VIPERINE GROUP. 



237 



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, OB DESERT SAW-VIPER (f nat. size). 



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 thje 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, 



