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 (pl. 81, fig. 43), or the leather turtle, is the largest of all 
living Chelonia, individuals having been known to weigh 1500\bs., 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 ( pl. 90, fig. 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 124 feet in length, 
8 feet broad, and 6 feet high. The sternal shell or plastron was 93 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 EHmys 
have been found in the Jurassic and tertiary strata of Europe. <A species 
of Chelonura, or snapping-turtle, is described, from the Ciningen marl. 
Trionyx, Chelys, and several other modern genera, have their fossil represen- 
tatives. Fossil species of Chelonide, or sea turtles, are not uncommon in the 
Jurassic, cretaceous, and tertiary strata of Europe; and one species, Chelonia 
cooper, is indicated from the State of Georgia. Many species of Emydide 
are found in the bone caves of Pennsylvania, most of them, however, identical 
with recent species. 
493 
