THE PBINCIPAL SPECIES OF POISONOUS SNAKES 75 



brown spots ; a vertebral series of brown, black-edged spots, which 

 assume a rhomboidal form ; sides of head dark brown, with a 

 trianguhxr hght mark in front of the eye, and an obhque hght 

 streak from behind the eye to the mouth ; belly pale olive, spotted 

 with black or vellow. 



Total length, 1,250 millimetres; tail 125. 



Habitat : West Africa, from Liberia to the Gaboon. 



(d) Cerastes. 



Head very distinct from the neck, covered with small juxta- 

 posed or slightly imbricate scales ; eyes small, with vertical pupils, 

 separated from the lips by small scales ; nostrils opening upwards 

 and outwards. Bod}- cylindrical ; scales keeled, with apical pits, 

 in 23 — 35 rows. Tail short ; subcaudals in 2 rows. 



(1) C. cornutiis (fig. 40). — Snout very short and broad ; two 

 erectile horns above the eyes, which are separated by 15 — 21 scales 

 and surrounded by 14 — 18 ; 4 — 5 series 



of scales between the eyes and the lips ; 

 12 — 15 supralabials ; 3 infralabials ; 

 scales on the body in 27 — 35 rows ; 

 130 — 165 ventrals ; 25 — 42 subcaudals. 



Colour yellowish-brown or grey, 

 with or without brown spots, forming ^^^^ iO.-Cerastcs comutus. 

 4 — 6 regular series, the two middle ones (After Dumerii and Bibrou.) 

 sometimes forming cross-bars ; an ob- 

 lique dark streak behind the eye ; belly white ; end of tail some- 

 times black. 



Total length, 720 millimetres ; tail 90. 



Habitat : Northern border of the Sahara, Egypt, Nubia, Arabia, 

 and Southern Palestine. 



(2) C. vipera. — Snout very short and broad ; head covered with 

 small, tubercularly keeled scales, to the number of 9 — 13 from eye 

 to eye ; no " horns "; 9 — 14 scales round the eye ; nostril between 



