ed with zig-zag black lines. I believe it is this
mottling, combined with the colour, which somewhat resembles the
appearance and texture of ship's canvass, that has given the bird its
trivial name; but there is some obscurity about the origin of this. In
colour, however, it so nearly resembles the `pochard,' or `red-head' of
Europe, and its near congener the red-head (_Anas ferina_) of America,
that at a distance it is difficult to distinguish them from each other.
The last-mentioned species is always found associated with the
canvass-backs, and are even sold for the latter in the markets of New
York and Philadelphia. A naturalist, however, can easily distinguish
them by their bills and eyes. The canvass-back has red eyes, with a
greenish black bill, nearly straight; while the eyes of the red-head are
of an orange yellow, its bill bluish and concave along the upper ridge.

"The canvass-back is known in natural history as _Anas valisneria_, and
this specific name is given to it because it feeds upon the roots of an
aquatic plant, a species of `tape-grass,' or `eel-grass;' but
botanically called `_Valisneria_,' after the Italian botanist, Antonio
Valisneri. This grass grows in slow-flowing streams, and also on shoals
by the seaside--where the water, from the influx of rivers, is only
brackish. The water where it grows is usually three to five feet in
depth, and the plant itself rises above the surface to the height of two
feet or more, with grass-like leaves of a deep green colour. Its roots
are white and succulent, and bear some resemblance to celery--hence the
plant is known among the duck-hunters as `wild celery.' It is upon
these roots the canvass-back almost exclusively feeds, and they give to
the flesh of these birds its peculiar and pleasant flavour. Wherever
the valisneria grows in quantity, as in the Chesapeake Bay and some
rivers, like the Hudson, there the canvass-backs resort, and are rarely
seen elsewhere. They do not eat the leaves but only the white soft
roots, which they dive for and pluck up with great dexterity. The
leaves when stripped of the root are suffered to float off upon the
surface of the water; and where the ducks have been feeding, large
quantities of them, under the name of `grass wrack,' are thrown by the
wind and tide upon the adjacent shores.

"Shooting the canvass-backs is a source of profit to hundreds of gunners
who live around the Chesapeake Bay, as these birds command a hi