appropriate name
_viridiflavus_, or the ground-colour of the back is greyish or olive-yellow
with brownish spots, which form more or less longitudinal rows on the
trunk, but gradually pass into blackish continuous lines on the tail; the
under parts are yellow or greenish white, often with many very small, dark
specks. The scales form seventeen or nineteen rows; the anal shield is
divided. There are two small postocular scales and one subocular; of the
eight labials, the fourth and fifth border the eye. This species is very
lively, attacks {613}and bites furiously, climbs well, and when suspended
from branches can protrude half of its length in a horizontal direction. It
eats any kind of Reptile, Bird, or Mammal it can master; small animals are
swallowed directly, rats and moles are first killed by constrictions. Large
specimens reach perhaps 6 feet in length.
_Z. hippocrepis_ is the representative species in the Iberian Peninsula and
in North-Western Africa. It is rarely more than 4 feet long, and is very
pretty, the ground-colour being reddish or olive-yellow with a row of
large, dark brown, yellow-edged spots along the back. Two rows of smaller
spots adorn the sides; where the dark spots are large, the pale
ground-colour is restricted to forming rings around the spots, producing a
pretty appearance. The under parts are yellow or orange, with black spots.
On the head is a dark, pale-edged patch in the shape of a horse-shoe, a
feature alluded to by the specific name. Structural characters are the
possession of a row of little subocular scales, which completely separate
the eye from the labials, the double anal shield, and the small and smooth
scales on the body, which form generally as many as twenty-seven rows.
_Z. constrictor._–The American Black Snake. The scales are smooth, and
arranged in seventeen rows; the anal shield is divided. The general colour
above is uniform bluish-black; below slaty, tinged with blue; the chin and
throat are silvery white, sometimes with a black spot. Large specimens
attain a total length of 6 feet.
Holbrook gives the following exhaustive account of this species, about
which many sensational stories are current even in would-be scientific
periodicals:–
The "Black Snake" is one of the commonest of North American species. It is
extremely active, climbing with facility, and running with great rapidity,
whence it is not uncommonly called the "Racer." It frequents shady places,
covered with thick shrubs, on the margins of water. It feeds on mice,
toads, or small birds; and, as it is an excellent climber, is frequently
seen on trees in search of birds' nests. It is a bold and daring serpent,
enters barns and out-houses without fear, and has been known to destroy
young chickens. Its specific name _constrictor_ would imply that it
suffocates or crushes its prey, but this according to Holbrook is at least
doubtful. In the {614}breeding season it is extremely irascible, and will
frequently attack persons passing at a distance of several steps; the tail
then quivers with rage, making a quick vibrating motion, which in forests
and among dead leaves sounds not unlike the Rattle-Snake; it now elevates
the head one or two feet from the ground, and darts upon its adversary;
luckily its bite is harmless, and not more painful than the scratch of a
pin.
"It will even descend from trees to attack its enemy if teazed, yet it does
not twine itself around the legs, as is commonly supposed.
"The same power of charming its prey has been attributed to the Black as to
the Rattle-Snake, and with still less appearance of reason; for this is a
nimble animal, and can pursue its prey, while the Rattle-Snake must lie in
wait for his. It is remarkable that the birds most commonly found 'charmed'
are the Cat-bird (_Turdus carolinensis_) or red-winged Black-bird (_Icterus
phoeniceus_). These birds choose thick and shady places on the margins of
streams for their residence, and generally build their nests on such shrubs
as the alder; the latter bird not unfrequently takes the precaution to
select such bushes as are on small islands, or such as have their roots
surrounded by water, and thus their home is more secure. Now the Black
Snake chooses precisely the same localities, knowing probably the haunts of
its prey. The serpent begins the war by besieging the nest; the old bird,
aware of its intention, attacks it with fluttering and uncertain motions,
accompanied by a plaintive cry of distress, and is then said to be
'charmed.' The snake is at last either driven off, or it captures the young
and not unfrequently the old bird too.
"Sometimes the old bird, by her cries, calls in the assistance of her
neighbours to drive away the aggressor. I have seen more than a dozen birds
thus engaged with a large Black Snake that had probably just committed some
depredation, but was now quietly stretched on a rock, basking in the sun;
and it was not a little singular that birds of very different genera, and
those seldom seen together, all united in this warfare against a common
enemy, and finally compelled him to seek shelter among some low, thick
shrubs, by the violence of their assault."
