2 36 SNAKES . 
nearly the whole of Africa, and is everywhere dreaded from its deadly nature. 
Inhabiting dry and sandy places, it derives its name from its habit, when angry or 
alarmed, of drawing in a full breath and causing the body to swell visibly. Then 
the air is allowed to escape gradually, producing as it does so a prolonged sighing 
or blowing sound which continues till the lungs are emptied, this process being 
repeated so long as the provocation lasts. Usually this reptile lies half-hidden in 
the sand, with its head fully exposed, and when approached merely rises without 
attempting to escape, and so virulent is its bite that even horses have been known 
to die within a few hours after being struck. The poison is used by the bushmen 
for their arrows, to the tips of which it is made to adhere by being mingled with 
the viscid juice of the amaryllis. 
HORNED VIPERS IN THE SAND (J liat. size). 
Horned vipers Next to the southern viper, or asp, no serpent was more feared 
by the ancients than the Egyptian cerastes, or horned viper ( Cerastes 
cornutus). As a genus, the two species are characterised by the small crescentic 
nostrils situated on the sides of the muzzle, the presence in the male, and some¬ 
times in the female, of a pair of scale-covered, liorn-like processes above the eyes, 
the arrangement of the scales of the body in oblique rows, and the short keels on 
the scales, which stop short of their tips. The common horned viper may be 
immediately recognised as an inhabitant of desert places from the general sombre 
and mottled tone of its coloration, which is so admirably adapted to such surround¬ 
ings. Usually attaining a length of about 2 feet, it is of a light brownish ground- 
