BIRDS OF KANSAS. 79 



general winter rendezvous. Beyond this to the south, I can find 

 no certain account of them. At the Susquehanna, they are called 

 Canvas-backs; on the Potomac, White-backs, and on the James 

 River, Shelldrakes. They are seldom found a great distance up 

 any of these rivers, or even in the salt water bay; but in that 

 particular part of the 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 Vallimeria, grows on fresh-water shoals 

 of from seven to nine feet (but never where these are occa- 

 sionally 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 

 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 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 re- 

 sort; while in waters unprovided with this nutritive plant they 

 are altogether unknown. 



"On the arrival of these birds in the Susquehanna, near Ha- 

 vre de Grace, they are generally lean, but such is the abundance 

 of their favorite food, that towards the middle of November 

 they are in pretty good order. They are excellent divers, and 

 swim with great speed and agility. They sometimes assemble 

 in -such multitudes as to cover several acres of the river, and 

 when they rise suddenly, produce a noise resembling thunder. 

 They float about the shoals, diving and tearing up the grass by 

 the roots, which is the only part they eat. They are extremely 

 shy, and can rarely be approached, unless by strategem. When 

 wounded in tlie wing, they dive to such prodigious distances, 

 and with such rapidity, continuing it so perse veringly, and with 

 such cunning and active vigor, as almost always to render the 

 pursuit hopeless. From the great demand for these Ducks, and 



