CRYPTOGAMIA. FILICES. £55 



Species. l.C.vestita. A'ephrodtum lanosum. Mich. Fl. 

 Am. 2. p. 27o'. 2. dealbota. Fh. Obs. Fronds 2 or 3 inches 

 higli, glaucous green, white and pulverulent on the 

 under side; stipes brown. Hab. In the crevices of rocks on 

 the banks of the Missouri about 50 miles above its con- 

 fluence; rare. v. -v. 



S30. DICKSONIA. L'Heritier. 



Sort punctiforni, marginal, roundish, and dis- 

 tinct. IndiLsium double, one superficial, opening 

 outwards, the other marginal and opening in- 

 wards. 



Species. 1. T). pilosiuscida. Common in Pennsylvania 

 and New Jersey. 



A small ercniis of tropical ferns, consisting- of about i6 

 species of uh cl there is an arborescent species in the 

 island of St. Helena, and another in the South-sea islands. 



€31. HYMENOPHYLLUM. Smith, 



Sorus marginal, inserted in a cylindric recep- 

 tacle. Indusium two-vaivcd, including the sorus. 



Species. 1. I[. ciliatum. — \ genus of more than 20 

 species, producing small diapijanous and membranaceous 



fronds. 



2. ISOETES. L, (Quill-wort,) 



Capsule nicmbranaccous, not opening, 1 -cel- 

 led, immersed in tlie base of the frond. Seeds 

 angular, attached to many filiform receptacles. 



Species. \. lacnstris. Abundant along- the inundated, 

 p^ravelly and mirey shores of the Delaware, near Philadel- 

 phia and other |)laces, also in the state of New York. 

 Obs. Root fibrous, fibres s:mj)le, broad and fistulous; 

 fronds dliaied and imbricate at the base, narrow and sub- 

 ulate, above flat, beneath ang-ularly convex, each pro- 

 ducing- 4 fistulous cavities. Fruit moiioicous; sori cordate- 

 oval, immersed in a corresponding cavity at the base of 

 the frond, partly bilobed, included in a membranaceous 

 integ-umeiit connected tog-ether by numerous transverse 

 columnar receptacles; male? sorus' filled wiih pulverulent 

 pollen, becoming white on drying; capsules (or seeds) glo- 

 bular, when dry presenting a snow-white pulverulent sur- 

 Y 



