Diagnosis.—Size medium (see measurements). Color dark; entire dorsal surface between (10") Pinkish Cinnamon and Cinnamon-Buff, purest on sides and flanks, upper parts strongly suffused with black; arietiform markings, pinnae of ears, plantar surfaces of hind feet, dorsal and ventral stripes of tail, blackish. Skull medium in size; rostrum long and narrow; nasals long; auditory bullae slightly distended; braincase vaulted.
Comparisons.—For comparisons with Dipodomys ordii cupidineus, Dipodomys ordii longipes and Dipodomys ordii ordii see accounts of those subspecies.
Remarks.—This subspecies of Dipodomys ordii is relatively isolated from other subspecies of the species. The Colorado River with its deep canyons is interposed between the ranges of D. o. chapmani and D. o. cupidineus. A high range of mountains separates D. o. chapmani from the range of D. o. longipes. The only race with which D. o. chapmani probably comes into contact is D. o. ordii to the southeast. No specimens are available from the southeastern part of the range of D. o. chapmani. Animals from the northwestern part of the range of D. o. ordii, without exception, have dark-colored pelage which is characteristic of D. o. chapmani. In the shape of the nasals, vault of the braincase, interorbital width and auditory bullae, animals from Rice, Arizona, resemble D. o. chapmani, but in other characters resemble D. o. ordii to which subspecies they are referred. Animals from 20 miles northeast of Calva, Arizona, are dark-colored and are intermediate between the dark D. o. chapmani and the pale D. o. ordii in size of the cranium and body but are referable to D. o. ordii. In the northwestern part of the range of D. o. chapmani the animals are not typical in that they have a shorter, wider rostrum and a heavier zygomatic arch than topotypes.
Specimens examined.—Total, 90, all from Arizona, distributed as follows: Mohave County: lower end Prospect Valley, 4500 ft., Grand Canyon, 7 (USBS); Kingman, 9 (LACM). Coconino County: Aubrey Valley, 10 mi. S Pine Spring, 4 (USBS); Bill Williams Mountain, 1 (USNM). Yavapai County: 3 mi. N Fort Whipple, 11 (USBS); Fort Whipple, 4 (2 USBS; 2 USNM); Willow Creek, 4 mi. N Prescott, 4 (MVZ); 1 mi. W Camp Verde, 1 (MVZ); Camp Verde, 33 (15 USBS; 3 MVZ; 3 AMNH; 9 LACM; 3 DRD); 1/2 mi. S Camp Verde, 4 (MVZ); Kirkland, 9 (USBS); Turkey Creek, 3 (USBS).
Dipodomys ordii montanus Baird
Dipodomys montanus Baird, Proc. Acad. Nat. Sci. Philadelphia, 7:334, April, 1855.
Perodipus montanus, Merriam, Proc. Biol. Soc. Washington, 17:140, July 14, 1904.
Perodipus ordii montanus, [Goldman], Proc. Biol. Soc. Washington, 30:113, May 23, 1917.
Dipodomys ordii montanus, [Grinnell], Journ. Mamm., 2:96, May 2, 1921.