Classification of Ferns and Fern Allies . 
39 
or elliptical indusium, attached along its length to the 
vein, and free all round the edges and upper end. 
Genus XXI. — Aspidium. Sori round, indusium round, fixed 
by its centre, peltate. 
Genus XXII. — Nephrodium. Sori kidney-shaped, indusium 
kidney-shaped, attached by its sinus. Pinnae not articu- 
lated. 
Genus XXIII. — Nephrolepis. Involucre reniform or sub- 
orbicular. Pinnae simple, articulated to the rachis. 
Genus XXIV. — Oleandra. Involucre reniform. Rhizome 
scandent, fronds simple. 
Division II. — Ex-involucratae. Sori without involucre or indu- 
sium. (Genera XXV. to XXX.) 
Genus XXV. — Polypodium. Sori round, or nearly round. 
Genus XXVI. — Nothochl^ena. Sori marginal, linear. 
Fronds two to three pinnate. 
Genus XXVII. — Gymnogramme. Sori oval, oblong, or 
linear, not marginal. Frond two to three pinnate. 
Genus XXVIII. — Vittaria. Sori in long lines near the 
margin. Fronds simple, grass-like, with several veins. 
Genus XXIX. — Monogramme. Sori linear, near the mid- 
rib. Frond simple, with one vein only. 
Genus XXX. — Acrostichum. Sori spread all over the back 
of the frond, not in dots or lines. 
Sub-Order IV. — Osmundace^e. Capsules stalked, opening at 
the top, and having an incomplete ring horizontally round one 
side. Vernation circinate. 
Genus XXXI. — Osmunda. Fertile pinnse, with almost no 
lamina. 
Genus XXXII. — Todea. Sori on the back of ordinary 
pinnae. 
