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 (Ch. 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 (T'halassochelys 
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 
