Remarks.—This jumping mouse, which was described from the Pine Forest Mountains, closely resembles Zapus princeps oregonus but differs in lighter color, slightly smaller body, less divergent tooth-rows, shorter palate, and narrower skull across the mastoid region.
The Pine Forest Mountains are isolated from neighboring boreal regions by a belt of the Upper Sonoran Life-zone, which is inhospitable to Zapus; therefore, intergrades between Z. p. oregonus and Z. p. curtatus are not known and probably do not exist. Nevertheless, Z. p. curtatus shows close affinity with Z. p. oregonus, as indicated by Taylor (1911:281), and I agree with Hall (1931:7) that the relationships of Z. p. curtatus are best expressed by arranging it as a subspecies of Zapus princeps.
Specimens examined.—Total, 18, all from Nevada, distributed as follows: Humboldt County: Pine Forest Mts.; Alder Creek, 6000 ft., 2 (MVZ); head of Big Creek, 8000 ft., 14 (MVZ); Leonard Creek, 6500 ft., 2 (MVZ); Meadow, 1 (MVZ).
Marginal records.—Nevada: Pine Forest Mts., Alder Creek; Meadow.
Zapus princeps idahoensis Davis
Zapus princeps idahoensis Davis, Jour. Mamm., 15:221, August 10, 1931.
Jaculus hudsonius, Allen, Bull. Essex Inst., 6:61, April, 1874 (part—the part in Carbon County, Wyoming).
Zapus hudsonius, Merriam, N. Amer. Fauna, 5:72-73, July 30, 1891.
Zapus princeps princeps, Preble, N. Amer. Fauna, 15:22-23, August 8, 1899 (part).
Type.—Male, adult, skin and skull; No. 54845, Mus. Vert. Zool.; 5 mi. E Warm Lake, 7000 ft., Valley County, Idaho; obtained on July 9, 1932, by Robert T. Orr; original No. 660.