28 CANVAS-BACK DUCK. 
one pound twelve or thirteen ounces. The latter writer says 
of the pochard, “The plumage, above and below, is wholly 
covered with prettily-freckled slender dusky threads, disposed 
transversely in close-set zigzag lines, on a pale ground, more 
or less shaded. off with ash;” a description much more 
applicable to the bird figured beside it, the red-head, and 
which very probably is the species meant. In the figure of 
the pochard given by Mr Bewick, who is generally correct, 
the bill agrees very well with that of our red-head ; but is 
scarcely half the size and thickness of that of the canvas- 
back; and the figure in the Planches Enluminées corresponds 
in that respect with Bewick’s. In short, either these writers 
are egreciously erroneous in their figures and descriptions, 
or the present duck was altogether unknown to them, 
Considering the latter supposition the more probable of the 
two, I have designated this as a new species, and shall proceed 
to detail some particulars of its history. 
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 
neighbourhood of the Chesapeake Bay, particularly the 
Susquehannah, the Patapsco, 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 Susquebannah, 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 Valisineria, 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 
