46 



of the Mallard's food 12.67 per cent, is pondweed; of the Can- 

 vasback, 42.35 ; and of the Scaup, 23.2 per cent. 



When the localities represented by my list of specimens 

 have been spotted on a map, the belt of occurrence shown there- 

 by rather roughly resembles an old and well-worn broom. 

 Beginning in the East, the loosened straws end along the 

 Atlantic Coast, from Virginia and Chesapeake Bay northward 

 to Massachusetts and Toronto. Thence westward, they 

 converge, by way of the Susquehanna, Delaware, Hudson, and 

 other streams, at Lake Ontario, where they are bound to the 

 shaft. At Lake Michigan the upper ends of the bound strands 

 have broken out in the Michigan and Illinois localities; and the 

 course of the broom handle is marked, westward, by the isolated 

 collections in Minnesota, South Dakota, and Oregon. 



Though the lines of spread from the Atlantic inland are 

 almost indistinguishable, the general course is that followed by 

 migrating ducks; and it appears wholly reasonable to regard 

 them as the carriers. Indeed, I cannot repress the suggestion 

 that the bringing of the crisp pondweed to North America is 

 attributable with far less certainty to the hand of man than to 

 such birds as the European Widgeon, which has been caught 

 straying on this continent more than eighty times. 



Illinois State Natural History Survey 

 Urbana, Illinois. 



