The distinctness of _M. f. olivacea_ from _M. f. peninsulae_ is not satisfactorily established due to inadequate material of _peninsulae_. Differences shown by the specimens seen indicate that, as compared with _olivacea_, _peninsulae_ is larger, has transversely wider light-colored underparts which possess more yellow, and a larger skull with more inflated tympanic bullae. In each of these characters, _olivacea_ is intermediate between _noveboracensis_ on the north and _peninsulae_ on the south. The question arises, therefore, whether the animals here recognized under the name _olivacea_ really constitute a recognizable subspecies or instead are only representatives of a subspecies which reaches its extreme development in Florida. In the latter event, the name _peninsulae_ would apply to all. Examination of more material from Florida, especially from the southern half of Florida, will be necessary to answer this question. This large weasel of the southeastern United States is remarkably different from _noveboracensis_. Indeed, were it not for actual intergrades such as the two from Fort Payne, Alabama, and York, South Carolina, which are described in the account of _M. f. noveboracensis_, and the six specimens from northwestern Alabama, which are referred to _olivacea_, the systematist, I believe, would have little or no hesitancy in designating the two as distinct species, especially on the basis of differences to be seen in the skull. Not only are the two forms structurally more different than usually is the case but between two geographically, adjacent subspecies of the same species of mammal, but the belt where intergradation occurs appears to be narrow. Nevertheless, when material of the two races is laid out in geographic order, and examined in mass, certain features are seen to undergo gradual change as a person's eye travels from specimens from, say, the center of the range of _noveboracensis_ to specimens from southern localities adjoining the territory occupied by _olivacea_. One of these features subject to gradual change is the color of the underparts. Beginning at the Adirondacks of New York where a large number of the specimens have white underparts, the underparts become more intensely yellowish southward through the range of _noveboracensis_ into that of _olivacea_. Indeed, this progressive trend seems to continue right on southward through the range of _olivacea_ into that of _peninsulae_. Turning in the opposite direction we find that the least width of the underparts decreases gradually northward toward the range of _noveboracensis_. There is, likewise, a decrease to the northward in length of the skull and relative, as well as actual, narrowing of the braincase and tympanic bullae. However, in least width of color of underparts and the mentioned cranial features, the trend stops relatively abruptly at the southern boundary of the geographic range of _noveboracensis_ and does not continue on,