_Perodipus longipes_, Warren, Mammals of Colorado, p. 77, 1910 (part--the part from Coventry, Colorado). _Dipodomys ordii longipes_, Moore, Journ. Mamm., 10:260, August, 1929 (part--the part from Monticello, Utah). _Type._--Male, adult, no. 149938, U. S. Nat. Mus. Biol. Surv. Coll.; 5 mi. W Naturita, Montrose County, Colorado; obtained on July 20, 1907, by Merritt Cary, original no. 1068. _Range._--West-central Colorado, southwest into San Juan County, Utah, north of the San Juan River; northwest into Grand County, Utah, to the Colorado River; and westward probably as far as the Colorado River; marginal occurrences are: in Utah, Cisco, 18 mi. NE Moab, and Blanding; in Colorado, 5 mi. W Naturita, and Coventry. _Diagnosis._--Size medium (see measurements). Color dark, entire dorsal surface between (_a_) Cinnamon-Buff and Clay Color, purest on sides and flanks, upper parts strongly suffused with black; arietiform markings, pinnae of ears, plantar surfaces of hind feet, dorsal and ventral tail-stripes blackish. Lateral white stripes of tail less than one fourth of diameter of tail. Skull large; rostrum long and narrow; nasals long; auditory bullae strongly inflated; braincase not inflated; pterygoid fossae ovoid. _Comparisons._--From _Dipodomys ordii sanrafaeli_, _D. o. nexilis_ differs in: Color darker; skull smaller in all measurements taken; auditory bullae noticeably smaller; width across zygomatic processes of maxillae less. From _Dipodomys ordii longipes_, _D. o. nexilis_ differs in: Size smaller; color darker in all respects; rostrum wider; breadth across auditory bullae less; interorbital width greater; breadth across zygomatic processes of maxillae less; cutting edge of upper incisors wider; zygomatic arch lighter and more nearly straight. Comparison with _Dipodomys ordii evexus_ is made in account of that subspecies. _Remarks._--This animal is apparently not abundant at any place in its range. Two different attempts, by me, to obtain topotypes were unsuccessful. A single specimen was obtained and that was only a skull saved from a mutilated animal that was taken away from a rattlesnake. The habitat at the type locality is such that a person would not expect it to be inhabited by kangaroo rats. The soil is a heavy clay with a generous admixture of stones but in isolated spots there are light sandy soils which should be suitable for kangaroo rats. Even so, 500 traps set in the area of the type locality over a period of two nights yielded no _Dipodomys_.