TURTLES. 51 



Fain. V. Turtles, (Cheloniadje). 



Head globose, shielded : nostrils rather tubular: jaws horny, na- 

 ked. Neck short, subre tractile. Feet very long-, not retractile, com- 

 pressed, fin-shaped : toes depressed, expanded at the end and often 

 armed with flat claws ; front feet longest. Tail short, thick. Shell 

 low, cordate, with a defined bony margin, covered with horny shields 

 or a leathery skin. Ribs free at the end. Sternum ring-like, car- 

 tilaginous in the centre, and only united to the thorax by a carti- 

 laginous suture. Seas of torrid and temperate zones, some eating 

 Algae, as Ch. Midas, which are used for food, and imported as a 

 luxury ; others, Mollusca and radiated animals, as Ch. Caretta, 

 only collected for their oil. The horny shields are used for orna- 

 mental purposes. 



Synopsis of the Genera. 



1. Sphargis. Shell covered with a coriaceous skin. Claws none. 



2. Caretta. Shell covered with 13 horny shields, imbricate and 



produced behind. Sternum strongly keeled on each side in all 

 ages. First and sometimes the second toes clawed. 



3. Caouana. Shell covered with 15 or more horny, truncated, not 

 imbricate shields, which are strongly keeled in the young. First 

 and second toes clawed. 



4. Cheloxia. Shell covered with 13 truncated, not imbricate, 



horny shields, smooth in all ages. First finger of each fin 

 clawed. 



I. Sphargis, Merrem. Coriudo, Fleming. Dermochelys, Blainv. 



Scytena, Wagler. 



Shell cordate, depressed, deeply longitudinally grooved, cover- 

 ed with a continuous coriaceous skin. Feet long. Claws replaced 

 by small coriaceous scales. 



The Luth. Sphargis coriacea, Gray, Syn. R. 51. Dum. et 

 Bib. E. G. ii. 560, t. 24, /. 2. Testudo coriacea, Linn. S. N. 

 350. Schneid. S. 312. Latr. Rept. i. 58, t. 2,/. 1. Shaiv, Zool. 

 t, 18,/. 1. Lacep. Q. O. i. t. 3. Coriudo c. Harlan, A. H. 85. T. 

 Lyra, Donnd. Sphargis Mercurii, Rond. t. 5,f. 3. S. mercuria- 

 lis, Merrem, Tent. 19. Tern. F. Japon. 6, t. 1 — 3. Dermochelys 

 atlantica, Lesueur, Cuv. R. A. ii. 14. Testudo tuberculata, Penn. 

 Phil. Trans, lxi. (young). Schoepf. t. 29. Gravenh. Delic. t. 

 Spinose Tortoise, and tuberculated Tortoise, Penn. Coriaceous 

 Turtle, Shaw. 



Thorax ovate, cordate, sharply 3-keeled. 



f2 



