Anas obscura rubripes. Vol. XIX ] BREWSTER, An Undescribed Form of Black Duck. 185 1902 chrome to canary or sulphur yellow, the legs and toes bright red, varying from light scarlet to deep orange, the dark feathers of the pileum and nape conspicuously margined with gray or fulvous, and the throat (as well as sometimes the chin, also) profusely spotted or streaked with blackish. All the dark markings on the cheeks, throat and neck are broader, blacker and more sharply defined than in true obscura and they often take the form of coarse, rounded spots which are seldom if ever present on the head or neck of the smaller bird. In typical examples of obscura the bill is greenish black, dusky olive, or olive green, the legs are olivaceous brown with, at most, only a tinge of reddish, the pileum and nape nearly or quite uniformly dark, the throat and chin immaculate, the markings on the neck and sides of the head fine, linear, and dusky rather than blackish. In respect to these characteristics obscura does not seem to vary with age or season for my series includes several young not sufficiently large and fully feathered to have been able to fly which are colored and marked precisely like specimens killed in late autumn, while breeding birds are distinguishable from the latter only by the more worn and faded appearance of their plumage. The males of both forms, however, are almost invariably larger than the females as well as more richly colored and heavily marked, especially on the head and neck; a fact which should be borne carefully in mind when specimens of the two are compared. Both races are evidently subject to a good deal of individual or geographical variation which tends to connect them by a series of intergrading specimens. Thus I have small birds with grayish crowns or streaked throats and even one or two which, in life, apparently had yellow bills and red legs, while several of the large ones have plain black crowns or immaculate throats. I have yet to see a specimen of obscura, however, which possesses the coarse, rounded, deep black spots that are usually present in greater or less numbers on the neck, as well as often on the throat, of rubripes. The existence of a small percentage of non-typical examples, like those just mentioned, does not necessarily affect the diagnos- tic value of the characters to which I have called attention.