_Comparisons._--Topotypical specimens of _stansburyi_ can be readily distinguished from those of _Thomomys bottae centralis_, _aureiventris_ and _albicaudatus_ by being smaller in every measurement taken, particularly those of the skull; the skull is weaker and smoother. In color _stansburyi_ is like _albicaudatus_ but is much darker throughout than _aureiventris_ and _centralis_. Comparisons of topotypes of _stansburyi_ with those of _Thomomys bottae sevieri_ show them to be of approximately the same size, but to differ as follows: Color: Darker throughout. Skull: Zygomatic arches shorter; tympanic bullae less inflated ventrally; zygomatic breadth less; mastoid breadth greater; width across alveolar processes of maxillae greater; alveolar length of upper molar series greater; molariform teeth larger. Compared with topotypes of _Thomomys bottae minimus_, _stansburyi_ is seen to be of larger size and darker color throughout, with a skull that is larger in most every measurement taken, although of the same slender, smooth, nonangular type. Among named races of _Thomomys bottae_, _stansburyi_ most closely resembles tivius, a small, dark, mountain form from central Utah. Size and color are almost the same but _stansburyi_ differs in: Tail shorter; hind foot averaging slightly longer. Skull: Generally larger in every measurement taken; zygomatic arches shorter; width across alveolar processes of maxillae greater; zygomatic arches more widely spreading, and widest in extreme posterior region rather than in region of jugal-squamosal suture. _Remarks._--The Stansbury Mountains are separated from the Oquirrh Mountains by the Stockton Bar, and from the Onaqui Mountains, which are in reality a continuation of the Stansbury Mountains, by only a low pass. Pocket gophers from Clover Creek, Onaqui Mountains and Little Valley, Sheeprock Mountains, although intergrades between _robustus_ and _albicaudatus_ are dark in color like _stansburyi_. These intergrades are large, dark colored, and have heavy, ridged, angular skulls. It appears that _stansburyi_ is a mountain subspecies derived from _albicaudatus_ of the valley. It would be instructive to artificially transplant gophers from mountains to valleys, and _vice versa_, so as to reveal what effects if any on the animals' morphology the environment might have in one or a few generations. Gophers are well known to be very plastic, and such an experiment as suggested might call for modification of the view, held here, that the differential features of gophers from South Willow Creek and, say, Bauer, are hereditary. _Specimens examined._--Total, 11, from the type locality. =Thomomys bottae albicaudatus= Hall _Thomomys perpallidus albicaudatus_ Hall, Univ. California Publ. Zooel., 32:444, July 8, 1930; Univ. California Publ. Zooel., 37:3, April 10, 1931.