82 FILICES 



II. Sori linear or oblong, placed obliquely between the midrib and 



the margin. (Fig. 53.) 



A very large genus, 2S species in S. \. 



22. Asplenium 



III. Frond tl.ibell.ite, with narrow segments. Sori submarginal, 



linear. 



1 tropical species also in Na, TV. 



23. Actiniopteris 



d. Sori not marginal, covered by a renitorm or circular, peltate indusium. 



I. Sori renitorm; indusium renitorm or elliptical \\\<\ attached to 



the vein tor its entire length, tree at the edge. 

 1 tropical species in Natal. 



24. Didymochlaena 



II. Sori subglobose ; indusium orbicular, attached in the centre, 



peltate. (Figs. 5: and 53.) 



A large genus. 6 species in S. A. 



25. Aspidium 



III. Sori subglobose; indusium renitorm, attached at the sinus. 



Pinnae not articulated. 



16 species in S. A. ib. Nephrodium 



IV. Involucre reniform or suborbicular ; pinnae simple, articulated 



to the rhachis. 



3 species in S. A. 27. Nephrolepis 



V. Involucre reniform ; rhizome scandent. Fronds simple. 



1 species reaching Natal. 2S. Oleandra 



B. Sori without involucre or indusium. 



I. Sori round or nearly so, dorsal. (Figs. 53 and 54; Plates 9 and 24.) 



A very large genus, 14 species in S. A. 



29. Polypodium 



I I. Sori marginal, at first oblong but soon confluent into a continuous 



marginal line; fronds 2 — 3-pinnate. (Plate <■).) 



4 species in S. A. 30. Notochlaena 



III. Sori oval, oblong or linear, not marginal. Fronds 2-— 3-pinnate. 



6 species in S. A. 31. Gymnogramme 



IV. Fronds simple, grass-like, with several veins. Sori in longi- 



tudinal lines near the margin. (Plate 9.) 



1 species in S. A. 32. Vittaria 



V. Sori covering the back of the frond, not in dots or lines. 



(Plate 9.) 



10 species in S. A. ^^. Acrostichum 



