THE PBINCIPAL SPECIES OF POISONOUS SNAKES 69 



(b) Yipera. 



(For the characters of this genus, see p. 23, — Europe.) 



In North Africa are found Vipera latastii, V. ammodytes, and 

 especially V. lebetina, the range of which extends from Morocco to 

 JNorthern India. Vipera superciliaris, which occurs on the coast 

 of Mozamhique, has the snout rounded, and the head covered with 

 small, imbricate, keeled scales, with a large supraocular shield ; 

 nostril very large, between two nasal shields ; scales on the body 

 strongly keeled, in 27 rows ; 142 ventrals ; 40 subcaudals. 



The colour is pale reddish-brown or orange, with blackish trans- 

 verse bars broken by a longitudinal yellow band on each side ; the 

 belly is white, spotted with black. 



Total length, 570 milhmetres ; tail 77. 



(c) Bitis. 



(Fig. 36.) 



The ViperidcB 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 ; '6 — 5 

 lower labials. The scales on the body are in 29 — 41 rows, and 

 strongly keeled ; ventrals 131 — 145 ; subcaudals 16 — 84. 



The body is thick, the head large and triangular, and the tail 

 very short. The colour is dirty yellow or orange, with large, 



