TORTOISES AND TURTLES. 



567 



esteemed as food; the hawk's-bill turtle (Cardta imbykata) [mmi\\ft% 

 much of the commercial tortoise shell. 



Testudinid.-e, 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 (Tstiido graca), and the extermi- 

 nated giant tortoises of the Mascarene and Galapagos Islands are good 

 representatives. 



ChelydidL'e, fresh water tortoises, more or less aquatic, with per- 

 fectly ossified carapace, and feet with sharp claws. Examples— C/ii'/i'j 

 fimbnata, from Brazil and the Guianas, \sith wart)- growths of decep- 



°d. ao 



Fn;, 194, — Heart, and associated vessels, of Tortoise, 

 (After NUHN, ) 



y.a^ Right .auricle ; superior vense ca\'?e (s.i'.c.) and inferior \'ena 

 cava('/.7',c)enter it. r.Z'. Right half of ventricle ; pulmonarj- arteries 

 {l>.a) and left aortic arch (/.<Zi') leave it: ccel coiliac ; d.ac. dorsal 

 aorta, l.a^ Left auricle: p.z'. pulmonary \'eins enter it, Lv, Left 

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

 subcla\lans ' s.ct), leaves it, 



tive appearance ; Eiiiys orbicularis common in S, Europe ; C/wfydra 

 and Macrotlcnuiiys, the aquatic terrapins of N, America, 



Trionychid:^, 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 — Trwnyx. 

 jaz'aniais, gauge/ it us, niloticus, from Ja\-a, the (ianges, and the Nile 

 respectively. 



