PUFF ADDERS. 83 



The genus Clotho consists of the Puff Adders of Africa, of which 

 there are at least four or five species. Among the best known of 

 them are the ordinary Puff Adder (C. arietans], and the Berg Adder 

 (C. atropos} of the Cape colonists. The Rhinoceros Puff Adder (C. 

 nasicornis of Guinea) has the scales over the nostrils of the male 

 produced into a long re-curved spine ; and in the Homed Puff Adder 

 (C. comuta, Fig. 20) of South Africa there is a group of small horn- 

 like scales over each eye. Examples of the Common and of the 





Fig. 20. The Horned Puff Adder, 



Rhinoceros Puff Adders may generally be seen in the reptile house of 

 the London Zoological Gardens. The last-mentioned is a huge 

 Viper of wondrous beauty, both of colouring and in the complex 

 pattern of its markings, especially as seen when it has newly shed 

 its epidermis ; but the aspect of its surprisingly broad, flat, and 

 triangular-shaped head, unmistakably betokens its terrific powers. 

 Its head is remarkably massive. One peculiarity of the Puff Adders 

 is that they sometimes hold on to their victim by their long fangs. 

 Thus, of the common C. arietans Sir A. Smith remarks that " although 

 generally inactive, it is by no means so when attacked its move- 

 ments are then bold and energetic, and when once it seizes the ob- 



