1918] Kellogg: Microtus calif ornicus Group of Meadow Mice 19 



Microtus californicus mariposae, new subspecies 

 Mariposa Meadow Mouse 



Microtus edax, Elliot (1898, p. 204), part. Big Trees, Calaveras County. 

 Microtus californicus, of authors, part. 



Type specimen. — Male adult ; no. 21724, Mus. Vert. Zool. ; 1% 

 miles west of El Portal, 1800 feet altitude, Mariposa County, Cali- 

 fornia; December 2, 1914; collected by "Walter P. Taylor; original 

 no. 7166. 



Bange. — Western foothill region of Sierra Nevada, from Minkler, 

 Fresno County, north to Dutch Flat, Placer County. Vertical range 

 from 200 feet up to at least 3800 feet ; zonal range Upper Sonoran and 

 Transition. (See map.) 



Total number of specimens examined, 37, from the following locali- 

 ties in California : Fresno County : Minkler, 4 ; Clovis, 1 ; Lane Bridge 

 (10 miles N Fresno), 1. Mariposa County: El Portal, 16; Pleasant 

 Valley, 5 ; Coulterville, 3 ; Sweetwater Creek, 1 ; Cascade, 1. Amador 

 County: Carbondale, 2. Eldorado County : Fyffe, 1. Placer County : 

 Dutch" Flat, 2. 



Diagnosis. — Size large (hind foot 21 to 26 mm., condylobasal 

 length of skull in largest individuals, 32.9 mm.) ; second upper molar 

 with or without open posterior internal lobe ; skull large, angular, and 

 strongly ridged in old adults (ratio of zygomatic breadth to condy- 

 lobasal length about 57%) ; interorbital region sometimes developing 

 single median ridge with age. 



Color. — Mass effect of dorsal area ranging from snuff brown to 

 Saccardo's umber, with varying admixture of long dark overhairs. 

 In fresh pelage : Hairs of upperparts blackish plumbeous basally, with 

 light tipped portions varying from pinkish buff to tawny-olive ; long 

 overhairs varying from light seal brown to aniline black. Sides lighter 

 than upperparts. Rump usually brighter than rest of upperparts. 

 Underparts pallid neutral gray, due to combination of plumbeous hair 

 bases with the whitish hair tips. Anal area pure white. Terminal 

 portions of whiskers grayish, with basal portions blackish. Nose 

 normally not much darker than area in front of eyes. Ears moderate 

 in size, well furred with hairs the same color as rest of upperparts. 

 Tail distinctly bicolor, approaching fuscous black above and pallid 

 neutral gray beneath. Hands and feet covered above with cinereous 

 hairs. In worn pelage: Duller and with greater conspicuousness of 

 long dark overhairs. 



Skull. — Characterized by long rostrum, narrow interorbital region, 

 and deep brain-case. Dorsal profile not as uniformly convex as in 

 californicus and with interorbital region depressed. Occiput obliquely 

 truncate, permitting the condyles to be visible when skull is viewed 

 from above. 



Brain-case subovate in dorsal view, the sides rounded and trun- 

 cated anteriorly by postorbital tuberosities, these being sufficiently 

 developed to produce a marked break in contour of skull. Very old 

 adults possess longitudinal ridges near outer edges of parietals, con- 

 tinuous posteriorly with lambdoidal ridge and extending forward to 



