Plains Pocket Gopher 
8i 
Type locality. — Bridger's Pass, Wyoming. 
Measurements. — Total length, 8.0; tail vert., 2.5; hind foot, 1.05. 
Description. — (From a specimen taken at Colorado Springs, Oct. 
nth): Above, brown, somewhat grayish, and a few black-tipped 
hairs intermingled; sides more ochraceous; feet whitish gray; under 
parts buffy white or pale fulvous; a little blackish on face; chin 
white ; tail gray. 
The skull of this species is rather light and thin; the interorbital 
constriction considerable; the posterior curve of the zygomata 
quite square. The incisors are small compared with those of 
T. fulvus. Auditory bullae of medium size. The nasals extend 
as far back as the maxillae. 
Distribution. — The Plains Pocket Gopher is reported from Wyo- 
ming, Utah, Colorado, and Idaho. In Colorado it has been recorded 
from El Paso and Larimer counties, and is apparently found along 
the base of the foothills, and does not go very far out onto the plains. 
At Colorado Springs it overlaps the range of Geomys lutescens. 
Thomomys clusius ocius (Lat. ocius, swift). Swift Pocket 
Gopher. 
Thomomys clusius ocius Merriam, Proc. Biol. Soc. Wash., xiv., 
p. 114 (1901). 
Type locality. — Fort Bridger, Uinta County, Wyoming. 
Measurements. — (From Merriam /. c): Total length, 7.75; 
tail vert., 2.25; hind foot, i.o. 
Description. — According to Merriam this subspecies is paler than 
T. clusius and the upper parts are pale buffy; sides of nose and 
region around mouth dusky plumbeous; cheeks pale buffy gray; 
sides whitish, tinged with buffy; feet and under parts white. This 
is from the type. A specimen taken near Craig, Routt County, June 
i4th,is actually somewhat darker than the above described specimen 
of T. clusius, and the color rather inclined to chestnut; the under 
parts are buffy ochraceous. The only strong point of difference 
is the blackish on face and chin. 
The skull is like that of T. clusius but the zygomata are less 
spreading; and bullae decidedly larger. 
Distribution. — This subspecies has been found in Colorado and 
Wyoming. In Colorado it has been taken only in Routt County, 
from Craig westward, and was reported by both Cary and Warren. 
It is found at least as far south as the Bear River as specimens were 
taken there south of Lay, and also at Lily, which is on the Bear. 
Cary thinks "the high escarpment of the Book Plateau probably 
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