Chapter II: Ophidian Reptiles, or True Snakes (1)

Reptiles are, as has been said in the preceding chapter, Vertebrated Animals, breathing by lungs, having red and cold blood; that is to say, not producing sufficient heat to render their temperature superior to that of the atmosphere. Destitute of hairs, of feathers, of mammary glands, and having bodies covered with scales.

Snakes, properly so called, have the tympanic bone, or pedicle of the lower jaw, movable, and nearly always suspended to another bone, analogous to the mastoid bone, which is attached to the cranium by muscles and ligaments, a conformation which gives to these animals the vast power of distension they possess. Their trachea is long, their hearts placed far back, and the greater number have one very long lung and vestiges of a second. They are divided into non-Venemous and Venemous; and the latter are subdivided into Venemous with maxillary teeth, and Venemous with isolated fangs.

The Snakes prey almost exclusively on animals of their own killing; the more typical species attacking such as are frequently larger than themselves: and the maxillary apparatus is, as we have seen, modified so as to permit of the requisite distension. According to Professor Owen's clear and intelligible description, the two superior maxillary bones have their anterior extremities joined by an elastic and yielding fibrous tissue with the small and single intermaxillary bone; the lower maxillary rami are similarly connected. The opposite extremity of each ramus is articulated to a long and movable vertical pedicle formed by the tympanic bone, which is itself attached to the extremity of a horizontal pedicle formed by the mastoid bone, so connected as to allow of a certain yielding movement upon the cranium. The other bones have similar loose movable articulations, which concur in yielding to the pressure of large bodies with which the teeth have grappled.

The class of Reptiles is divided into three orders:--the OPHIDIANS, comprehending the Snakes; the SAURIANS, the Lizards and Crocodiles; and the CHELONIANS, the Turtles and Tortoises.

OPHIDIANS.

In Ophidians, commonly known under the name of Snakes, the body is long, round, and straight. They have neither feet, fins, nor other locomotive extremities. Their mouths are furnished with pointed hooked teeth. In the Boas and Pythons the teeth are slender, curved, bending backwards and inwards above their base of attachment. In others each maxillary bone has a row of larger ones, which gradually decrease in size as they are placed further back. These teeth are not contiguous, being separated by considerable intervals. The smaller non-Venemous Serpents, such as the _Colubridæ_, have two rows of teeth in the roof of the mouth. Each maxillary and mandibular bone includes from twenty to twenty-five teeth. In the Rattlesnakes and some other typical genera of poisonous Snakes, the short maxillary bone only supports a single perforated fang. Their lower jaw is highly distensible; the opening beings longer than the skull. They have no neck; their eyelids are immovable; their skin is coriaceous, highly extensible, and scaly or granulous, covered with a thin caducous epidermis, which detaches itself in one entire piece, and is reproduced several times in one year. Their movements are supple and varied. In consequence of the sinuosity of their bodies,--for, though scale-clad, Snakes are without apparent means of progression,--they make their way with the utmost facility, by walking, leaping, climbing, or swimming.

According to the genus chiefly, the very numerous species inhabit either arid or moist places, the ground, or bushes and trees. Some pass much of their time in the water, and one family (that of the _Hydrophidæ_) is exclusively aquatic--even pelagic in the instance of one very widely diffused species, the _Pelamis bicolor_. In the Arboreal Snakes the tail is very long, and highly prehensile; in others, as the Vipers, it is short and without any prehensility. In the Sea Snakes (_Hydrophidæ_), it is laterally much compressed. Like other true reptiles, Snakes abound more especially in warm climates, and there are many kinds of them in Australia; but the order has not a single representative in New Zealand.

Most of the Snakes feed on living animals, only a few on birds' eggs. Several kinds of them prey habitually on other Snakes, as the genera _Hamadryas_, _Bungarus_, and _Elaps_, even _Psammophis_ occasionally; and there are rare instances of non-Venemous Snakes preying upon poisonous ones. The Venemous kinds first kill their victim by poisoning it; various others by smothering it between the coils of their body. As they do not possess organs for tearing the prey to pieces, nor a dentition fit for mastication, the prey is swallowed entire; and in consequence of the great width of the mouth, and of the extraordinary extensibility of the skin of the gullet, they are able to swallow animals of which the girth much exceeds their own. The Sea Snakes prey mostly upon fishes, and the ordinary Water Snakes (_Homolopsidæ_, &c.) on frogs and other Batrachians. Certain swallowers of birds' eggs have peculiar spinous processes proceeding from the vertebræ of the neck, the object of which is to fracture the shell of an egg during the process of deglutition.

Most of the Ophidian Reptiles are oviparous, but many are ovo-viviparous. The Pythons alone (so far as ascertained) perform a sort of incubation, which has been repeatedly observed of captive specimens of these huge Serpents.

Many Snakes are remarkable for their great beauty of colouring, or of the pattern of their markings; but on account of the poisonous property of so many of them, the whole order is popularly regarded with horror and apprehension, and the most foolish tales are current respecting various species of them. Thus many people suppose that there are Snakes which rob cows of their milk; and the skeleton of a child being found in the same hollow with a number of harmless Snakes (the North American _Coryphodon constrictor_), it was concluded, as a matter of course, that the Serpents must have both killed the child and stripped off its flesh, which latter is what no Snake could possibly do. People are prone to exaggerate, and commonly evince a fondness for the marvellous, which induce those of hot countries more especially, where the species of Ophidians are numerous, to declare every Snake met with as usually the most Venemous one in their country; and thus travellers often come away with exceedingly erroneous impressions on the subject. The Indian region surpasses every other part of the globe in the number and variety of its Ophidians, and almost every investigation of a limited but previously unexplored district, is tolerably sure to add largely to our previous knowledge of them. What, however, the late Sir J. Emerson Tennent asserts of those inhabiting Ceylon, is equally applicable to other parts of the Indian region. "During my residence in Ceylon," he remarks, "I never heard of the death of an European which was caused by the bite of a Snake; and in the returns of coroners' inquests made officially to my department, such accidents to the natives appear chiefly to have happened at night, when the reptiles, having been surprised or trodden on, inflicted the wound in self-defence. For these reasons the Cingalese, when obliged to leave their houses in the dark, carry a stick with a loose ring, the noise of which, as they strike it on the ground, is sufficient to warn the Snakes to leave their path."

