Vol. XIX 

 1902 



I Brewster, Ah Utide.scribcd Form of Black Duck. l8'^ 



chrome to canary or sulphur yellow, the legs and toes bright red, 

 var}'mg 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 ohscura 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 Avhich 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 

 rub ripe s. 



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. 



