_Type._--Female, adult, no. 262655, U. S. Nat. Mus. Biol. Surv. Coll.; Bird Island, Great Salt Lake, 4,300 ft., Tooele County, Utah; obtained on June 22, 1937, by W. H. Marshall, X-catalog no. 27969. _Range._--Bird, Carrington, Badger and Stansbury islands, Great Salt Lake; around western edge of Great Salt Lake north to Kelton, Box Elder County, Utah; around southern and southeastern edge of the lake to mouth of the Jordan River; marginal occurrences are: all in Utah, Kelton, 2 mi. W Grantsville, 14 mi. W Salt Lake City and Bird Island, Great Salt Lake. _Diagnosis._--Size medium (see measurements). Color pale, entire dorsal surface near Pinkish Buff, purest on sides, flanks and cheeks with but slight suffusion of black on upper parts; arietiform markings, pinnae of ears, plantar surfaces of hind feet, and dorsal and ventral stripes of tail, brownish. Skull medium in size; rostrum narrow and long; pterygoid fossae ovoid; cutting edge of upper incisors narrow; external auditory meatus round and small; jugal straight or nearly so. _Comparisons._--From _Dipodomys ordii pallidus_, _D. o. marshalli_ differs in: Hind foot smaller; color darker, arietiform markings more distinct; dorsal and ventral stripes of tail more pronounced; skull smaller; palate shorter and wider; jugals lighter; external auditory meatus smaller; cutting edge of upper incisors narrower; nasals shorter and less flared distally. From _Dipodomys ordii utahensis_, _D. o. marshalli_ differs in: Size smaller; color lighter; skull smaller, except least interorbital width and depth of auditory bullae which are greater; cutting edge of upper incisors narrower; nasals less flared distally. For comparison with _Dipodomys ordii celeripes_ see account of that subspecies. _Remarks._--This subspecies was described from Bird Island, Great Salt Lake, and was thought by Marshall (1940:153), who collected the specimens, to be restricted to that island. However, specimens taken over a period of years on the nearby mainland, by students from the University of Utah, are referable to this subspecies. Although these animals from the mainland are referable to _D. o. marshalli_, they have some characteristics of _D. o. utahensis_ from the eastern and southern mainland. Four specimens from Kelton, also on the mainland, are not typical of _D. o. marshalli_; nevertheless, more than half of their characters of taxonomic worth are as in _D. o. marshalli_ to which the animals are referred.