42. CHILOMENISCUS 871 



eight, sometimes nine, seven or six, second smallest, fourth 

 or fifth largest, first pair meeting on median line. Genials 

 in two pairs, posterior much smaller. Scales on body smooth, 

 in 13 rows. Anal plate divided. Gastrosteges varying in 

 number from 108 to 125. Urosteges in two series of from 

 21 to 29. 



The color above is reddish orange, soon fading to white 

 in alcohol, crossed by black or dark brown bars, bands or 

 rings. These dark markings may or may not reach or cross 

 the gastrosteges. They number from 18 to 28 on the body 

 and from three to five on the tail. On the tail they usually 

 are complete rings. The interspaces between the dark mark- 

 ings do not differ much from the dark markings in measure- 

 ment along the middorsal line. The posterior portion of 

 the head above, including the parietal, frontal and the upper 

 portions of the posterior supralabials are dark brown or black. 

 The lower surfaces are white ; where not involved by the 

 dark bars or rings. 



Length to anus 104- 202 225 



Length of tail 16 33 26 



Distribution. This little burrowing snake probably is 

 confined to the Lower Sonoran Zone. It has been secured 

 in California, Arizona, and Lower California. 



In California, it has been found only twice ; in Owen's 

 Valley, Inyo County, and near Fort Yuma, Imperial Coun- 

 ty. It probably occupies most of the intervening desert areas. 



In Arizona, it is fairly common in Pima County where 

 it has been collected near Tucson, in the foothills of the 

 Catalina Mountains, and in the Cabali Mountains. It has 

 been secured also at Cave Creek, Maricopa County, and on 

 the Yuma desert near Monument 200 of the Mexican 

 Boundary, and six miles west of Gila Bend. 



In Sonora, it has been secured at Guaymas. 



