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]
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.]