Pellcea, Ceratopteris, Lomaria. 8i 



sharp pointed or mucronate, in the fertile fronds entire, with the 

 margin narrowly recurved, in the rare sterile fronds sharply ser- 

 rated, especially toward the apices. Cal., Ore., Wyoming. IV. 



? 3. PLATYLOMA, J. Sm., Baker. Texture coriaceous, the 

 veins usually hidden, the ultimate segments broad and flat, the in- 

 dusium, so narrow as to be soon hidden by the fruit. 



12. P. Bridgesii,* Hook. Stipes 2' — 6' long, tufted, castane- 

 ous ; fronds 4' — 6' long, \' or more broad, simply pinnate ; pinnae 

 5 — 18 pairs, mainly opposite, nearly sessile, glaucous green, coria- 

 ceous, rounded or cordate at the base ; indusium narrow, formed 

 of the whitish margin of the pinna, soon flattened out exposing 

 the broad sorus. Cal! IV. 



13. P. flexuosa. Link. Rhizoma creeping, rather slender; 

 stipes reddish passing into a more or less flexuous or zigzag 

 rachis ; fronds 6' — 30' long, ovate-oblong, hi— tripinnate ; second- 

 ary and tertiary rachises usually deflected and zigzag, rusty pu- 

 berulent or nearly smooth ; pinnae mostly alternate ; ultimate pin- 

 nules 5"— 10" long, roundish-ovate, or sub-cordate, smooth ; mar- 

 gins at first reflexed soon flattened out. W. Tex. to Cal. V. 



XI. CERATOPTERIS, Brong. Floating-fern. 



Sori placed on two or three veins which run down the frond 

 longitudinally, nearly parallel with both the edge and midrib. 

 Sporangia scattered on the receptacles, sessile, sub-globose, with 

 a complete, partial, or obsolete ring. Indusia formed of the re- 

 flexed margins of the frond, those of opposite sides meeting at 

 the midrib. 



I. C. thalictroides, Brong. Stipes tufted, thick, inflated, filled 

 with large air cells ; fronds succulent in texture, the sterile ones 

 floating in quiet water, simple or slightly divided when young, bi — 

 tripinnate when mature ; fertile ones bi — tripinnate ; ultimate seg- 

 ments pod-like. Fla. VI. 



XII. LOMARIA, Willd. 



Sori in a continuous band next the midrib of the contracted 

 pinnae of the fertile frond, covered till mature by an elongated in- 

 dusium, either formed of the recurved and altered margin of the 

 pinna or sub-marginal and parallel to the margin. Veins of sterile 

 frond oblique to the midrib simple or forked and free. Fronds 

 mostly elongated, of two kinds, the sterile foliaceous, the fertile 

 commonly much contracted. 



I EULOMARIA. 



14— 



