1922] 



PFEIFFER — MONOGRAPH OF THE ISOETACEAE 205 



near Lancaster, in soft mud, half immersed, 1 October, 1866, 

 Porter (Mo. Bot. Gard. Herb.) ; in small ditches, not near 

 tide-water, near Darby, Philadelphia, 4 July, 1866, Hunt 

 (Mo. Bot. Gard. Herb.) ; Delaware Water Gap, June- July, 

 1870, Knipe (Mo. Bot. Gard. Herb.) ; mountain swamp, 2 

 miles southwest of Cornwall, Lebanon Co., 1 August, 1878, 

 Porter (Mo. Bot. Gard. Herb.) ; wholly immersed in a lake 

 at Delaware Water Gap, August, 1880, Canby (Mo., Bot. 

 Gard. Herb.) ; Delaware River, at Monroe, Buck Co., 21 

 July, 1886, J. A. & H. F. Ruth (Univ. Minn. Herb.) ; Mon- 

 roe Co., 26 July, 1886, Porter (Dudley Herb.); McCall's 

 Ferry, 2 miles south of Bethesda, July, 1898, Galen (Mo. 

 Bot. Gard. Herb.); Susquehanna River, Wayne Co., 20 

 July, 1900, Clute (Mo. Bot. Gard. Herb.) ; pool among rocks, 

 York Co., 2-6 July, 1901, Britton (Mo. Bot. Gard. Herb, and 

 N. Y. Bot. Gard. Herb.) ; Sayre, edge of river, August, Bar- 

 bour (Mo. Bot. Gard. Herb.) ; Delaware Water Gap, 3 July, 

 1887, Britton (Gray Herb.); vicinity of McCall's Ferry, 

 York Co., 5-7 July, 1904, Rose & Painter 8168, 8216 (U. S. 

 Nat. Herb.) ; in soft mud of a partially exsiccated pond, near 

 Warriorsmark, Huntingdon Co., at foot of Alleghenies, 20 

 August, 1868, Porter (Mo. Bot. Gard. Herb, and Gray 

 Herb.) ; in clay mud and water of a pond in the barrens of 

 Huntingdon Co., 1200 ft. above sea-level, September, 1870, 

 Porter (Mo. Bot. Gard. Herb, and Gray Herb.) ; Smithville, 

 Lancaster Co., August, 1865, Porter (Mo. Bot. Gard. Herb.) ; 

 same, 1 October, 1866, (Mo. Bot. Gard. Herb.); pond near 

 Warriorsmark, October, 1870, Davis (Mo. Bot. Gard. Herb.). 



Delaware: Wilmington, 1860, Tatnall (Gray Herb.); in a bog 



near Wilmington, 1858, Tatnall (Gray Herb.) ; Wilming- 

 ton, 16 June & 23 July, 1866, Canby (Mo. Bot. Gard. Herb, 

 and Gray Herb.); in a ditch near Ogletown (dry at time 

 of collection), 4 August, 1866, Commons (Mo. Bot. Gard. 

 Herb.); ponds, Townsend, 4 July, 1896, Canby (Mo. Bot. 

 Gard. Herb.) ; in small ditch along Baltimore River, y 8 mile 

 below Stanton Station south of Wilmington, 21 September, 

 1866, Canby (Mo. Bot. Gard. Herb.); same, August, 1867, 



Bot. Gard. Herb.) ; Wilmington, 1865, Durand (Mo. 

 Bot. Gard. Herb.) ; Wilmington, 25 September, 1866, Canby 

 (Mo. Bot. Gard. Herb, and Gray Herb.) ; Wilmington, ditch- 



