THE SNAKES 319 



the fangs will be found proportionately very small, look- 

 ing like those of an elapine snake, but they may be 

 raised and lowered at will and fold against the roof of 

 the mouth when the jaws are closed, in true Viperine 

 fashion. An adult Cape Viper is barely a yard in 

 length. The species is common throughout southern 

 Africa. 



In its habits the Cape Viper about reverses every 

 characteristic attributed to the subfamily. While the 

 vipers produce living young, this is an egg-laying spe- 

 cies. 1 It is quick in its motions, gliding away as fast 

 as a colubrine snake, while it has failed to keep up the 

 dignified habits of vipers generally, of preying upon 

 warm-blooded animals ; it feeds mostly upon frogs, sud- 

 denly grasping a specimen and swallowing it amid a 

 series of struggles, as if forgetting for the moment 

 the existence and use of the fangs. 



One of the writer's specimens deposited ten eggs on 

 the first of September. These were creamy-white, with 

 a tough leathery shell, adhesive in a cluster and each 

 contained a thread-like embryo coiled like the hair- 

 spring of a watch. A measurement of one of the eggs 

 showed it to be one and one-quarter inches long, and 

 seven-sixteenths of an inch in diameter. Another snake 

 laid twelve eggs on the twentieth of the same month. 



Vipera, containing ten species, large and small, is 

 represented in Europe, Asia, northern and tropical 

 Africa. The Common Viper, V. berus, the only poi- 

 sonous snake occurring in the British Isles, is one of the 

 smaller species. The forward portion of the head is 

 covered with fairly regular shields, though these look 

 more crowded than with colubrine snakes; the eye has 



i Another genus, A tractaspis, composed of small, burrowing species comes 

 under this head. 



