The Mergansers 31 
lamellz of varying development; the number of tail- 
feathers varies from fourteen to twenty-four; the legs 
are short and the anterior toes fully webbed ; the hind 
toe is small and jointed above the level of the others ; 
the eggs are numerous, white, pale greenish or creamy, 
and unspotted ; the young are covered with down when 
hatched, and able to run or swim, at once. 
All the North American genera are included in a single 
family—Anatide. This, for convenience, can be divided 
into five subfamilies, as follows :— 
Key or THE SUBFAMILIES. 
A. Tarsus as long as the middle toe without claw ; with reticulate 
scales all round. 
a. Neck very long, as long as the body ; lores naked in the adults. 
Cygnine, p. 71. 
b. Neck moderate, no naked patch on, the lores. 
Anserinz, p. 65. 
B. Tarsus shorter than the middle toe without claw, scutellate 
in front. 
a. Hind toe not lobed. Anatine, p. 35. 
b. Hind toe lobed. 
a' Bill flattened and depressed. Fuliguline, p. 49. 
b! Bill cylindrical and compressed. Merginz, p. 31. 
Subfamily MERGINA. 
The Mergansers have a narrow, almost cylindrical, 
bill, with the lamella only present in the upper man- 
dible and developed into prominent tooth-like serrations ; 
tarsi compressed, scutellate anteriorly ; hind toe lobate ; 
head usually crested; sexes unlike. 
Kry oF THE GENERA AND SPECIES. 
A. Bill chiefly red, about as long as the head ; crest low and only 
in, the occipital region (Mergus). 
a. Nostrils near the middle of the bill, breast all white in 3 
M. americanus, p. 32. 
b. Nostrils nearer the base of the bill; breast with w patch of 
reddish-brown in ¢ M. serrator, p. 33. 
B. Bill chiefly black, shorter than the head ; crest highly developed, 
erect and semicircular (Lophodytes). L. cucullatus, p. 34. 
