THE REPTILIA 317 



agos Islands weigh over three hundred pounds and are probably 

 over four hundred years old. These giant tortoises live on 

 cacti, leaves, berries, and coarse grass. They have been perse- 

 cuted for food and for scientific purposes so persistently that 

 extermination in a wild state seems certain within a few years. 



Sea Turtles. - - The sea turtles are the giants of the turtle 

 class. The green turtle (Fig. 195), so called because of the green 



FIG. 105. Green Turtle. (Photo, of living animal furnished by American 

 Museum of Natural History.) 



color of its fat, sometimes has a shell four feet in length, and 

 weighs 500 pounds. It is famous as an article of food, and is 

 common in the markets of the large cities of the eastern United 

 States. It feeds largely on aquatic vegetation, and probably 

 eats fish and other animals also. 



The hawk's-bill or tortoise-shell turtle (Fig. 196) has the shields 

 of its carapace arranged like the shingles on a roof. These 

 shields of which a large specimen yields about eight pounds, are 

 the " tortoise shell " of commerce. The shields are detached 

 either after the turtles have been killed and immersed in boiling 