In some parts of the vast Indian region the natives regard the innocuous Chameleon as Venemous; in other parts various Geckos, or other Lizards. In Bengal there is a current notion regarding a terrifically poisonous Lizard, which is termed the _Bis-cobra_, but which has no existence except in the imagination of the natives--who bring the young of the Monitors and occasionally other well-known Lizards as exemplifying the object of their dread. Again, the little harmless Burrowing Snakes (_Typhlops_), which, superficially, have much the appearance of earth-worms, are there popularly regarded as highly poisonous, though not only are they harmless, but physically incapable of wounding the human skin. Strangers who are little versed in zoology are commonly led astray by such errors on the part of natives of those countries, and, unfortunately, there is a number of stock vernacular names which are applied to very different species in different localities. Thus Europeans in India are familiar with the appellation "Carpet Snake," as denoting a very deadly reptile, but nobody can there point out what the Carpet Snake really is; and the one most generally supposed to bear that name is a small innocuous Snake (_Lycodon aulicus_), which is common about human dwellings. In the Australian colony of Victoria, however, the appellation Carpet Snake is bestowed upon a terribly Venemous species (_Hoplocephalus curtus_); while in the neighbouring colony of New South Wales, a harmless and even useful creature (_Morelia spilotes_) is habitually known as the Carpet Snake.

With regard to the poison of Venemous Snakes, attention has lately been directed to the virtue of ammonia or volatile alkali. This should be administered internally, mixed with alcoholic spirit and water, in repeated doses; and it should also be injected into a vein--about one drachm of the _liquor ammoniæ_ of the shops being mixed with two or three times that quantity of water. The patient should be kept moving as much as possible, and the effects of a galvanic battery should also be tried in cases where animation is nearly or quite suspended. By these means it is asserted that quite recently, in Australia, some very remarkable cures have been effected.

The _Ophidia_ have many enemies, as the well-known Mongoose among mammalia, also Swine, and various ruminating quadrupeds, as Deer and Goats. In the bird class, the famous Serpent-eater, or Secretary-bird of South Africa, is one of their chief destroyers; and there are various other Snake-devouring birds of prey, besides the great African Ground Hornbill,--even the Pea-fowl and sundry Storks and other waders. Comparatively large birds of the King-fisher family prey chiefly upon Snakes and Lizards in Australia; and of reptiles, besides those Snakes which prey upon other Snakes, the Monitor Lizards frequently seize and devour them.

The series of Ophidians is arranged by our most eminent herpetologist, Dr. A. Günther, into five subordinate groups, which he characterises as follows:--

I. _Burrowing Snakes_, living under ground, only occasionally appearing above the surface. They are distinguished by a rigid cylindrical body, short tail, narrow mouth, small head not distinct from the neck, little teeth in small number, and by the absence or feeble development of the ventral shields. They feed chiefly on small invertebrate animals. Not any of them are Venemous.

II. _Ground Snakes_, or species which live above ground, and only occasionally climb bushes or enter the water; their body is more or less cylindrical, very flexible in every part, and of moderate proportions. Their ventral shields are broad. They feed chiefly on terrestrial vertebrate animals. By far the greater number of Snakes belong to this category, and it is represented by many variations in all of the three sub-orders to be noticed presently.

III. _Tree Snakes_, or species passing the greater part of their life on bushes and trees, which they traverse with the utmost facility. They are distinguished either by an exceedingly slender body, with broad, sometimes carinated, ventral shields, or by a prehensile tail. Many of the species are characterised by their vivid coloration, of which green forms the principal part. We shall see, in the sequel, that the first and third sub-orders offer numerous instances of Tree Snakes; the Tree Snakes of the second sub-order being confined to Tropical Africa. They feed on animals which have a mode of life similar to their own; only a few species on eggs.

IV. _Fresh-water Snakes_, distinguished by the position of the nostrils, which are placed on the top of the snout, and by a tapering tail. They inhabit fresh-waters, and are, therefore, excellent swimmers and divers; only a few species (which also in external characters approach the following group, that of the true Sea Snakes) venture out to sea. They feed on fishes, frogs, crustaceans, and other water animals, and are viviparous. Not any of them are Venemous.

V. _Sea Snakes_, distinguished by a strongly compressed tail, and by the position of the nostrils, which are placed as in the last group. They live in the sea, only occasionally approaching the land, feed on marine fishes, are viviparous and Venemous. One genus only (_Platurus_) has the ventral shields so much developed as to be able to move on land. No Oceanic Serpent is known of gigantic dimensions, such as is currently alleged to have been seen by unscientific observers.

"Although these five groups," remarks Dr. Günther, "are not separated from each other by defined lines of demarcation, and frequently pass into one another by intermediate forms, yet a family and genus which should be composed of species of several of these groups would be a very unnatural assemblage of heterogeneous forms."

