alis_, with long tail; in the Pacific Coast strip of
Washington and Oregon occurs the race _P. a. occidentalis_, with, among
other characters, relatively short tail. Other parallels are to be found
in the genera _Psaltriparus_, _Thryomanes_ and _Pipilo_.

[Illustration: Fig. 2. Tail of _Penthestes gambeli gambeli_
(no. 27784, Mus. Vert. Zool.; [Male], full-grown juv.;
Sierra Ancha, Gila Co., Arizona; June 26, 1917). x 1.00.]

[Illustration: Fig. 3. Tail of _Penthestes gambeli abbreviatus_
(no. 24059, Mus. Vert. Zool.; [Male], full-grown juv.; Yolla
Bolly Mt., Tehama Co., California; August 5, 1913). x 1.00.]

It is improbable that the fact of subspecific differentiation in
_Penthestes gambeli_ has been altogether overlooked previous to the
present time. A premonition of the geographic variation now formally
pointed out is to be found in the early writings of Baird (1858, p.
394), who remarked that "a specimen, apparently of this species [_Parus
montanus_], from Medicine Bow creek [Wyoming], (5643,) though marked
female, is larger than those from California, as shown by the
measurements." Also, some of the differences in proportions in the
subspecies now recognized are shown in the table of measurements given
by Ridgway (1904, p. 409).

For a detailed description of the Mountain Chickadee as a _species_,
the reader is referred to Ridgway (1904, p. 408).

=Penthestes gambeli gambeli= (Ridgway)

Rocky Mountain Chickadee

_Parus montanus_ Gambel (1843, p. 259); and of authors, part.
This name preoccupied (see Ridgway, 1904, p. 409).

_Parus gambeli_ Ridgway _in_ American Ornithologists' Union
Committee (1886, p. 335); and of authors, part. Substitute
name.

_Parus gambeli thayeri_ Birtwell (1901, p. 166). Based on
adventitiously colored specimen from Albuquerque, New Mexico.
Type in United States National Museum.

_Penthestes gambeli_, of authors, part.

_Type locality._--Santa Fe, New Mexico.

_Diagnosis._--Among the four subspecies of _Penthestes gambeli_ here
recognized, color alone is sufficient for distinguishing _P. gambeli
gambeli_. The flanks, sides of body and back in this form are pervaded
with a distinct tinge of cinnamon--more exactly, the "pinkish buff" of
Ridgway (1912, pl. 29). In addition, this race shows the greatest length
of tail, and slenderest bill.

_Measurements._--Average of 14