1922] Kellogg: Calif or nian Forms of Microtus Montanus 257 



Mammals, United States National Museum; Mr. A. Brazier Howell, 

 of Pasadena, California; and Mr. Chase Littlejohn, of Redwood City, 

 California. The writer also wishes to acknowledge his thanks for the 

 help in many ways that he has received from Dr. Joseph Grinnell, 

 director of the Museum of Vertebrate Zoology, and from Mr. Harry S. 

 Swarth, Mr. Tracy I. Storer, and Mr. Joseph Dixon, of the staff of 

 the same institution. 



LIST OF SUBSPECIES OF MICROTUS MONTANUS, WITH 

 TYPE LOCALITIES 



Microtus montanus montanus (Peale). Headwaters of Sacrameuto River [prob- 

 ably near Sisson], near Mount Shasta, California. 



Microtus montanus arizonensis Bailey. Springerville, Apache County, Arizona. 



Microtus montanus caryi Bailey. Milford, Fremont County, Wyoming. 



Microtus montanus dutclieri Bailey. Big Cottonwood Meadows, [southeast of] 

 Mount Whitney, Inyo County, California. 



Microtus montanus riimlaris Bailey. St. George, Washington County, Utah. 



Microtus montanus yosemite Grinnell. Yosemite Valley, Mariposa County, 

 California. 



KEY TO SUBSPECIES OF MICROTUS MONTANUS 



1. Size large, total length of old adults 177-190 mm.; skull large (condylobasal 

 length about 28 mm.). 

 2. Bullae larger. 



3. Skull with well developed longitudinal ridges; tail medium, 47-58 mm. 

 4. Colors dark, upperparts bister or brownish, strongly lined with black- 

 ish overhairs; hind feet large, 20-23 mm.; lateral pits of palate 



deep montanus 



4:'. Colors bright, upperparts yellowish or rusty brown, less heavily lined 

 with blackish overhairs; hind feet smaller, 20-21 mm.; lateral 



pits of palate shallower arizonensis 



3'. Skull with longitudinal ridges poorly developed; tail short, 43-48 mm. 

 Colors dull and pale, upperparts dull bister, lined with blackish over- 

 hairs; hind feet large, 21-23 mm rivulai-is 



2'. Bullae smaller. 



Skull angular, with well developed longitudinal ridges; tail medium, 

 45-58 mm. Colors dull, upperparts buffy or grayish, lined with blackish 



overhairs; hind feet large, 20-22 mm yosemite 



v. Size medium, total leng-th of old adults seldom exceeding and usually less' than 

 190 mm.; skull small (condylobasal length less than 28 mm.) and with well 

 developed longitudinal ridges. 

 5. Colors bright, upperparts reddish or brownish ; underparts with buffy suf- 

 fusion; tail medium, 47-56 mm.; hind foot large, 21-23 mm.; occiput 



obliquely truncate dutclieri 



5'. Colors dull, upperparts buffy or grayish; underparts without buffy suf- 

 fusion; tail short, 41-45 mm.; hind foot smaller, 20-21 mm.; occiput 

 not obliquely truncate caryi 