It is also remarked by the same naturalist that there is no sharp boundary line between the order of Snakes and that of Lizards. There are various limbless Saurians of Ophidian appearance, but the systematic position of which is decided by the structure of their jaws. The Common Orvet, or Slow-worm, is a familiar instance. On the other hand, certain Ophidians remind us, by several characters, of the Saurian type,--as the Snakes constituting the families _Typhlopidæ_, _Tortricidæ_, _Xenopeltidæ_, and _Uropeltidæ_, which are distinguished by polished, closely adherent, rounded, sub-equal scales, much resembling the smooth scales of various Scincoid Lizards; most of them have a very narrow mouth, unlike the enormous gape of the typical Serpents, and some are without that longitudinal fold in the median line of the chin which is so characteristic of most Ophidians; moreover, most of them have rudiments of the bones of a pelvic arch. "The reason," alleges Dr. Günther, "why we adopt the view of those systematists who refer such reptiles to the Ophidians, instead of associating them with the limbless Scincoid Lizards, is the loose connection of the jaw-bones, a character which must be considered as peculiar to the Ophidians, and which is only somewhat less developed in the families mentioned than in the typical forms. The two halves of the lower jaw in Ophidians, namely, are not united by a bony symphysis, but by an elastic ligament. The peculiar mobility of the jaw bones enables the Snakes to extend the gape in an extraordinary degree, and to work their prey down through the collapsed pharynx."

The same naturalist classifies the _Ophidia_ into three sub-orders, in which the Venemous Snakes are separated from the others; but to some herpetologists this arrangement must appear rather forced, as his _Venemous Colubrine Snakes_ have certainly a much nearer resemblance in other respects to the _Colubridæ_ than they have to the _Viperine Snakes_. For the most part, these reptiles are provided with numerous teeth, which are lengthened, conical, thin and pointed like a needle, and more or less bent backwards.

In Dr. Günther's _first sub-order_, that of _Non-Venemous Snakes_, the teeth are either entirely smooth, or only the last of the maxillary series is provided with a faint longitudinal groove, which is not intended to convey a virus into the wound, the groove appearing rather to increase the strength of the tooth. Many of them have long teeth in front of the jaws or of the palate, but these are never grooved or perforated, and only serve to afford a firmer hold on the living and struggling prey.

"The structure of the venom-tooth is not the same in all poisonous Snakes: in some it is fixed to the maxillary bone, which is as long or nearly as long as in the non-Venemous Snakes, and generally bears one or more ordinary teeth on its hinder portion. The venom-tooth is fixed more or less erect, not very long, and its channel is generally visible as an external groove. The poisonous Snakes with such a dentition have externally a more or less striking resemblance to the non-Venemous Serpents, and on this account they are designated as _Venemous Colubrine Snakes_, forming our _second sub-order_." Two very distinct families are here brought together--viz. the _Elapidæ_ (which comprises the Cobras and many others), and the _Hydrophidæ_ (or Sea Snakes).

"In the other Venemous Snakes, composing the _third sub-order_, the maxillary bone is extremely short, and does not bear any teeth except an exceedingly long fang, with a perfectly closed externally invisible channel in its interior. Although this tooth also is fixed to the bone, the bone itself is very mobile, so that the tooth, which is laid backwards when at rest, can be erected the moment the animal prepares to strike. This tooth or fang, like all the other teeth, is not only occasionally lost, but appears to be shed at regular intervals. From two to four other venom-fangs in different stages of development, destined to replace the one in action, exist between the folds of the gum, and are not anchylosed to the bone." The more characteristic Venemous Snakes appertain to this sub-order--viz. the two families _Crotalidæ_ (comprehending the Rattlesnakes, the Fer-de-lance, &c.) and _Viperidæ_ (comprising the Vipers, Puff-adders, &c.).

Let it be particularly borne in mind that the supposed distinguishing characters of all poisonous Snakes, as assigned by sundry mischievously ignorant writers, are those of the third of the foregoing sub-orders almost exclusively. Even the broad, flat, and lanceolate form of head is exemplified in certain Tree Snakes of the non-Venemous genus _Dipsas_, and not in the Cobras and others that are quite as deadly--e.g. _Hoplocephalus_, _Bungarus_, _Naja_, _Elaps_, and others constituting the Colubriform family _Elapidæ_.

FIRST SUB-ORDER.

_Ophidii Coluberiformes_ (Günther), Innocuous Snakes.

These are distributed by Dr. Günther under numerous families, of which we can only notice the more prominent, and some of the more conspicuous species, in a popular exposition.

The _Typhlopidæ_, or Blind Snakes, comprise forms which are the most remote from the true Ophidian type. They live under ground, their rigid body and short curved tail being adapted for burrowing. After showers of rain they occasionally appear above ground, and then they are tolerably agile in their serpentine movements. The eye, which is scarcely visible in many species, can give to them only a general perception of light. They feed on worms and small insects, the tongue being forked, and, as in other Snakes, frequently exserted. They are oviparous. The smallest species of Snakes belong to this family, some of them being only half the size of a common earth-worm, to which they bear a superficial resemblance. Such, indeed, are the small vermiform Snakes already referred to, as being foolishly considered Venemous by most natives of India. Species of this family inhabit almost every country within and near the tropics.

The _Tortricidæ_ are akin to the _Typhlopidæ_, and have rudiments of hind limbs hidden in a small groove on each side of the vent, also a longitudinal fold at the chin. The "Coral Snake" of Demarara (_Tortrix scytale_) appertains to this family; and the genus _Cylindrophis_, different species of which inhabit the great Asiatic archipelago, with the island of Ceylon.

