A SMALL BOA-CONSTRICTOR SEIZING AND DEVOURING A RAT.
Illustrating the consecutive phases of seizing, strangling, and subsequently gorging the prey, as practised by the largest and smallest members of the class.
Snakes, like lizards, are most abundant in tropical countries, the Indian and Malay regions in particular being richest in numbers and varieties. The British Islands support but three representatives of the class—the Adder, the Common Ringed and the Smooth Snakes—this number, by a coincidence, being identical with that of the Lizard Tribe indigenous to the same islands. Many of the smaller species are little over 1 foot long, while the huge Pythons and the Anaconda may attain to or exceed 30 feet. Regarding their habits, some are purely terrestrial, frequenting the rocks or sandy deserts, or even burrowing beneath the earth's surface. Others are essentially arboreal, many amphibious, and some, like the Turtles among the Chelonians, entirely marine. As with the Lizards, the majority of snakes lay eggs enclosed within a white leathery shell, while with a considerable number the young are brought forth alive. The eggs, deposited in the earth, sand, or among vegetable debris, are usually left to be hatched by the heat of the sun. In the case of the Pythons, however, they are incubated by the parent.
Photo by W. P. Dando, F.Z.S.] [Regent's Park.
BOA-CONSTRICTOR READY TO STRIKE.
The neck, thrown back in one or more loops, can be projected, with immense force and lightning-like rapidity, to strike or seize an intended victim.
A small group of snakes which is usually placed at the head of the series in systematic classifications share the subterranean habits of the Amphisbænas among the Lizards; and the eyes being rudimentary and functionless, they are commonly known as Blind-snakes. A structural peculiarity which separates these singular reptiles from all other members of the Snake Tribe is the entire absence of teeth from either the upper or lower jaw. The food of the blind-snakes consists largely of ants and the larvæ of beetles and other insects which lead a subterranean life. Although spending the greater portion of their existence underground, they occasionally come out upon the surface, such migrations more generally taking place during showery weather. About 100 species of blind-snakes are known, and are mostly confined to tropical countries. One small worm-like form occurs in Greece and the adjacent islands, its range extending through a considerable area of South-western Asia.
The step from the small worm-like Blind-snakes, with their functionless eyes and underground habits, to the Boas and Pythons, the largest and most highly organised members of the Serpent Tribe, would seem at first sight to be altogether unwarranted. In one essential character, however, they agree very remarkably. In both groups the bony skeleton exhibits a far more generalised structural plan than in any of the succeeding ones, so that they may be regarded as more nearly resembling the primitive stock from which the other more specialised kinds—such as the Vipers, with their death-dealing poison-fangs—have been evolved.
The Pythons and Boas, or Boa-constrictors, as they are popularly known, belong entirely to the non-venomous section of the Snake series. The teeth, forming two rows in the upper jaws, gradually decrease in size from before backwards, and none of them are grooved or modified in the form of poison-fangs. The body is usually more or less compressed, and the tail prehensile. The Typical Pythons, or Rock-snakes, as they are called, with reference to their rock-frequenting habits, are distributed throughout South-eastern Asia, Australia, and Central and South Africa.