178 REPTILES AND BATRACHIANS 



almost entirely on lizards. Fitz-Simmons says that it 

 cannot be kept in captivity, as, when taken away from its 

 natural conditions, it refuses food, declines in health, and 

 dies after a very short period. 



All the members of the genus Bitis are very inert and 

 sluggish, but are, nevertheless, much feared on account of 

 their generally fatal bite. 



In Cerastes^ of North Africa, Arabia, and Palestine, the 

 head, which is covered with very small scales, is most 

 distinct from the neck. The eye is rather small, with a 

 vertical pupil. The body is cylindrical ; the dorsal scales 

 form straight, longitudinal series with club-shaped keels, 

 which do not extend to the extremity of the scale ; the 

 lateral scales are smaller and point downwards. The tail 

 is short. The genus is represented by two species, C. 

 cornutus, which often has a pair of large erect, horn- 

 like scales situated above the eyes, and C. vipera, in 

 which these " horns " are constantly absent. Both are 

 yellowish or pale brown above, and harmonize with the 

 sand of the desert which they inhabit ; neither attain 

 a length of more than two feet. 



The Horned Viper, C. cornutus, is usually found con- 

 cealed in the sand with only the " horns " of the head 

 visible, and the old writers, to whom this snake was well 

 known, stated that these appendages were intended to 

 entice birds to them, seeing in them a resemblance to grains 

 of barley, or insects. It frequents perfectly dry localities, 

 and its presence, therefore, in the island in the middle of 

 Lake Moeris is most remarkable, as it never enters water. 

 Anderson and other writers state that it feeds exclusively 

 on small mammals, the majority of specimens inhabiting 



