SEA-SNAKES 337 



away from the shore, when they remind the spectator of miniature alligators. 

 When on shore, several individuals may frequently be seen in company basking 

 in the rays of the tropical sun. To fit it for its amphibious mode of life, this lizard 

 has all its toes fully webbed and the long tail laterally compressed so as to act as 

 an efficient rudder in swimming. 



An almost exclusively marine group is constituted by the sea- 



snakes, which are related to the cobras, although forming a separate 



sub-family, Hydrophiince, of their own. In all these snakes, of which there 



are several generic ■ types, the tail is laterally compressed for the purpose of 



swimming, and in some kinds this compression extends also to the body. The 



GALAPAGOS SEA-LIZARD. 



scales are small, and in most of the species of nearly similar size all round 

 the body, the enlarged transversely elongated scales on the lower surface of the 

 bodies of ordinary snakes, which are used for progression on land, being generally 

 absent. These snakes inhabit all tropical seas from the Persian Gulf to Central 

 America, and are frequently found far out at sea : on land they soon die. One 

 species, as previously mentioned, inhabits a fresh-water lake in the Philippines. 

 All the species produce living young, and all are extremely poisonous. On the 

 coasts of India fishermen are not infrequently bitten by them, and the bite in 

 some cases proves fatal. They are for the most part marked with broad vertical 

 bands of two colours, and their general colouring approximates to that of mackerel, 

 thus being of an eminently protective type. The largest species of all, Hydrus 

 major, is, however, an exception in this respect, as its vertical bands are alternately 

 vol. in. — 22 



