Compared with the skull of _M. f. peninsulae_, of which only one good skull, and that a female, is available, that of _M. f. olivacea_ averages smaller and has relatively and actually smaller and less inflated bullae. As compared with the skull of _M. f. noveboracensis_, that of _olivacea_ in the case of males is larger in every part measured and relative to the basilar length is broader across the zygomatic arches and mastoids. However, the rostrum and interorbital region are relatively narrower. The orbitonasal length is relatively less. The tympanic bullae are broader and more inflated. The same differences hold as between females of _noveboracensis_ and _olivacea_. Indeed, the females of these two races differ more than do the males. Additional, selected differential cranial characters in the females are, in _olivacea_, as follows: Weight averaging 3.8 grams rather than 1.7 grams; braincase with, rather than without, sagittal crest; anterior border of tympanic bulla separated from foramen ovale by breadth of less than, rather than breadth of more than, 4 upper incisors (including I3); height of tympanic bulla not less than, rather than less than, distance from its anterior margin to foramen ovale; squamosal bone, between anterior margin of tympanic bulla and foramen ovale, ventrally concave rather than ventrally convex. Comparisons of the skulls with those of _M. f. arthuri_ and _M. f. primulina_ are made in the accounts of those subspecies. _Remarks._--Excepting two young specimens from South Carolina in the Charleston Museum, no specimens of this race of large weasel seem to have been preserved until Arthur H. Howell, in the course of his study of the mammals of Alabama, procured specimens on which his name, _olivacea_, was based. Later, Francis Harper obtained three instructive specimens from Okefinokee Swamp. Really adequate material, for the localities represented, owes its preservation to the alertness of Charles O. Handley, when he resided at Thomasville, Georgia, and to Hallie E. Fuller of Geneva, Talbot Co., Georgia.