THE VENOM 



249 



None of these snakes are found in Europe or America. 



HydrophincB-^ProteroglyphcB living in the sea, and possessing a 

 flat tail.— These snakes can be seen swimming in families far out 

 ':n the Indian Ocean, but are also found in all Eastern tropical seas. 



Fig. 38. — Vipeva russellii Shaw. 

 This is the Tic Polonga of Ceylon. 



The genera of the Hydrophinae (Boulenger) are: — Distera Lacepede; Aca- 

 lyptus Dumeril and Bibron; Hydrophis Daudin; Enhydrina Gray; Hydrelaps 

 Boulenger; Hydrus Schneider; Thalassophis Schmidt; Enhydris Merrem; 

 Platuvus Latreille; Aipysurus Lacepede. 



The best-studied species is Enhydrina valakadien Boie. Another 

 species, Distera semperi Garm., lives in fresh water in the Philippine 

 Islands. It is, of course, dangerous to fishermen. 



FAMILY VIPERID^ Bonapatite, 1840. 



Definition.^ — -The vipers are characterized by their triangular head 

 and their tubular poison-fangs (hence the name Solenoglypha), 

 with are situated anteriorly in the mouth, and are provided with 

 a wide foramen, piercing the base anteriorly for connection with 

 the duct of the poison gland. They possess a stout body and short 

 tail, and are all viviparous. 



The Viperidae are divided into:— 



Crotalinse Boulenger. — Vipers with a deep pit, probably 

 sensory in function, situated between the nostril and 

 the eye on each side of the head. 



Viperinae Boulenger. — Vipers without such a pit. 



Crotalinae. — 'The Crotalinae include the rattlesnakes, so called 

 because they have a number of horny rings which fit into one 

 another at the end of the tail. 



