1918] Taylor: Revision of the Rodent Genus Aplodontia 459 
Externally they give a mass effect of grayish rather than brownish 
as in the Marmot examples. The differences are slight, however, and 
are not shown to the same extent by examples from nearby localities, 
as Mount Vernon, Hamilton, Sauk and Easton, in Washington, and 
the Chilliwack-Sumas district in British Columbia. The form from 
the vicinity of Seattle was recently described by the writer under the 
name Aplodontia rufa grisea (Taylor, 1916c, p. 497), but the exam- 
ination of considerable additional material indicates the propriety of 
synonymizing grisea under rufa. 
The effects of varying degrees of local isolation seem to be shown 
by specimens of Aplodontia rufa from the rough and mountainous 
region embraced in its range in southern Oregon and northern Cali- 
fornia. Groups of specimens from particular localities, however, do 
not show the constant differences which would be necessary to entitle 
them to recognition as subspecies. Examples of rufa from the Siski- 
you-Trinity region of northern California (recently deseribed by 
Kellogg, 1914, p. 295, as Aplodontia chryseola) tend to have the eali- 
ber of the audital tube less than in typical rufa, the outline of the 
external auditory meatus a little flatter, the nasals slightly narrower 
and shorter, and coloration and quality of pelage slightly different. 
These tendencies, however, are overshadowed by the magnitude of the 
individual variation in the series. There appear to be several other 
local races of rwfa as well entitled to subspecifie recognition as chry- 
seola, but if they were to be described, no logical ranges could be given, 
and the degree of overlapping would make identification of specimens 
difficult if not impossible. 
Intergradation between Aplodontia rufa rufa and neighboring 
subspecies is hinted at or directly demonstrated by specimens 
examined as follows: Intergradation with columbiana, by specimens 
from Sumas and Chilliwack, British Columbia; with rainieri, by 
examples from Easton, Washington; with olympica, by an example 
from Steilacoom, Washington; with pacifica, by specimens from Lane 
County, Oregon, and from Siskiyou, Oregon; with californica, by 
examples from Mount Mazama, Oregon, and Canyon Creek, Cali- 
fornia; and with humboldtiana by specimens from the divide between 
the Trinity and Klamath rivers, twelve miles north of Hoopa Post 
Office, northern California. 
A considerable series of specimens from Siskiyou, Oregon, is puz- 
zling, being pacifica-like in coloration, but larger, and in certain 
cranial characters more like rufa. As in other series, the range of 
