As a result of these studies and due to the paucity of specimens from Utah, it is advisable, for the present, to refer all these Utah animals to _fossor_. Additional specimens may reveal characters that will merit the separation of the Utah animals from typical _fossor_; a desertlike area unfavorable to _Thomomys_ exists between the type locality and eastern Utah. _Specimens examined._--Total, 21, distributed as follows: _Grand County_: Oak Spring, Middle Fork Willow Creek, 15 mi. N Thompson, 8 (C. M.); La Sal Mountains, 1 (U. S. N. M.); Warner Ranger Station, La Sal Mountains, 3 (B. Y. U.). _San Juan County_: Geyser Pass, 18 mi. SE Moab, La Sal Mountains, 3 (1, B. Y. U.; 2, C. M.); 5 mi. W Monticello, 1 (C. M.); Cooley Pass, 8 mi. W Monticello, 2 (C. M.); Joshua Flat, Elk Ridge, 8,300 ft., 3 (M. V. Z.). =Thomomys talpoides parowanensis= Goldman _Thomomys fossor parowanensis_ Goldman, Journ. Washington Acad. Sci., 28:334, July 15, 1938. _Thomomys talpoides parowanensis_ Goldman, Journ. Mamm., 20:234, May 14, 1939; Long, Journ. Mamm., 21:176, May 14, 1940. _Thomomys fossor_ Bailey, N. Amer. Fauna, 39:112, November 15, 1915; Barnes, Bull. Univ. Utah, 12 (No. 15):85, April, 1922; Bull. Univ. Utah, 17 (No. 12):102, June, 1927; Hall, Univ. California Publ. Zooel., 37:4, April 10, 1931; Presnall, Zion-Bryce Mus. Bull., 2:14, January, 1938; Tanner, Great Basin Nat., 1:111, 1940. _Type._--Male, adult, skin and skull, No. 158072, U. S. National Museum (Biological Surveys Collection); Brian Head, Parowan Mountains, 11,000 ft., Iron County, Utah; September 8, 1908; collected by W. H. Osgood; original number 3483 (after Goldman, type not seen). _Range._--High mountains of eastern Iron and Beaver counties, and western Kane and Garfield counties. _Diagnosis._--Size medium (see measurements). Color: Upper parts Sayal Brown moderately mixed with black, lightest on head; sides lightly washed with Buff; underparts Pinkish Buff, clearest on inguinal and pectoral regions; nose and cheeks dusky; postauricular patches large and black; front feet, hind feet and distal half of tail white. Skull: Long and fairly slender; zygomatic arches not widely spreading; nasals long; rostrum long and slender; posterior ends of nasals truncate or moderately emarginate; extension of premaxillae posterior to nasals usually short; tympanic bullae relatively small; upper incisors long and narrow; molariform teeth large. _Comparisons._--Compared with _Thomomys talpoides kaibabensis_, _parowanensis_ differs as follows: Size smaller. Skull: Shorter; nasals shorter; zygomatic breadth less; nasals truncate or shallowly emarginate posteriorly as opposed to rounded; upper incisors narrower.