Thomomys talpoides (Richardson)
Thomomys talpoides is a northern species that in Utah approaches the southern limits of its range. The animals of this species inhabit the mountains and high valleys. In the southward extension of their range, as in Utah, they are found at higher elevations which zonally represent lower elevations at more northern latitudes. The specific characters are: Sphenorbital fissure absent; incisive foramina anterior to infraorbital canal; anterior prism of P4 triangular; interparietal relatively large; lambdoidal suture concave posteriorly in region of interparietal, in Utah specimens.
Thomomys talpoides gracilis Durrant
Thomomys quadratus gracilis Durrant, Bull. Univ. Utah, 39 (No. 6):3, February 28, 1939.
Thomomys talpoides gracilis Durrant, Bull. Univ. Utah, 30 (No. 5):6, August 24, 1939; Goldman, Journ. Mamm., 25:414, December 12, 1944.
Thomomys quadratus fisheri Hall, Univ. California Publ. Zoöl., 37:4, April 10, 1931.
Thomomys uinta Bailey, N. Amer. Fauna, 39:114, November 15, 1915; Barnes, Bull. Univ. Utah, 12 (No. 15):83, April, 1922; Bull. Univ. Utah, 17 (No. 12):104, June, 1927.
Type.—Male adult, skin and skull; No. 44866, Museum of Vertebrate Zoölogy, University of California; Pine Canyon, 6,600 ft., 17 mi. NW Kelton, Box Elder County, Utah; July 12, 1930; collected by Annie M. Alexander; original number 676.
Range.—Mountainous regions of extreme northwestern Utah.