TORTOISES AND TURTLES. 



5 6 7 



esteemed as food; the hawk's-bill turtle (Caretta imbricata) furnishes 

 much of the commercial tortoise shell. 



Testudinidae, land tortoises, with convex perfectly ossified carapace 

 and feet adapted for walking. They are found in the warmer regions 

 of both the old and the new world, but not in Australia. In diet they 

 are vegetarian. The common tortoise ( Testudo graca], and the extermi- 

 nated giant tortoises of the Mascarene and Galapagos Islands are good 

 representatives. 



Chelydidse, fresh water tortoises, more or less aquatic, with per- 

 fectly ossified carapace, and feet with sharp claws. Examples Chelys 

 fivibriata, from Brazil and the Guianas, with warty growths of decep- 



FIG, 194. Heart, and associated vessels, of Tortoise. 



(After NUHN.) 



r.a, Right auricle ; superior venae cavae (s.v.c.) and inferior vena 

 cavafz'.z/.rr.) enter it. r.v. Right half of ventricle ; pulmonary arteries 

 (p. a) and left aortic arch (Lew) leave it ; coel coeliac ; d.ao, dorsal 

 aorta. /. a, Left auricle; p.v. pulmonary veins enter it. l.u, Left 

 half of ventricle ; right aortic arch (r.ao), giving off carotids (c) and 

 subclavians (s.cf), leaves it. 



tive appearance ; Emys orbicularis common in S. Europe ; Chelydra 

 and MacrodemmyS) the aquatic terrapins of N. America. 



Trionychidoe, fresh water turtles, with depressed carapace covered 

 with soft skin, with webbed digits. Each foot has sharp claws on the 

 three inner digits. They are carnivorous in habit. Examples Trionyx^ 

 javanicus, gangeticus, niloticus, from Java, the Ganges, and the Nile 

 respectively. 