The family _Xenopeltidæ_ consists of a single species only, so far as hitherto known, the _Xenopeltis unicolor_, which is common in the Indo-Chinese and Malayan countries. It grows to three or four feet in length, and when alive is uniformly steel-blue, most beautifully iridescent, beneath white; but the blue fades to brown after long immersion in spirits. Young examples have a white collar. Mr. W. Theobald remarks of it that "this Snake is common in Lower Pegu and the Tenasserim provinces, and is very malignly beautiful, though of repulsive physiognomy. The skin is loose and thick, and its habits are nocturnal. The following illustrates its ferocious nature:--I once remarked a Colubrine Snake (_Ptyas mucosa_), some five feet in length, in the hedge of the Circuit-house of Bassein. On running downstairs, the Snake had vanished, but on searching for it I saw its tail sticking out of a hole beneath a wooden plant-case. Do what I might I could not drag it out, as it seemed held fast within. I therefore, with some trouble, overturned the plant-case, and then saw that the unlucky Colubrine Snake was firmly pinned by a large _Xenopeltis_, into whose hole it had unwittingly entered. The _Xenopeltis_ seemed about four feet in length; but, on perceiving itself uncovered, released its hold of the _Ptyas_ and made its escape." The _Xenopeltis_ preys chiefly on small mammalia, which it hunts for in their subterranean holes; and in some respects it approximates the _Pythonidæ_.

The _Uropeltidæ_, or Shield-tails, constitute a very curious family of Burrowing Snakes, which bear considerable resemblance to the _Typhlopidæ_, but have a very peculiar, short, strong, posteriorly shielded tail, adapted for working their way below the surface. The species are mostly small, and hitherto they have been found chiefly in Ceylon, but a few also in the peninsula of India. They are by no means scarce, but escape observation from their peculiar mode of life. Dr. Kelaart remarks that "they are timid creatures, seldom making their appearance above ground; living chiefly in ant-hills or dunghills, sometimes also several feet deep in rich loamy soil. They feed on ants, small earth-worms, and the larvæ of insects, and at least one species has been ascertained to be viviparous. Five genera and eighteen species of them are recognised."

The _Calamaridæ_ form an extensive family of diminutive slender Snakes, from one to two feet in length, many species of which inhabit both the Old World and the New, though the same kinds are not found both East and West. They keep to the ground, beneath stones, fallen trees, &c.; and their food appears to consist chiefly of insects. They are gentle, and never attempt to bite, and themselves very commonly become the prey of the smaller _Elapidæ_, certain of which indeed bear considerable resemblance in appearance to the _Calamaridæ_, but are readily distinguished by possessing the poison-fangs.

The _Oligodontidæ_ are another extensive family of small ground Snakes, which are peculiar to South-eastern Asia and its great archipelago. They conduct to the terrene genera of the great family _Colubridæ_.

The _Colubridæ_ are divided by Dr. Günther into ground Colubrines (_Coronellinæ_), true Colubrines (_Colubrinæ_), bush Colubrines (_Dryadinæ_), and fresh-water Colubrines (_Natricinæ_); and he remarks that "they are found in every part of the temperate and tropical regions, but are only scantily represented in Australia and in the islands of the Pacific. The species are so numerous and show such a gradual passage between extreme forms, that, although genera can be easily characterized, it is almost impossible to distinguish wider groups by definite characters." Among them the _Coronellinæ_ approximate the immediately preceding families, and, like them, live on the ground, and are not generally of brilliant colouring, though a few species which frequent grassy plains are of a bright green colour. The _Colubrinæ_ "form, as it were," writes Dr. Günther, "the nucleus of the whole sub-order of innocuous Snakes: they are typical forms, not characterized by the excessive development of some particular organ, but by the fairness of the proportions of all parts. Yet some of them have a more slender body than others which always live on the ground; they are land Snakes, but swim well when driven into the water, or climb when in search of food. They are of moderate or rather large size." In the _Dryadinæ_ the form is elongate and somewhat compressed, indicating their climbing propensities; they have the body not so excessively slender as in the true Tree Snakes, to which they lead off. They are much more numerous in the New World than in the Old, and their ground-colour is very commonly green. The _Natricinæ_ are generally not very elongate or compressed, and most of them have keeled scales. They freely enter the water in pursuit of their food, which consists chiefly of frogs and fishes. All the Snakes of the preceding three sub-families overpower their prey by throwing some coils of the body round or over it, and commence to swallow it only after it has been smothered, or at least exhausted; but the _Natricinæ_ swallow their prey immediately after they have seized it.

Of the sub-family _Coronellinæ_, one species of the typical genus _Coronella_ is widely diffused over Europe, and has only of late years been recognised as an inhabitant of the British Islands, the _Coronella austriaca_. Another, _C. girondica_, occurs in Italy. Others are found in Africa, America, and Australia. The _C. austriaca_ has somewhat the appearance of the common Adder, for which it is often mistaken; but it is non-Venemous, though rather a fierce reptile, which bites and holds on; and as it occurs in Malta (where no Venemous species is known to exist), it is doubtless the supposed Viper which seized upon the apostle Paul. Several other genera are recognised.

Of the _Colubrinæ_, _Rhinechis scalaris_, _Coluber æsculapii_, _C. quadrilineatus_, _Elaphis quater-radiatus_, and three species of _Zamenis_ inhabit Europe: there are five of _Coluber_ in North America, and the well-known "Black Snake" of the Anglo-Americans is the _Coryphodon constrictor_. Other species of _Coryphodon_ or _Ptyas_ inhabit South-eastern Asia, as the different "Rat Snakes" of Anglo-Indians, of which _Ptyas mucosus_ is particularly common in India, where it is encouraged by reasonable people as a destroyer of the far more troublesome Brown Rat (_Mus decumanus_).

