_Zapus hudsonius americanus_, Batchelder, Proc. New England Zool. Club, 1:6, February 8, 1899; Preble, N. Amer. Fauna, 15:19, August 8, 1899. _Zapus hudsonius hardyi_, Bole and Moulthrop, Sci. Publ. Cleveland Mus. Nat. Hist., 5:165, September 11, 1942 (part--the part from New York, Ohio, and Pennsylvania). _Zapus hudsonius brevipes_ Bole and Moulthrop, Sci. Publ. Cleveland Mus. Nat. Hist., 5:168, September 11, 1942, type from Bettsville, Seneca County, Ohio. _Zapus hudsonius rafinesquei_ Bole and Moulthrop, Sci. Publ. Cleveland Mus. Nat. Hist., 5:169, September 11, 1942 (part--the part from southeastern Ohio), type from Cat Run, extreme southeastern Belmont County, Ohio. _Type._--No type specimen designated. _Dipus americanus_ was characterized from jumping mice obtained by Barton near the Schuylkill River, a few miles from Philadelphia, Pennsylvania. _Range._--Southeastern United States and lower peninsula of Michigan; east of central Indiana; from central New York and Massachusetts southward to northern Georgia. See fig. 47. Zonal range: Austroriparian (Lower Austral), Carolinian (Upper Austral), Alleghanian (Transition), and Canadian. _Description._--Size small; back from near Light Ochraceous-Buff to near Ochraceous-Buff with admixture of black-tipped hair forming distinct dorsal band; sides bright, lighter than back from near Light Ochraceous-Buff to near Ochraceous-Buff; lateral line usually distinct and of color of sides; underparts white, sometimes with slight suffusion of color of sides; tail bicolored, brown to brownish-black above, yellowish-white to grayish-white below; ears narrowly edged and heavily flecked with color of sides; feet white to grayish-white above; skull short; braincase relatively narrow; incisive foramina relatively broad; skull relatively narrow across zygomata; interorbital region relatively broad; distance from incisors to postpalatal notch relatively short; auditory bullae relatively small. _Comparisons._--Compared with _Zapus hudsonius canadensis_, _Z. h. americanus_ differs as follows: Smaller; paler (in a sense brighter because more ochraceous and less tawny); skull smaller; auditory bullae narrower, less inflated; incisive foramina relatively more bowed; condylobasal length averaging less. From _Zapus hudsonius intermedius_, _Z. h. americanus_ differs as follows: Smaller; color brighter, more ochraceous, less yellow; braincase relatively narrower; auditory bullae usually smaller; incisive foramina broader; inferior ramus of zygomatic process of maxillary usually with median projection; interorbital region averaging broader. For comparison with _Zapus hudsonius acadicus_ see account of that subspecies.