SNAKES 175 



vertebral column frequently forming an undulous band. 

 The large head, which is most distinct from the neck, has 

 large symmetrical dark markings, and two light lateral 

 bands uniting on the snout. When disturbed this viper, 

 which is usually of very sluggish habits, hisses violently 

 with each inhalation and expulsion of the breath, the 

 hissing sounds produced being clearly audible at a distance 

 of thirty feet. Although it seldom attacks, when it does 

 do so it will throw itself at its enemy with such force 

 that the body, in the act of striking, actually leaves the 

 ground. Russell's Viper brings forth about twenty-five 

 living young, which are frequently still surrounded by 

 their leathery covering at birth, thus of a brood of sixteen 

 born recently in Regent's Park, four were hampered by 

 the membrane. Its food consists entirely of mammals ; 

 adult specimens will not eat snakes, although, according 

 to Wall, the young will sometimes devour one another. 

 Many authors state that this snake will not feed in 

 captivity ; the numerous examples at the Zoological 

 Gardens, however, feed with remarkable regularity, 

 devouring on an average a dozen mice a month each. 



Russell's Viper is even more venomous than the majority 

 of Cobras, its bite killing fowls in from thirty seconds to 

 a few minutes, dogs in from ten minutes to four or five 

 hours, and man in under twenty-four hours. 



In Causus, of Tropical and South Africa, of which four 

 species are known, the head is scarcely distinct from the 

 neck, and is covered with large symmetrical shields. The 

 body, which is moderately elongate, is covered with either 

 keeled or smooth scales. The tail is short. The eye is 

 rather large, with a round pupil. The poison gland is 