The _Dryadinæ_ are chiefly American, and do not call for particular further remark; but the _Natricinæ_ are very numerous, and there are three species in Europe of its most prominent genus, _Tropidonotus_--viz. _T. natrix_, _T. hydrus_, and _T. viperinus_. [Dr. Günther gives as many as twenty-one species of this genus as inhabitants of the Indian region alone, and there is reason to believe that that number is far from being complete. Others inhabit North America and North-western Australia, and some generic groups have been detached that are not very conspicuously separable.]

The Ringed Snake, _Tropidonotus natrix_, is often found in fine seasons near human habitations. It deposits its eggs, which are fifteen to twenty in number, commonly in dunghills, in one agglutinated mass. Exposed to the air, these eggs soon shrivel and dry, and the embryos within them perish. The Ringed Snakes are also found near rivers and meadows, by the side of water-courses, into which they love to plunge; hence they are sometimes called Water Serpents, Swimming Serpents, Hedge Eels, and other provincial synonyms. They sometimes attain to as much as and more than a yard in length. The summit of their head is covered with nine large scales, disposed in four rings. The upper part of the body is of a more or less darkish grey colour, marked on each side with irregular black spots. Between the two rows of spots are two other longitudinal rows, which extend from the head to the tail. The belly varies from black to a bluish white. Upon the neck are two whitish or pale yellowish spots, which form a kind of half collar or ring, from which its name is derived; these two spots become much more apparent from being contrasted with two other very dark triangular spots placed near them. They prey upon lizards, frogs, and mice, and they even surprise young birds, and devour the eggs in their nests, for they climb trees with facility. Towards the end of the autumn they seek the warmest places, approaching near to houses; or they retire into subterranean holes, often at the bottom of some hedge, which is almost always in an elevated place, secure from inundations. The Ringed Snake is found in nearly all European countries, and can be handled without danger. Lacépède gives some interesting details, showing the gentleness of its habits. They are easily tamed, and can be kept in houses, where they soon accustom themselves to those who have the care of them. At a sign from their keeper, they will twist themselves round his fingers, arms, and neck, insinuate their heads between his lips to drink his saliva, and to hide and warm themselves they creep under his clothes. In their wild state, the adult Ringed Snake lives in the fields; and, when full-grown, shows great irritation when attacked. When exasperated, they move their tongues, erect themselves with great vivacity, and even bite the hand which tries to seize them; but their bite is quite harmless.

[This Ringed Snake is the _Natrix torquatus_ of Ray, well known to naturalists. The female is larger than the male. Its food consists a good deal of frogs, which are generally caught by the leg, and swallowed alive, in spite of resistance and very distressing cries.

When the skin has just been cast, the Ringed Snake presents beautiful markings, especially when seen swimming across some clear running stream, its head and neck raised above the limpid water, and the sun shining on its bright enamelled skin. It has been supposed, not unnaturally, that the Snake casts its skin at fixed intervals; this, Mr. Bell considers to be a mistake. He has always found that it depended on the temperature of the atmosphere and on their state of health and feeding. "I have known the skin thrown off" he adds, "four or five times during the year. It is always thrown off by reversing it, so that the transparent covering of the eyes and that of the scales are always found in the exuviæ. Previous to this curious phenomenon, the whole cuticle becomes somewhat opaque, the eyes dim, and the animal is evidently blind. It also becomes more or less inactive, until at length, when the skin is ready for removal and the new skin perfectly hard underneath, the animal bursts it at the neck, and creeping through some dense herbage or low brushwood, leaves it detached, and comes forth in brighter and clearer colours than before."

The Ringed Snake begins to hybernate, in some warm hedge or under the root of some tree, or other sheltered situation, about the end of autumn; and there they coil themselves up, sometimes in numbers, till the spring again calls them forth. Many instances are told of this Snake being tamed. Mr. Bell had one which knew him from all other persons; it would come to him when let out of its box, and crawl under the sleeve of his coat, and every morning come to him for its draught of milk.]

The Green and Yellow Snake is also about a yard in length, and is common in the south and west of France; they have been taken in the forest of Fontainebleau. The beautiful colours in which they are clothed causes them to be easily distinguished from the Viper. The eyes are edged with golden-coloured scales; the upper part of the body is of a very dark greenish colour, upon which is extended a large number of radiating lines, composed of small yellowish spots of different shapes, some long, others lozenge shape, giving it a chequered appearance. These chequers extend from the head to the tail. The belly is yellowish; the large plates which cover it have a black spot at each end, and are bordered with a very thin black line. This inoffensive reptile is extremely timid, and generally hides itself from observation, taking to flight at the least alarm. They are said to be easily tamed.

The Viperine Snake (Fig. 12) has the body of a greyish or dirty yellow colour, having on the middle of the back a series of blackish spots so close to each other as to give the idea of one small continuous wavy line from head to tail. The sides are covered with isolated spots, forming lozenge-like figures, the centres of which are of a greenish tint. This is the smallest of all the European _Colubridæ_, and, like the others, it is found in most parts of Europe.

[The _Psammophidæ_, or Desert Snakes, are akin both to the _Colubridæ_ and to the Tree Snakes of the next family; but the latter, remarks Dr. Günther, may always be distinguished either by their green coloration, by the horizontal pupil to the eye, or the absence of a long, anterior, maxillary tooth. In the _Psammophidæ_ the pupil of the eye is round or vertical. Most of the species of this family belong to the fauna of tropical Africa, which also produces a slender form (in _Psammophis elegans_). The other species are of a stouter habit, frequenting plains, or at all events living on the ground. Of the Indian _Psammophis condanarus_, Dr. Jerdon procured one which had killed and was swallowing a small Viper (_Echis carinata_), this being one of the few instances in which a non-Venemous Snake has been known to overpower a poisonous one. We have heard the same of a small Boa-like Serpent (_Chilabothrus?_) in the West Indies, which is said to prey upon the formidable _Crotalidæ_. The _Psammodynastes pulverulentus_ has a wide geographical range over South-eastern Asia and its islands. Although innocuous, it has the aspect of a Venemous species.

