220 VERTEBRATA: REPTILIA OR REPTILES. 



turtles are called the TrionychidaB, because they have only 

 three nails to each foot. The body is very flat, the neck 

 and head long, and the latter is terminated by a long 

 leathery snout. 



The Sea Turtles, as already stated, are furnished with 

 flippers instead of feet. The Green Turtles, the Hawk- 

 bill .or Tortoise-shell Turtle (Fig. 253), and the Logger- 

 heads are all of enormous size weighing from two hun- 

 dred to five hundred pounds or more and are included 

 in one family, the Chelonioidae. 



There is another family of sea-turtles called the Sphar- 

 gididse or Leather-back Turtles, whose general form is 

 something like that of a flattened pyramid, and whose 

 body is covered with a thick coriaceous skin instead of a 

 hard shell. They inhabit the Atlantic and Mediterranean, 

 and are the largest of all turtles, attaining a weight of 

 twelve hundred to two thousand pounds ! 



Fossil turtles are found in the rocks as old as the Juras- 

 sic. One species found in the Tertiary rocks of India had 

 a shell twelve feet in length, and had a total length of 



O * d 1 



twenty feet ! According to Cope, a species (Atlantochelys 

 gigcLs) found in Kansas had a breadth, between the tips 

 of its extended flippers, of fifteen feet ! 



SUB-SECTION III. 

 THE ORDER OF DINOSAURIA OR DINOSAURS. 



UNDER the general name of SAURIA are included all the 

 reptiles except the Turtles and Serpents. It maybe stated 

 in general terms, that the Saurians have a long body and 

 a long tail, generally four legs although in some cases 

 only two, or none the eyes in most cases furnished with 



