Compared with topotypes of _Thomomys bottae centralis_, _virgineus_ differs in: Size smaller; tail shorter; hind foot smaller. Color: Deeper Cinnamon Buff, thus darker in overall appearance. Skull: Smaller, but relatively wider; zygomatic processes of maxillae heavier; region of maxillo-jugal sutures thicker; jugals more concave laterally; tympanic bullae more inflated ventrally; molariform teeth larger. _Remarks._--This pocket gopher occupies practically the same range in Utah as the large kangaroo rat _Dipodomys deserti deserti_ Stephens. Both are found in the Beaverdam Wash. The type locality of _virgineus_ is but a short distance down the Beaverdam Creek at Littlefield, Arizona. It intergrades with _birdseyei_, the mountain form to the north and east (see remarks under _birdseyei_). There are evidences of intergradation with _planirostris_ of the Virgin River Valley above the narrows of the Virgin River where it cuts through the Beaverdam Mountains (see the discussion under _planirostris_). There are intergradational tendencies exhibited towards _centralis_ in some specimens. Some of the animals are practically indistinguishable in color and there are intergrading cranial characters in the nasals, zygomatic arches and tympanic bullae. _Specimens examined._--Total, 20, distributed as follows: _Washington County_: Beaverdam Wash, 8 mi. N Utah-Arizona border, 7; Beaverdam Wash, 5 mi. N Utah-Arizona border, 2,600 ft., 13. =Thomomys bottae planirostris= Burt _Thomomys perpallidus planirostris_ Burt, Proc. Biol. Soc. Washington, 44:38, May 8, 1931. _Thomomys bottae planirostris_ Hall and Davis, Proc. Biol. Soc. Washington, 47:52, February 9, 1934; Goldman, Proc. Biol. Soc. Washington, 48:156, October 31, 1935; Presnall, Zion-Bryce Mus. Bull., 2:14, January, 1938; Long, Journ. Mamm., 21:176, May 14, 1940. _Thomomys perpallidus aureus_ Bailey, N. Amer. Fauna, 39:75, November 15, 1915; Barnes, Bull. Univ. Utah, 12 (No. 15):85, April, 1922; Bull. Univ. Utah, 17 (No. 12):100, June, 1927; Woodbury, Ecological Monographs, 3:193, April, 1933. _Thomomys bottae centralis_ Hall and Davis, Proc. Biol. Soc. Washington, 47:52, February 9, 1934; Presnall, Zion-Bryce Mus. Bull., 2:14, January, 1938. _Thomomys perpallidus centralis_ Hall, Univ. California Publ. Zooel., 23:445, July 8, 1930. _Thomomys bottae nicholi_ Goldman, Journ. Washington Acad. Sci., 28:337, July 15, 1938, type from Shivwits Plateau, 20 mi. S Wolf Hole (road to Parashonts), 5,000 ft., Mohave County, Arizona; Hardy, Ecological Monographs, 15:98, January, 1945. _Thomomys bottae trumbullensis_ Hall and Davis, Proc. Biol. Soc. Washington, 47:52, February 9, 1934.