24 University of California Publications in Zoologij [Vol. 21 



in the region of Walker Pass. The specimen from Taylor Meadow 

 listed under hernensis, approaches more closely to vallicola in external 

 coloration than it does to k&rnensis, but cranial characters place it 

 with the latter. 



Microtus californicus scirpensis Bailey 

 Amargosa Meadow Mouse 



Microtus scirpensis Bailey (1900, p. 38). Amargosa Eiver (near Nevada 



line), Inyo County. 

 Microtus scirpensis, of authors. 



25979 



Type specimen. — Female adult ; no. — — - , Biol. Surv. Coll., U. S. 



ooooD 



Nat. Mus. ; Amargosa River (near Nevada line [spring near Shoshone, 

 1560 feet altitude] ) , Inyo County, California ; February 26. 1891 ; 

 collected by Vernon Bailey ; original no. 2520. 



Range. — Known only from a small tule marsli at a spring near 

 Shoshone on the Amargosa River, in eastern Inyo County. Altitude 

 of station 1500 to 1600 feet; zonal range Lower Sonoran. (See map.) 



Total number of specimens examined, 7, from the following locality 

 in California. Invo County: Amargosa River [near Shoshone], 7 

 (Biol. Surv. Coll., U. S. Nat. Mus.). 



Diagnosis. — Size large (hind foot, 25 to 25.5 mm., condylobasal 

 length of skull in largest individuals, 31 mm.) ; second upper molar 

 with open posterior lobe or triangle ; skull long, lighter than in 

 vallicola. with longitudinal ridges much less conspicuous in old adults 

 (ratio of zygomatic breadth to condylobasal length about 60%) ; inter- 

 orbital region not developing single median ridge with age, but always 

 with definite sulcus between ridges ; colors brighter than in aestuarinus 

 or vallicola. 



Color. — Mass effect on dorsal area much brighter than in valli- 

 cola; exact shade variable due to long dark overhairs, but usually 

 near snuff brown. In fresh pelage : Upperparts with light terminal 

 portions of hairs varying from cinnamon buff to buckthorn brown, 

 inconspicuously lined mid-dorsally with long blackish overhairs. 

 Basal portions of hairs blackish plumbeous. Sides much lighter than 

 middle upperparts, with larger proportion of cinnamon-buff tipped 

 hairs. Upperparts pallid neutral gray, irregularly darkened by ap- 

 pearance at the surface of blackish plumbeous hair bases; anal area 

 nearly pure white. Terminal portions of whiskers whitish ; basal 

 portions blackish. Upper and lower lips whitish. Nose more blackish 

 than region in front of eyes. Ears large, partially concealed by fur, 

 with anterior border covered by light tipped hairs of same color as 

 those of upperparts. Tail distinctly bicolor, bone brown above and 

 pallid neutral gray below, though when tail is scantily haired the 

 yellowish scales show through. Young: Very young individuals are 

 almost pure black, excepting that there is a suffusion of light tipped 

 buffy hairs on sides and on head. With age the blackish cast of the 

 young changes to brownish. 



