48 CHELONID^. 



genera, viz, : — The Green Turtle, CheJone mijdas, the Hawlvsbill, 

 Chelone imbricata, and the Loggerhead, Thcdassoclielys caretta, all 

 three of which occur in the Indian Ocean, The Green Turtle is 

 valuable as an article of food, the Hawksbill for the tortoise-shell 

 (the epidermal horny shields) ; whilst the Loggerhead is of no 

 commercial value, or produces but a very inferior quality of tortoise- 

 shell. 



The Chelonida^ are thoroughly marine turtles, approaching the 

 shores only for the purpose of depositing their eggs, which are 

 very numerous, soft-shelled, and buried in the sand. As these 

 eggs are large and excellent eating, they are much sought for. 



The genera are thus distinguished : — 



Costal shields 4 pairs Chelone, p. 48. 



Costal shields 5 or more pairs Thalassochelys, p. 49. 



Genus CHELONE, 

 Brongniart, Bull. Soc. Philoin. iii^ 1800, p. 89. 



Carapace with persisting fontanelles between the costal and 

 marginal plates. Costal shields four pairs. An intergular shield 

 and a series of inframarginal plastral shields. 



T\\o species are known. 



Synopsis of Species. 



Upper jaw not hooked C. mydas, p. 48. 



Upper jaw hooked C. ivihricata, p. 49. 



44. Chelone mydas. 



Testudo mydas, Limi. Syst. Nat. i, p. 350. 



Chelonia mydas, tSc/ncciyy. Prodr. p. "22; Boideny. Cat. Chel. ^-c. p. 180. 

 Chelouia virgata, Sclnveif/g. Prodr. p. 22 ; Cantor, J. A. S. B. xvi, 

 1847, p. G17 ; Guntli. lieft. B. I. p. 53; Theoh. Cat. p. 33. 



Carapace feebly unicarinate in the young (sometimes with slight 

 indication of lateral keels), arched or subtectiform in the adult ; 

 dorsal shields juxtaposed ; margin not or but indistinctly serrated, 

 formed of 25 shields. 8nout very short ; jaws not hooked ; horny 

 sheaths of upper jaw with feebly denticulated edge and striated 

 inner surface, of lower jaw with strongly denticulated edge ; 

 alveolar surface of upper jaw with two strong denticulated ridges ; 

 symphysis of lower jaw short ; one pair of pra^frontal shields. 

 Limbs usually with a single claw; the second digit sometimes 

 provided with a distinct claw in young specimens. Young dark 

 brown or olive above, the limbs margined with yellow ; yellow 

 beneath, with a large dark brown spot on the hand and foot. 

 Carapace of adult olive or brown, spotted or marbled with yellowish. 



Length of shell 4 feet. 



Hah. Tropical and subtropical seas. Rather rare in the Bay of 

 Bengal. Herbivorous ; edible, but occasionally poisonous. 