In a kindred African family, the _Rachiodontidæ_, the species of _Dasypeltis_ have the maxillary teeth minute and few in number (four to seven); but they have also some remarkable gular teeth, which are formed by the elongated inferior spinous processes of the hinder cervical vertebræ. The object of the latter is to crush the shells of birds' eggs, upon which the Snakes in question habitually feed.

Of the more characteristic Tree Snakes, the _Dendrophidæ_ have the body and tail much compressed, or very slender and elongated; the head generally lengthened, narrow, flat, and distinct from the slender neck; the snout rather long, obtuse or rounded in front; cleft of the mouth wide; and the eye of moderate size, or large, with round pupil. These are Diurnal Snakes, which live entirely upon trees, where they prey chiefly on arboreal lizards and frogs. Species of them inhabit all tropical countries. They are mostly of great beauty, and the Indian _Chrysopelea ornata_ is excessively so, being variegated with yellow and crimson upon a black ground; but the crimson soon fading when a specimen is immersed in spirit. Others are very variable in their colouring, as the African _Bucephalus capensis_ and the Indian _Dendrophis picta_.

The next family of _Dryiophidæ_, or the Whip Snakes, have a still more slender and elongated body, which has been aptly compared to the thong of a whip. The head is very narrow and long, with tapering snout, ending in a protruded rostral shield, which is sometimes modified into a flexible appendage; eyes of moderate size, and all the Asiatic species have the pupil of the eye horizontally linear, and a long fang-like tooth in the middle of the maxillary. The whole of this group are provided with a posterior grooved tooth. They are chiefly nocturnal, and their movements are wonderfully rapid and graceful among the branches of trees. They are numerous almost everywhere in tropical countries. In general the various Whip Snakes are of a bright leaf-green colour, with two white stripes on the belly, so that they are difficult to discern among the foliage. In the genus _Langaha_, which is peculiar to Madagascar, the muzzle is elongated into a fleshy appendage, which is covered with small scales, constituting about one-third of the total length of the head. This appendage is dentated in one species (_L. crista-galli_), and not so in another (_L. nasuta_). In the Indian genus _Passerita_ the snout is long and pointed, terminating in a flexible appendage. The name of Whip Snake is applied by Anglo-Indians to all of the species of _Dendrophidæ_ and of _Dryiophidæ_, and the erroneous notion prevails that they are highly Venemous, and that they spurt venom into people's eyes. The same is believed in South Africa of the _Bucephalus capensis_. Even Gordon Cumming asserts that one night a Snake which his servant had tried to kill with his loading-rod flew up at his eye, and "spat poison into it. Immediately," he adds, "I washed it well at the fountain. I endured great pain all night, but next day my eye was all right."[12]

[12] "A Hunter's Life in South Africa," vol. ii. p. 133. _Vide_
also Chapman's "Travels in the Interior of South Africa," vol. ii.
p. 34. We have personally captured or assisted in capturing various
species of both families in India, and it is no easy matter to
do so sometimes, from the rapidity of their movements among the
branches of trees and bushes; but most assuredly we never saw one
of these most beautiful reptiles attempt to dart or to spurt at
anybody, and as they have no poison fangs the latter must needs be
an error.--ED.

Of a beautiful green species (_Philodryas viridissimus_), appertaining to the family of _Dendrophidæ_, in Brazil, Dr. Wurcherer writes:--"I am always delighted when I find that another Tree Snake has settled in my garden. You look for a bird's nest, the young ones have gone, but you find their bed occupied by one of these beautiful creatures, which will coil up its body, of two feet in length, within a space not larger than the hollow of your hand. They appear to be always watchful; for at the instant you discover one, the quick playing of the long, black, forked tongue will shew you that you too are observed. On perceiving the slightest sign of your intention to disturb it, the Snake will dart upwards through the branches and over the leaves, which scarcely appear to bend beneath the weight. A moment more, and you have lost sight of it." Some of the true Whip Snakes attain to six or seven feet in length, or even more; and with reference to the vague application of vernacular names (_vide_ p. 42), it may here be remarked that the "Little Whip Snake" of the Australian colony of Victoria denotes a poisonous Snake of a very different family (the _Hoplocephalus flagellum_).

The _Dipsadidæ_ are a numerous family of tropical Tree Snakes, which also have a much compressed body, but short and triangular-shaped head, which is broad behind; the eye large, having generally a vertical pupil. Some of them attain to six or seven feet in length, and all live on warm-blooded animals. It is remarkable that certain of the species prey on birds solely, whilst others attack only mammalia. Their coloration varies a good deal, and species of them inhabit most tropical and subtropical countries.

The _Lycodontidæ_ are an extensive family of small Ground Snakes, inhabiting Africa and tropical Asia, which have the body generally of moderate length, or rather slender, and the head also of moderate length and width, with generally a depressed, flat, and somewhat elongated muzzle; maxillary with a fang-like tooth in front, but without a posterior grooved tooth. The African species feed on Mice and other small nocturnal mammalia; while the Indian species (which have a vertical pupil) prey chiefly, if not wholly, on the smaller Scincoid Lizards, which they would appear to follow into the place of their retreat. _Lycodon aulicus_ is one of the commonest Snakes of the Indian region, and is quite harmless, though often ignorantly supposed to be dangerously poisonous.

