The animals from Fairfield, Utah County, are closer geographically to the type locality of _albicaudatus_ than any other series, but morphologically are the least like topotypes. At first glance one is struck with the differences. They are uniformly Clay Color above, with Cinnamon Buff sides and flanks and Pinkish Buff underparts. Their color closely approaches that of _robustus_ to the west which has Cinnamon Buff on the upper parts. Examination of eleven measurements of males and the same number for females, shows that the animals are nearest to _robustus_ in two measurements, to _albicaudatus_ in 12, distinct in 7 and intermediate in one. The general appearance of the skull is intermediate between that of the two above mentioned forms. The differences from _albicaudatus_ in size and color may be correlated with the differences in soil at Fairfield and Provo. At Fairfield the soil is light-colored clay, but at Provo it is sandy and darker. Although they are intergrades between _robustus_ and _albicaudatus_, the animals are referred to the latter race. Utah Lake and its outlet, the Jordan River, make a partial barrier between populations at Fairfield and at the type locality at Provo. During Pleistocene times, when Lake Bonneville was present it formed a complete barrier. Enough time has evidently elapsed since the disappearance of this lake to allow _albicaudatus_, the mainland form, to expand its range to the west. Intergradation has taken place, with the result that the animals from Fairfield, although unstable, agree with the mainland form, _albicaudatus_, in a majority of their characters.
Pocket gophers were taken at four localities from north to south in eastern Juab County. They range in color from Ochraceous Tawny on the upper parts and Cinnamon Buff on the underparts to shades that are slightly lighter. All are much lighter than topotypes of _albicaudatus_. The general configuration of the skull is the same as that of _albicaudatus_, and this is especially true in the females. In the narrower rostrum and weaker dentition they approach _contractus_, but are distinctly lighter colored. Hall (1931:3) referred one specimen from Nephi, Juab County, to _Thomomys bottae aureiventris_. Since that time _Thomomys bottae lenis_ which has some affinities with _aureiventris_ has been described (see account of _contractus_). The large series now available from Nephi and nearby localities do show some intergradation with _lenis_, in that four characters are more as in _lenis_ and _contractus_ and seven characters are more as in _albicaudatus_. Although differing markedly in many respects from topotypes of _albicaudatus_ they fit the aforementioned concept of this subspecies, and are being treated as a variable local population of it.