438 



MANUAL OF ZOOLOGY 



In the Chelonia (Fig. 263) the body is short and broad, 

 enclosed in a hard "shell," consisting of a dorsal part or 

 carapace and a ventral part ox plastron. These are firmly 

 united, apertures being left between them for the head and 

 neck, the tail and the limbs. The neck is long and mobile ; 

 the tail short. The limbs are fully developed, though short. 

 In some (land and fresh-water tortoises) they are provided 

 each with five free digits terminating in curved horny claws ; 

 in the turtles the digits are closely united together, and the 



Fig. 262. — Hatteria punctata. (After Brehm.) 



limb assumes the character of a "flipper" or swimming 

 paddle. The cloacal aperture is longitudinal. 



The Crocodilia, the largest of living reptiles, have the 

 trunk elongated and somewhat depressed, so that its breadth 

 is much greater than its height. The snout is prolonged, 

 the neck short, the tail longer than the body and compressed 

 laterally. The limbs are relatively short and powerful, with 

 five digits in the manus and four in the pes, those of the 

 latter being partly or completely united by webs of skin. 



