Total length, 570 millimetres; tail 77.
(c) Bitis.
([Fig. 36].)
The Viperidæ belonging to this genus have the head very distinct from the neck, covered with small imbricate scales; the eyes rather small, with vertical pupils, separated from the lips by small scales; the nostrils directed upwards and outwards, usually pierced in a single nasal shield, with a rather deep pit above, closed by a valvular supranasal. The postfrontal bones are very large, in contact with the ectopterygoids. Scales keeled, with apical pits, in 22-41 rows; ventrals rounded. Tail very short; subcaudal scales in 2 rows.
(1) B. arietans (the Puff Adder; [fig. 37]).—This viper has the nostrils on the upper surface of the snout, and two series of scales between the supranasal shields; 12-16 supralabials; 3-5 lower labials. The scales on the body are in 29-41 rows, and strongly keeled; ventrals 131-145; subcaudals 16-34.
The body is thick, the head large and triangular, and the tail very short. The colour is dirty yellow or orange, with large, transverse or oblique, chevron-shaped black bands; an oblique black band extends behind the eye. The belly is dirty yellow, uniform, or marked with small black spots.
Total length, 1,350 millimetres, sometimes more; tail 160.
Fig. 36.—Skull of Bitis arietans (the Puff Adder). (After G. A. Boulenger, op. cit.)
Habitat: This snake is met with throughout Africa, from Southern Morocco, Kordofan, and Somaliland, to the Cape of Good Hope, and also in Southern Arabia. It is especially common near the Niger and on the Congo.