ORNITHOLOOfOAL EXPLORATIONS. 161 



The Scaup Duck of tbe region is in every particular identical witli 

 the common form inliabiting the Atlantic portion of the i)al8Barctic con- 

 tinent, the true A. marila, from which is distinguishable a representa- 

 tive of the American Aythya affinis (Eyton), found in China and Japan, 

 and entitled to recognition as Aythya affinis mariloides (ViGr.). Nor must 

 A. marila be confounded with its American subspecies Aythya marila 



nearctica Stejneger, wliich differs from the true marila in exactly the 

 same manner as does A. affinis from A. affinis mariloides. The differ- 

 ence in size and in the light markings on the i^rimaries is easily ob- 

 servable both in tlie males and the females. The males have the same 

 additional distinguishing characters, and their differences maybe tabu- 

 lated thus : 



«' Size smaller; reflections on head chiefly pnrple; flanks narrowly vermiculated 

 with dusky. 

 6'. Pj-iniaries from the fourth f£nill without whitish on the inner web, the latter 

 being onlj' a trifle paler than the rest of the quills. 



1. A. affinis (Eyton). 



Hal). — Nearctic Region, generally. 

 Ifl. Primaries from the fonrth with a distinct white area on the inner web. 



la. A. affinis mariloides (Vigors). 



Hat. — Pacific coast of Asia, from Japan southward. 

 a'': Size larger; reflections on head green; Flanks uniform white without dusky ver- 

 miculatioHS. 

 fei. Primaries from the fourth qnill with a distinct white area on the inner web. 



2. A. marila (Lin.), 



Hob. — Palsearctic Region, generally. 

 6*. Primaries from the fourth quill with a grayish — but not white — area on the 

 inner web. 



2a. A, marila nearctica Stejneger. 



Hob. — Nearctic Region. Specimens examined from 

 Alaska, Pacific coast, Guatemala, Arctic and Atlan- 

 tic coasts, and interior of the United States. 



Quite extensive series have been examined and the characters found 

 to hold good in every single instance. As will be seen, the Palsearctic 

 forms agree in the pattern of the wing, having a quite pronounced 

 white area on the inner webs of the inner primaries, a design only 

 faintly marked in their American representatives, which have the cor- 

 responding area dull brownish gray. 

 15861 Bull. 29 11 



