ictorville, 3 (vagrants).
Riverside County: San Jacinto Mts., 29; Thomas Mt., 1; Santa Rosa Mts.,
10. Orange County: Santa Ana Mts., 3000 ft., 1 (vagrant?). San Diego
County: Julian, 1; Cuyamaca Mts., 6.

_General remarks._--In making use of the intrinsic color characters,
which are important here in distinguishing subspecies, it is, of course,
essential that the effects of extraneous factors be taken into account.
Prolonged wear and fading evidently serve to weaken the intensity of the
color tones, more especially the buffy ones. Then, too, chickadees seem
peculiarly susceptible to discoloration by smoke, soot and charred wood;
for example, our series from Cisco and Blue Canon, stations along the
Central Pacific Railway over the Sierra Nevada, even though taken in
September and October almost immediately after completion of the fall
molt, are obviously more or less begrimed with soot. On the other hand,
the autumn- and winter-taken series from the Yosemite region and from
the Siskiyou Mountains are clean, and show their intrinsic color tones
to good advantage.

Intergradation undoubtedly connects the four races of the Mountain
Chickadee into a continuous series of forms. Abundant material at hand
from that portion of the Sierra Nevada immediately south of Mount
Whitney shows complete transition from _Penthestes gambeli baileyae_ to
_P. g. abbreviatus_; in fact, many of the specimens can only be placed
arbitrarily in one category or the other. Several examples from the
vicinity of Mono Lake, in Mono County, California, and from along the
west flank of the Sierras in Inyo County, insensibly bridge the interval
between _P. g. abbreviatus_ and _P. g. inyoensis_, especially when
considered in connection with the individual variation to which each
race is subject in about normal degree.

Material at hand from different parts of the Great Basin is
unsatisfactory either in that it is scanty or because of the worn state
of the plumage. A summer-taken series of 13 Mountain Chickadees (nos.
8952-8964, Mus. Vert. Zool.) from the Pine Forest Mountains, Humboldt
County, Nevada, shows in color no approach to _P. gambeli gambeli_. In
this respect it is like _P. g. inyoensis_, but the tail averages nearly
as short as in _P. g. abbreviatus_. Taking all features into account it
seems best placed under _abbreviatus_. Fresh-plumaged fall specimens
from this locality would make determination more certain.

A specimen ([Male], no. 547, M