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).