_Zaocys_, with about half-a-dozen species in South-Eastern Asia, is closely
allied to _Zamenis_. _Z. carinatus_, of the Malay {615}Islands, grows to 10
feet in length; it is consequently one of the largest harmless Colubrine
snakes. The scales form only sixteen to eighteen rows. The sub-caudals are
double. The general colour above is dark olive, passing into greenish brown
farther back. The under parts are yellowish; black and yellow posteriorly.
The fifth and sixth labials border the eye.
[Illustration: FIG. 162.–_Zaocys carinatus._ × ¼.]
_Coluber._–The maxillary teeth are of equal size, but the anterior
mandibular teeth are the longest. The head is distinct from the neck. The
nasals are distinct; not fused with the loreals. The eye is rather large,
with a round pupil. The scales, smooth or keeled, have apical pits; the
ventrals are rounded or angulate laterally; the sub-caudals are double.
They all lay eggs and constrict their food. Nearly fifty species in the
Periarctic region.
_C._ (_Elaphis_) _quatuorlineatus_ s. _quaterradiatus_ inhabits Italy and
South-Eastern Europe. It occurs also in the Southern Tyrol. The scales of
this large snake, which grows to nearly 6 feet in length, are arranged in
twenty-five rows, and are feebly {616}keeled. The anal is divided. Adult
specimens have a yellowish-brown ground-colour with a pair of black streaks
on each side of the back. A black line extends from the eye to the angle of
the mouth; the under parts are yellow, mostly closely spotted with brown.
This snake is good-tempered, and keeps well in captivity. They live on
sparrows, mice, lizards, etc., and are very fond of eggs. Large specimens
can swallow several fowls' eggs in succession; the crushed remains of the
shells are later disgorged. This handsome snake climbs extremely well in
search of birds and their eggs, and it is not afraid of the water. The prey
is caught either with the teeth or by a rapid twist of the tail; in any
case, the prey is always strangulated by the constriction of coils thrown
round it. A sparrow thus secured is literally passed through the moving
coils along the snake's body into a position convenient for swallowing.
Hungry snakes catch and secure several birds or mice before eating them. My
own specimens became almost affectionately tame, never attempted to bite,
and took food from the hand.
_C. leopardinus_ is smaller, but is one of the handsomest snakes of
Southern Italy, South-Eastern Europe, and Asia Minor. It is closely allied
to the previously described species. The ground-colour is pale brown with a
dorsal series of dark brown or reddish, black-edged, transverse spots, and
a lateral alternating series of smaller black spots, or with two dark
brown, black-edged stripes bordering a yellowish vertebral stripe; usually
with a forked black mark on the occiput and nape. The under parts are
white, checkered with black, sometimes with the latter colour prevailing.
_C. flavescens_ s. _aesculapii_ is the Aesculap-Snake, for which the almost
unknown name of _longissimus_ has now been unearthed in deference to the
fetish of priority. This snake is of an extremely graceful and slender
build, with a very long tail. Its home is the South of France, Italy, and
South-Eastern Europe. It occurs sporadically in the Tyrol, for instance
near Bozen, in Austria, at Baden near Vienna, in Germany only in the
Taunus, especially at Schlangenbad, which has received its name from the
frequent occurrence of this snake. This sporadic distribution favours the
idea that these snakes were introduced by the Romans as inmates of the
temples erected to Aesculapius at such watering-places. Specific characters
are the smooth and shiny scales, {617}which are arranged in twenty-one to
twenty-three rows, the distinctly angulate ventrals and the double anal and
sub-caudals; the fourth and fifth of the upper labials border the eye,
which has a round pupil. The coloration is very variable, as a rule
olive-brown above with a dark streak behind the eye; the upper lips and a
triangular patch on the temples are yellow; the under parts are uniform
pale yellow. Some specimens are pale golden brown; others are very dark,
almost black; while some have four darker stripes along the body, and
lastly whitish specks occur on the upper surface. Large Aesculap snakes
grow to a length of 5 feet. Their food consists chiefly of mice. They
become very tame, although many of them at first bite furiously. Their
climbing capacities are astonishing, the snakes being able to scale high
and vertical walls provided there is the slightest "foothold." Some of my
specimens escaped in the room and were at last found near the ceiling,
resting on the rods of the curtains, up the folds of which they had managed
to wriggle. Boulenger kept one for many years in a glass cage, where the
snake entwined himself round the branches of a stick and allowed us to take
him with the stick out of its socket and to inspect him. Being kept in an
inhabited room, the snake did not exactly hibernate, creeping into the moss
at the bottom of the cage; but it refused to feed, and remained in a rather
drowsy condition coiled up on its favourite stand. During the pairing
season they frequently resort to the water, at Schlangenbad at least; the
few eggs are deposited under dry moss or in dry, decayed wood, and are
hatched in about six weeks.
