_Remarks._--_T. b. aureiventris_ has one of the most extensive ranges of any race of _T. bottae_ occurring in Utah. The range extends from the valleys of the northwest corner of the state south along the extreme western margin of the state approximately to the southern end of the Deep Creek Mountains. This ascribed range practically bounds the northwest and western margins of the great salt desert in Box Elder and Tooele counties. As far as known, this great waste area harbors no members of the Geomyidae. Pocket gophers were available from four localities in addition to the type locality. In these four localities all of the animals were intergrades. The three specimens from Queen of Sheba Canyon, Deep Creek Mountains, although smaller than _aureiventris_ in every measurement taken, resemble it in color and general configuration of the skull. The animals from Trout Creek and Ibapah at the southern end of the range, although referred to _aureiventris_, are intermediate between it and _centralis_. In color and measurements they more closely resemble _centralis_, but the skulls closely resemble those of _aureiventris_. The skulls show some slight characteristics of _bonnevillei_, the form to the east, which indicate an early relationship between the two. Specimens from the east side of Tecoma Range, adjacent to Pilot Peak, although referred to _aureiventris_ are intergrades between it and _centralis_. Although this locality is nearer the type locality of _aureiventris_ than any of the other record stations, the animals show the maximum departure from topotypes in morphological features. In color they approach _centralis_, and agree with it in one-half of the measured characters. The general configuration of the skull and a majority of the critical diagnostic characters, for example, jugal thickening, are more nearly as in _aureiventris_. From the above remarks it is readily understood that this subspecies is extremely variable. _Specimens examined._--Total, 55, distributed as follows: _Box Elder County_: Fehlman Ranch, 3 mi. N Kelton, 4,255 ft., 8 (7, M. V. Z.); Utah-Nevada Boundary, E Side Tecoma Range, 4,300 ft., 12. _Tooele County_: Ibapah, 5,000 ft., 21. _Juab County_: Queen of Sheba Canyon, W side Deep Creek Mountains, 5,600 ft., 11. =Thomomys bottae robustus= new subspecies _Type._--Male, adult, skin and skull, No. 2726, Museum of Zooelogy, University of Utah; Orr's Ranch, Skull Valley, 4,300 ft., Tooele County, Utah; June 19, 1938; collected by S. D. Durrant; original number 1583. _Range._--Skull Valley, Tooele County, Utah.