CAOUANA. 51 



Fourth Family. 

 MARINE TURTLES— CHELONW^. 



The Marine Turtles are at once distinguished by their long, compressed, fin-shaped, non- 

 retractile feet, the toes being enclosed in a common skin, out of which only one or two 

 claws project. The carapace is broad and much depressed, so that when these animals are 

 on shore and are turned over on theu' back, they cannot regain their natural position. 

 Large interspaces between the extremities of the ribs and portions of the sternum are never 

 ossified, but always remain cartilaginous, so that the carapace in these Turtles is specifically 

 lighter than that of the preceding families. The head is large and globose, and cannot be 

 retracted within the shell ; it is covered above with symmetrical homy shields, and the jaws 

 are armed with sharp horny sheaths. They are thoroughly marine animals ; their pinnate 

 feet and their light shell render them the best swimmers in the class of Eeptiles ; they 

 sometimes live hundreds of miles distant from shore, to which they periodically return, in 

 order to deposit from 100 to 250 soft-shelled eggs, which are buried in the sand. The 

 food of some species consists exclusively of algae ; others subsist upon fish and mollusca. 

 They are found in all the intertropical seas ; sometimes they travel far into the temperate 

 regions. The flesh and eggs of all the species are edible, although the Indian Turtles 

 are much less appreciated in this respect than those of the Atlantic. At certain seasons 

 the flesh of Chelonia mrgata acquires poisonous qualities, and lamentable instances of 

 death have been ascribed to its use*. 



The Indian Turtles belong to the following genera : — 



Vertebral and costal shields 15 Caouana, p. 51. 



Vertebral and costal shields 13, not imbricate Chelonia, p. 52. 



Vertebral and costal shields 13, imbricate Caretta, p. 53. 



The whole animal, with the carapace, is covered with a coriaceous skin . Dermatochelys, p. 55. 



CAOUANA, Gray. 



Fifteen vertebral and costal shields, which are thin and not imbricate. 

 A ridge or a series of prominent knobs along- the rows of vertebral and 

 costal shields in young animals. 



Carnivorous, eating fishes, mollusca, and Crustacea. The genus comprises an Atlantic 

 species, the Loggerhead, which does not appear to extend into the Indian Ocean, and the 

 following, which, on the other hand, is confined to the East Indies. 



* Sir J. E. Tennent, Nat. Hist. Ceylon, p. 292. The case there mentioned happened in the month of 

 October. 



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