VIPERIDAE CROTALINAE 



645 



restricted to America, but other Pit-Vipers occur in North and 

 South America and in the southern half of Asia. 



Ancistrodon. — Without a rattle. The upper surface of the 

 head is covered with nine large shields, but the internasals and 

 prefrontals are sometimes broken up into scales. The scales of 

 the body have apical, sensory pits. About ten species, some in 

 Central and North America, others in the Caspian district {A. 

 halys), in the Himalayas {A. himalayanus), in Ceylon, Java, etc. 



Pia^p 



Fig. 177. — Ancistrodon 2}iscivorus (Water- Viper). 



A. piscivorus s. Trigonocepilialus ccnchris (part), the " Water- 

 Viper," inhabits North America from Carolina and Indiana to 

 Florida and Texas. The general colour is reddish to dark lu'own, 

 with darker cross-bands or with C-shaped markings ; a dark, 

 light-edged band extends from the eye to the angle of the mouth. 

 The under parts are yellowish, spotted with black, or the latter 

 is the prevailing colour. Total length up to 5 feet. The 

 Water- Viper is semi-aquatic and lives chiefly on fishes, but it 

 also eats other snakes and various Amphiliia, Birds, and Mammals. 

 This snake is very good-humoured in captivity, and becomes 



