Many writers have commented on the yellowish color, sometimes with a greenish tinge, found on the fur of weasels in the white winter coat. The stain is more often found on the tail and hinder-parts of the body than elsewhere. Possibly, partly on this account, some have ascribed this color to the smearing of the fur with urine. Still others have thought it resulted from the smearing of the fur with secretions from the anal scent glands. Schumacher (1928) takes this point of view, and while it may be that he has not proved his point, still his conclusions fit the known facts and seem sound to me. Schumacher points out that the same soiling of the fur is present in summer as well as in winter, but that on the summer pelage the stain can be detected only on the light-colored underparts. It is from this point of view that he criticizes the systematic worth of white versus yellowish-white underparts in the summer pelage of geographic races of _Mustela erminea_ and _Mustela nivalis_. Although in the long-tailed weasels (_Mustela frenata_) the underparts of all the races are pigmented with some form of red, orange or yellow, it seems probable to me that the additional color resulting from the soiling effect of this glandular secretion explains the greater variation, found at a single locality, in the color of underparts than of upper parts in the summer pelage. I have neither seen nor heard of a black weasel in any part of the New World or of the Old World. I have found only one albino among American specimens. It is an adult female, no. 121424, American Museum of Natural History, of _Mustela erminea richardsonii_, taken on August 30, 1935, at Hot Springs, Northwest Territory. This place, I am told by G. G. Goodwin who obtained the animal, is on the "Nahanni River where the rugged mountain ridges rise abruptly from the low mud flat lands, latitude 61, longitude 125." The shortness and coarseness of the hair corresponds to that of the summer pelage and not winter pelage. The pelage is everywhere white, even the tip of the tail. True, all except the nape and top and sides of the head has a faint yellowish-green tinge which has been supposed to result from staining by secretion of the anal scent glands but there is no pigment in the hair as in erythristic specimens. From the Old World, Farurick (1873:17) has recorded what he regards as an albino of _Mustela vulgaris_ since it had no black hairs on the tip of its tail. Flintoff (1935:228, 229) records what may have been an albino _Mustela vulgaris_ from Yorkshire and an albino _M. erminea_ from an unstated locality. Jäckel (1873:459) mentions specimens of _Mustela erminea_ and _Mustela vulgaris_, which were partly "albinistic" or "erythristic." Among the American specimens of _M. erminea_ I have not recorded any which appeared to be either partly or wholly erythristic or only partly albinistic. Among the 1550 skins of _M. frenata_ which were in summer pelage or brown winter