1 86 Brewster, An Undescribed Form of Black Duck. [a"'' 



Indeed it would be possible to contend that these aberrant or 

 intermediate specimens are really hybrids, for in the series before 

 me they do not exceed in number the birds (no less than nine) 

 which show unmistakable traces of an infusion of Mallard blood. 

 Since two species so obviously distinct as are the Mallard and 

 Black Duck are connected by intergrades k?iowti to be hybrids, 

 why should we not assume that the scarcely more numerous inter- 

 grades between the red-legged and brown-legged Black Ducks are 

 also hybrids ? Not that I am disposed to seriously press this argu- 

 ment for, however plausible it may seem, my present impression is 

 that the forms of the Black Duck here considered are only sub- 

 specifically distinct. 



There can be no reasonable doubt that the smaller of the two 

 is the original Anas obscura. This name has remained unchanged 

 in form and uncoupled with any s3monym ever since it was insti- 

 tuted, more than one hundred years ago, by Gmelin (Syst. Nat. I, 

 part ii, 1788, 541), vvho based it on the "Dusky Duck" of Pen- 

 nant. This is described (Arct. Zool., II, 564) as coming " from the 

 province of New York" and having "a long and narrow dusky 

 bill, tinged with blue : chin white : neck pale brown, streaked 

 downwards with dusky lines." Pennant adds that the legs in one 

 of his birds were " dusky, in another yellow " ; but as the specimens 

 which he examined were evidently dried skins (in the Blasius 

 Museum) this statement, as well as that relating to the color of the 

 bill, loses much of its apparent importance. 



At Lake Umbagog, where the Black Duck breeds rather plenti- 

 fully, I have not cared to incur the odium of breaking the game 

 laws and the reproaches of my own conscience by killing birds 

 which were sitting on their eggs or in charge of broods of tender 

 young, but I have shot a few specimens in late August and ver}?^ 

 many during the month of September. Among these I have found 

 only one example of rubripes, a nearly typical female taken on 

 September 28, 1S89. With this single exception I have never met 

 with the red-legged form at this locality before October 8. Soon 

 after that date it becomes common, remaining until the waters of 

 the lake are closed by ice. 



In Massachusetts, also, the locally bred birds or early migrants 

 from the north, which we kill during September and the first half 



