10. UTA 181 



much shorter than the tail. The head-plates are large, the 

 largest (interparietal) being larger than the ear-opening. 

 The superciliaries are imbricate. The dorsal scales are 

 small and may be either uniform or heterogeneous. The 

 labials are not imbricate. The ear-opening is large with a 

 strong anterior denticulation. One or more transverse 

 gular folds and long series of femoral pores are present. 



This genus occurs in the United States and Mexico. 

 More than 20 species and subspecies have been described. 

 These are mostly of small size, but Ufa thalassina and its 

 three close relatives are large lizards. These may well be 

 regarded as forming the subgenus Petrosaurus. The so- 

 called U. stansburiana group may be referred to the sub- 

 genus Uta, and the remaining species to the subgenus 

 Urosaurus. 



SYNOPSIS OF SPECIES AND SUBSPECIES 



a. Dorsals all small, granular, smooth, of nearly equal 

 size, not imbricate, a little larger than laterals 5 

 adults more than 75 mm. from snout to anus; one 

 or more blackish bars across shoulders. (Subgenus 

 Petrosaurus). 

 b. Caudal scales small, not mucronate. 



c . Anterior half of back with three blackish cross- 

 bands 5 snout longer. 



U. thalassina. p. 186. 



c 8 . Anterior half of back with four blackish cross- 

 bands; snout shorter. 



U. repens. p. 189. 



b a . Caudal scales large, imbricate, keeled, and mu- 

 cronate j a single narrow black band across 

 shoulders. 



cc. Throat with numerous round light spots. 



U. mearnsi. p. 191. 



