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of the Genesee River, as well as a portion west of the Niagara, 

 as its radius was one of fifty miles about Buffalo. The Cayuga 

 Flora of Professor Dudley (1886) was for the basin of Cayuga 

 Lake and some adjoining ground, though covered in part already 

 by Paine's Oneida list. The three lists mentioned do not record 

 the plant. In the " Plants of Monroe County and Adjacent Ter- 

 ritory," published in 1886 by the Rochester Academy of Sciences, 

 it is listed for places near the Genesee River, being abundant in 

 some of them. Macoun does not give it in any list of Canadian 

 plants up to 1890, that being the date of some entries as " addi- 

 tions and corrections to parts I-IV " of his Canadian catalogue. 

 I can add as a matter of personal observation, that in the summers 

 of 1882 and 1884 I spent some weeks examining streams, lakes, 

 and ponds in western New York for the study of Najadaceae, 

 but collected other plants as well. The localities were princi- 

 pally south of the area recorded in the Rochester list and east of 

 that of the Buffalo list, being in the counties of Wyoming, Genesee, 

 Livingston, and some adjoining parts of Monroe and Ontario 

 counties. I did not meet with the plant. Judging by the rate 

 at which it has spread since it was first observed in the Desplaines 

 valley, it is not likely to be present in a locality for any length of 

 time without becoming abundant enough to attract attention, since 

 it soon forms extensive mats or beds in favorable localities, 

 - Though the year of discovery is not generally given in the 

 publications cited, the time of publication is covered by ten years 

 for places as widely separated as Rochester, Painesville, Detroit, 

 and Chicago. This is about seventy years after the first notice 

 by Barton and Nuttall by the Delaware. The distribution 

 between these places and the seaboard and between one another, 

 if in any way connected, must be ascribed to other causes than 

 that of steady accretion of area along lines of natural or unaided 

 seed distribution, however this may act in localities where a 

 plant is once established. Nor are the places mentioned so con- 

 nected by water communication that plants of this character 

 would be likely to traverse the spaces in the reverse direction to 

 the course of drainage, however this may aid when the direction 

 of flow is in their favor. Yet they are on main lines of railway 



