32 University of California Puhlications in Zoology [Vol. 21 



Jacinto Mountains), 4; Jurupa Mountains (7 miles NW Riverside), 3. 

 Los Angeles County: El Monte (San Gabriel River), 2; Oak Knoll 

 (near Pasadena), 1; Linda Vista (near Pasadena), 3; Arroyo Seco 

 (Switzer's Camp), 1. San Bernardino County: South Fork Santa 

 Ana River (San Bernardino Mountains), 3; Fish Creek, 1; Bluff 

 Lake, 14; Mouth of Reche Caiion (near Colton), 4; Devil's Canon 

 (San Bernardino Mountains), 1. Ventura County: Mount Pinos, 3; 

 Matilija, 6. Orange County : Santa Ana Caiion, 2. 



Diagnosis. — Size large (hind foot, 21 to 25 mm., condylobasal 

 length of skull in largest individuals, 32 mm.) ; second upper molar 

 without posterointernal lobe or loop ; skull long, broad and heavily 

 built (ratio of zygomatic breadth to condylobasal length about 60%), 

 the interorbital region not developing a ridge with age ; superior sur- 

 face of maxillary root of zygoma wider than that in huperuthrus. 



Color. — Upperparts and sides as a rule brighter than in huper- 

 uthrus. Dorsal area not as strongly mixed with brownish and black- 

 ish overhairs. In fresh pelage: Light tipped hairs of upperparts 

 ranging from buckthorn brown, slightly darkened by long overhairs 

 along middle of back, to cinnamon-buff, brightening nearly to pinkish 

 buff on flanks and sides of neck; basal portions of hairs blackish 

 plumbeous. Long overhairs varying from bright Vandyke brown to 

 blackish. Color of upperparts shades into a lighter cinnamon-buff 

 on sides and rump, with long dark overhairs conspicuously absent. 

 Plumbeous bases of hairs usually visible on sides, and these contribute 

 to the general coloration. Underparts plumbeous, overlaid by white 

 tipped hairs and often slightly washed with buffy in pectoral region. 

 In some specimens this suffusion becomes a rather definite light buff. 

 Anal area pure white. Whiskers mixed white and some shade of dark 

 brown. Upper and lower lips whitish. Nose lighter than remainder 

 of head owing to presence of but few dark overhairs. Ears large, 

 not concealed by fur ; anterior border covered with blackish hairs ; 

 posterior border covered with hairs of same shade as light tipped hairs 

 of upperparts. Tail may or may not be distinctly bicolor ; usually the 

 same color above as dark overhairs of upperparts, whitish below. 

 When tail is scantily haired beneath, the yellowish scales show 

 through. Hands and feet washed with grayish white. In worn 

 pelage: Much more grayish buffy, with dark overhairs not conspicu- 

 ously darkening the upperparts. Tips of hairs of upperparts pinkish 

 buff; overhairs dark Vandyke brown. Under parts almost devoid of 

 buffy suffusion, while plumbeous bases of hairs appear lighter in tone 

 owing to a thinning out or wearing down of the hairs. 



Skull. — Separable as a rule from that of huperuthrtis by the more 

 spreading and heavier zygomatic arches, the relatively broader ros- 

 trum, and larger bullae. Dorsal profile more evenly convex and not 

 flattened as in huperuthrus. Occiput more obliquely truncated and 

 not rounded, but concealing a large part of condyles, when skull is 

 viewed from above. Ventral profile essentially the same as in huper- 

 uthrus. 



Nearly all skulls examined characterized by broad brain-case, its 

 sides rounded and truncated anteriorly by well developed postorbital 

 tuberosities. Longitudinal ridges along outer edges of parietals, con- 

 tinuous posterior] V with lambdoidal ridge and anteriorly with inter- 



