398 CHELONIAN EEPTILES. 



usually composed of bony pieces, surrounds the 

 carapax, and connects all the ribs together. The 

 vertebrae of the neck and tail only are move- 

 able, and the bones of the shoulder and pelvis are 



F:G. 331. SKELETON OF TURTLE. 



literally situated inside the body. The outer sur- 

 faces of the carapax and plastron are covered with 

 a series of horny or sometimes leathery plates, of 

 regular angular forms, closely fitted to each other. 

 The jaws are clothed in horn, like the beak of a 

 bird, which they much resemble, both in appearance 

 and action. The eggs of the Chelonians are covered, 

 like those of birds, with a hard, brittle, white shell, 

 and are deposited by the female in the warm sand, 

 where they are hidden from observation and left to 

 be hatched by the heat of the sun. 



Tortoises possess amazing tenacity of life : some 

 have been known to move for many weeks after de- 

 capitation. Very little nourishment is necessary for 

 them, and they can pass entire months, without 

 eating. 



The Chelonian Eeptiles may all be arranged. in 

 four principal families, according to the following 

 Table: 



