26 TORTOISES, TERRAPINS, AND TURTLES 



mies. In some species the shell is a remarkably perfect 

 means of defence. 



These reptiles have no teeth, but the edges of their strong, 

 horny jaw r s are sufficiently sharp and chisel-like to enable 

 them to cut up vegetable food. The head and neck move 



SKELETON OF A FALSE GEOGRAPHIC TURTLE. 



(Graptemys pseudogeographicus.) 



P, plastron, 

 C, carapace, 

 Ra, radius, 



UI, ulna, 

 Hu, humerus, 

 Tib, tibia, 



Fib, fibula, 

 Fe, femur, 

 Sc, scapula. 



freely, in and out. The skin is very tough and leathery. 

 Like other reptiles, the members of this Order reproduce by 

 laying eggs and burying them, to be hatched by the sun. 

 Some of the large tortoises live to the greatest age attained 

 by any living creatures now on the earth. 



In the original classification of the land-going tortoises, 

 and the water-loving turtles and terrapins, it was an unfor- 



