Comparison with _semplei_ is made in the account of that subspecies.
Skull indistinguishable from that of _polaris_.
_Remarks._--The person who studies specimens of this subspecies finds labels inscribed with the names of naturalists well known to all readers of literature on the Arctic. Sir John Franklin, R. McFarlane, R. Kennicott, E. W. Nelson and R. M. Anderson are names which appear commonly. Of Alaskan specimens prepared according to modern methods, a large share was obtained by O. J. Murie and L. R. Dice.
The ermine was observed in the far north by early explorers and was mentioned in the literature, almost always under the name then used for the ermine of northern Europe and Asia. In 1896 Bangs misapplied to it the name _richardsonii_ but Merriam in the same year corrected the application of this name and proposed as new for this weasel the name _arctica_, the name in use today. For almost 50 years after Merriam and Bangs wrote about it, _arctica_ was treated, nominally at least, as a species distinct from its other relatives in both the Old-and New-World. The subspecific status of _arctica_ was emphasized in 1944 (555) by the present writer in reporting in detail upon the specimens, of _Mustela erminea_, from Eastern Asia which were made available on loan by Professor B. S. Vinogradov and the late Anatol I. Argyropulo of the Leningrad Academy of Sciences. Specimens of _Mustela erminea kaneii_ from the Asiatic side of Bering Strait and _Mustela erminea arctica_ from the American side are distinguishable by slight cranial characters but in coloration and external measurements I can detect no differences. Merriam's (1896:16) mention of more golden-colored upper parts and darker underparts in American specimens than in _erminea_ was the result of his comparison of Alaskan and northern European specimens. When Old World specimens from eastern Siberia, instead of from Europe, are used the differences mentioned by Merriam do not apply. Incidentally, many Siberian specimens have the white border, on the ear, which Merriam (_loc. cit._) noted as a distinguishing feature of _arctica_. When Merriam named _arctica_ he said (1896:15, 16) "_Putorius arcticus_ . . . has heretofore been confounded with _erminea_ or _richardsonii_. . . . It is interesting to find in this country an Arctic circumpolar weasel which, though specifically distinct, is strictly the American representative of the Old World _erminea_." Bearing in mind that Merriam's concept of species and subspecies (see Merriam, 1919:6) differed from that of nearly all modern systematists it is clear from his statement quoted above that he correctly understood the zoölogical relationship obtaining between the ermines of the Old and New Worlds.