REPTILIA. 289 



are true oars or paddles, with but a faint trace of one or two claws externally ; 

 the anterior are much larger than the posterior. There are two genera, 

 one Sphargis, with a naked skin on the shell, and Chelonia with plates. 

 Sphargis coriacea {pi. SI, Jig. 43), or the leather turtle, is the largest of all 

 living Chelonia, individuals having been known to weigh ISOOlbs., with a shell 

 six feet in length. Chelonia imbricata, or the hawks-bill turtle, found among 

 the "West India Islands, and in other localities, furnishes the valuable tortoise- 

 shell of commerce. C. mydas, or the green-turtle {pi. 90. Jig. 11), is highly 

 prized by epicures. It is caught in great numbers among the West India 

 Islands and on the coast of Florida, especially about Key West. Most sea 

 turtles are vegetable eaters. 



We shall now make a brief reference to the fossil Chelonia, having 

 purposely deferred their consideration until the last. Numerous species of 

 Testudo are found in the Tertiary of Europe, and one or two in that of 

 Brazil. The Himalaya furnishes an enormous species of land tortoise 

 closely allied to Testudo, in Colossochelys atlas, an animal which with a 

 total length of 18 feet, had a carapace or back shell 11^ feet in length, 

 8 feet broad, and 6 feet high. The sternal shell or plastron was 9^ feet long, 

 8 broad, and over 6 inches in thickness. The feet must have equalled, or 

 exceeded in size, those of the largest rhinoceros. Many species of Emys 

 have been found in the Jurassic and tertiary strata of Europe. A species 

 of Chelomira, or snapping-turtle, is described, from the Q^ningen marl. 

 Trionyx, Chelys, and several other modern genera, have their fossil represen- 

 tatives. Fossil species of ChelonidcB, or sea turtles, are not uncommon in the 

 Jurassic, cretaceous, and tertiary strata of Europe ; and one species, Chelonia 

 cooperi, is indicated from the State of Georgia. Many species of Emydidcc 

 are found in the bone caves of Pennsylvania, most of them, however, identical 

 with recent species. 



i93 