_C._ (_Rhinechis_) _scalaris_ has the smooth scales disposed in
twenty-seven rows. The snout is strongly projecting, and has a V-shaped
dark mark on the top; a black streak runs through the eye, and another
black spot lies below the eye. Young specimens are pale brown with a series
of dark H-shaped marks on the back, suggesting a ladder, hence the specific
name. In the adult these marks are replaced by a pair of brown stripes
running along the back; the under parts are always uniform yellow. Total
length about 3 feet. This snake is restricted to the Iberian Peninsula and
to the South of France. Most specimens are very ill-tempered. The young
live upon locusts and small lizards, the old eat mice and small birds. In
captivity they also take dead animals–a rare habit with snakes.
{618}_Dendrophis_ with about ten species inhabits South-Eastern Asia and
Australia. They are typical Tree-Snakes. The scales are keeled, and form
only thirteen or fifteen rows; those of the vertebral row are enlarged; the
ventrals have a pair of suture-like lateral keels and a notch on each side,
arrangements which are of great assistance in climbing, these snakes being
able to slide up the branches of trees in almost straight lines instead of
having to twist and undulate their way up.
[Illustration: FIG. 163.–_Dendrophis punctulatus._ × ½.]
_D. punctulatus_, of Northern and Eastern Australia, is olive-brown above,
uniform or with black edges and yellow outer borders to the scales. The
upper lips, the throat and anterior ventrals, are yellowish. Total length
up to 6 feet.
_Leptophis_ is a Neotropical genus of Tree-Snakes. The body and the
extremely long, whip-like tail are very slender. The head is very distinct
from the neck; the eye is large, with a round pupil. The scales form
thirteen or fifteen rows; the ventrals are sometimes angulate laterally;
the sub-caudals are double. _L._ (_Ahaetulla_) _liocerus_ is a beautiful
snake, green above {619}with a golden lustre, while the under parts are
yellow or white. The total length of this species amounts to 6 feet, the
tail then being nearly 2 feet long. These graceful Tree-Snakes live upon
small reptiles and birds and their eggs. When shaken out of a tree or
frightened off they let themselves fall down from considerable heights,
coiling body and tail like a watch-spring, and alighting on the ground upon
the spiral, which breaks the fall.
[Illustration: FIG. 164.–_Leptophis liocerus._ × ½.]
_Coronella._–The teeth are nearly all of equal size and form continuous
series. The scales are smooth and have apical pits; the sub-caudals are
double. The head is scarcely distinct from the neck. The pupil is round.
This genus, with nearly twenty species, is widely distributed except in the
Australian region, the northern half of Asia, and South America. We can
mention only the two European species, one of which occurs in England.
{620}[Illustration: FIG. 165.–_Coronella laevis_, Smooth Snake (left), and
two _Vipera berus_, Common Viper (right). × ½.]
