TURTLES. 157 
Turtles are the largest of their genus: they swim with great faci- 
lity, and can remain a long time under water. The external orifice 
of the nasal canal is furnished with a sort of valve, which the animal 
raises when it is in the air and closes when submerged ; but it rarely 
leaves the sea except in the breeding season, when Nature prompts it 
to seek the shore to lay its eggs. Some species, however, frequent 
the shore in the night, to browse on terrene plants. On land they 
move with difficulty, and even with pain; but not so in the sea, where 
they are remarkabiy active. Some species feed upon sea-weed and 
algee, while others prefer living animals, such as crustaceans, zoophytes, 
and molluscs, which they seize with their horny jaws, which are hard 
and trenchant as the beak of a bird of prey. 
We have seen how regularly and systematically the Land Tortoises 
proceed when ready to deposit their eggs; nor is less method adopted 
by the Turtle. The females, accompanied by the males, frequently 
traverse hundreds of miles of sea in order to deposit their eggs in 
some favoured locality, and resort, year after year, with the greatest 
punctuality, to the same island where they drag themselves ashore 
sufficiently inland to be safe from the tide. Using their hind flippers 
as a shovel, they excavate holes about thirty inches deep. Here they 
lay frequently a hundred eggs, afterwards covering them with sand. 
Having carefully levelled the surface, they return to sea, leaving the 
eggs to be hatched by the solar rays. ‘The eggs are round, slightly 
depressed at both ends, and furnished with a coriaceous shell. 
From the high temperature communicated to the sand-bank, they are 
hatched in about fifteen days. The females seem to have two or 
three layings in the season, at intervals of two or three weeks. When 
the young turtles are hatched, their instincts lead them at once to 
the sea; they are then feeble, white, and about the size of frogs. 
Under the fostering care of their mother, those which have escaped 
the birds of prey on their way to the sea and the fishes lying in 
wait for them, rapidly develop, and attain, under favourable cir- 
cumstances, an enormous size—some of the Sphargis, or Leathery 
Turtles, having been known to weigh from 1,500 to 1,600 pounds, 
—while others, whose carapaces measured more than fifteen feet in 
circumference and seven feet in length, exceeded 1,800 pounds. 
Turtles are met with in herds more or less numerous in all seas 
in the tropical regions.: The shores of the Antilles, the Gulf of 
Mexico, and the Indian Ocean, are their favourite haunts. Those 
occasionally found by navigators in the North Atlantic seem to be 
stragglers who have wandered from their companions. 
Of all Chelonians, the Turtle is the most useful to man. In 
