FILICES. (FERNS.) 623 



TRIBE VI. BL.ECHNE.aE. Fruit-dots dorsal, linear or oblong, borne on transverse 

 veins parallel to the midrib. Indusium fixed by its outer margin, and opening at the 

 inner one. 



10. BLECHNUM. Fruit-dots linear, elongated, covered by a continuous indusium. 



11. WOODWARDIA. Fruit-dots linear-oblong, in a series near the midrib, covered by 



separate indusia. 



TRIBE VII. ASPLENIE^E. Fruit-dots dorsel, linear or oblong, oblique or at right 

 angles to the midrib. Indusium fixed by one margin to the veinlet, opening at the 

 other. 



12. CAMPTOSORUS. Fruit-dots straight or curved, scattered irregularly on the more or 



less reticulated veins, or facing each other in pairs. Frond simple. 



13. ASPLENIUM. Fruit-dots oblique, on the upper side of the veins, rarely on both sides 



of them. Veiiis free. 



14. SCOLOPENDRIUM. Indusia in pairs, and opening towards each other. 



TRIBE VIII. ASPIDIE^E. Fruit-dots at or below the ends of the veins, round, or 

 somewhat oblong and then placed across the vein. Indusium round or nearly so, 

 fixed in the middle and opening at the margin, or reniform and fixed at the sinus. 



* Fertile and sterile fronds alike. 



15. CTSTOPTERIS. Indusium on the back of the veinlet, hood-shaped, fixed at the base 



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



16. ASPIDIUM. Indusium mostly on the back of the veins, orbicular or round reniform, 



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



17. NEPHROLEPIS. Indusium at the end of a free vein, reniform, fixed at the sinus or by 



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



18. PHEGOPTERIS. ludusium obsolete. 



* * Fertile and sterile fronds different. 



19. ONOCLEA. Fertile fronds contracted, the divisions rolled up and berry-like. 



THIBE IX. WOODSIEJE. Fruit-dots round, borne on the back of a free vein. In- 

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



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



TRIBE X. DICKSONIE JE. Fruit-dots marginal, roundish, borne at the ends of the 

 free veins. Indusium cup-shaped ortwo-valved, its outer part composed of a reflexed 

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



21. DICKSONIA. Indusium (in our species) small, nearly globular, membranaceous. 



SUBORDER II. HYMENOPHYLLEJE. Sporangia borne on a setiform 

 or slender receptacle, cellular-reticulated, surrounded by a complete transverse 

 ring. Involucres marginal, at the ends of the veins, cup-shaped or two-valved. 

 Fronds delicately membranaceous and pellucid. 



22. TRICHOMANES. Involucre cup-shaped or funnel-shaped, sometimes 2-lipped. 



SUBORDER III. SCHIZ-^EINE^. Sporangia large, borne on narrow seg- 

 ments of the frond, oval, cellular-reticulated, crowned by the converging stria3 

 of a complete apical ring, opening longitudinally. 



23. LYGODIUM. Sporangia attached laterally in two rows to the narrow divisions of the 



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



24. ANEIMIA. Sporangia attached by their bases to the narrow divisions of the panicled 



fertile brandies of the frond. Indusium none. 



