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 hill swollen laterally. Nostrils large, rounded. Color 
black, with white patches on head. 
Melanetta. —Feathers of side of hill 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 hack 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 Bendus, XLIII, Sept. 1856, nearly as follows : 
Fuliguleae. — Fulix, Aythya. 
Clanguleae. — Encephala, Histrionicus, Harelda. 
Oidemieae. — Oidemia, Pelionetta , Melanetta. 
Somaterieae. — Polysticta, Lampronetta, 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 Micropterus , and Hymenolaemus among 
Microptereae. 
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... Fvdix, Aytliya. 
Crissum and anal region white. Inside of wing and axillars black... Bucephala, Harelda. 
Belly dusky centrally ; reddish brown on the sides. 
Prevailing color plumbeous, with white spots No white inside of wings ...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 white. Somateria, Lampronetta. 
Head and neck white. The latter with a black collar... Camptolaemus. 
Body entirely black, with or without white patch on head or wing, including inside of 
wings. 
