_Remarks._--_Thomomys bottae centralis_ has one of the most extensive ranges of any of the known races of _T. bottae_. The eastern limits extend into extreme western Utah. Specimens from Utah for the most part are intergrades between _centralis_ and _aureiventris_, the race to the north. Some minor intergradation is also noted between _centralis_ and _sevieri_ and _bonnevillei_, the races to the east. Intergradation is the expected condition because the animals belonging to _centralis_ are at the extremes of their range in this area. The greater affinities of these animals with _aureiventris_ is to be expected because both _aureiventris_ and _centralis_ are forms of the western mainland of the Pleistocene Lake Bonneville; while the races to the east, although closest geographically, were isolated from the gophers of the western mainland during prehistoric times by this lake. They are still isolated and enough time has elapsed so that only vestiges of morphological intergradation exist between _centralis_ and these eastern forms. Two specimens from Cedar City, Iron County, are intergrades between _Thomomys bottae wahwahensis_, _centralis_ and _planirostris_. Their skulls are slightly convex as in _planirostris_, and the rostrum is short and wide as in _wahwahensis_. In shape of the zygomatic arches, length of the nasals, and color, they resemble _centralis_ to which they are here referred. _Specimens examined._--Total, 49, distributed as follows: _Millard County_: 1 mi. SE Gandy, 5,000 ft., 15 (M. V. Z.); White Valley (Tule Spring), 60 mi. W Delta, 4, (3 in R. W. Fautin Vertebrate Collection); Robison Ranch, 5,300 ft., (on Hendry Creek) Simonsons Ranch, 4,596 ft., 2 (M. V. Z.); 1 mi. E Garrison, 5,000 ft., 21; 5 mi. S Garrison, 5,400 ft., 5 (M. V. Z.). _Iron County_: Cedar City, 2 (M. V. Z.). =Thomomys bottae sevieri= new subspecies _Type._--Female, adult, skin and skull, No. 2530, Museum of Zooelogy, University of Utah; Swasey Spring, House Mountains, 6,500 ft., Millard County, Utah; May 16, 1938; collected by S. D. Durrant; original number 1380. _Range._--Known only from the type locality.