1922] 



PFEIFFER MONOGRAPH OF THE ISOETACEAE 199 



(Gray Herb.); Horn Pond, 11 July, 16 September, 1867, 

 Boott (Mo. Bot. Gard. Herb, and Gray Herb.) ; Waushakum 

 Pond, So. Framingham, 29 June, 20 July, 1890, Sturtevant 

 (Mo. Bot. Gard. Herb.) ; sandy bottom, Lake Attitash, 

 Amesbury, August, September, 1895, Eaton (Mo. Bot. Gard. 

 Herb., U. S. Nat. Herb., and Univ. Minn. Herb.); Quan- 

 naponit Lake, Wakefield, 10 September, 1869, Boott (N. 

 Y. Bot. Gard. Herb.) ; Attitash, Essex Co., Eaton 960 (Mo. 

 Bot. Gard. Herb.); same, 27 June, 1896, Eaton 197 (Mo. 

 Bot. Gard. Herb.); same, 31 July, 1896, Eaton 882 (Mo. 

 Bot. Gard. Herb.) ; Chebacco Pond, Essex Co., 15 July, 1896, 

 Dodge (N. Y. Bot. Gard. Herb.) ; Chebacco Lake, Essex Co., 

 August, 1896, Eaton (Mo. Bot. Gard. Herb, and Univ. Minn. 

 Herb.); same, without date, Eaton 378 (Mo. Bot. Gard. 

 Herb.); Chebacco Lake, Essex Co., 18 July, 1896, Dodge 

 (Gray Herb.) ; Bate's Pond, Wenham, 29 July, 1896, Eaton 

 376 (Mo. Bot. Gard. Herb.); Nine-Mile Pond, Cape Cod, 

 4 September, 1898, Greenman 424 (Mo. Bot. Gard. Herb.) ; 

 Watson's Pond, Taunton, 15 September, 1903, Eaton (Mo. 

 Bot. Gard. Herb.) ; Winneconnet Pond, Norton, 14 July, 

 1903, Eaton (Mo. Bot. Gard. Herb.) ; Merrimac River, New- 

 buryport, August, 1896, Dodge (N. Y. Bot. Gard. Herb.) ; 

 in fresh water, tidal shores Merrimac R., Newburyport, 1896, 

 Eaton (Mo. Bot. Gard. Herb.); Kimball's Pond, Ames- 

 bury, July, 1896, and August, 1897, Eaton (Mo. 

 Bot. Gard. Herb.) ; Kimball's Pond, Amesbury, 27 

 June, 1896, Eaton (Univ. Minn. Herb.); Kimball's 

 Pond, Essex Co., 13 August, 1899, Eaton (Mo. Bot. 

 Gard. Herb.) ; near Jerry's Pond, West Tisbury, 

 Martha's Vineyard, 24 August, 1916, Seymour 1017 (Gray 

 Herb.) ; Lake Cochichewick, North Andover, 24 September, 

 1903, Pease 2640 (Gray Herb.) ; submerged in shallow water, 

 sandy margin of Great Pond, Weymouth, Norfolk Co., 2 

 September, 1918, Churchill (Mo. Bot. Gard. Herb.) ; car- 

 peting the sandy bottom of Spectacle Pond, Wellfleet, Barn- 

 stable Co., 19 September, 1918, Fernald & Weatherby 15950 

 (Gray Herb, and Mo. Bot. Gard. Herb.) ; sandy bottom, 

 Great Pond, Weymouth, 2 September, 1918, Knowlton (Mo. 

 Bot. Gard. Herb, and Gray Herb.) ; Buck Pond, Harwich, 

 wet sandy lower beach and inundated margin, 30 August, 



