318 



REPORT OF NATIONAL MUSEUM, 1898. 



in my private collection from Sonora the dorsal scales are precisely 

 those of the U. symmetrica^ but the posterior legs are shorter thau the 

 distance between the vent in collar in all of them. 



The difference in the regularity of the dorsal scales in specimens from 

 Texas and Utah and California (as Cat. No. 2742) is so strongly marked 

 that I am inclined to separate them as a decided variety, if not as a 

 good species. The coloration is much the same. 



They have the fine set scales above smaller and more regular. The 

 dorsal plates are in four pretty regular series from near head to tail, 



Fig. 42. 



TJta symmetrica Baird. 



X 2.5. 



Cat, No. 8557, U.S.N.M. 



embracing along their median line two series of smaller ones, making 

 six in all. Sometimes the median small scales are in greater number. 

 The plates on the cheeks and chin appear more minute. 



The head is very broad; the width reaching to the posterior extrem- 

 ity of the occipital. The tail is from one and one-half to two times the 

 leng,th of head and body. The coloration is very much the same; the 

 ground tint above darker. 



Cat. No. 4275 from the San Francisco Metropolitan National Museum 

 has the scales on the back quite uniform and regular, much as in 

 U. gracoisa. 



