1918 | Taylor: Revision of the Rodent Genus Aplodontia 469 
Molt.—The molting process is just beginning in specimens of this 
subspecies taken June 19, June 29, July 17, and September 12. The 
example taken on the date last named is exceptional in molting so 
late. The end of the molt is shown by specimens secured on October 6 
and October 24. Others taken October 5, 9, and 24 have completely 
assumed the new pelage. 
Remarks.—A plodontia rufa pacifica is usually separable from A. r. 
olympica by both external and eranial characters. Cranially the ab- 
sence in pacifica of the postorbital process on the jugal in most cases 
serves to distinguish it from olympica. The nasals tend to be nar- 
rower as well as shorter in pacifica, and to be straighter sided. The, 
skull is usually smaller in pacifica, and the temporal lines are more 
accentuated. Pacifica is grayer headed than is olympica, and there 
is In pactfica a concentration of blackish on the middle line of the 
back which is not so apparent in olympica. There is more brownish 
dorsally in pacifica. Ventrally pacifica has a conspicuous brown wash, 
while in olympica the ventral brownness is less noticeable. 
From Aplodontia rufa rufa, A. r. pacifica may usually be separated 
through having a greater concentration of blackish dorsally. A uni- 
form brownish tone dorsally is never observed in typical pacifica, but 
in rufa it is often observed. In specimens which are not so distinctly 
brownish pacifica tends to be blackish while rufa tends to be grayish. 
Color fails completely to allocate certain specimens from intermediate 
localities. Thus examples from Siskiyou, Oregon, are in coloration 
pacifica, while in size and certain skull characters they are closer to 
rufa. Others from the vicinity of Eugene and other localities in Lane 
County, Oregon, have the coloration of rufa but certain other char- 
acters of pacifica. Cranially pacifica is usually separable from rufa 
through possession of nasals narrower anteriorly and proportionally 
broader posteriorly, lighter zygomatic arches, smaller average measure- 
ments throughout, audital tubes shorter and of lesser caliber, and 
shallower fossae anterior of the lambdoidal crests. 
Smaller size and different coloration separate Aplodontia rufa 
pacifica from A. r. humboldtiana. From A. r. pacifica one gets the 
impression of rich brown with black hairs plentifully insprinkled and 
specially emphasized on the middle line of the back, while from 
humboldtiana one receives the impression of black sparsely inter- 
spersed with buffy. Cranially pacifica, while very close to humboldt- 
iana, can usually be separated therefrom through the possession of 
nasals with straighter lateral outline. 
, 
