_Dipodomys ordii idoneus_ differs from _Dipodomys ordii attenuatus_ in larger size, generally darker color and larger skull. _Remarks._--This subspecies of _Dipodomys ordii_ is paler than either of the subspecies with adjoining geographic ranges. Measurements of the skull, in proportion to external measurements, are larger than in any other subspecies of _Dipodomys ordii_. Cranially, this new subspecies is more closely allied to _Dipodomys ordii fuscus_ but in color appears to be much closer to _Dipodomys ordii attenuatus_ from which it differs markedly in cranial features. _Specimens examined._--Total, 3, all from Durango, distributed as follows: San Juan, 12 mi. W Lerdo, 3 (UM). =Dipodomys ordii priscus= Hoffmeister _Dipodomys ordii priscus_ Hoffmeister, Proc. Biol. Soc. Washington, 55:167, December 31, 1942. _Perodipus longipes_, Allen, Bull. Amer. Mus. Nat, Hist., 8:246, November, 1896 (part--the part from Kinney Ranch, Wyoming). _Perodipus montanus richardsoni_, Cary, N. Amer. Fauna, 33:141, August 17, 1911 (part--the part from Lay, Colorado). _Periodipus_ [_Dipodomys_] _ordii luteolus_, Svihla, Journ. Mamm.; 12:262, August, 1931 (part--the part from Linwood, Utah). _Type._--Male, no. 89119, Mus. Vert. Zool., Univ. California; Kinney Ranch, 21 mi. S Bitter Creek, 7100 ft., Sweetwater County, Wyoming; obtained on September 16, 1939, by Donald T. Tappe, original no. 766. _Range._--Southwestern Wyoming, extreme northeastern Utah and northwestern Colorado; marginal occurrences are: in Wyoming, 7 mi. N Ft. Washakie and 10 mi. SW Granger; in Colorado, Lay and Snake River south of Sunny Peak. _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.