228 AVES: ANSERES. XXXV. 



tomium); bill narrow, head more or less crested; hind toe lobate. 

 Fish ducks. (Mergince.) 

 d. Serrations of both mandibles very conspicuous, tooth-like, strongly 



recurved at tip MERGANSER, 349. 



dd. Serrations of mandibles short, blunt, not distinctly recurved at tips. 



LOPHODYTES, 350. 



cc. Lower mandible with a very distinct series of lamelhe along side be- 

 sides the series along upper edge; bill rather broad. (Anaiina.) 

 e. Hind toe without distinct membranous lobe; " river ducks." 

 x. Bill not spatulate, scarcely widened toward tip. 

 y. Tail feathers narrow, rather pointed, no crest. 

 z. Tail not very acute, the middle feathers not produced in cf 

 (speculum green, violet or white). ANAS, 351, 351 a (etc.) 

 zz. Tail pointed, the middle feathers much produced in & ; ? 

 with tail much shorter (speculum violet). DAFILA, 353. 

 yy. Tail feathers broad, rounded at tip; cf with a high crest. 



Aix, 354. 

 xx. Bill spatulate, narrow at base and very broad toward the tip. 



SPATULA, 352. 



ee. Hind toe with a broad, membranaceous lobe; "sea-ducks." 

 f. Tail feathers with their bases well hidden by the coverts. 



g. Feathering on lores or forehead not reaching forward beyond 



posterior border of nostril. 



h. Graduation of tail less than length of bill from nostril; 

 width of nail not one-third width of bill at middle. 



AYTHYA, 355. 

 hh. Graduation of tail much more than length of bill from 



nostril. 



i. Bill ordinary, not gibbous nor appendaged. 

 j. Nail of bill narrow, distinct; tail moderate. 



k. Nostril anterior, its front much nearer tip of bill than 

 loral feathers (eyes yellow). CLANGULA, 356. 



Tck. Nostril sub-basal, its front much nearer loral feathers 

 than tip of bill; (eyes brown). 



CHARITONETTA, 357. 



jj. Nail of bill large, fused; tail in cf with its middle 

 feathers produced, about as long as wing ; (no specu- 

 lum) HARELDA, 358. 



t. Bill variously gibbous or else appendaged on base or on 

 side. 



I. Bill not gibbous, but appendaged with a lobe at 



base of commissure; (speculum violet). 



HISTRIONICUS, 359. 



II. Bill not gibbous, but with a leathery expansion on 



side of upper mandible ; cheeks bristly; (specu- 

 lum white). .... CAMPTOLAIMUS, 360. 

 ///. Bill gibbous at base, then broad, depressed, with 

 a large fused nail and without frontal processes. 

 OIDEMIA, 362. 



gg. Feathering on forehead or lores reaching anteriorly to or be- 

 yond posterior end of nostril; bill gibbous at base and 

 with large frontal processes ; (no speculum). 



SOMATERIA, 361. 



