_Specimens examined._--Total 70, as follows: _Alaska_: Circle, 664 ft., 1; Chatanika River, 700 ft., 14 mi. E and 25 mi. N Fairbanks, 13; Twelve Mile Summit, 3225 ft., Steese Highway, 6; 1 mi. SW Fairbanks, 440 ft., 3; N side Salcha River, 600 ft., 25 mi. S and 20 mi. E Fairbanks, 28; Yerrick Creek, 21 mi. W and 4 mi. N Tok Junction, 9; Fish Creek, 3400 ft., 5 mi. N and 1 mi. E Paxson, 3; Glenn Highway, 6 mi. WSW Snowshoe Lake, 1. _Yukon Territory_: Jct. Grafe and Edith Creeks, 1; 6 mi. SW Kluane, 2550 ft., 2; SW end Dezadeash Lake, 1. _British Columbia_: Stonehouse Creek, 5½ mi. W jct. Stonehouse Creek and Kelsall River, 2. _Remarks._--Alcorn found the tundra mouse in many of the localities at which he trapped in east-central Alaska. Specimens were taken above timberline, along roads, in grassy areas which had been cleared of timber, and in low vegetation bordering streams. On August 17 at Fish Creek, 5 miles north and 1 mile east of Paxson, Alaska, Alcorn obtained one of these mice in a tree in the daytime. Immature specimens taken at Stonehouse Creek are, to my knowledge, the first records for this species in British Columbia. Mus musculus Linnaeus House Mouse _[Mus] musculus_ Linnaeus, Syst. Nat., ed. 10, 1:62, 1758. (Type from Upsala, Sweden.) _Specimens examined._--Total 6, as follows: _Alaska_: 1 mi. NE Anchorage, 100 ft., 2. _Yukon Territory_: McIntyre Creek, 2259 ft., 3 mi. NW Whitehorse, 2; 2 mi. NNW Whitehorse, 2100 ft., 1. _Alberta_: Assineau River, 1920 ft., 10 mi. E and 1 mi. N Kinuso, 1. _Remarks._--Alcorn took house mice in and near areas inhabited by man. One mouse was taken near Whitehorse on July 10 under a building which had not been occupied for one year. Another was taken at the Whitehorse city dump. Near Kinuso, one specimen was obtained at the site of an old sawmill. Zapus hudsonius hudsonius (Zimmermann) Meadow Jumping Mouse _Dipus hudsonius_ Zimmermann, Geogr. Gesch., 2:358, 1780. (Type from Hudson Bay, Canada.) _Zapus hudsonius_ Coues, Bull. U. S. Geol. and Geogr. Surv. Terr., ser. 2, 1:253, January 8, 1876. _Specimens examined._--Total 8, as follows: _British Columbia_: 1 mi. NW jct. Irons Creek and Liard River, 3; Hot Springs, 3 mi. WNW jct. Trout River and Liard River, 1; E side Minaker River, 1 mi. W Trutch, 1; 5 mi. W and 3 mi. N Fort St. John, 1. _Alberta_: Assineau River, 1920 ft., 10 mi. E and 1 mi. N Kinuso, 1. _Remarks._--The jumping mice listed above have been compared with specimens of _Z. h. hudsonius_ from Ontario and Michigan. The zone of contact between _Z. h. hudsonius_ and _Z. h. alascensis_ is still unknown; Alcorn obtained no specimens between Irons Creek and Whitehorse. To my knowledge there are no records from this extensive area. Alcorn took _Zapus_ in grassy areas at the edge of water, in an old gravel pit, and at the site of an old sawmill. Animals were taken as early as June 30 and as late as September 2. Zapus hudsonius alascensis Merriam