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.] The Pythons are large Serpents of Asia and Africa. They live in marshy places, and near the margins of rivers. They are non-Venemous, but possessed of immense muscular power, which enables some of the species to kill, by constriction, animals of much larger circumference than themselves.