102 DIVISION I. VERTEBRAL ANIMALS.—CLASS II. AVES. 
ORDER LAMELLIROSTRES. GEESE, DUCKS, AND 
MERGANSERS. 
Tus very large, widely-distributed, and extremely-varied group, com- 
prehends some of the most valuable birds which have been used for the 
support of man. 
In the family Anatid@ are comprehended all the Geese and Ducks of the 
world, and in the Mergid » are placed the Sheldrakes and Mergansers. 
Famiry ANATIDEA. GEESE anp Ducks. 
Of the ducks, the Mallard and Eider Ducks are well known in both hem- 
ispheres ; and the far-famed Canyas-back Duck is known to almost every 
inhabitant of the United States. 
Wilson’s account of the last-named species is one of the most interesting 
that we have met with. He says, — 
“The Canvas-back Duck arrives in the United States, from the north, 
about the middle of October; a few descend to the Hudson and Delaware ; 
but the great body of these birds resort to the numerous rivers belonging to, 
and in the neighborhood of, the Chesapeake Bay, particularly the Susque- 
hanna, the Patapseo, Potomac, and James Rivers, which appear to be their 
general winter rendezvous. Beyond this, to the south, I can find no certain 
accounts of them. At the Susquehanna, they are called Canvas-backs ; on 
the Potomac, White-backs; and on James River, Sheldrakes. They are 
seldom found at a great distance up any of these rivers, or even in the salt- 
water bay, but in that particular part of tide-water where a certain grass- 
like plant grows, on the roots of which they feed. This plant, which is 
said to be a species of Vallésneria, grows on fresh-water shoals of from 
seven to nine feet (but never where these are occasionally dry), in long, 
narrow, grass-like blades, of four or five feet in length: the root is white, 
and has some resemblance to small celery. This grass is in many places so 
thick that a boat ean with difficulty be rowed through it, it so impedes the 
oars. The shores are lined with large quantities of it, torn up by the ducks 
and drifted up by the winds, lying, like hay, in windrows. Wherever this 
plant grows in abundance, the Canvas-backs may be expected, either to pay 
occasional visits, or to make it their regular residence during the winter. 
It occurs in some parts of the Hudson; in the Delaware, near Gloucester, 
a few miles below Philadelphia, and in most of the rivers that fall into the 
Chesapeake, to each of which particular places these ducks resort ; while, 
in waters unprovided with this nutritive plant, they are altogether unknown, 
