CHELONIA. 



ORDER I. CHELONIA.* 



A VERY natural and well-defined group, distinguish- 

 ed at the very first view by the solid and immoveahle 

 armour in which the greater part of their body is en- 

 cased, and which, opening at the two extremities, 

 leaves only sufficient space for the head and fore-legs 

 to pass out at the one, and the tail and hind-legs at 

 the other. This bony case is composed of two parts ; 

 the upper portion, which may be called, by way of 

 distinction, the shell, consists of the vertebrae, and 

 the ribs, which are united and compacted into a con- 

 tinuous surface; the lower represents the sternum, 

 united to the ribs, that is, to the shell, by several 

 pieces immoveably soldered together. Externally 

 this armour is covered by broad plates, of a horny 

 consistence, which in some are joined in every part 

 of their edges to the neighbouring ones, but in others 

 have a part of their edge free and overlapping. The 

 skin which covers the exposed parts is so hard that 

 the sharpest instruments can with difficulty pierce it ; 

 it is closely fastened to the shell, a little within its 

 edge. The head is situated at the end of a neck of 

 considerable length, which can be protruded or drawn 

 into' the shell, at the will of the animal. The jaws 



* XXyv, clielone, a sea-tortoise. 



