ANIMAL LIFE IN THE SEA 165 



tortoises (Chelonia). The very curious leathery turtle 

 {Sphargis coriacea) is apparently found in all tropical 

 seas, but it is either very rare or its habits make it 

 infrequently seen and caught. It is a large animal, 

 sometimes measuring six and a half feet long, and feeds 

 exclusively on fish, molluscs, and Crustacea. The limbs 

 are turned into paddles, the anterior ones being very 

 long, and the animal is apparently pelagic in habit and a 

 swift swimmer, though it is tied to the land by the need 

 of breeding there. The eggs are laid on sandy shores, 

 especially on the eastern side of tropical America. 



The green or edible turtle of commerce (Chelone 

 mydas) is also marine, but the fact that it is vegetarian, 

 feeding upon algae and other aquatic plants, binds it 

 closely to the shore, though the animals are good 

 swimmers. As usual the eggs are laid on sandy beaches. 

 Another species of the same genus is the hawksbill 

 turtle {GJi. imbricata), which supplies the tortoiseshell 

 of commerce, and is carnivorous, feeding upon fish and 

 molluscs. Both these forms have a wide distribution 

 in warm seas, while the loggerhead (Thalassochelys 

 caretta) extends into the Mediterranean and Bay of 

 Biscay. This is a carnivorous form, and occurs hun- 

 dreds of miles from land, floating on the surface. Again, 

 however, it must approach the land at the breeding- 

 season. 



We have already spoken of the marine lizard of the 

 Galapagos Islands (p. 149), and there are also sea- 

 snakes (Hydrophis) similarly adapted for life in the 

 sea. These animals, which are especially found off the 

 coasts of the Indian Ocean, have compressed swimming- 

 tails, and feed upon fish. As in the case of so many 

 forms which have secondarily returned to the aquatic 

 life, their dependence on the land is especially shown 



