Ognev (1935:31) seems to have been the first to use the name combination _Mustela erminea arctica_ for Alaskan specimens. Thereby he expresses the view adopted here, namely that the American ermine is subspecifically but not specifically distinct from the Old World animal. Whether actual intergradation (crossbreeding) ever takes place across the narrow Bering Strait I do not know. I doubt that crossbreeding occurs but considering the Diomedes (islands), that might serve as a half way stopping point, and remembering Mr. Charles Brower's oral statement to me that he had seen tracks of ermine as far as 10 miles from the northern shore of Alaska out on the ice, the possibility must be granted of an occasional individual crossing from one side to the other of Bering Strait on the ice in winter or of being carried across when the ice broke up and drifted. If transfers of this kind occurred often one would expect ermines to occur also on Saint Lawrence Island where apparently they do not. The one skin (U. S. Nat. Mus. no. 259046) seen as labeled from there, my friend, Otto William Geist ascertained was imported as a skin with other furs from Siberia. Ognev (_op. cit._) who used the name combination _Mustela erminea arctica_ for Alaskan specimens, applied it also to animals from Kamchatka. At the same time he recognized the animal from the eastern mainland of Siberia (as opposed to the peninsula of Kamchatka) under the name _Mustela erminea orientalis_ Ognev 1928. Hall (1944:556) applied the earlier proposed name _Putorius kaneii_ Baird 1857, to the animal on the eastern mainland of Asia and proposed the new name _Mustela erminea digna_ for the ermine of Kamchatka. In comparing material of these two Asiatic races with topotypes and other specimens of _M. e. arctica_ from Alaska, it seemed to me that the degree of relationship, one with the other, was about the same. _M. e. digna_ has a slightly larger preorbital region than _M. e. kaneii_, and the skull is longer. In both of these particulars _digna_ approaches closer to _arctica_. _M. e. kaneii_ has longer tympanic bullae and a wider skull than _digna_ and therein approaches more towards _arctica_ than toward _digna_. As nearly as I can make out, _digna_ and _kaneii_ show a nearly equal degree of resemblance to _arctica_. Also the degree of difference between _digna_ and _kaneii_ is about the same as between either one of them and _arctica_. In view of the above considerations the ermines of the New and Old worlds are here regarded as only subspecifically distinct.