Additional females, with external measurements carefully taken, are much needed from Southampton Island, because the available females are insufficient to show the degree of sexual dimorphism. If the meager data available be accepted, the difference in size between the two sexes is less than in other subspecies. My own feeling is that a better sample of females would show the secondary sexual difference in size to be more than available data indicate. _Specimens examined._--Total number, 183, arranged from north to south by islands, or regions attached to the mainland, and from north to south in each region or island. Unless otherwise indicated, specimens are in the Zoological Museum, University of Copenhagen, Denmark. =Baffin Island.= Pond[s] Inlet, 8; (5[77]); Tulukan (sometimes spelled Tulukat), 6; Cape Eglinton, 1[7]; Gifford River, 2; Clyde, 3[86]; head of Cumberland Sound, 1[91]; Pangnirtung, 2[77]; Kingnait Fiord, 1[91]; Kikkulin Island, Cumberland Sound, 1[7]; Blacklead Island, Cumberland Gulf, 1; merely Cumberland Gulf, 1[7]; merely east Baffin Island, 34[7]; Cape Dorset, 2[2]; SW coast of Baffin Island, 1[75]. =Melville Peninsula.= Iglulik, 3; Pingerqalik, 2; Kingadjuaq, Amitsog, 3; Rae Isthmus, 3; Lyons Inlet, 13(9[2]); M[N?] alugsitaq, Lyon Inlet, 5; Itibdjeriang, 2; Repulse Bay, 27 (22[2], 2[19]); Drichetts Cove, Hurd Channel, 1[2]; Gore Bay, 1; Haviland Bay, 1; Cleveland Harbor, Frozen Strait, 1. =Southampton Island and adjacent islands.= Danish Island, 11; Vansittart Island, 4. Southampton Island: Coral Inlet, 19 (1[77], 18[9]); Prairie Point, 1[9]; Munnimunnek Point, South Bay, 5[9]; Native Point, 1[9]; Ranger Rim, 1[9]; Koodloatok (not found on map), 1[77]; merely Southampton Island, 1[77]; Gore Bay, 1[2]; Fox Channel, 2[2]. =Mainland to west of Southampton Island.= Cape Fullerton, 3 (1[77], 2[2]); Chesterfield Inlet, 4 (1[77], 1[9]); Tavane, 1[77]; N of Wagner Inlet, 1; Eskimo Point, 1[86]. =Mustela erminea kadiacensis= (Merriam) Ermine Plates 2, 3, 4, 9, 10 and 11 [_Putorius arcticus_] subspecies _kadiacensis_ Merriam, N. Amer. Fauna, 11:16, June 30, 1896. _Putorius kadiacensis_, Preble, Proc. Biol. Soc. Washington, 12:169, August 10, 1898. _Mustela kadiacensis_, Miller, U. S. Nat. Mus. Bull., 79:97, December 31, 1912. _Mustela erminea kadiacensis_, Hall, Journ. Mamm., 26:179, July 19, 1945. _Type._--Male, subadult, skull and skin; no. 65290, U. S. Nat. Mus., Biol. Surv. Coll.; Kodiak Island, Alaska; April 25, 1894; obtained by B. J. Bretherton, original no. 304. The skull lacks the basioccipital, part of the basiphenoid, the occipital region on the right side and the posterior part of the right tympanic bulla. The third, upper, left incisor is missing. Otherwise the teeth all are present and entire.