3. rODOCXEMIS. 



201 



Mcsoplastral bones small, lateral, weclpefl in between tlio liyo- 

 and the hypoiilastra ; plastron large, without hinge, wilh strong 

 axillary and inguinal buttresses. A bony temporal roof, the quad- 

 ratojugal forming a suture with the parietal ; alveohir surface of 

 upper jaw Avith one or more ridges ; a single shield between the 

 eyes ; a pair of large parietal shields and an interparietal. Digits 

 broadly webbed, fore foot with five claws, hind foot with four. 

 Tail very short. 



South America and Madagascar. 



Shell of Podocnemis sextiiberculata. 



Syaojpsis of tlie Sjpecies. 



I. Forehead concave ; jugal and quadrate bones separated. 



A. Alveolar ridges of upper jaw strong, running along the whole 

 length of the jaw. 



Mental barbels two ; a single inter- 

 parietal shield 1. dumeriUana, p. 202. 



Mental barbels two ; two azygous shields 



between the parietals 2. Icwi/ana, p. 203. 



A single barbel 3. umfilis, p. 203. 



