52 



Umversity of California PuhlioaUoiis in Zoology [Vol. 21 



sides is slate gray at base with terminal portion white, while the over- 

 hairs are entirely white (see fig. B, c, d). Hair on underparts, includ- 

 ing under side of tail, white from base to tip (see fig. B, e, f). All 

 color terms used are according to Ridgway (1912). 



Adults in worn pelage sometimes acquire a rusty tinge over the 

 entire dorsal surface. This appearance is due to the light pinkish 

 cinnamon of the terminal portions of the underfur. The oldest adults, 

 judging from cranial characters, are not always the rustiest, and in 

 individuals of comparable age the rusty tinge is much less pronounced 

 in fresh fall pelage than in the worn summer pelage. This change 

 in color could not well be called fading, since the animals are nocturnal 

 and the change is from a duller to a brighter hue. 



4mm 



'icjhfbuff 



6mm 



l4mrn 



amm Id/ate orau 



black 



slate 



r^i 



5mm 



7mm 



y^nife M mm 



slate qfOL 



arau 



all white. 



emm 



all white 



lomm 



alt ivhiie 



Fig. B. Diagrams to illustrate coloration of typical hairs in pelage of 'Neo- 

 toma oinerea cinerea: a, underfur of back; b, overhair of back; c, underfur of 

 side of body; d, overhair of side; e, underfur of under surface of body; /, over- 

 hair of under surface. 



The Juvenal pelage of N. c. cinerea, as illustrated by a series of 

 specimens from the Mount Wliitney region and from the White Moun- 

 tains, shows considerable variation in color, some specimens being 

 much paler than others taken at the same time and locality. The 

 underfur and overhairs are both shorter and finer than in the adults. 

 The basal portions of these hairs are slate gray as in adults, but the 

 terminal portion of the underfur is much lighter, being pale pinkish 

 buff. Extensive black tipping of the overhair in certain juvenals 

 obscures the paler underfur and gives the animals a dark appearance 

 as viewed dorsally. In this connection it is interesting to note that 

 certain young examples of cinerea from the Mount Wliitney region 

 are indistinguishable from juvenal co-types of Neotoma c. lucida from 

 Charleston Peak, Nevada, this race having been described as being 

 paler than cinerea {Goldman, 1917, p. 111). 



Cranial characters. — The cranial characters and dentition of 

 Neotoma have been so well covered by J. A. Allen (1894) and by 

 Goldman (1910) that it seems unnecessary to deal with this subject 

 in the present paper. It may not be amiss, however, to mention the 



