The characters that distinguish _moorei_ from _Thomomys talpoides parowanensis_ are: Color: Lighter throughout. Skull: Broader, more angular and more nearly flat; zygomatic arches more widely spreading; zygomatic processes of maxillae heavier; posterior ends of nasals emarginate rather than rounded; upper incisors longer. For comparisons of _moorei_ with _Thomomys talpoides levis_ and _wasatchensis_ see accounts of these forms. _Remarks._--Specimens from Colton, show intergradation between _moorei_, _uinta_ and _wasatchensis_, but are referable to _moorei_ in the majority of characters. Specimens from Mount Nebo, and the mouth of Reddicks Canyon, in the Wasatch and San Pitch mountains, respectively, are intergrades between _moorei_ and _wasatchensis_, but are referable to _moorei_. That part of the Wasatch Mountains south of Spanish Fork Canyon is inhabited by pocket gophers that are intergrades between _moorei_ and _wasatchensis_, but the cranial details show them to be referable to _moorei_. The range here ascribed to _moorei_ consists of the Wasatch Plateau to the east of Sanpete Valley, the San Pitch Mountains and the southern part of the Wasatch Mountains. The type locality of _moorei_ is situated in the southern end of a high valley that separates the Wasatch Plateau from the San Pitch and Wasatch mountains. Topotypical animals are larger and have more ridged, angular skulls than those from the mountains. _Specimens examined._--Total, 48, distributed as follows: _Utah County_: Near Payson Lake, 1 (R. H.); Mt. Nebo, 25 mi. SE Payson, 10,000 ft., 20; Colton, 8 (B. Y. U.). _Sanpete County_: 1 mi. S Fairview, 6,000 ft., 12 (U. S. N. M.). _Juab County_: Mouth of Reddicks Canyon, Wales Mountain (= San Pitch Mountains), 7,500 ft., 5. _Emery County_: Lake Creek, 11 mi. E Mt. Pleasant, 2 (C. M.). _Additional records._--_Sanpete County_: Ephraim, 5 (see Goldman, 1938:336). =Thomomys talpoides fossor= Allen _Thomomys fossor_ Allen, Bull. Amer. Mus. Nat. Hist., 5:51, April 28, 1893; Bailey, N. Amer. Fauna, 39:111, 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. _Thomomys talpoides fossor_ Goldman, Journ. Mamm., 20:234, May 14, 1939. _Type._--Male, adult, skin and skull, No. 5240/4120, American Museum of Natural History; Florida, 7,200 ft., La Plata County, Colorado; June 25, 1892; collected by Charles P. Rowley (after Allen, type not seen). _Range._--In the mountains of San Juan and Grand counties, east of the Colorado and Green rivers.