_Remarks._--The affinities of _nesophilus_ of Antelope Island are unquestionably with _albicaudatus_ of the eastern and southern mainland. At the time of this writing (1945), Antelope Island is not truly an island, but only the tip of a broad peninsula projecting westward into Great Salt Lake. Nevertheless, the area of occurrence of _nesophilus_ is effectively isolated by the exposed, sandy lake bottom that is unsuited to occupancy by pocket gophers. Fluctuations in the level of the Great Salt Lake have broken and reestablished this connection with the mainland many times. Each of the several other kinds of mammals which are known from both the island and the mainland show no differentiation on the island. These are kinds (see Marshall, 1940:156), which more freely cross the exposed, sandy lake bottom. I, myself, have noted tracks of coyotes going to and from the island. The pocket gopher, _nesophilus_, so far as known is the only mammal which has developed a subspecies endemic to the island. The beach levels of Pleistocene Lake Bonneville are well marked on both Antelope Island and Stansbury Island, which is fifteen miles west of Antelope Island. On the eastern side of Antelope Island the lower beach levels of this prehistoric lake are farmed. Although sought for elsewhere on this island, pocket gophers were found only in the farmed land. On Stansbury Island there has been no farming, and the endemic pocket gophers, _minimus_, although sought for elsewhere on that island were found only above the highest beach levels of the ancient lake. Evidently these pocket gophers still occupy only that part of Stansbury Island that projected above water during the greatest height of Lake Bonneville. Farming on Antelope Island may have developed a more favorable environment for pocket gophers, thus causing them to move down to the lower levels from that part of the island that was above water during Pleistocene times. _Specimens examined._--Total, 5, from the type locality. =Thomomys bottae stansburyi= new subspecies _Type._--Female, adult, skin and skull, No. 2045, Museum of Zooelogy, University of Utah; South Willow Creek, Stansbury Mountains, 7,500 ft., Tooele County, Utah; July 2, 1937; collected by O. S. Walsh and S. D. Durrant; original number 1257 of Durrant. _Range._--Stansbury Mountains, Tooele County, Utah. _Diagnosis._--Size small (see measurements). Color: Upper parts Saccardo's Umber, darker on head; sides and underparts Pinkish Buff; nose, chin and postauricular patches black; front and hind feet and distal third to half of tail white. Skull: Small, slender, weak and smooth; zygomatic arches light and not widely spreading; zygomatic arches actually as well as relatively short; interparietal generally quadrangular; nasals relatively long and slender; interpterygoid space narrowly V-shaped; basioccipital fairly wide; tympanic bullae moderately inflated ventrally; dentition light.