P. heterophyllus, Schreb.; Hook., F1.IL, 172; Pursh, Fl. I., 120. Common in streams from the Atlantic to the Pacific. In flowing water at Coal Branch, Kent Co.; Tobique River, and Salmon River, N.B. (Fowler, Oat.) Lake Utopia, N.B. (Wetmore.) Little Tobique Lake, N.B. (Say.) Titusville, N.B. (Brittain.) Flowing water at Truro, N.S.; Salt Lake, Anticosti; in a rapid stream between West-wood and Peterboro, Ont; vicinity of Belleville, Hastings Co., Ont.; River St. Clair, near Windsor, Ont. (Macoun.) Wabigoon River, west of Lake Superior. (Fletcher.)

Var. (near) graminifolius, Fries.

In shallow water, Lake Mistassini, N.E.T. (J. M. Macoun.) Ottawa River. (Fletcher, Fl Ott.)

Var. maxim US, Morong.

Flowing water, Becscie River, Anticosti. (Macoun.) Not uncommon at Ottawa. (Fletcher, Fl. Ott.)

Var. heterophyllus, Fries.

The common form and found throughout the country. Grand Val-lée, Gaspé coast, Q. (Macoun.). Abundant in the vicinity of Ottawa. (Fletcher, Fl. Ott.) Nation River, Ont. (Billings.) Mud Lake, near Kingston, Ont. (Millman.) Near Belleville, Hastings Co., and general throughout central Ontario in rivers, lakes and ponds, and westward to Lake Superior, where it is particularly abundant. (Macoun.) Parry Sound, Georgian Bay. (Burgess.) Lake Mistassini, N.E.T., and Missinaibi River, Ont. (J. M. Macoun.) Oba Lake, Ont. (R. Bell.) Jones Falls, Ont. (Millman.) Abundant in fresh water ponds throughout the prairie region, through the Rocky Mountains, and west ward to the Pacific, where it becomes common in ponds and lakes on Vancouver Island, near Victoria, Nanaimo, Qualicum and Alberni. (Macoun.) Cumberland House on the Saskatchewan. (Hooker, Fl.)

(2438.) P. lucens, Linn.; Gray, Man. Ed. V., 487.

Pictou Co., N.S. (McKay.) St. Lawrence River, at Prescott, Ont. (Billings.) Bay of Quinte, and in the mill pond at Stirling, and in Elziver, Hastings Co.; also in the still waters of the Trent River, Seymour, Northumberland Co., Ont. (Macoun.) Nelson River, Keewatin. (B. Bell.)

(2439.) P. Zizii, Mertens & Koch.

P. lucens, var. minor, Nolte; Gray, Man. Ed. V., 488; Macoun, Cat. No. 1734, var. minor.

Apparently rare in Canada. Nation River at Casselman, near Ottawa; Big Bushkong and other lakes up Gull River, Victoria Co., Ont. (Macoun.) Vicinity of Hamilton, Ont. (Buchan.) Meech's Lake, near Chelsea, Q. (Fletcher, Fl. Ott.)

(2440.) P. prselongus, Wulfen.; Hook., Fl. II., 172.

P. lucens, Michx., Fl. I., 102; Pursh, Fl. I.120. Not uncommon in deep water of lakes and quiet rivers. Earltown Lakes, Colchester Co., N.S. (McKay.) Bass River, Kent Co.; Tobi-que Lake, N.B. (Fowler, Cat.) Woodstock, N.B. (Hay.) St. Stephen, N.B. (Vroom.) St. Lawrence River, near Point St. Charles, Montreal, 1821. (Dr. Holmes.) Bay of Quinte, at Belleville; Weller's Bay, Lake Ontario, and in deep water in the River Trent, Seymour, Northumberland Co.; abundant in Lake Superior, at the mouth of the Kaministiqua, and in the lake expansions of Nipigon River. (Macoun.) Goulais River, Lake Superior. (B. Bell.) In the Athabasca River, above Lake Athabasca, lat. 58°; Lost Lake, near Cedar Hill, and Lang-ford and Shawnigan lakes, near Goldstream, Vancouver Island. (Macoun.) English River, north of the Saskatchewan. (Hooker, Fl.)

