Occasional Papers of the Museum of Zoology 7 



lars, 2; temporals, i-f-i-f- (upper labials, oculars, and tem- 

 porals the same in number on each side) ; dorsal scales in 15 

 rows thronghout the body length; neck ring, i^^ scales wide, 

 not interrupted, but a slight median projection of its posterior 

 black border present; ventral color covering about lYi oi the 

 lowermost rows of dorsal scales on each side. The coloration, 

 as preser\-ed in alcohol, is as follows : Above, about a dark 

 olive-gray, darker posteriorly ; head a little darker above ; neck 

 ring about cream color ; ventral color a massicot yellow. l)e- 

 coming reddish posteriorly and under the tail ; ventral scales 

 irregularl}- and rather prominently spotted with black, the 

 light colored dorsal scales flecked with black, and the tail with 

 only a very few small black spots. Total length. 442 milli- 

 meters ; tail length. ^6 millimeters. Sex. female. 



Key to the Western Forms of Diadophis 



The ringneck snakes of the rcgalis and aniabilis groups may 

 nearly always be distinguished from all other forms of the 

 genus in the United States by the possession usually of more 

 than 180 ventral plates, and by the encroachment of the ventral 

 color upon one or more of the lowermost rows of dorsal scales. 



Within these groups most specimens may be identified by 



the following key : 



a \'entrals in males more than 206, in females more than 220. 



b Xeck ring present, 2 to 4 scales in width 



D. rcgalis ariconae, suhsp. nov. 



(Central Arizona, sonth into Sonora.) 



b.. Neck ring absent, or much reduced 



D. rcgalis rcgalis { Baird & Girard ) . 



(Central Texas to southeastern Arizona.) 



a.. Ventrals in males less than 206, in females less than 220. 



c^ Scale rows, 17-15 (rarely 15-15)- 



