They are frequently divided into two great sections; the one, which is by far the most numerous, comprehending all those in which the poison-fangs are wanting, and which are consequently dangerous only in proportion to the extent of their muscular force; and the other consisting of those in which the fangs are present, and the bite of which is accompanied with the pouring out of a venomous secretion. At the head of the first of these divisions rank the Boas, which in the Linnean arrangement comprehended all those snakes, whether venomous or not, whose under surface was covered with narrow transverse plates, and whose tail was destitute of rattle. Later zoologists have, however, confined that appellation to those among the Linnean Boas, which are without poisonous fangs and have claws near the vent, and have regarded as a distinct genus the snakes which in addition to these latter characters have the scales of the under surface of the tail so arranged as to form two distinct rows. To the latter, which inhabit the Old Continent exclusively (while the former are all of them natives of America), they have assigned the name of Python.
The present species, which is commonly exhibited under the popular but erroneous title of the Boa Constrictor, appears to be the Pedda Poda of Dr. Russell’s Indian Serpents. It is said by that writer to attain a length of eight or ten feet; but living specimens have been brought to this country of twice that size, and some of those now in the Tower are fifteen or sixteen feet long. The number of transverse plates on the under surface of the body is stated to be two hundred and fifty-two, and that of the pairs of scales beneath the tail sixty-two. The back is elegantly marked with a series of large irregular brown blotches bordered with black; and numerous smaller spots are scattered along the sides. The ground colour is yellowish brown, lighter beneath.
The extent of muscular power which these serpents possess in common with the Boas is truly wonderful. To the smaller among them the lesser quadrupeds and even birds fall an easy prey; but the larger, when excited by the stimulus of hunger, are capable of crushing within their spiral folds the largest and most powerful of beasts. The sturdy buffalo and the agile stag become alike the victims of their fatal embrace; and the bulk of these animals presents but little obstacle to their being swallowed entire by the tremendous reptile, which crushes them as it were into a mass, lubricates them with the fetid mucus secreted in its stomach, and then slowly distending its jaws and œsophagus to an extent proportioned to the magnitude of the object to be devoured, and frequently exceeding by many times its own previous size, swallows it by one gradual and long-continued effort.