TURTLES. 
83 
for the beautifully mottled horny shields of its shell, which are the sole source of 
the tortoise-shell of commerce. In its young state, the hawksbill may be readily 
distinguished from the preceding species by the circumstance that the horny 
shields on the back of the three-ridged shell overlap one another like the tiles on a 
roof. With advancing age the shields gradually, however, become smooth, and in 
very old specimens they meet at their edges, as in other members of the order. 
At all ages the hinder margin of the carapace is more or less strongly serrated; 
and the compressed and sharply hooked beak will always serve to distinguish at a 
glance a hawksbill from a green turtle. Moreover, the limbs always have two 
HAWKSBILL TURTLES SWIMMING Hat. size). 
claws. In the adult, the shields of the carapace are beautifully marbled and 
mottled with yellow and dark reddish brown, while the plastron is yellow, and the 
shields on the head and paddles are brown with yellow margins. In size this 
species is somewhat inferior to the green turtle, the carapace attaining a length of 
about 32 inches, against 42 inches in the latter. In habits the hawksbill differs 
markedly from the green turtle, being exclusively carnivorous. 
Loggerhead The third, and probably the largest species of turtle, is the 
Turtle. loggerhead (Thalassochelys caretta), easily recognised by its enormous 
head and the presence of at least five costal shields on each side of the carapace, 
which differs from that of the two preceding species by becoming completely 
ossified in the adult state. The beak is strongly hooked; and while in the young 
