This subspecies of _Dipodomys ordii_, inhabiting west-central Colorado and southeastern Utah, is darker than any other subspecies with which its range comes in contact. The races to both the north and south are larger, with the exception of the hind foot which is longer in _D. o. nexilis_ than in either _D. o. sanrafaeli_ or _D. o. longipes_. The affinities of _D. o. nexilis_ are with _D. o. longipes_ rather than with any of the other known subspecies of _Dipodomys ordii_. Intergradation between _D. o. nexilis_ and _D. o. longipes_ is shown by animals from Bluff, San Juan County, Utah, which, however, are referable to the latter. In animals from sixteen miles northwest of Moab, Grand County, Utah, there is intergradation in size of skull and in color between _D. o. nexilis_ and _D. o. sanrafaeli_. The specimens are referred to _D. o. sanrafaeli_. _D. o. nexilis_ is apparently prevented from extending its range to the northward by the presence there of _D. o. sanrafaeli_. To the south _D. o. nexilis_ encounters _D. o. longipes_ and the San Juan River. To the east it is limited by the Rocky Mountains and to the west by the deep canyons of the Colorado River. Warren (1942:183) did not apply the name _D. o. nexilis_ to Ord kangaroo rats in Colorado. He listed specimens from Montrose, Montezuma and Mesa counties as being referable to _D. o. longipes_. The specimens from Montezuma County, Colorado, probably are _D. o. longipes_ and those from Montrose and Mesa counties (for which Warren gives no precise localities) are _D. o. nexilis_. _Specimens examined._--Total, 35, distributed as follows: =Utah=: _Grand County_: Cisco, 4 (CM); 18 mi. NE Moab, 6000 ft., 1 (UU). _San Juan County_: 15 mi. N Monticello, 4 (MVZ); Blanding, 1 (UU). =Colorado=: _Delta County_: Hotchkiss, 1 (USBS). _Montrose County_: Paradox, 1 (DRD); Bedrock, 4 (AMNH); 5 mi. W Naturita, 2 (USBS); Coventry, 3 (1 USBS; 2 AMNH). =Dipodomys ordii cupidineus= Goldman _Dipodomys ordii cupidineus_ Goldman, Journ. Washington Acad. Sci., 14:372, September 19, 1924. _Type._--Male, no. 243093, U. S. Nat. Mus. Biol. Surv. Coll.; Kanab Wash, at southern boundary of Kaibab Indian Reservation, Arizona; obtained on October 12, 1922, by E. A. Goldman, original no. 23384. _Range._--Northeastern Arizona and south-central Utah; marginal occurrences are: in Utah, Escalante, near Paria and S of Virgin; in Arizona, 6 mi. N Wolf Hole, 20 mi. S Wolf Hole, 5 mi. S Trumbull Spring and 10 mi. S Jacobs Pools in Houserock Valley.