382 SAURIA. 



else variegated with sinuous black lines. The inferior regions are 

 whitish in the young, and dull yellowish in the adult, spotted or 

 streaked with black. On the sides of the throat, there is a bluish 

 spot, margined with black. 



In the male, the throat is black, with a blue spot on each side, some- 

 times confluent, forming a collar. The chin may be entirely black or 

 else whitish. The neck, from the pit to the shoulder, and likewise 

 the anterior portion of the forearm, may be black also. The pectoral 

 region is whitish or yellowish, together with the middle of the abdo- 

 men, the sides of which are blue, the periphery of the blue patch 

 being margined with black. Sometimes, the sides of the abdomen and 

 the anterior portion of the thighs are likewise black. The inferior 

 surface of the limbs exhibits the same hue as the middle of the abdo- 

 men : whitish or yellowish, with a shade of blackish. 



Log. — This species inhabits the country lying between the Missis- 

 sippi Valley and the Atlantic Ocean, New Jersey, and the Gulf of 

 Mexico. Though not amongst those collected by the U. S. Exploring 

 Expedition, a description and figures of the same were imperatively 

 demanded, since some specimens, brought home from the western 

 coast of America, belong to a species so closely related to it, that it 

 would have proved an ungrateful task to attempt describing the one 

 without the other. 



Plate XIX, fig. 15, represents, in profile, the male sex of Sceloporus 

 undulakis, size of life. 



Fig. 16, is an under view of the same individual. 



Fig. 17, the head, viewed from above ; 



Fig. 18, a front view of the head. 



Fig. 19, the left hand, seen from above. 



Fig. 20, exhibits a group of dorsal scales ; 



Fig. 21, a group of abdominal scales. 



Figs. 17-21, are somewhat magnified, in order to show, more dis- 

 tinctly, the structures they are intended to represent. 



