_Color._--Winter pelage either all white, or brown as in summer; upper parts about Raw Umber, or tone 2 of Carbo Brown of pl. 342 of Oberthür and Dauthenay. Underparts white at least on thoracic region; approximately three-fourths of specimens with brown rictal spot at angle of mouth or with this area covered by brown upper parts which extend down on each side and meet on the underparts in about one specimen out of three; upper lips and hind feet ordinarily brown; toes of forefeet ordinarily white (see under remarks for details of color pattern). Least width of color of underparts in the specimens in which the dark color of the upper parts does not encircle the body averages 60 per cent of greatest width of color of upper parts, or including all specimens the percentage is 42. _Skull_ (based on specimens from Pa. listed in table of cranial measurements, which see and plates 14 and 15).--Basilar length 29.7 and 28.6 in male and 28.0 in female; weights unavailable; otherwise as described in _M. e. richardsonii_. The length of the tympanic bullae seems to be actually less, and less in relation to the basilar length, than in other American subspecies of _M. rixosa_. _Remarks._--Robert Kennicott's mention in 1859 (p. 245) of what seems to be this subspecies is the earliest reference to it that I can identify in the literature. He used the specific name _pusillus_ and it was not until 1900 that Samuel N. Rhoads proposed the name _Putorius allegheniensis_. Since 1900, several records of occurrence have been published which have made the geographic range of this race better known. An adequate number of specimens has been gathered only from Ohio and from western Pennsylvania. Many from Ohio are without accurate external measurements taken in the flesh. The majority of the specimens from Pennsylvania owe their preservation to the willingness of local officials, who pay bounties on weasels, to save the skins of _Mustela rixosa_. These specimens ordinarily comprise the skin with locality but because the feet, external measurements in the flesh, and skulls are unavailable, the material is far from adequate and to give an accurate notion of the usual or average cranial characters of _allegheniensis_ in Pennsylvania, skulls from there are especially desirable. A smaller percentage of the specimens from Ohio than from Pennsylvania have the brown color of the upper parts meeting on the underparts. Also, more of the specimens from Ohio are lighter colored and this suggests intergradation with the subspecies _campestris_ and _rixosa_ to the westward.