452 



MANUAL OF ZOOLOGY. 



the l< tortoise-shell " so largely used for ornamental purposes. 

 The Leathery Turtle is remarkable in having the carapace 

 covered with a leathery skin in place of the horny plates which 

 are found in other species. 



In the second section of the Chelonia^. in which the limbs are 

 adapted for an amphibious life, are the Mud-turtles or soft 

 Tortoises (Tri<mydd&\ and the Terrapins (Emydida). In the 

 Trionycidce the development of the carapace is imperfect, the 

 ribs being expanded and united to one another only near their 

 bases, and leaving apertures near their extremities. The 

 entire carapace is covered by a smooth leathery skin, and the 

 horny jaws are furnished with fleshy lips. All the Trionytidce 

 inhabit fresh water and are carnivorous in their habits. Good 



Fig. 195. Hawk's-bill Turtle (Chelone i 



after Bell. 



examples are found in the Soft-shelled Turtle ( Trionyx ferox), 

 and the large and. fierce Snapping Turtle (Chelydra serpentind) 

 of the United States ; but other species are found in Egypt 

 and in the East Indies. The Terrapins (Emys) have a horny 

 beak, and have the shield covered with epidermic plates. They 

 are inhabitants of fresh water, and are most of them natives of 

 America. 



The third section of the Chelonia comprises only the Land 

 Tortoises (Testudinida), in which the limbs are adapted for ter- 

 restrial progression, and the feet are furnished with short nails. 

 The carapace is strongly convex, and is covered by horny 

 epidermic plates ; the head, limbs, and tail can be completely 

 retracted within the carapace. Though capable of swimming, 