{621}_C. austriaca_ s. _laevis_, the Smooth Snake. The scales are arranged
in nineteen rows. Mostly the third and fourth labials border the eye. The
anal shield is divided. The general colour is brown or reddish above, often
with one or two lighter stripes, with small dark brown or red spots; two
dark brown or red stripes on the nape, usually confluent with a large dark
patch on the occiput; a dark streak extends from the nostril through the
eye to the angle of the mouth. The under parts are red, orange, brown, grey
or blackish, either uniform or speckled with black and white. The
coloration is, however, subject to much variation, and some specimens
strikingly resemble some of the Common Viper, which is also very variable
in its coloration. The resemblance is enhanced when the Smooth Snake
broadens its head by widening the jaws, as it is in the habit of doing. Two
such similarly coloured specimens are represented in Fig. 165. On closer
inspection the differences are great enough, the harmless snake having
smooth scales, and the top of the head being covered with large shields;
while the Viper has keeled scales, the top of the head being covered mostly
with scales, a vertical (not round) pupil, and, moreover, when attacked,
usually coils itself into a spiral disc with the head standing out in the
middle, ready to strike. However, these two species are sometimes mistaken
for each other.–The Smooth Snake prefers lizards as food to anything else,
but it also takes mice. The prey is hunted chiefly in the late afternoon
and in the evening, and is constricted by the coils of the snake. When
caught or even when handled after months of captivity, the Smooth Snake
bites deliberately and firmly, selecting a suitable spot, for instance a
finger, opens the mouth widely and almost chews the spot. The bite is of
course quite harmless, and scarcely draws blood, few of these snakes
attaining a length of more than 2 feet. They are viviparous, bringing forth
about half-a-dozen young at a time. The range of the Smooth Snake extends
over the greater part of temperate Europe, from England and the Iberian
Peninsula to Berlin, and south-eastwards to Asia Minor. In England it
occurs in a few counties only, for instance in Hampshire and in
Dorsetshire.
_C. girondica_, of the South of France, Italy, the Iberian Peninsula and
North-Western Africa, much resembles the English Smooth Snake, from which
it differs in a few points only. The scales are arranged in twenty-one,
rarely in nineteen, rows; usually the fourth and fifth labials border the
eye; and the rostral {622}shield, covering the end of the snout, is much
broader than high. The coloration is variable, but there is always a pair
of elongated blackish spots or a U-shaped mark on the nape.
SUB-FAM. 3. RHACHIODONTINAE.–With only a few teeth on the posterior part of
the maxillaries, on the palatines and dentaries. Some of the vertebrae in
the region of the lower neck have strongly developed hypapophyses, which
are directed forwards and pierce the oesophagus. They are used for filing
through or breaking the birds' eggs which seem to be the chief food of
these snakes.
[Illustration: FIG. 166.–_Dasypeltis scabra._ × ½.]
_Dasypeltis scabra_, the only species, inhabits Tropical and South Africa;
although it reaches scarcely more than two feet and a half in length, such
a specimen is able to swallow an ordinary fowl's egg. Pigeons' eggs are
swallowed by snakes little more than one foot in length, which seems at
first sight quite impossible. The swallowed egg distends the skin to its
utmost capacity; it then slides down further, the snake makes some slight
contortions and the swelling collapses; after a while the broken and
sucked-out shell is vomited out as a crumpled up {623}mass. Miss Durham has
illustrated this curious process in a series of drawings.[190]
SERIES B. OPISTHOGLYPHA.
One, or a few, of the posterior maxillary teeth have a groove or furrow in
front, which conducts the secretion of the enlarged upper labial glands.
Apparently all these snakes are more or less poisonous, paralysing their
prey before or during the act of deglutition. So far as man is concerned
they are rather harmless, since the poison is not very strong, not
available in large quantities, and above all because the small poison-teeth
stand so far back that the snakes cannot easily inflict wounds with them.
The Opisthoglypha are of considerable morphological interest, since they
connect the Colubridae with the Viperidae, the characteristic poisonous
apparatus of which seems to have been derived from that of the
Opisthoglypha by the reduction or shortening of the anterior portion of the
maxillaries and the harmless teeth, so that the posterior or poison-fangs
come to the front.
The Opisthoglypha comprise about three hundred species and are
cosmopolitan, including Madagascar but excepting New Zealand. They contain
truly terrestrial, arboreal, and thoroughly aquatic forms.
SUB-FAM. 1. DIPSADOMORPHINAE.–The nostrils are lateral and the dentition is
well developed. Long-tailed, terrestrial, and arboreal forms. Most of the
arboreal species are green above, often with white or yellow longitudinal
bands, while the under parts are white or yellow. They feed chiefly upon
lizards, birds and their eggs.
_Dipsadomorphus_ s. _Dipsas_ (part).–Typical, very long-bodied and
long-tailed Tree-Snakes, with a vertical pupil. The median or vertebral row
of smooth scales is enlarged; the broad ventral scales are bent at an
obtuse angle on the sides, the resulting ridge assisting in climbing. The
sub-caudals are arranged in two rows. Ten to fourteen maxillary teeth are
followed by two or three enlarged, grooved fangs.
