From _Dipodomys ordii cupidineus_, _D. o. longipes_ differs in: Size larger; color lighter; rostrum longer and narrower; nasals longer; interorbital width greater; breadth across zygomatic processes of maxillae greater; auditory bullae more inflated; zygomatic arches heavier and more bowed laterally. For comparisons with _Dipodomys ordii medius_ and _Dipodomys ordii nexilis_ see accounts of those subspecies. _Remarks._--The large reddish _Dipodomys ordii longipes_ is notably distinct from those subspecies which have adjoining ranges. The subspecies closest, geographically and morphologically, is _Dipodomys ordii nexilis_ with which _D. o. longipes_ intergrades, in size of body and color of pelage, north of the San Juan River, Utah. This intergradation is probably the result of a migration of _D. o. longipes_ around the head waters of, or above the place in, the river where there is constantly flowing water. It is probably impossible for these animals to cross a constantly flowing stream as wide as the San Juan is in its lower reaches. The San Juan River, however, in 1896, and again in 1934, was so low that it ceased to flow below Aneth (Gregory, 1938:6, 19). Consequently, at these times, _Dipodomys_ could have crossed the river from one side to the other, at least above the Goosenecks. Intergradation is noted also with _Dipodomys ordii medius_ at Chama Canyon, New Mexico, where the color is like that of _D. o. medius_, although the cranial characters are as in _D. o. longipes_; specimens from Chama Canyon are referred to the latter. Ten miles southwest of Quemado and at Riley, New Mexico, intergradation with _Dipodomys ordii ordii_ occurs in the shape of the nasals and the intermediate size of the skull. In color and external measurements these animals more closely resemble _D. o. longipes_.