Classification of Ferns and Fern Allies. 
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one side, over the top, and partly down the other side, and 
opening horizontally at the part where the band is awanting. 
Sori on the back of frond, vernation circinate. 
Division I. — Involucratae. Sori furnished with an involucre or 
indusium. (Genera IV. to XXIV.) 
* Involucre cup-like, enclosing the sorus, or scale-like, and 
placed under it. 
Genus IV. — Cyathea. Involucre at first completely enclos- 
ing the sorus, afterwards bursting at the top, and remaining 
as a cup under and around the capsules, which surround a 
raised receptacle. Stem, tree-like. 
Genus V. — Hemitelia. Involucre only a scale placed under 
the capsules which surround a raised receptacle. Stem, 
tree-like. 
Genus VI. — Woodsia. Involucre at first enclosing the 
sorus, afterwards bursting at the top into several lobes. 
Plant small, herbaceous. 
** Indusium covering the sorus, and opening toward the 
margin of the frond. 
Genus VII. — Davallia. Sori marginal, roundish. Indu- 
sium united below and at the sides, only the outer edge 
being open. 
Genus VIII. — Cystopteris. Involucre like a scale attached 
under the sorus by its wide end, and at first having the 
other end turned hood-like over the sorus. 
Genus IX. — Lindsaya. Sori linear, marginal, covered by a 
linear indusium, opening outward. 
*** Sori Marginal. Indusium composed of the edge of the 
frond (often changed in texture) reflexed over the sorus, 
and opening towards the mid-rib. 
Genus X. — Adiantum. Capsules produced on the under- 
side of the indusium, which varies from kidney-shaped to 
long, and is produced on the points of the pinnules. 
