16 University of California Piiblications in Zoology [Vol. 21 



ish than region in front of eyes. Ears large, not concealed by fur, 

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

 as those of upperparts. Tail distinctly bicolor, usually dark aniline 

 black above and light neutral gray below, though when tail is scantily 

 haired the appearance may be otherwise. Hands and feet fuscous 

 overlaid with cinereous hairs. In worn pelage : Much duller, lighter, 

 and with long black overhairs largely absent. General coloration, or 

 mass effect, more nearly approaching sayal brown. The whitish 

 suffusion of underparts more inclusive of sides than in specimens with 

 fresh pelage. 



Skull. — Very broad, heavy, rather deep, and attaining a marked 

 degree of angularity in old age. Dorsal profile convex with exception 

 of interorbital region, where it is somewhat depressed. Occiput ab- 

 ruptly truncated, allowing posterior portion of condyles to be visible 

 when skull is viewed from above. Ventral profile similar to that in 

 californicus. 



Brain-case in outline subovate, truncated anteriorly by blunt post- 

 orbital tuberosities (formed by apex of alisphenoid and adjoining 

 border of squamosal, for attachment of temporal muscles) . In adults 

 there are well developed longitudinal ridges near outer edges of 

 parietals wliich are contiguous with lambdoidal ridge posteriorly and 

 which continue anteriorly to frontals where they unite with inter- 

 orbital ridges. These ridges enclose an approximately equally five- 

 sided area. The interorbital ridges strongly converge in interorbital 

 region, but in all cases there is a definite sulcus between the two. 

 Lambdoidal ridge similar to that in californicus but more flaring. 

 Interparietal moderate, its area less than that of parietal, but wider 

 and more quadrangular than in californicus; posterior border variable, 

 but in all cases more convex than anterior border and lacking median 

 projection, with outer extremities rather squarely truncate. Frontals 

 convex or emarginate posteriorly and somewhat elevated anteriorly. 



Front of rostrum wide, gradually widening posteriorly, somewhat 

 wider than interorbital region, rather deep proximally, but not equal 

 to twice its distal depth, the least depth behind incisors slightly greater 

 than width in same region. Nasals long, broad, spatulate or some- 

 what wedge-shaped, and bent well down ; posterior terminations trun- 

 cate or emarginate, but not reaching posterior margins of ascending 

 portions of premaxillae. Ascending arms of premaxillae reaching to 

 or beyond plane of lacrimals. Opening for anterior nares with trans- 

 verse diameter equal to, or greater than, vertical diameter. Ante- 

 orbital foramen about as in californicus, the plate forming outer wall 

 and continuous with lacrimal bone internally, absent inferiorly, but 

 present superiorly though incomplete. 



Occiput strongly convex, the median depth in majority of skulls 

 examined about 58% of greatest, width across lambdoidal ridge of 

 brain-case. Foramen magnum subtriangular, the sides meeting more 

 or less acutely at corners. Paroccipital processes well developed, 

 relatively heavy, directed more downwards than backwards, but with 

 their tips extending behind most posterior point on supra-occipital 

 above foramen magnum. Posterior margins of paroccipital processes 

 continued upwards as conspicuous ridges of supra-occipital, but usu- 

 ally not touching interparietal superiorly. 



