268 Umversifu of California Publications in Zoology [Vol. 21 



The skull of the type of Microfus montanns yosemite differs from 

 normal adults in being smaller, with more pronounced ridges on dorsal 

 surface of brain case and on supraoccipital, more rectangular inter- 

 parietal and smaller nasals. 



Microtus montanus dutcheri Bailey 



Mount Whitney Meadow Mouse 



Microtus dutclieri Bailey (1898, p. 85) ; and of authors. 

 Microtus dutclieri, Bailey (1900, p. 32), part. 

 Microtus montanus dutclieri, Grinnell (1913, p. 317). 



29769 

 Type specimen. — Male adult ; no. „ ', coll. Biol. Surv., U. S. 



Nat, Mus. ; Big Cottonwood Meadows, southeast of Mount Whitney, 

 10,100 feet altitude, Inj'o County, California; July 10, 1891 ; collected 

 by B. H. Dutcher; original no. 69. 



Range. — Mount Whitney region of Sierra Nevada, from Cotton- 

 wood Lakes, Inyo County, and Whitney Creek, Tulare County, south 

 to Jackass Meadow, Tulare County. Vertical range from 6700 feet 

 up to 11,000 feet; zonal range, Canadian to Iludsonian. (See map, 

 fig. Y.) 



Total number of specimens examined, 77, all in Mus. Vert. Zool. 

 and from the following localities in California. Tulare County : Whit- 

 ney Meadows (9800 feet), 16; Little Brush Meadow, west slope of 

 Olancha Peak (9750 feet), 1; Jordan Hot Springs (6700 feet), 3; 

 Jackass Meadow (7750 feet), 25; Whitney Creek (10,650 feet), 18; 

 Monache Meadows (8000 feet), 1. Inyo County: Cottonwood Lakes 

 (11,000 feet), 12; Little Cottonwood Creek (9500 feet), 1. 



Diagnosis. — Size medium (hind foot 21 to 22 mm., condylobasal 

 length of skull in largest individuals 28.7 mm.) ; brain case more 

 inflated and angular than in yosemite (ratio of zygomatic breadth 

 to condylobasal length about 60 per cent) ; bullae slightly smaller, less 

 inflated and more depressed below meatus; pelage brownish, under- 

 parts with buify suffusion when viewed in mass effect; ears medium, 

 not concealed by fur. 



Measurements. — Average of 14 specimens : total length, 169.78 

 mm. (159-194) ; tail vertebrae, 49.7 mm. (41-69) ; hind foot, 21.14 

 mm. (19.5-22) ; condylobasal length, 27.72 mm. (27-28.7) ; occipito- 

 nasal length, 26.25 mm. (25.4-26.9) ; basilar length, Hensel, 25.1 mm. 

 (24.3-26) ; nasal length, 7.94 mm. (7.2-8.7) ; zygomatic width, 16.65 

 mm. (15.8-17.5) ; interorbital constriction, 3.86 mm. (3.7-4) ; inter- 

 parietal width, 8.35 mm. (7.8-8.9) ; shelf of bony palate, 16.85 mm. 

 (16-17.5) ; height cranium at bullae, 9.89 mm. (9.6-10.3) ; mastoid 

 width, 12.38 mm. (11.9-13) ; length upper molar series, 6.63 mm. 

 (6.4-7) ; length mandible, 17.47 mm. (16.9-18.4). 



