SNAKES 177 



a very large head, which is covered with small scales, and 

 which is very distinct from the neck. The body and tail 

 are short and very stout, and covered with keeled scales. 

 The eye is moderate or large, with a vertical pupil. The 

 fangs are very highly developed. 



The Puff Adder, B. arietans, of Southern Morocco and 

 Somaliland to the Cape of Good Hope, and also of Southern 

 Arabia, derives its name from its loud hissing, which 

 has been compared to puffing ; the sounds produced, 

 however, are not nearly so intense as those of Russell's 

 Viper of India. The snake, which grows to a length of 

 three and a half feet, is yellowish or pale brown above, 

 marked with regular, chevron-shaped, dark brown or black 

 bands. 



The Gaboon Viper, B. gabonica, and the Nose-horned 

 Viper, B. nasicornis, both found in East and West Africa, 

 are undoubtedly the most evil-looking of all serpents, their 

 heads being very distinct from their rather narrow necks, 

 while their snouts are surmounted by a pair of horns 

 covered with scales ; in the case of the Nose-horned Viper 

 the horns may measure over half an inch in length. Both 

 these snakes are very gaudily coloured. B. gabonica, of 

 which a record specimen, measuring exactly five feet in 

 length and weighing twelve pounds, is at present living 

 in Regent's Park, is pale yellowish-brown above, with 

 numerous hour-glass-shaped dark markings, while B. nasi- 

 cornis, which does not attain quite so large a size, is 

 purplish or reddish above, with angular black, yellow, 

 and white markings. 



The brown and white hornless Berg Adder, B. atropos, 

 is a mountain form, inhabiting South Africa, where it feeds 



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