282 TJniversiiy of Calif ornia Puhlioations in Zoologi/ [Vol. 21 



measurements as above and would make little or no difference in the 

 conclusions derived from the data. The second interpretation seems 

 to be justified. 



LIST OF CALIFORNIA SUBSPECIES OF MICEOTUS MOEDAX, WITH 



TYPE LOCALITIES 



Microtus mordax mordax (Merriam). Sawtooth Lake, east base of Saw- 

 tooth Mountains, Blaine County, Idaho. 



Miorotus mordax angusticeps Bailey. Crescent City, Del Norte County, 

 California. 



Microtus mordax herriardinus Merriam. Dry Lake, at north base of San 

 Gorgonio Peak, San Bernardino Mountains, San Bernardino County, 

 California. 



Microtus viordax sierrae, new subspecies. Tuolumne Meadows, Yosemite 

 National Park, Tuolumne County, California. 



KEY TO SUBSPECIES OF MICEOTUS MOEDAX IN CALIFORNIA 



1. Size medium, total length of old adults seldom greater than 180 mm., and 

 usually less; longitudinal ridges of skull normally poorly developed. 



Skull medium (condylobasal length about 27 mm.) and narrow; colors bright, 

 reddish or brownish angusticeps 



v. Size large, total length of old adults at least 190 nmi., sometimes over 200 mm. ; 

 longitudinal ridges of skull Avell developed. 



2. Skull large (condylobasal length about 29 mm.) ; longitudinal ridges promi- 

 nent; colors dark, brownish sierrae 



2'. Skull smaller (condylobasal length about 28 mm.); longitudinal ridges less 

 prominent. 



3. Incisive foramina constricted posteriorly; colors light, sides grayish; 

 dorsal tail stripe sharply contrasted with ventral surface mordax 



S'. Incisive foramina not constricted posteriorly; colors dark, sides dusky; 

 dorsal tail stripe not sharply contrasted with ventral surface 



bernardinus 



