Zapus hudsonius campestris Preble, N. Amer. Fauna, 15:20, August 8, 1899.
Type.—Male, adult, No. 65872 U. S. Nat. Mus., Biol. Surv. Coll.; Bear Lodge Mt’s [Crook County], Wyoming; obtained on June 21, 1894, by B. H. Dutcher, original No. 600.
Range.—Southeastern Montana, southwestern South Dakota, and northeastern Wyoming. See [fig. 47]. Zonal range: Transition.
Description.—Size large; back from near Ochraceous-Tawny to near Ochraceous-Buff with admixture of black tipped hair forming distinct dorsal band; sides lighter than back, from near Ochraceous-Buff to near Yellow Ocher with black hair interspersed; lateral line usually distinct, of clear Ochraceous-Buff; belly white, usually with moderate suffusion of Ochraceous-Buff; tail bicolored, brownish to brownish-black above, grayish-white to yellowish-white below; ears dark, edged with Ochraceous-Buff; feet grayish-white above; auditory bullae large, well inflated; incisive foramina long and usually truncate at posterior border; pterygoid fossae broad; zygomata relatively wide-spread and long; large medial projection on inferior ramus of zygomatic process of maxillary; condylobasal length and occipitonasal length relatively great; mastoid region and palatal region relatively broad; interparietal bone usually broad.
Comparisons.—From Zapus hudsonius pallidus, Z. h. campestris differs as follows: Coloration darker (more black and yellow but less orange); averaging larger in all measurements taken except in least interorbital constriction and distance from incisors to postpalatal notch which are slightly larger and breadth across zygomatic arches which is same; zygomatic arch heavier; incisive foramina larger; interparietal bone broader.
Compared with Zapus hudsonius intermedius, Z. h. campestris differs as follows: Coloration more tawny and ochraceous, less yellow; auditory bullae averaging larger, more inflated; condylobasal length averaging greater; zygomata averaging more wide-spread and longer; distance from incisors to postpalatal notch averaging longer; mastoid region broader; incisive foramina longer and more truncate posteriorly.
From Zapus hudsonius hudsonius, Z. h. campestris differs as follows: Size larger; color lighter, more ochraceous, less tawny; occipitonasal length averaging greater; mastoid region broader; zygomata averaging longer; zygomatic arch more widely bowed; distance from incisors to postpalatal notch averaging longer; incisive foramina longer; auditory bullae broader, more inflated.
For comparison with Zapus hudsonius preblei see account of that subspecies.
Remarks.—Animals from the Black Hills of South Dakota and Wyoming are thought of as most characteristic of this geographic race. Intergradation is noted with Zapus hudsonius pallidus and is discussed in the account of that subspecies.
Specimens examined.—Total, 66, distributed as follows: