Like other subspecies of the species _D. ordii_, _D. o. terrosus_ prefers sandy soils to those of any other type. Two miles east and 1 mile south of Forsyth, Montana, animals were trapped on lenses of sandy soil. These lenses alternated with areas of black loam of similar size. It was noteworthy that burrows were found only in the areas of sandy soil, although paths used by the rats when foraging did extend onto and several crossed the lenses of black loam. We were not permitted to excavate any of these burrows, but conversation with farmers of the immediate vicinity indicated that the burrows were not deep. An eight-inch disc would frequently plow out nests and food caches. It was said that each of several caches contained as much as a peck of wheat. Intergradation was noted in animals from 23 miles southwest of Newcastle and Arvada, Wyoming. In animals from both localities the pterygoid fossae are more as in _D. o. luteolus_ but referable to _D. o. terrosus_. The specimens from Arvada, although immature, possessed cranial characters which were intermediate between those of _D. o. terrosus_ and _D. o. luteolus_ but the specimens are referable to the former. _Specimens examined._--Total, 74, distributed as follows: =Montana=: _Petroleum County_: 24 mi. N Roundup, 8 mi. SW Flatwillow, 2 (UM). _Garfield County_: Jordan, 10 (1 UM; 2 MVZ; 7 AMNH). _Dawson County_: Glendive, 9 (USNM). _Musselshell County_: Harvey Ranch, Melstone, 3 (MVZ). _Rosebud County_: Yellowstone River, 5 mi. W Forsyth, 2750 ft., 7 (MVZ); 2 mi. E and 1 mi. S Forsyth, 2600 ft., 8 (KU). _Custer County_: Miles City, 1 (USBS). _Yellowstone County_: Billings, 2 (1 USBS; 1 MVZ). _Big Horn County_: Fort Custer, 1 (USBS); Crow Agency, 1 (USBS). _Powder River County_: Powderville, 4 (USBS). _Carter County_: Medicine Rocks, 15 mi. N Ekalaka, 2 (USBS); Medicine Rocks, 14 mi. N Ekalaka, 2 (USBS); Clark's Fork, 1 (USBS). =Wyoming=: _Big Horn County_: Dry Creek, 10 mi. W Germania, 1 (USBS); 3 mi. E Germania, 1 (USBS); Greybull, 2 (USBS); Bighorn Basin, 1 (USBS). _Sheridan County_: Arvada, 8 (USBS). _Campbell County_: Little Powder River, 1 (USBS). _Weston County_: Newcastle, 2 (USBS); 23 mi. SW Newcastle, 4 (USBS). _Fremont County_: Wilson's Ranch, Sheep Creek, S base Owl Creek Mountains, 1 (USBS). _Additional records._--=Canada= (Anderson, 1946:131): _Alberta_: near Medicine Hat, 1; _Saskatchewan_: near Shackleton, 45-50 mi. NW Swift Current, 1; near Tompkins, 50 mi. W Swift Current, 1. =Dipodomys ordii fremonti= Durrant and Setzer _Dipodomys ordii fremonti_ Durrant and Setzer, Bull. Univ. Utah, 35 (no. 26):21, June 30, 1945. _Type._--Female, no. 15661, Carnegie Museum, Pittsburgh, Pennsylvania; Torrey, 7000 ft., Wayne County, Utah; obtained on July 19, 1938, by W. F. and F. H. Wood, original no. 1562. _Range._--Known only from the type locality.