228 AVES: ANSERES. — XXXV. 
tomium); bill narrow, head more or less crested; hind toe lobate. 
Fish ducks. (Mergine.) 
d, Serrations of both mandibles very a el tooth-like, strongly 
recurved attip. . . . - « MERGANSER, 349, 
dd. Serrations of mandibles stharts blecrt, ot distinctly recurved at tips. 
LopHopyTes, 350. 
cc. Lower mandible with a very distinct series of lamellx along side be- 
sides the series along upper edge; bill rather broad. (Anatine.) 
e. Hind toe without distinct membranous lobe; ‘river ducks.” 
a. Bill not spatulate, scarcely widened toward tip. 
y. Tail feathers narrow, rather pointed, no crest. 
# Tail not very acute, the middle feathers not produced in df 
(speculum green, violet or white), Anas, 351, 351 a (etc.) 
zz. Tail pointed, the middle feathers much produced in d; ? 
with tail much shorter (speculum violet). Darra, 353. 
yy. Tail feathers broad, rounded at tip; g' with a high crest. 
AIX, 354. 
zz. Bill spatulate, narrow at base and very broad toward the tip. 
SPATULA, 352. 
ee. Hind toe with a broad, membranaceous lobe; ‘‘sea-ducks.” 
J. 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 Dill from nostril; 
width of nail not one-third width of bill at middle. 
AyTuya, 355. 
hh, Graduation of tail much more than length of bill from 
nostril. 
z. Bill ordinary, not gibbous nor appendaged. 
Jj» Nail of bill narrow, distinct; tail moderate. 
k. Nostril anterior, its front much nearer tip of bill than 
loral feathers (eyes yellow). CLANGULA, 356. 
kk. 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 ¢ with its middle 
feathers produced, about as long as wing; (no specu- 
lum)... - - + + « « « + HARBELDA, 358. 
ti. Bill variously gibbous or else appendaged on base or on 
side. 
1. Bill not gibbous, but appendaged with a lobe at 
base of commissure; (speculum violet). 
HistRionicvs, 359. 
i. Bill not gibbous, but with a leathery expansion on 
side of upper mandible; cheeks bristly; (specu- 
' lum white). . . . . Camproxarmus, 860. 
Ul, Bill gibbous at base, then broad, depressed, with 
a large fused nail and without frontal processes. 
Omemta, 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). 
SomaTertA, 361. 
