90 The Mammals of Colorado 
Revision, Merriam, A^. A. Fauna, No. 8 (1895). 
Resembling Geomys in external characters, but at once distin- 
guished by the upper incisors, which have only one longitudinal 
groove instead of two ; upper premolar with no enamel on its pos- 
terior face as is also the case with the first and second upper 
molars; posterior upper molar with a sulcus on its outer face, 
dividing it into two imperfect prisms. Skull large and massive. 
This genus inhabits the Great Plains of the United States, 
from southern Colorado extending southward through the 
eastern tableland of Mexico to the States of Mexico and 
Pueblo. 
Eight species were recognized by Merriam in his revision, 
all of w^hich are confined to Mexico, except one here described, 
which forms part of the Colorado fauna. 
Cratogeomys castanops (Grk. kastanos, the chestnut tree, 
+ opsis, appearance). 
Pseudostoma castanops Baird, Report, Stansbury's Exp. to Great 
Salt Lake, p. 313 (1852). 
Type locality. — "Prairie Road to Bent's Fort," near Las Animas, 
Bent Co., Colorado. 
Measurements. — Total length, 10.5; tail vert., 2.6; hind foot, 1.5. 
Description. — (From a specimen taken at Springfield, Baca Co., 
Colo., April 12th) : Above yellowish brown, with black-tipped hairs 
intermixed; feet grayish; under parts buffy; tail like back, except 
tip which is blackish. A darker colored, larger, heavier built, and 
bulkier animal than G. lutescens. 
The skull is proportionately much larger and more massive 
than in G. lutescens, with strong, widely spreading zygomata, and 
very large incisors. 
Distribution. — The Chestnut-faced Pocket Gopher is reported from 
southeastern Colorado, eastern New Mexico, western Oklahoma, 
western Texas, and the States of Coahuila and Chihuahua, Mexico. 
Its range in Colorado is practically confined to the region south of 
the Arkansas River, although it has been taken a few miles to the 
north, near Lamar. It is recorded from Bent, Prowers, Las Animas, 
Pueblo, and Baca counties, and no doubt is found also in Otero 
County. It has been taken as far west as the city of Pueblo. . 
Habits. — Because of its larger size this species is possibly 
