Diagnosis.—Size medium (see measurements). Color light, entire dorsal surface between (c) Light Ochraceous-Buff and Ochraceous-Buff, purest on sides, flanks and cheeks; upper parts slightly suffused with black; arietiform markings, pinnae of ears, plantar surfaces of hind feet, dorsal and ventral stripes of tail, grayish to blackish in different individuals. Skull medium in size; rostrum long and narrow; nasals long; auditory bullae relatively narrow and skull long, giving appearance of much narrower skull than is actually the case; zygomata weak; upper incisors moderately wide at cutting edge.
Comparisons.—From Dipodomys ordii uintensis, D. o. priscus differs as follows: Hind foot longer; color lighter in all pigmented areas, and skull smaller in all measurements taken.
From Dipodomys ordii sanrafaeli, D. o. priscus differs in: Color decidedly less red in upper parts; ventral stripe of tail not continuous to end of pencil; nasals longer; auditory bullae less inflated.
For comparisons with Dipodomys ordii luteolus and Dipodomys ordii terrosus see accounts of those subspecies.
Remarks.—The characters of this subspecies are stable throughout most of its geographic range. It is not known to intergrade with adjacent forms. One specimen, a male, available from the Snake River, south of Sunny Peak, Colorado, however, is not typical of D. o. priscus, in that it has a wider and deeper rostrum than any other specimen from the entire range. Between D. o. priscus and D. o. luteolus, the skull, but not the color, provides diagnostic differences.
The Red Desert of Wyoming is mostly sandy but there are large exposures of rock and gravel. At the type locality of D. o. priscus rockier soil predominates but is interspersed with stabilized sand dunes where the kangaroo rats are abundant. Traps set on the rocky soils, in a continuous line between the dunes, yielded no kangaroo rats.
Kangaroo rats in the area of the Kinney Ranch, Wyoming, apparently form a good source of food for owls, since many bones (jaws and limb elements) were found in owl pellets at the bases of cliffs approximately 5 miles northeast of the ranch buildings.
Specimens examined.—Total, 72, distributed as follows:
Wyoming: Fremont County: 7 mi. N Fort Washakie, 1 (USBS); Fort Washakie, 1 (USBS); Wind River, 1 (USBS). Sweetwater County: Eden, 1 (USBS); 5 mi. E Rock Springs, 1 (UM); 10 mi. SW Granger, 13 (UM); Bitter Creek, 9 (6 AMNH; 3 CNHM); Kinney Ranch, 21 mi. S Bitter Creek, 18 (MVZ); Shell Creek, 25 mi. S Bitter Creek, 3 (CM); 30 mi. S Bitter Creek, 3 (KU); 33 mi. S Bitter Creek, 8 (KU). Carbon County: 20 mi. W Baggs, 2 (USBS).
Utah: Daggett County: E bank Green River, 4 mi. E Linwood, 4 (CM).