GRYPTOGAMIA. rillCES. 253 



SfECiES. I.e. veptita. J'v'eph) odium lariosiim. IMich. Fl. 

 Am. 2. p. 270. 2. dealbata. Fh. Obs. Fronds 2 or 3 inches 

 hig-h, .irlaucous green, white and pulvtrulent on the 

 undei- side; stipes brown. H ab. In the crevices of rocks o\\ 

 tht- banks of the Miasoiiri about 50 miles iibove i^s con- 

 fluence; rare. v. v. 



§30. DIGKSONiA. rHeriticr. 



Son punctiforni, marginal, roinidishj iind dis- 

 tinct. Indasiuun\ydh]Q. one superficial, opening 

 outwards, the other marginal and opening in- 

 wards. 



Species. 1. D. pilosivsada. Common in Pennsylvania 

 and New Jersey. 



A small j^enis of trnpicur'fcins, consisting' of about 16 

 species of v.lic'r there i-^ an arborescent species 'n the 

 island of St. Helens^ and another in the South-sea islands. 



«31. HYMENOPHYLLUM. Smiik. 



Sorus marginal, inserted in acylindric r^cep- 

 ^acle. Iiidasium two-valved, including the sorus. 



Species. 1. H. ciUatvm. — \ g-enus of more than 20 



species, producing small diaphanous and membi anaceous 

 fronds- 



83-2. ISOETES. L. (Quill-wort.) 



Capsule jienjbranaceous, not openijig, t-ccl- 

 kd, imir.frs^.d in the base of th;' hiy(\i\. Seeds 

 aj^g«'^?.r, attac'hed to miiny fil itorm rece})tnrles. 



Species. I. lacusttis. Abundant aloiv.^ the inundated, 

 fi^iaveliy and ml rev shores of the Delaware, ne:.r Phlladel- 

 j)hla and other places, also in the state of New York., 

 <Jbs. J^col fibrous, tibres sin^.ple, broad and fistuiort:; 

 fronds dilated and irribricate at tlic base, narrow and sub- 

 ulate, above fiat, benealh anj^ularly convex, each pio- 

 ducini;- 4 fistulous caviues F-uit monoious; son cnrdaie- 

 oval, i'-j-inKi-sed in a conespondinj; cavity at tjie base of 

 the frond, partly bilohed, included in a nienibran.iCirou.s 

 integ-ihuent connected to.y^ether by numerous transverse 

 co'umi ir receptacles; rriale? sorus filled wi.h prdveruienc 

 poll'-n, bccomijig- white on drying; capsules (or stcds) glo- 

 bular, wiitrn dry presenting- a snow-while puiverultnt sur- 

 Y 



