VIPERINE GROUP. 
237 
any passing animal. So great is the terror which its sight inspires in horses, 
that I have known mine, when I was riding in the Sahara, suddenly start and rear, 
trembling and perspiring in every limb, and no persuasion would induce him to 
proceed. I was quite unable to account for his terror, until I noticed a cerastes 
coiled up in a depression two or three paces in front, with its basilisk eyes steadily 
fixed on us, and no doubt preparing for a spring as the horse passed.” According 
to Bruce, this snake, when about to attack, moves rapidly forward with a 
sideways motion, unlike that of any other serpent. Attacking when quite 
unprovoked, the horned viper is more dreaded than any other North African 
snake, men frequently dying from its bite within half an hour. Its food consists 
of desert-haunting rodents, together with lizards, and perhaps birds. 
Desert saw- While agreeing with the horned vipers in having the lateral 
Vipers. body-scales arranged in oblique rows, the present genus may be dis¬ 
tinguished by its two species having but a single series of shields beneath the tail, 
colour, more or less tinged with yellow, upon which are six longitudinal rows 
of circular or quadrangular dark markings, increasing in size from the middle 
of the back towards the sides. Beneath the eyes runs a dark brown band, while 
the middle of the head is marked by a light brownish yellow streak, dividing 
posteriorly, and uniting on the sides of the neck with another stripe coming from 
the chin. The scales surrounding the mouth are a bright sandy yellow, the 
shields on the under surface being also either bright yellow or whitish. The 
scales of the body are arranged in from twenty-nine to thirty-three rows; the anal 
shield is single, while the shields beneath the tail form a double series. The range 
of this snake includes Northern Africa, East of Morocco, as well as Kordofan and 
Arabia; the second species being likewise North African. Canon Tristram writes 
that the usual habit of the horned viper is “ to coil itself on the sand, where it 
basks in the impress of a camel’s footmark, and thence suddenly to dart out on 
THE EJA, OR DESERT SAW-VIPER (f liat. size). 
