1918] Grinnell: The Subspecies of the Mountain Chickadee 507 
of relatively short tail, proves to have two outlying divergent forms. 
These three forms are alike in their lack of any cinnamon tinge, this 
being replaced in two of them by a buffy tinge and in one form by 
leaden gray. The tail in one of the outlying forms is long, in the 
other short. The habitats concerned are, respectively, the desert 
mountains of the Inyo region of eastern California, and the coastal 
mountains of southern California. This differentiation within the 
Pacifie district, particularly within the state of California, will be 
better understood in its geographic bearing by reference to the aecom- 
panying map (fig. 1). 
The behavior of the tail of Penthestes gambeli—long in the Rocky 
Mountain district, short in the Pacific district (see figs. 2, 3)—is par- 
alleled in the Penthestes atricapillus group of chickadees across the 
North American continent in about the latitude of the state of Wash- 
ee 
— 
Fig. 2. Tail of Penthestes gambeli gambeli (no. 27784, Mus. Vert. Zool.; ¢, 
full-grown juv.; Sierra Ancha, Gila Co., Arizona; June 26, 1917). X 1.00. 
Fig. 3. Tail of Penthestes gambeli abbreviatus (no. 24059, Mus. Vert. Zool.; 
3, full-grown juv.; Yolla Bolly Mt., Tehama Co., California; August 5, 1913). 
xX 1.00. 
ington. In the northern Rocky Mountains oceurs the race P. a. sep- 
tentrionalis, with long tail; in the Pacific Coast strip of Washington 
and Oregon occurs the race P. a. occidentalis, with, among other char- 
acters, relatively short tail. Other parallels are to be found in the 
genera Psaltriparus, Thryomanes and Pipilo. 
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 for- 
mally 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 ereek [Wyoming], (5643,) 
though marked female, is larger than those from California, as shown 
by the measurements. ’ 
in the subspecies now recognized are shown in the table of measure- 
ments given by Ridgeway (1904, p. 409). 
For a detailed description of the Mountain Chickadee as a species, 
the reader is referred to Ridgway (1904, p. 408). 
b) 
Also, some of the differences in proportions 