The _Amblycephalidæ_, or Blunt-heads, comprise a few species of moderate or small size, akin to the _Dipsadidæ_, but the narrow mouth of which necessitates their feeding on insects, and they live on trees and bushes, or under the roofs of huts. Of the Indo-Chinese and Malayan _Amblycephalus boa_, Dr. Günther remarks that "the head of this most singular Snake resembles much that of a mastiff, the lips being arched and tumid. It climbs with great facility, frequenting the roofs of the natives' huts in pursuit of its insect food. It attains to a length of three feet, the tail being a third." Of a second genus, _Pareas_, three species inhabit the same region.

The _Pythonidæ_, or Pythons, and Boas, are celebrated for the enormous magnitude to which some of the species attain. These are emphatically the great constrictor Serpents, to all of which the name of _Boa-constrictor_ is popularly applied, although this appellation refers properly to one only of them which is peculiar to South America. Various genera of them inhabit Africa, South-eastern Asia and its islands, Australia, and South America, with the West Indies.]

The Pythons are large Serpents of Asia and Africa. They live in marshy places, and near the margins of rivers. They are non-Venemous, but possessed of immense muscular power, which enables some of the species to kill, by constriction, animals of much larger circumference than themselves.

Aristotle tells us of immense Lybian Serpents, so large that they pursued and upset some of the triremes of voyagers visiting that coast. Virgil's Laocoon, so vividly represented in the well-known marble group, owes its origin, no doubt, to the descriptions current of constricting Serpents. Quoting Livy, Valerius Maximus relates the alarm into which the Roman army, under Regulus, was thrown by an enormous Serpent, having its lair on the banks of the Bagradus, near Utica. This Serpent Pliny speaks of as being a hundred and twenty feet long. But, without multiplying instances to which time has lent its fabulous aid, and coming to more modern times, Bontius speaks of Serpents in the Asiatic islands as beings so various that he despairs of even enumerating them all. "The great ones," he says, "sometimes exceed thirty-six feet, and have such capacity of throat and stomach, that they swallow entire Boars." Adding that he knew persons who had partaken of a Hog cut out of the stomach of a Serpent of this kind. "They are not poisonous," he adds, "but they strangle by powerfully applying their folds round the body of their prey." Mr. M'Leod, in his interesting voyage of the _Alceste_, states that during a captivity of some months at Whidah, on the coast of Africa, he had opportunities of observing Serpents double this length, one of which engaged a negro servant of the governor of Fort William in its coil, and very nearly succeeded in crushing him to death. There can be no doubt that the length is here much exaggerated. About thirty feet is the utmost length attained by the most gigantic Serpents of which we possess accurate knowledge.

The body of the PYTHON is large and round. They live on trees in warm damp places, on the banks of streams or water-courses, and attack the animals which come there to slake their thirst. Hanging by the tail to the trunk of a tree they remain immovable in their ambush until their opportunity comes, when they dart upon their prey, fold their bodies round it with amazing rapidity, and crush it in their monstrous folds. Animals as large as Gazelles, and even larger, thus become their victims. Their jaws are extremely distensible, as we have seen; for, having neither breast-bone nor false sides, they can easily increase the diameter of the opening, so as to swallow the most voluminous prey.

The Ophidians (as we have seen) surpass all other Reptiles in the number of their vertebræ, with incomplete hæmal arches; these constitute the skeleton of the long, slender, limbless trunk. All these vertebræ coalesce with one another, and are articulated together by ball-and-socket joints. Besides this articulation to the centrum, the vertebræ of Ophidians articulate with each other by means of joints which interlock by parts reciprocally receiving and entering one another, like the tenon-and-mortise joint in carpentry. "The vertebral ribs have an oblong articular surface, concave above and almost flat below, in the Python. They have a large medullary cavity, with dense but thin walls, with a fine cancellated structure at their articular ends. Their lower end supports a short cartilaginous membrane, closing the hæmal arch, which is attached to the broad and stiff abdominal scute. These scutes, alternately raised and depressed by muscles attached to the ribs and integuments, aid in the gliding movement of serpents."

The peculiar motion of Snakes was first noted by Sir Joseph Banks, and commented on by Sir Everard Home. Sir Joseph was observing a _Coluber_ of unusual size, and thought he saw its ribs come forward in succession, like the feet of a caterpillar. To test this, he placed his hand under the animal, the ends of the ribs were distinctly felt pressing upon the surface in regular succession, leaving no doubt that the ribs formed so many pairs of levers, by means of which it moves its body from place to place.

The muscles which bring forward these ribs, according to Sir Everard, consists of five sets. One from the transverse process of each vertebra and the rib immediately behind it, which rib is attached to the next vertebra. The next set goes from the rib near the spine, and passes over two ribs, sending a slip to each, and is inserted into a third, a slip connecting it with the next muscle in succession. Under this is a third set, issuing from the posterior side of each rib, passing over two ribs, and sending a lateral slip to the next muscle, and is also inserted in the third rib behind. And so on throughout the five sets of muscles.

On the inside of the chest there is a strong set of muscles attached to the anterior surface of each vertebra, and passing obliquely forward over four ribs is inserted into the fifth one only in the centre. From this part of each rib a strong flat muscle comes forward on each side, before the viscera, forming the abdominal muscles and uniting in a middle tendon, so that the lower half of each rib which is beyond the origin of this muscle, and which is only laterally connected to it by a loose cellular membrane, is external to the belly of the animal, and is used for the purpose of progressive motion, while that half of each rib which is next the spine, as far as the lungs extend, is employed in respiration.