_D. trigonatus_, of India, grows to one yard in length. Yellowish olive or
pale grey above, with a white, black-edged {624}zigzag band along the back,
or with a series of white, black-edged spots.
_D. cyaneus_, of Northern India, Assam, etc., is a beautiful Tree-Snake,
green above, with the skin between the scales black, uniform greenish
yellow below. Total length up to 4 or 5 feet.
_Dipsas_ e.g. _D. bucephala_.–Maxillaries with eleven or more teeth.
Pterygoids toothless. Body strongly compressed, with thirteen rows of
smooth scales; the vertebral row enlarged; sub-caudals double; tail very
long. Tropical South America.
_Leptognathus_ with many species in Central and South America, like
_Dipsas_, but with teeth on the pterygoids.
_Coelopeltis._–Terrestrial and diurnal, with a round pupil. The row of
small maxillary teeth is followed by one or two much larger, grooved fangs
situated at a level below the posterior border of the eye. The first
half-a-dozen mandibular teeth are much larger than the rest. The scales of
the adult are more or less distinctly grooved longitudinally, hence the
generic name, and are arranged in seventeen or nineteen rows. The
sub-caudals form two rows; the ventrals are rounded off laterally. Two
species in the Mediterranean countries and in South-Western Asia.
_C. monspessulana_ s. _lacertina_ is one of the largest snakes in Europe,
reaching a length of 6 feet, of which the tail takes up 18 inches.
Olive-brown or yellowish or reddish above, frequently with small, dark,
light-edged spots. The sides are often blackish, with whitish specks. The
under parts are yellowish white, with or without brownish markings. Some
specimens are very green, with a dull blackish neck. One of the specific
names of this terrestrial snake is the latinised form of Montpellier; the
other refers to the shape of the head, which is not unlike that of a
lizard, partly owing to the concave forehead. This species inhabits rather
dry localities studded with shrubs, where it hunts for lizards, birds, and
mice. It is sure to attract notice by its loud hissing when it is
disturbed. When driven into a corner it strikes out furiously, but does
not, as a rule, bite. I have caught some which after a few days became
quite gentle. Small animals become torpid a few minutes after they have
been bitten.
_Macroprotodon cucullatus_ occurs in Andalucia, the Balearic Islands, and
in North Africa. The dentition is peculiar. The {625}fourth and fifth
maxillary teeth are enlarged, followed by an interspace, then follow
several small teeth, and lastly the two enlarged, grooved teeth. The sixth
mandibular tooth is very long, separated by a space from the much smaller
posterior teeth. The general colour of this sand-loving snake is pale brown
or grey above with small spots or streaks on the trunk, and with a large
black patch behind the head extending over the sides of the neck, hence the
specific name. The under parts are bright red or yellowish, sometimes
spotted with black. Total length under 2 feet.
SUB-FAM. 2. ELACHISTODONTINAE.–With only a few teeth on the posterior part
of the maxillary and dentary bones, and on the palatines and pterygoids.
Some of the vertebrae in the thoracic region have much-developed unpaired
hypapophyses, which are directed forwards and pierce the dorsal wall of the
gullet. In this respect _Elachistodon westermanni_, of Bengal, the only
species, bears a striking resemblance to the South African Aglyphodont
_Dasypeltis_ (see p. 622), and it is probable that this apparently very
rare Indian snake also swallows eggs. It is brown above, with a yellowish
vertebral stripe; yellowish below.
SUB-FAM. 3. HOMALOPSINAE.–The nostrils of these absolutely aquatic and
viviparous snakes are valvular, and are situated on the upper surface of
the snout. The eyes are small with vertical pupils. The two dozen species,
mostly very ugly, inhabit the rivers and estuaries of the East Indies from
Bengal to North Australia. Some species have very small and narrow ventral
scales, recalling the Hydrophinae, or the burrowing snakes, none of which
use their ventral scales for locomotory purposes.
