_Remarks._--_Zapus hudsonius alascensis_ is a fairly well marked subspecies retaining most of its characters throughout its range. Variation is noted in specimens from the southwest end of Dezadeash Lake, 2400 ft., Yukon Territory, and seems to be the result of intergradation between _Zapus hudsonius hudsonius_ and _Z. h. alascensis_. These animals are like _Z. h. hudsonius_ in the shape of the auditory bullae but are otherwise more nearly like _Z. h. alascensis_ to which they are here assigned. Alaskan specimens from 7 mi. SSE Haines, and from a point 9 mi. W and 4 mi. N Haines average slightly larger than _Z. h. alascensis_ in most measurements taken; however, in coloration they more nearly agree with _Z. h. alascensis_ than with _Z. h. hudsonius_ or _Z. h. tenellus_ the geographic ranges of which adjoin that of _Z. h. alascensis_. _Specimens examined._--Total, 56, distributed as follows: ALASKA: Cook Inlet, Tyonek, 1 (USBS); head Chalitna River, 2 (USBS); Lake Clark, 4 (USBS); east side Chilkat River, 100 ft., 9 mi. W and 4 mi. N Haines, 8; Yakutat, 3 (USBS); Lake Iliamma, 1 (USBS); Lake Aleknagik, 1 (USBS); _Kokwok_, 1 (USBS); _Nushagak River_, 3 (USBS); _Chilkat Peninsula, 10 ft., 7 mi. SSE Haines_, 18; Nushagak, 3 (USBS); Chignik Bay, 1 (USBS); Portage Cove, Revillagigedo, 1 (MVZ); _Izembek Bay_, 1 (USBS); Frosty Peak, 1 (USBS). BRITISH COLUMBIA: _west end Kelsall Lake, 2900 ft._, 1; Stonehouse Creek, 5-1/2 mi. W junction Stonehouse Creek and Kelsall River, 4. YUKON: SW end Dezadeash Lake, 2400 ft., 2. _Marginal records._--Alaska: Lake Aleknagik; head Chalitna River. Yukon: SW end Dezadeash Lake, 2400 ft. Alaska: E side Chilkat River, 100 ft., 9 mi. W and 4 mi. N Haines; Portage Cove, Revillagigedo Island; Yakutat; Cook Inlet, Tyonek; Chignik Bay; Frosty Peak. =Zapus hudsonius americanus= (Barton) _Dipus americanus_ Barton, Trans. Amer. Philos. Soc., 4:115, 1799. _Jaculus americanus_ Wagler, Nat. Syst. Amphibien, 23, 1830. _Meriones microcephalus_ Harlan, Proc. Zool. Soc. London, p. 1, 1839, based on two specimens from "the farm of Mr. Beck, in Philadelphia County, a few miles northeast of the city [= Philadelphia, Pennsylvania]." _Jaculus hudsonius_, Baird, Repts. Expl. and Surv. 111, 8 (pt. 1): 433, July 14, 1858 (part--the part from Massachusetts, Connecticut, New York, New Jersey, and Pennsylvania). _Zapus hudsonius_, Coues, Bull. U. S. Geol. and Geog. Surv. of the territories, 2nd ser. No. 5:260, 1877 (part--the part from Massachusetts, Connecticut, New York, and Pennsylvania); Preble, N. Amer. Fauna, 15:17, August 8, 1899 (part--the part from Peterboro and Waterville, New York, southeastern Massachusetts, Connecticut, New Jersey, Pennsylvania, West Virginia, Maryland, North Carolina, and Ohio).