788 U. S. p. R. R. EXP. AND SURVEYS — ZOOLOGY — GENERAL REPORT. 



Pelionetta. — Feathers of forehead extending far forward ; nearly to end of the 

 gibbosity, which is plain above ; those on the sides not beyond the angle of the 

 mouth ; basal portion of bill swollen laterally. Nostrils large, rounded. Color 

 black, with white patches on head. 

 Melanetta. — Feathers of side of bill extending obliquely forward from the angle 

 of the mouth as far as those above. Nostrils very open and sub-circular ; quite 

 close to feathers around the base of bill. Nail very broad and truncate at the 

 end. Colors black, with white patch on wing. 

 C. Bill narrow, compressed, tapering to the end. Feathers of forehead running forward in 

 a long narrow point, and of cheeks extending along the lower edge of bill, so that the two 

 strips embrace between them a linear portion of the bill, one half the length of culmen, and 

 which extends back further than the lower edge of mandible. 



SoMATERiA. — Nostrils situated beyond the middle of commissure. Nail very 

 broad, thickened, and greatly overlapping tip of lower mandible. Tail short, 

 rounded ; about two-fifths the wing. 

 In the arrangement of the sea ducks I have established three sections, which embrace species 

 agreeing with each other more or less, although there are others of rather close alliance which 

 are thereby separated. The more natural succession of the genera appears to be that of 

 Bonaparte in Comptes Rendus, XLIII, Sept. 1856, nearly as follows : 

 FuLiGULEAE. — Fulix, Aythya. 

 Clanguleae. — Bucephala, Histrionicus, Harelda. 

 OiDEMiEAE. — Oidemia, Pelionetta, Melanetta, 

 SoMATERiEAE. — Polysticta, Lamprouetta , Somateria. 

 MicROPTEREAE. — Camptolaemus. 



Where Camptolaemus should come is a matter of uncertainty, as it differs very much from all 

 the other genera in the stiffened cheek feathers, the membranous expansion at the end of bill, 

 the very large and unusually distant lamellae of the lower mandible, the broad, depressed bill, 

 and other features. By Bonaparte it is placed with 3Iicropterus, and Eymenolaemus among 

 Microp)tereae. 



The colors of the sea ducks furnish an excellent clue to their systematic arrangement, as shown 

 by the following schedule : 

 Belly white. 



Crissum and anal region black. Sides and back with waved feathers. Inside of wings 



and axillars white Fulix, Aythya. 



Crissum and anal region white. Inside of wing and axillars \>\-Ack... Bucephala, Harelda. 

 Belly dusky centrally ; reddish brown on the sides. 



Prevailing color plumbeous, with white spots. No white inside of yf'mgs... Histrionicus. 



Much white on head and wings. Inside of wings white Polysticta. 



Belly and under parts black. Inside of wings and axillars white. 



Head, neck, and fore part of body M'hite Somateria, Lampronetta. 



Head and neck wliite. The latter with a black collar Camptolaemus. 



Body entirely black, with or without white patch on head or wing, including inside of 

 wings. 