_Homalopsis buccata_, _Cerberus rhynchops_ and _Hypsirhina_, e.g. _H.
plumbea_, have well-developed ventral scales; the other scales of the first
two genera are keeled, those of the third are smooth. In _Hipistes_ the
whole head is covered with very small scales; all the scales of the body
are smooth except the very narrow ventrals, which have double keels. _H.
hydrinus_, of Siam and the Malay Peninsula, has a compressed body, and in
its general appearance much resembles the Hydrophinae. It lives, like its
allies, upon fishes, and it swims far out into the sea.
SERIES C. PROTEROGLYPHA.
The anterior maxillary teeth are deeply grooved, or so folded {626}as to
appear hollow or perforated. Behind these enlarged poison-fangs the maxilla
carries a series of smaller, solid teeth; hence the term "proteroglyphous,"
which means that the anterior teeth are grooved, in opposition to
"opisthoglyphous." Both series have been developed independently.
The Proteroglypha are all extremely poisonous, mostly viviparous, and
widely distributed over the whole of the Australian, Palaeotropical and
Neotropical regions, with the exception of Madagascar and New Zealand; they
extend northwards into the warmer parts of North America, and they also
range over a great portion of the Palaearctic sub-region, being found in
North Africa and South-Western Asia. They form two natural sub-families:
Elapinae, with cylindrical tails, and Hydrophinae or Sea-Snakes, with
laterally compressed tails.
SUB-FAM. 1. ELAPINAE.–The tail is cylindrical. The Elapinae comprise nearly
150 species, which have been grouped into a great number of, mostly
somewhat imaginary, genera. In Australia they constitute the great majority
of Snakes, there being besides the deadly Elapinae only a few Pythons and
Typhlopidae, and very few Colubrinae.
[Illustration: FIG. 167.–Map showing the distribution of the Elapine
Snakes.]
_Naja._–The pair of large and grooved poison-fangs are separated by an
interspace from one to three small, faintly grooved teeth near the
posterior end of the maxillaries. The scales are smooth and without pits,
and are arranged in fifteen to twenty-five oblique rows on the trunk,
although more occur in the region of the neck; the vertebral row is not
enlarged. The head is but slightly distinct from the neck. Each nostril
lies between two nasals and the internasal. The sub-caudals form two rows.
The pupil is round. The neck-region can be expanded {627}into a hood by the
spreading and moving headwards of the ribs. Several species in Southern
Asia and in Africa.
[Illustration: FIG. 168.–_Naja tripudians_ (the Cobra). × ⅕.]
_N. tripudians_ (the "Cobra").–The coloration varies much. The typical form
is yellowish to dark brown with a black and white spectacle-mark on the
dorsal side of the hood, and with a large black and white spot on each side
of the corresponding under surface. Other specimens are uniform pale brown
to blackish grey, without any markings on the hood. The Cobra is widely
distributed, from Transcaspia to China and to the Malay Islands; in the
Himalayas it ascends to about 8000 feet above the level of the sea. Very
large specimens are said to attain more than 6 feet in length, but a cobra
of 5 feet, inclusive of the tail of 9 inches, is considered large. The
Cobra prefers places which afford it a convenient hole to retire into; for
instance, deserted hills of termites, ruins, heaps of stones and stacks of
wood, and it has the disagreeable habit, like the harmless Rat-snake,
_Zamenis mucosus_, of making itself at home in inhabited houses, probably
attracted by the rats. Its chief food consists of small Vertebrates;–frogs,
lizards, rats, occasionally fishes and {628}small birds. It drinks much,
and hunts chiefly in the late afternoon and in the evening, although it
possesses a round pupil. It avoids hot sunshine. Many observations show
that the cobras live in pairs, otherwise they do not take much notice of
each other or of other kinds of snakes. The female lays about a dozen
soft-shelled eggs as large as those of pigeons.
This cobra is used by Indian conjurers. The "dance" is the habit of these
snakes of erecting themselves, when agitated, upon the hinder third or
quarter of their length, whilst they spread out the hood and sway the head
and neck to the right and left, always in an attitude ready for striking.
They are docile and by nature not vicious. Most of the performing cobras
have their teeth drawn, and they then know well that they cannot bite. They
only strike at the hand, just as uninjured specimens soon avoid biting into
the iron rod with which they are lifted up in menageries. The drawing of
the teeth is an operation which has to be repeated, since reserve-teeth
soon take the place of the lost pair.
