THE CANVASS-BACK DUCK. 141 



grows, on the roots of which they feed. This plant, which 

 is said to be a species of valisineria, grows on fresh-watcT 

 shoals of from seven to nine feet (but never where these 

 are occasionally dry), in long, narrow, grass-like blades, of 

 fout 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 can 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 Canvass- 

 Backs may be expected, either to pay occasional visits, or 

 to make it their regular residence during the winter. I 

 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. 



On the first arrival of these birds in the Susquehanna, 

 near Havre-de-Grace, they are generally lean ; but such is 

 the abundance of their favourite food that, towards the 

 beginning of November, they are in pretty good ordei. 

 They are excellent divers, and swim with great speed and 

 Egility. They sometimes assemble in such multitudes as 

 to cover several acres of the river, and when they rise sud- 

 denly, produce a noise resembling thunder They floa* 