(2441.) P. perfoliatus, Linn.; Michx., Fl. L, 101; Pursh, Fl. I., 120; Hook., Fl. II., 172.

Rather common in rivers and lakes throughout the country. Cow Bay, Halifax Co., N.S. (Sommers, Cat.) Ponds and slow streams, Norton, N.B. (Fowler, Cat.) Becscie River, Anticosti. (Macoun.) Rivers of the north shore of the Gulf of St. Lawrence. (St. Cyr.) Riviere du Loup, Q. (Thomas.) River St. Pierre and at Three Rivers, Q. 1821. (Dr. Holmes.) Green's Creek, Ottawa; very rare, only once collected. (Fletcher, Fl. Ott.) Abundant in the Bay of Quinte, and at

Weller's Bay, Lake Ontario. (Macoun.) Kemptville, Ont. (Porter.) Kingston, Ont. (Millman.) Canada to Slave River. (Hooker, Fl.)

Var. lanceolatus, Robbins, Gray, Man. Ed. V., 488.

This seems to be the western and northern form, as it is abundant westward where the species seems to be absent. St. Clair Flats, Ont. (J. M. Macoun.) Abundant at Ottawa, in all waters. (Fletcher, Fl. Ott.) Lake of the Woods. (Burgess.) In the still waters of the lake expansions of Nipigon River, and in the mouths of rivers north of Lake Superior. (Macoun.) Lake Mistassini, N.E.T.; and Missinaibi River, Ont. (J. M. Macoun.) James Bay, at Moose Factory. (Cottar & Dr. Hayden.) Nelson River, Keewatin. (R. Bell.) Moose Mountain Creek, Man. (J. M. Macoun.) Long Lake, north of Regina, Assini-boia; in a small pond on Copper Mountain, Rocky Mountains. (Macoun.) Lewes River, lat. 62°. (Dawson.)

(2442.) P. zosterifolius, Schum.; Hook., Fl. II., 172.

P. compressus, Fries.; Gray, Man. Ed. V., 488; Macoun, Cat. No. 1732. Rather common in still water. Still and slow flowing water, St. John, N.B. (Fowler, Cat.) Vicinity of Ottawa; common. (Fletcher, Fl. Ott.) Near Montreal, 1821. (Dr. Holmes.) St. Lawrence River and slow streams; common at Prescott, Ont. (Billings.) Jones Falls, Rideau River, Ont. (Millman.) London, Ont. (Burgess.) Abundant in the Bay of Quinte, and in all the rivers in central Ontario; Gull River, Peterboro Co., Ont., and in Lake Hannah, Nipigon River, Lake Superior. (Macoun.) Oba Lake and river, and Missinaibi River, Ont. (R. Bell.) Burlington Marsh, Hamilton, Ont. (Buchan.) York Factory, Hudson Bay, and from Cumberland House, on the Saskatchewan, to Portage La Loche, lat. 57°. (Hooker, Fl.)

(2443.) P. obtusifolius, Mertens & Koch.

A few specimens were gathered in mud on the margin of a small lakelet near Point Fame Lighthouse, Gaspé coast, Q., in August, 1882. (Macoun.)

(2444.) P. pauciflorus, Pursh, Fl. I., 121.

P. gramineum, Michx., Fl. I., 102. P. pusillum, Hook., Fl. II., 172.

Not uncommon in still water. Restigouche River, N.B.; rather doubtful. (Fowler, Cat.) Madeline River, Gaspé, Q.; abundant in the Bay of Quinte, and in the Trent River at Trenton; also Gull River, Peterboro Co., Ont. (Macoun.) Smith's Falls, Ont. (Prof. Fowler,) Billings Bridge, Ottawa. (Fletcher, Fl. Ott.) Marsh at Hamilton, Ont.