FRESH-WATER SNAKES. 225 



the head, and provided with a valvule. Another peculiarity 

 is that the last or back tooth of the maxillary bone is a 

 grooved fang, a transitional tooth between an ordinary one 

 and a fang ; but there is no evidence of any poisonous 

 saliva connected with it. Indeed, as we may repeat. Dr. 

 Giinther distinctly affirms that all the fresh-water snakes are 

 harmless and tJioroiigJdy aquatic, though a few are occasion- 

 ally found on the beach. They inhabit rivers and estuaries, 

 feeding on fish, and rarely coming to land ; some of them 

 frequent brackish waters, and even enter the sea. These 

 latter in their organization approach the true marine ser- 

 pents. One Indian example, Hydriniis, is semi-pelagic. 

 They are all viviparous, producing their young in the water ; 

 and they belong to the tropical or semi-tropical regions. 

 In Australia they are found only in the far north ; but in 

 America some so-called * water snakes,' which spend most 

 of their time in the water, frequent rivers which are frozen 

 over in winter, during which season they probably undergo 

 hibernation in holes near the banks. 



Several of the older naturalists describe 'water snakes' in 

 words which leave us no doubt as to the mivibers, though 

 of their name we cannot be so certain. Carver in 1796 

 mentioned some small islands near the western end of Lake 

 Erie, so infested with snakes that it was dangerous to land 

 upon them. It is impossible that any place can produce 

 a greater number of all kinds of snakes, particularly the 

 * water snake,' than this. He says : * The lake is covered 

 near the banks of the islands with the large pond lily, the 

 leaves of which lie on the surface of the water so thick as to 



cover it entirely for many acres together, and on each of 



p 



