2. Allosorus = Dorsal-fruited Eerns, with the sori
covered by reflexed, unaltered margins of the frond.
B . A s p id i e æ = Eerns whose sori have a special indusium,
of a circular or roundish form, and springing here
and there, from the back of the veins. It contains
the genera Wwdsia, Lastrea, BolysticJium, and
Cystopteris.
3. Woodsia — Dorsal-fruited Eerns, having the indusinm
attached beneath the sori, and divided
into hair-like segments.
4. Lastrea — Dorsal-fruited Eerns, having a reniform
indusium, attached by its indented side.
5. Polystichum — Dorsal-fruited Eerns, having a circular
indusium, attached by its centre.
G. C^«ï!opiîem=Dorsal-fruited Eerns, having a cucnllate
or hooded indusium, attached by its broad base.
C. A s p e en ieæ = E erns whose sori have a special indusium,
of an oblong or elongated form, and springing from
the sides of the veins. I t contains the genera
Athyrium, Asplenium, Ceterach, and Scolopendrium.
7. Athyrium = Dorsal-fruited Eerns, having an oblong
reniform indusium, attached by its concave side,
the other side fringed with hair-hke segments.
Î = Dorsal-fruited Eerns, having the indusium
straight and elongate, and attached
by the side towards the margin of the pinnæ or
pinnules.
9. Ceterach — Dorsal-fruited Eerns, having the indusium
obsolete, and the sori hidden among densely
imbricated, rust-coloured, chaffy scales.
10. Scolopendrium— ~Dor&al-ixmioà Eerns, having the
sori elongate, and proximate in parallel pairs, the
indusium opening along the centre of the twin
sorus.
B . Ptbridbæ = Eerns, the margin of whose fronds is
either soriferous, and continuously or interruptedly
changed into a special indusium, or whose spore-
cases are in lines parallel with the margin. It contains
the genera Pteris, Adiantum, and Blechnum.
^ 1. Pteris Dorsal-fruited Eerns, having the spore-
cases in a continuous line at the edge of the
frond, beneath an indusium formed of the altered
margin.
12. Adiantum — Dorsal-fruited Eerns, having the
spore-cases in patches, on the reflexed, altered
apices of the lobes of the fronds.