THE PRINCIPAL SPECIES OF POISONOUS SNAKES 47 
in most cases die in less than two minutes. A horse succumbed 
in half an hour, and another in eleven hours. 
It appears that in India many cattle are killed by Daboias while 
grazing (Fayrer). 
(b) Pseudocerastes. 
(Fig. 29.) 
This genus is represented by a single species (Pseudocerastes 
persicus), which appears to be exclusively confined to Persia. 
The head is very distinct from the neck, and covered with small 
imbricate scales; the eyes, which are small, have vertical pupils; 
they are separated from the lips by 
small scales. The nostrils are 
directed upwards and _ outwards. 
The snout is very short and rounded. 
The cylindrical body has 23—25 
rows of scales; 151—156 ventrals 
43—49 subcaudals. 
The coloration is gray or brown, FIG. 29.—Pseudocerastes persicus. 
with four series of large black spots, ee Damen and eibiea.) 
and the head exhibits two longitu- 
dinal black streaks behind the eyes. The belly is whitish, dotted 
with black. 
Total length, 890 millimetres ; tail 110. 
(c) Cerastes. 
The vipers belonging to this genus are much more common 
in North Africa, and we shall therefore study them in conjunction 
with the African snakes. Cerastes cornutus alone, the special 
habitat of which is Egypt, is sometimes met with in Arabia and 
on the eastern bank of the Suez Canal. 
