384 TRANS. ST. LOUIS ACAD. SCIENCE. 



and dark gray when dry; in some I find the warts much smaller than in 

 others, but never wanting; microspores also quite dark brown, 



* * With peripheral bast-bundles. 

 t Velum partial. 



9. I. Engelmanni, a. Braun. Our largest species with numerous (25 

 to 100) long (9 to 20 inches or more) light green leaves with abundant 

 stomata; sporangium usually oblong to linear-oblong, unspotted ; velum 

 narrow; ligula elongated from a triangular base ; macrospores 0.40 to 0.52 

 mm. thick, delicately honeycomb-reticulated ; microspores 0.024 to 0.028 

 mm. long, generally smooth. — Flora 1. c. ; Am. Jour. 1. c. ; Gray Man. 1. c. 



Var. GRACILIS, Engelm. Often submerged, with fewer (8 to 12) leaves, 

 9 to 12 inches long; the bast-bundles sometimes quite small, or only two 

 of them. —Gray Man. I.e. 



Var. VALiDA, Engelm. The stoutest of all our species; leaves 50 to 

 100 or even 2co, 18 to 25 inches long, keeled on the upper side; sporan. 

 gium often linear-oblong (4 to 9 lines long), J or often } or even § covered 

 by the broad velum ; macrospores rather smaller, 0.32 to 0.48 mm. thick; 

 microspores 0.024 to 0.027 mm. long, spinulose,— Gray Man. I.e. 



Var. Georgiana. Similar to the type; leaves few (in the only speci- 

 mens seen 15, 10 to 12 inches long), rather slender ; oval sporangium with 

 narrow velum; macrospores larger, 0.48 to 0.56 mm. thick; microspores 

 0.028 to 0.031 mm. long, smooth. 



In ponds and ditches, immersed in mud, rarely found in slow-running 

 streams, in company with the ordinary vegetation of such localities, 

 Bi'dens, Polyg07ium. Lycofus-, Carices, Leirsia, etc.; mature in summer; 

 probably throughout the middle States, but thus far only found — from 

 Massachusetts : Arlington brook, Alewife brook. West Cambridge brook, 

 Woburn, IVtn. Boott. Rhode Island : Newport, W. G. Farloiv. Connec- 

 ticut : Meriden, F. W. Hall— io New York: Peekskill, W. H. Leggett. 

 New Jersey: E. Durand, C. F.Austin, and others. Pennsylvania, Beth- 

 lehem, C. J. Moser, E. Durand, S. Wolle; Delaware Water-Gap, 5. W. 

 Knipe; Darby, J. G. Hunt: Philadelphia, E. Durand, C. E. Smit/i, and 

 others. Delaware: Wm. M. Canby, A. Commons. Virginia: Salt Pond 

 "iilo\xnta.\n, with Parnassia asart/olia, IV.M. Canby. Missouri: St. Louis, 

 N. Riehl and G. Engehnann, 1842, in a single locality, where it was soon 

 afterwards destroyed by cultivation : not found otherwise west of the Alle- 

 ghany Mountains. Var. gracilis seems to be a northern form : Brattle- 

 borough, in Clark's Pond, C. C. Frost ; Colebrook's, in a shallow stream 

 with gravelly bottom, J. W. Bobbins ; New Haven, in fresh water on a 

 tidal shore, D. C. Eaton; Newport, Bridges, G. Thurber ; Passaic river, 

 near low- water mark, J. Ennis. Var. valida was discovered in Pennsyl- 

 vania near Warrior's Mark, Huntington Co., and Smithville, Lancaster 

 Co., T. C. Porter ; and in Delaware, Wilmington, W. M. Canby. Var. 

 Georgiana comes from a mountain streani, Georgia, the Horseleg creek, 



