Barrett-Hamilton in 1904 named the animal at "Fort Simpson, British Columbia" _Putorius arcticus imperii_. Preble (1908:232) pointed out that Fort Simpson on the Mackenzie undoubtedly was the place intended, and arranged _imperii_ as a synonym of _M. e. richardsonii_. The type specimen of _imperii_ was stated to have been received from B. M. Ross who is known to have collected specimens, including specimens of this species (now in U. S. Nat. Mus.), at Fort Simpson on the Mackenzie. I know of no Fort Simpson in British Columbia. If, as seems improbable, Port Simpson, British Columbia, was the place that Barrett-Hamilton intended to designate (where so far as I know Ross did not collect), the name _imperii_ still would seem to be a synonym of _richardsonii_ because _richardsonii_ seems to be the race of weasel at Port Simpson. In proposing the name _Putorius arcticus imperii_, Barrett-Hamilton stressed that the weasel, which he was naming, was a subspecies of _P. arcticus_, gave characters which applied perfectly to _richardsonii_ but made no reference to _richardsonii_. Barrett-Hamilton did not refer to _richardsonii_ possibly because he relied on Merriam's classification of 1896 wherein _richardsonii_ is treated as a species distinct from _arctica_. Merriam, it will be remembered, held that slight degree of morphological difference rather than intergradation was the criterion for subspecies. Although I have no record of having examined the type specimen of _imperii_ I have but little hesitancy in treating it as a synonym, and would have no hesitancy at all in so doing if the type was certainly known to have been obtained at Fort Simpson on the Mackenzie. The name _Mustela cicognanii mortigena_ Bangs, 1913, proposed for the ermine of Newfoundland, is placed as a synonym of _richardsonii_ only after repeated, detailed comparisons. In advance of study I supposed that the isolation of the ermine, in Newfoundland, had contributed to its differentiation, which, however, the original describer, Bangs, indicated was slight. Bangs was a careful worker and I am confident that the differences he described really existed between his specimens. Material more nearly adequate than he had from the mainland, shows the males, so far as my measurements and comparisons go, to be in nowise different from those in Newfoundland. Females in Newfoundland may have, on the average, slightly longer hind feet than on the opposite mainland but I am not certain that they do and even if there is a slight difference in this regard as suggested by available data, I think it insufficient basis, alone, for according subspecific status to the insular animal.