_Zapus princeps palatinus_ Hall (1931:8) was described as having: palatal bridge long, incisive foramina wide posteriorly, posterior border of palate straight or convex posteriorly, and color pale. These characteristics are to be found in some individuals in most populations of _Z. p. oregonus_. Additional well marked cranial similarities, such as small auditory bullae, broad interorbital region, and nasals narrow posteriorly offer additional evidence as to the close relationship of _Z. p. palatinus_ and _Z. p. oregonus_. Hall (_loc. cit._), with a small sample available to him for comparative purposes (14 specimens of _Z. p. palatinus_ and 12 specimens of _Z. p. nevadensis_), was impressed by the condition of the palate in _Z. p. palatinus_ and wrote: "the generally straight, or even posteriorly convex, posterior border of the palate seems to be unique among described forms of _Zapus_. The name _palatinus_ is given in allusion to this structural feature." With more than 300 specimens of _Z. p. oregonus_ available for study I find that a straight or posteriorly convex posterior border of the palate occurs in more than 50 per cent of the individuals examined. Specimens displaying this described palatal condition are known from all parts of the range of _Z. p. oregonus_, but do occur in a higher percentage of specimens in the area ascribed by Hall (_loc. cit._) to the range of _Z. p. palatinus_. Intergradation with _Zapus princeps idahoensis_ and _Zapus princeps cinereus_ is discussed in the accounts of those subspecies. _Specimens examined._--Total, 340, distributed as follows: CALIFORNIA: _Modoc Co._: Buck Creek R. S., 1 (CAS); _Willow Ranch_, 4 (CAS); _Sugar Hill, 5000 ft._, 1 (MVZ); _Goose Lake Meadows, near Sugar Hill_, 4 (MVZ); _Parker Creek, Warner Mts., 5500 ft._, 18 (MVZ); _Dry Creek, Warner Mts., 4800 ft._, 3 (MVZ) _east face Warner Peak, Warner Mts., 8700 ft._, 1 (MVZ); _5 mi. NW Eagle Peak, 7000 ft._, 5 (MVZ); Lassen Creek, 1 (SDM); _Happy Camp_, 1 (CAS). IDAHO: _Boise Co._: Bald Mtn. R. S., Boise Nat'l Forest, 10 mi. S. Idaho City, 7400 ft., 2 (USBS). _Elmore Co._: Trail Creek, Boise Nat'l Forest, 2 (USBS). _Washington County_: 1 mi. NE Heath, SW Slope Cuddy Mtn., 4000 ft., 20 (5 MVZ). NEVADA: _Elko County_: _6 mi. SW Mountain City, Cobb Creek, 6500-6550 ft._, 44 (MVZ); _summit between heads of Copper and Coon creeks, Jarbidge Mts._, 18 (9 MVZ); _head of Ackler Creek, 6800 ft._, 2: Steel Creek, 7000 ft., 11 (4 MVZ); _summit of Secret Pass, 6200 ft._, 8; _south fork Long Creek, 7830 ft._, 4; Harrison Pass R. S., Green Mtn., Canyon, 6050 ft., 12. _Eureka County_: 4 mi. S Tonkin, Denay Creek, Roberts Mt's, 1 (MVZ). _Humboldt County_: _Martin Creek R. S._, 1 (MVZ); 13 mi. N Paradise Valley, 6700 ft., 19 (MVZ). _Lander County_: Kingston R. S., 7500 ft., 4 (MVZ). _Nye County_: Wisconsin Creek, 7000 ft., 12 (MVZ). _White Pine County_: Willow Creek, 2 mi. S Elko County line, Ruby Mts., 6500 ft., 24 (2 MVZ).