_Description._--Size medium; back dark, from near Tawny-Olive to near Cinnamon with heavy admixture of black hair forming dorsal band; sides lighter than back and from near Tawny-Olive to near Cinnamon, sometimes with admixture of black hair giving sides streaked appearance; lateral line usually distinct, clear Ochraceous-Buff; underparts white, sometimes with slight suffusion of Ochraceous-Buff; tail bicolored, brown to brownish-black above, grayish-white to yellowish-white below; ears dark, usually edged with ochraceous; feet grayish-white above; incisive foramina relatively short and broadly rounded; zygomata relatively short; braincase relatively broad; auditory bullae flat, long, and relatively broad; pterygoid fossae relatively narrow; nasals relatively broad and short. _Comparisons._--From _Zapus hudsonius alascensis_, _Z. h. hudsonius_ differs as follows: upper parts generally darker, more black tipped hair; sides darker with greater suffusion of dark hair; lateral line brighter, more distinct; size averaging smaller; zygomatic arches less bowed outward; distance from incisors to postpalatal notch shorter; zygomata shorter; occipitonasal length less; mastoid region narrower. From _Zapus hudsonius intermedius_, _Z. h. hudsonius_ differs in: color darker, more tawny dorsally; sides averaging darker, more black-tipped hairs; size averaging larger; braincase averaging broader; distance from incisors to postpalatal notch averaging slightly shorter; zygomata averaging longer; mastoid region averaging broader; incisive foramina averaging shorter. From _Zapus hudsonius tenellus_, _Z. h. hudsonius_ differs as follows: upper parts averaging darker; tail averaging shorter; condylobasal length averaging more; braincase averaging broader; auditory bullae broader and less inflated; interparietal averaging broader; incisive foramina more broadly rounded and averaging longer. For comparison with _Zapus hudsonius canadensis_ and _Zapus hudsonius campestris_ see accounts of those subspecies.