FILICES. (ferns.) 587 



Tribe Vll. ASPIDIE^^. — Fruit-clots at or holow the ends of the veins, round, or 

 somewhat oblong and tlicu placed iicross the rein. Indusium round or nearly bo, flxcd 

 in the middle and opening at the margin, or reniform and tixod at the 8inus. 

 • Fertile and sterile fronds alike. 



12. CTSTOPTEUl?. Indusium on the back of the vcinlet, hood-shaped, fixed at tlie baee 



partly under the fruit-dot, opening toward the apex of the segment 



13. ASl^IDIUM. Indusium mostly on the back of tlio veins, orbi.ular or round-reniform, 



fixed in tlio middle or at the sinus, opening all round the margin. 



14. NEI'UKOLEIMS Indusium at the end of a free vein, reuiform, fixed at the sinus or by 



the arcuate base, opening toward the margin of the frond. 



• * Fertile and sterile fronds didorent. 



15. OXOCLEA. Fertile fronds contracted, the divisions rolled up and berry-like. 



Tribe Mil. AVOOD*<IE^. — Fruitnlots round, borne on the back of a free vein. In- 

 dusium fixed beneath the fruit-dot, saucer-shaped, or gloliose and bursting at the top. 



16. WOODSIA. Indusium divided into irregular lobes, or a capillary fringe. 



Tribe IX. DICKSONIEjE. — Fruit-dots marginal, roundish, borne at the eni!< of the 

 free veins. Indusium cup-shaped or two-valvcd, its outer part composed of a rctlexed 

 lobe of the frond, or more or less united with it. 



17. DICKSONIA. Indusium (in our spwies) small nearly globular, membranaceous. 



SuBOKDER II. IIY:\IEX0PHYLLE.E. Sporangia borne on a seti- 

 form or slender receptacle, cellulai'-reiiculated, surrounded by a complete 

 transverse ring. Involucres marginal, at the ends of the veins, cup-shaped 

 or two-valved. Fronds delicately nu'Uibranaeeous and pellucid. 



18. TRICIIOMAXES. Involucre cup-shaped or funnel-shaped, sometimes 2-lipped. 



Suborder III. SCHIZ.^INEiE. Sporangia large, borne on narrow 

 segments of the frond, oval, cellular-reticulated, crowned by the converg- 

 ing striiE of a complete apical ring, opening longitudinally. 



19. LTGODIDM. Sporangia attached laterally in two rows to the narrow divisions of the 



pinnae, each one covered by a scale-like indusium. 



20. AXEIMIA. Sporangia attached by their bases to the narrow divisions of the panicled 



fertile branches of the frond. Indusium none. 



Suborder IV. OSMUNDINEyE. Sporangia large, nearly sessile 

 on the back or margins of the mostly contracted fertile fronds, two- 

 valved, opening vertically at the apex. King rudimentary or none. 



21. OSMUNDA. Sporangia globular, covering the contracted fronds or portions of fronds. 



Suborder V. OPHIOGLOSSEiE. Sporangia very large, sessile, 

 spiked or panicled, coriaceous, not reticulated, on narrow divisions of the 

 frond, destitute of a ring, transversely two-valved. Fronds not circinate 

 in vernation. 



22. BOTRYCHIUM. Sporangia in panicled spikes. Steri'e part of the frond pinnatcly di- 



vided. 



23. OPIIIOGLOSSUM. Sporangia in a simple spike. Sterile part of the frond simple in our 



species. 



