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2/8 Miller, Classification of the Scoters. [ 



Auk 

 July 



THE CLASSIFICATION OF THE SCOTERS. 



BY W. DEW. MILLER. 



The Scoters form a group of sea-ducks allied to the Eiders, 

 marked by their prevaiHng black plumage and their particolored 

 and variously swollen bills. The unbarred plumage of the females, 

 the unmodified syrinx, and the buffy instead of greenish eggs are 

 other diagnostic features. 



The six species are usually combined in one genus, Oidemia, with 

 three subgenera. These have at times been recognized as full 

 genera, as by Baird, Brewer, and Ridgway in 1884. Reichenow 

 (1913) considers Pelionetta (the Surf Scoter) sufficiently distinct 

 from the two other subgenera combined to stand by itself. The 

 unnaturalness of the latter arrangement is obvious in view of the 

 facts cited below, and on the other hand I believe the recognition 

 of three genera is unnecessary. 



The form and feathering of the bill is quite unlike in the tliree 

 subgenera ■ — indeed no two species agree in these respects and for . 

 this reason the value of these differences as generic characters is 

 very doubtful. However, three well-marked structural characters 

 that have been more or less lost sight of, though all three are 

 described by MacGillivray in Audubon's Birds of America, to- 

 gether with a number of other peculiarities, render it necessary, in 

 my opinion, to restrict Oidemia to 0. nigra and 0. americana. 

 Melanitta will then be used generically for the three White-winged 

 Scoters, M. fusca, M. deglandi and M. carho, and also for the Surf 

 Scoter, M. perspicillata (subgenus Pelionetta). 



Dr. Dwight, in his article in 'The Auk' (July, 1914, p. 293) has 

 called attention to the emarginate outer primary in true Oidemia, a 

 character strangely forgotten for many years. Correlated with 

 this is another structural peculiarity that has been largely over- 

 looked though mentioned by Coues in his 'Key.' In Oidemia 

 there are sixteen tail-feathers, in Melanitta and Pelionetta only 

 fourteen. Further, in the first-named the tail is longer and much 

 more graduated, the feathei's narrower and more pointed. 



The third difference is in the form of the trachea. In the males 



