_Specimens examined._--Total number, 42 as follows. Arranged alphabetically by Territory and District and unless otherwise indicated in the United States National Museum. =Alaska.= Barrow and Point Barrow, 19 (8[2] 7[74], 2[1], 1[50]); Wainwright, 1[57]; Mts. back of Icy Cape, 1[77]; west of Beechey Point, 1[2]; west edge of Colville River Delta, 1[2]; Koyukuk River, 16 mi. above Beetles, 1; upper Yukon, 1; Fort Yukon, 1; Stephens Village, 1; Wales, 1[57]; McDonald Creek, tributary of Salcha Slough, 1; near head of Toklat River, 1; head of Kantishna River, 1; St. Michael, 4 (2[74]); Tyonek [= Tyonek], 1; Bethel, 3; vic. Bristol Bay, 1. =Yukon.= La Pierre's House, 1; Klotassin River, tributary of White River, 1. =Mustela rixosa rixosa= (Bangs) Least Weasel Plates 14 and 15 _Putorius rixosus_ Bangs, Proc. Biol. Soc. Washington, 10:21, pl. 1, fig. 6, pl. 2, fig. 6, pl. 3, fig. 4, February 25, 1896; Merriam, N. Amer. Fauna, 11:14, pl. 2, figs. 7, 7a, June 30, 1896. _Putorius pusillus_, Baird, Mamm. N. Amer., p. 159, 1858. _Putorius (Gale) vulgaris_, Coues, Fur-bearing animals, p. 102, 1877. _Mustela rixosa_, Thomas, Proc. Zoöl. Soc. London, p. 168, March, 1911. _Mustela rixosa rixosa_, Miller, U. S. Nat. Mus. Bull., 79:96, December 31, 1912; Swenk, Journ. Mamm., 7:327, November 23, 1926. _Type._--Female, adult, skin and skull; no. 642 Bangs Coll. in Mus. Comp. Zoöl.; Osler, Saskatchewan; July 15, 1893; obtained by W. C. Colt; original no. 79 according to describer. The skull lacks the basioccipital, basisphenoid, and left zygomatic arch. The "crowns" of the lower canines are missing; otherwise the teeth are present and entire. The skin is fairly well made, with soles of hind feet up, in good condition and in summer pelage. _Range._--From northern British Columbia and Great Slave Lake south on the west side of the Rocky Mountains to Ootsa Lake, British Columbia, and on the east side of the Rocky Mountains, south to central Montana, North Dakota and Minnesota; eastward in Canada, entirely north of St. Lawrence River, to Atlantic Ocean. See figure 28 on page 180.