_Mustela frenata spadix_ has just one structural feature of a "unique" kind which serves to differentiate it from the geographically adjoining subspecies. This feature is large size. The other diagnostic characters ascribed to _spadix_ are of an intermediate sort--intermediate as between two extremes, one found to the westward in _longicauda_ and the other to the eastward in _noveboracensis_. For example, the dark-colored upper parts are merely darker than in _longicauda_ and merely lighter than in _noveboracensis_. The color is not "different"; it is only "intermediate." Furthermore, each of the characters ascribed to _spadix_, including large size itself, undergoes change from one part of its geographic range to another; the characters are not constant over a wide area. Indeed, excepting the large size which remains relatively uniform over the northern two-thirds of the range, no two localities have been found from which the specimens can be said really to agree in characters. By way of illustration, the coloration of the upper parts may be cited. Near the range of _noveboracensis_ the average coloration of individuals from one locality is only a little lighter than in _noveboracensis_. Farther westward the average coloration is a little lighter and farther westward yet, toward the range of the extremely light colored _longicauda_, the average coloration is lighter still. Although all these animals are darker than _longicauda_ and lighter than _noveboracensis_, those from the three places do not agree among themselves. Because of the lack of more than one character of a "unique" kind and because of the inconstancy, geographically, of other characters, and for that matter, lack of constancy geographically in combination of characters, the writer regards _spadix_ as a barely recognizable subspecies. Examination of the specimens of _spadix_ shows that the individual variation in a single species is greater in a region of intergradation than it is some distance inside the borders of the geographic range of a well-marked subspecies. This is illustrated by three specimens of _M. f. spadix_ in fresh summer pelage from the single locality, Elk River, Minnesota. In these, the color of the upper parts varies from a little darker than Cinnamon Brown to Vandyke Brown. At any one locality well within the range of _longicauda_, or _noveboracensis_, there is nowhere nearly so much variation in color, even in much larger series of specimens.