These observations of Sir Everard Home apply to all Snakes; but the muscles were compared with a skeleton of the _Boa-constrictor_ in the Hunterian Museum, which is thirteen feet nine inches in length. The habit of attaching themselves to trees, and holding on by the tail, their heads and bodies floating listlessly on some sedgy river, is explained by the structure of the tail. Dr. Meyer has minutely described the manner in which they hook themselves on to a tree, which gives them the power of a double fulcrum. The apparatus which gives this power is a spur or nail on each side of the vent in the _Pythonidæ_, in which the anatomist discovered the elements of an unguinal phalanx articulated with another bone much stronger, which is concealed under the skin.

Following the arrangement of the _Pythonidæ_, adopted by Dr. J. E. Gray in the Catalogue of the British Museum, we find:--

I. _Morelia_, having a strong prehensile tail, distinct head, truncate muzzle, crown of the head with small shield-like plates. Of this genus there are two species. The Diamond Snake (_M. spilotes_), a native of Australia, and of a bluish-black colour; and the Carpet Snake (_M. variegata_), from Port Essington and Swan River. It is whitish, with irregular black-edged olive spots, and an olive head, with two or three white spots in the centre of the crown.

II. _Python_, having the crown shielded to behind the eyes.

Of this genus there are two species, which have sometimes been referred to the Boas. The Pythons bear the same general appearance. Upon their bodies is traced a sort of blackish-brown chain, presenting nearly quadrangular links upon a clear yellowish ground, extending from the nape of the neck to the extremity of the tail. The suscephalous region is partly covered by a large brownish-black spot. Upon each side of the head is a black band, which frequently extends from the nostril, passing by the eye, as far as, and up to, the commissures or corners of the lips.

_P. reticulatus_, the Ular Sawad of the Malay countries, found also in Burmah and Siam, has the four front upper labial plates pitted; the frontal plate simple; the head has a narrow, longitudinal, brown stripe. This is one of the most handsomely marked species of the whole family, its body being covered with a gay lacing of black and golden yellow. It is said to attain the great length of thirty feet, and is stout in proportion. In its native wilds the powers of this gigantic reptile are said to be enormous, being able to subdue a full-grown Buffalo; and even a Man has been said to fall a prey to its fury. A Malay prao had anchored for the night under an island of the Celebes. One of the crew had gone ashore in search of the favourite betel nut, and is supposed on his return to the beach to have fallen asleep. In the dead of the night his comrades were roused by his screams; they pulled ashore with all expedition, but came too late; the cries had ceased, and the wretched man had breathed his last in the folds of one of these enormous Serpents. They killed the creature, cut off the head, and carried it, together with the lifeless body of their comrade, to the vessel. The right wrist of the corpse bore the mark of the Serpent's teeth, and the disfigured body showed that the man had been crushed by the constrictive folds of the reptile round the head, breast, and thighs. The Ular Sawad arranges its eggs by placing them in a group, which is covered by the body. This statement, first made by Mr. Bennett, has been confirmed by the observations of M. Lamare Picquot, and by observations on other species of Python in the Jardin des Plantes, Paris, and in the London Zoological Gardens.

The Rock Snake of India and Ceylon (_P. molurus_) is another species to which the name of Boa-constrictor has been given. It has the two pairs of front upper, and three hind lower labial shields pitted, and the frontal plates double. Of this gigantic Serpent several specimens are generally to be seen in the Zoological Gardens.

III. _Hortulia_, having the upper and lower labial shields deeply pitted; muzzle and forehead with symmetrical shield; nostrils lateral. They are natives of Africa, and three species are known, namely, the Natal Rock Snake, having the lower labial shields deeply pitted, the muzzle and forehead with symmetrical shields, the nostrils lateral; the Guinea Rock or Fetish Snake (_H. Sebæ_), closely resembling the last in many structural points; and the Royal Rock Snake (_H. regia_), having the four pairs of the upper front labials pitted, the upper ocular plate single, the lower labial shields four in number and broad.

The Royal Rock Snake inhabits Western Africa. It is black in colour, marked on the middle of the back with a series of oblong white spots, the sides being marked by another series of large white spots, with one or two black spots in the upper part; the head black, with a streak over the nostrils and the top of the eyes, another from the lower edge of the eye, the lips and chin beneath are white.

The Natal Rock Snake (_H. natalensis_, Fig. 13) is described by Sir Andrew Smith as being gigantic in size, he having seen a skin measuring twenty-five feet, although part of the tail was absent. "It feeds," he says, "on small quadrupeds; and for some days after swallowing one it remains in a torpid state, when it may be easily destroyed." Of this opportunity, however, the South Africans never avail themselves; they have a horror of the reptile, but believe that it has an influence over their destinies, and affirm that no one has ever been known to kill one and prosper.

The Guinea Rock or Fetish Snake (_H. Sebæ_, Fig. 14) is typical of the genus, and has also been referred to the Boa-constrictor, and closely resembles the Natal Rock Snake. It is a native of the warmer parts of Africa. A living specimen at the Zoological Gardens is estimated to weigh a hundredweight.

Of the genera _Liasis_ and _Nardoa_ there are five species, very imperfectly known.

IV. _Epicrates_, an American and West Indian species, having the crown scaly; the forehead with symmetrical shields.

The Aboma (_E. cenchria_) is one of the largest of the group, sometimes attaining dimensions quite gigantic. It is yellowish in colour, with a row of large brown rings running the whole length of the back, and variable spots on the sides; these are generally dark, with a whitish semi-lunar mark. This formidable Reptile has all the habits of its congeners; it is found in the marshy swamps of tropical America, and near the rivers, where it lies in wait for its prey.