=Arizona=: _Mohave County_: near S Boundary Kaibab Indian Reservation, 4 (MVZ); 6 mi. N Wolf Hole, 8 (MVZ); 4 mi. N Wolf Hole; 3 mi. NW Diamond Butte, 7 (USBS); 20 mi. S Wolf Hole, 1 (USBS); 1 mi. W Diamond Butte, 1 (USBS); 6 mi. N Mt. Trumbull, 1 (USBS); Nixon Springs, 6250 ft., W Base Mt. Trumbull, 6 (3 USBS; 3 MVZ); 5 mi. S Trumbull Spring, 1 (USBS). _Coconino County_: Fredonia, 3 (USBS); 2 mi. W Lees Ferry, 3 (MVZ); Jacobs Pools, 4000 ft., Houserock Valley, 15 (MVZ); 10 mi. S Jacobs Pools, Houserock Valley, 2 (MVZ); Houserock Valley, 10 (USBS). =Dipodomys ordii palmeri= (Allen) _Dipodops ordii palmeri_ Allen, Bull. Mus. Comp. Zool., 8:187, 1881. _Cricetodipus ordii palmeri_, Trouessart, Catalogus Mammalium, 1:581, 1897. _Perodipus ordii palmeri_, Goldman, Proc. Biol. Soc. Washington, 30:113, May 23, 1917. _Dipodomys ordii palmeri_, Grinnell, Journ. Mamm., 2:96, May 2, 1921. _Cotypes._--Two males, adults, nos. 5886 and 5887, Mus. Comp. Zool.; San Luis Potosí, Mexico; obtained on May 1, 1878, and September 1, 1878, respectively, by Dr. Edward Palmer. (Types not seen.) _Range._--Eastern Zacatecas, Aguascaliente, northern Jalisco, San Luis Potosí, Hidalgo, and probably Querétaro; marginal occurrences are: Zacatecas, Canitas and Berriozobal; Aguascaliente, 1 mi. N Chicalote; Jalisco, 9 mi. N Encarnación; Guanajuato, Celaya; Hidalgo, Irolo. _Diagnosis._--Size small (see measurements). Color dark, entire dorsal surface (_h_) between Cinnamon and Sayal Brown, purest on sides and flanks, upper parts strongly suffused with black; posterior surfaces and fold of pinnae of ears, white; arietiform markings, plantar surfaces of hind feet, inside of pinnae of ears, dorsal and ventral stripes of tail, blackish. Skull small; nasals long; rostrum long and narrow; interorbital region relatively wide; degree of inflation of auditory bullae about average for species; zygomatic arches light and bowed laterally; pterygoid fossae subcircular; braincase but slightly vaulted. _Comparisons._--From _Dipodomys ordii ordii_, _D. o. palmeri_ differs as follows: Size somewhat larger; color darker; skull larger; nasals longer and flaring distally; interorbital width greater; narrower across auditory bullae; interparietal region narrower; breadth across maxillary arches greater; zygomatic arches bowed laterally as opposed to relatively straight; pterygoid fossae more nearly circular; rostrum longer and narrower. From _Dipodomys ordii sennetti_, _D. o. palmeri_ differs in larger size, darker color, longer tail and longer skull. For comparisons with _Dipodomys ordii obscurus_ and _Dipodomys ordii fuscus_ see accounts of those subspecies.