146 THE INFLUENCE OF INANIMATE SUKBOUNDINGS. 



fresh water, lives and thrives perfectly ia the Bay of Kiel as 

 well as in. the North Sea, and specimens of this fish, caught at 

 Wiirzburg in the month of May, were even placed at once in 

 sea-water without. sustaining any injury.''^ 



B. Marine animals in fresh water. — Cases of this sort are 

 just as frequent as those we have just been discussing, and 

 occu.r among both the Vertebrata and Invertebrata. Among 

 the Yertebrata we must first mention the American Manatus, 

 which lives in the great rivers of South America, hundreds of 

 miles, from the sea ; then a true dolphin of the genus Globioce- 

 phalus, -which is found far inland in the Irawady river, .600 

 miles from the sea, and which is quite different from GlohiocB' 



Fig. S7. — Platurusvulcanwus, a water-snake livingin the fresh-water lake of TaaL (Luzon), 

 and having a paddle-like tail. 



phalus indicvs, which lives in the Indian Ocean. Among the 

 reptiles the family of Hydrophidce contains only sea-snakes, 

 which are very common in the seas of the eastern hemisphere, 

 and are often fovind there swimming in the high seas ; it is only 

 at breeding-time that they go to land.*^ The only exception to 

 this rule is found in a new species — here represented for the 

 first time — of the genus Platv/rus (fig. 37), which I myself dis- 

 covered in the fresh-water lake of Taal in Luzon,: which is 

 famous for its still active volcano ; it is true that this lake is 

 connected with the sea by a not very long river. Together 

 -irith this snake and associated with typical fresh-water forms — 

 as Neritina, Melania, Palmmon, <fec. — other marine animals are 

 found , such as Pristis Perrotteti (the saw-fish), which is very 



