EXPLANATION OF THE PLATES. 703 



TAB. XVIH. 



CYSTOPTERIS. Piece of the frond of C. bulbifera, Bernh. (1); a lobe in fruit (2) 

 enlarged; and a small portion more magnified (3), bearing a fruit-dot with 

 its indusium thrown back. 



WOODSIA. Small frond of W. glabella, R. Br. (1); a part of a fruiting pinna of 

 the same (2), magnified; and a separate indusium (3), more magnified; a 

 piece of a fruitful pinnule of W. obtusa, Torr. (4), enlarged; and a fruit with 

 the opened indusium beneath (5), more magnified. 



ASPIDIUM. Pinna of A. (Dryopteris) marginale, Swartz (1); and a magnified 

 fruiting portion (2); piece of A. (Polystichum) acrostichoides (3); and a 

 small fruiting portion (4), magnified. 



ONOC LEA. Sterile and fertile frond of 0. sensibilis, L. ; front view of a fruiting 

 contracted pinnule, enlarged (1); and the same laid open and viewed from 

 the other side (2): on one lobe the sporangia are removed from the veins. 



TAB. XIX. 



SCHIZ^A. Plant of S. pusilla, Pursh., of the natural size; a fertile pinna with 

 eleven sporangia (1), magnified; and a separate sporangium (2), more mag- 

 nified. 



LYGODIUM. Summit of frond of L. palmatum, Swartz (1), with fertile and 

 sterile divisions; a fruiting lobe enlarged (2), with two of the lower scales, or 

 indusia, removed, displaying a sporangium under each ; and a sporangium 

 more magnified (3). 



OSMUND A. Small piece of the frond of 0. Claytoniana, L. (1), with a fertile and 

 a sterile pinna; a portion of the fruit magnified (2); and one sporangium more 

 magnified (3). 



BOTRYCH1UM. Plant of B. lunarioides, Swartz; and a portion of the fruit (1), 

 with six sporangia, magnified. 



OPHIOGLOSSUM. Frond of 0. vulgatum, L.; and a portion of the fruiting spike 

 enlarged (1). 



Genera of Equisetaceae, Lycopodiacese, &c. 



TAB. XX. 



EQUISETUM. Upper part of fertile plant of E. limosum, L. (1); one of the 

 shield-shaped scales or receptacles of the spike, with the six sporangia under- 

 neath (2), enlarged; same seen from below, discharging the spores (3); a 

 magnified spore with the club-shaped filaments spreading (4); and (5) the 

 same with the filaments coiled up. 



LYCOPODIUM. Plant of L. Carolinianum, L. ; and (1) a magnified scale of the 

 spike removed, with the sporangium in its axil, discharging powdery spores. 



SELAGINELLA. Plant of S. rupestris, Spring; part of a fertile spike, en- 

 larged (1) ; scale from the upper part of it (2), with its sporangium, contain- 

 ing innumerable powdery spore*; scale from the base (3), with its sporangium 

 containing few large spores; and (4) three large spores. 



ISOETES. Plant of I. lacustris (1); sporocarp containing the minute spores, cut 

 across (2), enlarged; same divided lengthwise (5); s-porocarp with the large 

 spores, divided lengthwise (3); and (4) three large spores more magnified. 



AZOLLA. Plant (1); a portion magnified (2), with two kinds of organs; sterile 

 sporocarp, or antheridium, more magnified (3); fertile sporocarp more mag- 

 nified (4); the same burst open, showing the stalked sporangia (5); one of 

 the latter more magnified (6); another bursting (7); and three spores (8), 

 beset with bristles. 



THE END. 



