26 THE NAUTILUS. 



Michigan : The writer has records from 52 of the 83 counties of 

 the state, indicating a general distribution throughout the state. 

 The counties represented are shown by the map (plate II). 



Minnesota : Lake Albert Lea; Fergus Falls (Pils.); Stearns Co.; 

 Lake Minnetonka ; Cannon Lake, Rice Co.; Shackleton Lake 

 (Walker); Minneapolis; Lake Minnewaska, Pope Co.; Vermilion 

 Lake, Winona, Lake Co.; St. Louis Co. (Grant); Clearwater, 

 Wright Co. (Sargent); Harriet Lake, Hennipen Co. (Daniels); 

 Heron Lake, Jackson Co.; Eagle Lake, Sherburne Co. (Stearns). 



Mississippi : None. 



Missouri : Pettis Co.; Lamar, Barton Co. (Sampson). 



Montana : Mingusville, now Wibaux (Squyer). 



Nebraska : Sidney (Walker); streams of eastern Neb. (Aughey); 

 Omaha (Tryon). 



Nevada : None. 



New Hampshire : Profile Lake (Walker); Keene (Walker and 

 Coolidge). 



New Jersey : Greenwood Lake, Passaic Co.; Raritan River; 

 Cedar Lake, White Pond, Warren Co.; Swartzwood Lake, Sussex 

 Co.; Center Twp., Camden Co.; Delaware Water Gap; Princeton, 

 Mercer Co.; Lake Hopatcong, Budd's Lake, Morris Co.; Hacken- 

 sack Valley; Closter, Bergen Co.; Trenton; Gloucester Co. (Pils.). 



New Mexico : Las Vegas; South Spring River, Roseville; Tre- 

 mentina; Santa Fe; Arroyo Pecos, Las Vegas (Pils.). 



New York : Cazenovia; Skaneatales Lake; Long Island; Niagara; 

 Hudson River, Fort Warren, Ridgewood; Racquette Lake, Hamil- 

 ton Co.; Queens Co.; Squaw Island, Niagara River; Troy (Pils.); 

 Gannagagee Creek, Erie Co.; Alfred; Watertown; Canandarago 

 Lake, Otsego Co.; Cedar Lake, Herkimer Co.; Old Forge (Walker); 

 Sunset Creek, Otsego Co. (Smith); Chatauqua Lake (Maury); 

 Schuyler's Lake, Otsego Co.; Mohawk River, Little Lakes and Erie 

 Canal and Litchfield, Herkimer Co. (Lewis); Onondaga Co. (Beau- 

 champ); Rochester (Walton); Huntington, Centerport, Long Island 

 (Smith & Prime); Cayuga Lake (Ferriss MSS). 



North Carolina : Asheville ; Greenfield Pond, Wilmington 

 (Walker). 



North Dakota; Hankinson (Pils.); Fort Stevenson (Stearns). 



Ohio: Columbus; Geanga Co. (Pils,); Hudson (Walker); Cincin 

 nati (Harper and Wetherby); Tuscawaras Co. (Sterki); " The Re- 

 serve " (Naturalist). 



