_Description._--Size medium; back from near Warm Buff to near Ochraceous-Buff with admixture of hair tipped with black or dark brown usually forming distinct, broad, dorsal band; sides lighter, from near Warm Buff to near Ochraceous-Buff with sparse mixture of dark-tipped hairs; lateral line often poorly marked but when present of clear Ochraceous-Buff; belly white, sometimes with slight suffusion of color of sides; tail bicolored, grayish-brown to brownish-black above, white to grayish-white or yellowish-white below; ears dark, narrowly edged with color of sides; feet white to grayish-white above; tail relatively short; lateral margins of nasals parallel; auditory bullae relatively short, broadly rounded, and moderately inflated; incisive foramina relatively long and narrow; pterygoid fossae relatively narrow; zygomata relatively long; inferior ramus of zygomatic process of maxillary frequently lacking a median projection. _Comparisons._--From _Zapus hudsonius pallidus_, _Z. h. intermedius_ differs as follows: Coloration duller, not so bright, more yellow or buff and less bright Ochraceous-Buff; interorbital region averaging narrower; incisive foramina averaging longer and narrower; condylobasal length averaging greater; braincase averaging broader; mastoid region averaging broader. For comparisons with _Zapus hudsonius hudsonius_, _Zapus hudsonius campestris_, and _Zapus hudsonius americanus_ see accounts of those subspecies. _Remarks._--_Zapus hudsonius intermedius_ has a large geographic range. There is some variation detectable when individuals from widely separate localities are compared, but where there is much variation it is obviously the result of intergradation. All characters differentiating _Z. h. intermedius_ from any contiguous subspecies are not present in every specimen even in the type series. Nevertheless, a certain series of cranial characters (narrow incisive foramina, short rounded auditory bullae, parallel lateral margins of nasals and narrow pterygoid fossae) is diagnostic. Animals obtained from extreme southwestern Indiana and from eastern Illinois approach _Z. h. americanus_ in color and in shape of the incisive foramina, but in the shape of the nasals, width of the pterygoid fossae and breadth of the zygomata are most nearly like _Z. h. intermedius_ to which they are here referred. Specimens from Lake and Kane counties, Illinois, also show affinity with _Z. h. americanus_ in color, but cranially are most nearly like _Z. h. intermedius_ and are assigned to that subspecies.