I cannot refrain from relating an abstract of a ridiculous episode which
happened in the Munich Aquarium in the year 1882. One of six specimens of
the African species _Naja haje_ was missing. The police closed the
establishment, which during the following eight days was turned inside out
without any other effect than that two other, harmless, snakes were
discovered. Twice the building was fumigated with sulphur, until the Cobra
was at last found suffocated, fifteen days after the beginning of the
search. This snake caused the owner of the Aquarium a loss of nearly £1500.
But the cruel joke was, that during the commotion the man who had collected
and sold the six snakes declared upon oath that their teeth had been so
well drawn and the germs of possible reserve-teeth had been so thoroughly
destroyed that the snakes were rendered absolutely harmless. But he was not
believed, in spite of a commission of professors and doctors appointed, who
experimented upon the remaining five Cobras with sulphur and did not find
any poison-fangs, "although the mouth was probed and poked into as far down
as the larynx."
Cobras have quite a number of enemies. Peafowl and Jungle-cocks are said to
be partial to young snakes; pigs eat them greedily, and are to a certain
extent immune against {629}their bite. The same applies, according to the
most recent observations, to the famous Mongoos. Sir E. Tennent, in his
_Natural History of Ceylon_, quoted several times in the present book,
makes the following remarks about the immunity of this little creature:–
"I have found universally that the natives of Ceylon attach no credit to
the European story of the Mongoos (_Herpestes griseus_) resorting to some
plant, which no one has yet succeeded in identifying, as an antidote
against the bite of the venomous serpents on which it preys. There is no
doubt that, in its conflicts with the cobra and other poisonous snakes,
which it attacks with as little hesitation as the harmless ones, it may be
seen occasionally to retreat, and even to retire into the jungle, and, it
is added, to eat some vegetable.... A number of plants, such as the
_Ophioxylon serpentinum_ and _Ophiorhiza mungos_, the _Aristolochia
indica_, the _Mimosa octandria_, and others, have each been asserted to be
the Ichneumon's specific.... If the Ichneumon were inspired by that courage
which would result from the consciousness of security, it would be so
indifferent to the bite of the serpent, that we might conclude that, both
in its approaches and its assault, it would be utterly careless as to the
precise mode of attack. Such, however, is far from being the case; and next
to its audacity, nothing can be more surprising than the adroitness with
which it escapes the spring of the snake under a due sense of danger, and
the cunning with which it makes its arrangements to leap upon the back and
fasten its teeth in the head of the cobra. It is this display of
instinctive ingenuity that Lucan celebrates where he paints the Ichneumon
diverting the attention of the Asp by the motion of his bushy tail, and
then seizing it in the midst of its confusion. See _Pharsalia_, lib. iv.
verses 729-734."
There is a widespread belief in the efficacy of "Snake-stones," which are
generally pieces of charred bone, well polished, occasionally pieces of
chalk or some similar porous substance, which, if pressed upon the bleeding
wound, are supposed to absorb the poison. Snake-charmers profess to prepare
such "stones," and to preserve the composition as a secret. The manufacture
is a lucrative trade. The Boers bought them, imported from India, at high
prices. Mr. Selous saw one, or heard of one, that was kept as an heirloom.
Snake-stones are {630}also made, and used, in Mexico, of charred hartshorn;
they are called "piedras ponsonas."
The use of the Snake-stone, called "Pamboo-Kaloo," has probably been
communicated to the Singhalese by the itinerant snake-charmers who resort
to the island from the coast of Coromandel.
Although Sir E. Tennent describes several instances of the successful
application of snake-stones as well authenticated, he has never himself
been an eye-witness. Although two cases have been fully described, they do
not at all exclude the possibility, nay the probability, that the Tamils
imposed upon the Europeans in order to sell the snake-stones.
"No doubt the snake-stones, owing to their porous nature, adhered to the
bleeding wound, became saturated with blood, and then fell off. Very
likely, in case of a poisonous bite, some of the venom would be sucked up
too, but we do not know if those snakes were still in the possession of
their poison-fangs. Properly conducted experiments with snake-stones have
proved as little efficacious as the application of dry cup.
"Theoretically snake-stones as quick absorbent agents of the blood with the
poison are good; they will certainly prevent some of the poison from
entering the system, but that would, at best, be a partial cure only.