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.