Zapus princeps cinereus Hall, Univ. California Publ. Zool., 37:7, April 10, 1931.
Type.—Female, adult, skin and skull; No. 45422, Mus. Vert. Zool.; Pine Canyon, 6600 feet altitude, Raft River Mountains, 17 mi. northwest Kelton, Boxelder County, Utah; obtained on July 14, 1930, by Annie M. Alexander; original No. 689.
Range.—Raft River Mt’s in northwestern Utah and in isolated mountains in southern Idaho. See [fig. 46]. Zonal range: Transition and Canadian.
Description.—Size, medium; back with broad mid-dorsal band, varying from pale brown mixed with Pinkish-Buff to dark brown mixed with Warm-Buff or Ochraceous-Buff; sides varying from near Pinkish-Buff to near Ochraceous-Buff; ventral surface white to base of hairs, not suffused with other color; tail bicolored, pale brown above and white to yellowish-white below; ears dark, edged with white or yellowish-white; upper teeth divergent anteriorly; auditory bullae small; skull relatively long; zygomata relatively weak and not widely bowed; nasals wide posteriorly; pterygoid fossae relatively narrow.
Comparisons.—From Zapus princeps nevadensis, Z. p. cinereus differs as follows: Size averaging smaller; entire coloration lighter; zygomata not so widely bowed; incisive foramina not so wide posteriorly; auditory bullae smaller; nasals wider posteriorly; pterygoid fossae narrower.
From Zapus princeps idahoensis, Z. p. cinereus can be distinguished by: generally paler color; smaller auditory bullae; broader interorbital region; anteriorly diverging tooth-rows; narrower pterygoid fossae.
For comparison with Zapus princeps utahensis see account of that subspecies.
Remarks.—Davis (1939:343) writes that “since cinereus was described from nine specimens, only two of which are near adult, one cannot place much value on the coloration ascribed to it by Hall (1931:7).” I examined the type series and found, as did Davis (loc. cit.), that the type is much lighter and grayer than is a near adult paratype, which was obtained the same day; however, I do not concur with Davis (loc. cit.) that specimens from Mt. Harrison, 10 mi. S Albion, Idaho, which are darker and much more ochraceous than the paratype, necessarily are more nearly typically colored. These individuals, judged by cranial characters, are more nearly typical of cinereus but show intergradation with Z. p. idahoensis in their darker and more ochraceous pelage.
Durrant (1952:387) found that the gray color of Z. p. cinereus was not diagnostic in separating Z. p. cinereus from Z. p. utahensis, because gray animals are also found in Z. p. utahensis. Specimens from Camp Tendoy, Pocatello, Idaho, are intermediate in color and in cranial characters as between Z. p. idahoensis and Z. p. cinereus, but here are referred to Z. p. cinereus. Whitlow and Hall (1933:268) compared these individuals with specimens of Z. p. princeps and Z. p. cinereus, finding them intermediate but in the aggregate of several differential characters better referred to the latter.
Specimens examined.—Total, 35, distributed as follows: