382 
FILICES. 
2. Polypodium. Sori circular, naked ; margin of the frond 
flat not reflexed. 
3. Woodsia. Sori circular with an inferior involucre divided 
at the edges into numerous capillar}' segments. 
Tr. II. ASPIDIEAZ. Sori nearly circular, covered by an in- 
dusium. 
4. Lastrea. Indusium reniform, attached by the sinus. 
Veins distinct after leaving the midrib, not uniting with 
those of the adjoining pinnule. 
5. Polystichum. Indusium circular, attached by the centre. 
Veins distinct after leaving the midrib. 
6. Cystopteris. Indusium attached bv its broad hooded 
base under the sori, with a lengthened fringed free extremity 
at first covering the thecEe. 
Tr. HI. A S PLENIEJE. Sori oblong or linear, covered by an 
indusium opening longitudinally on one side. 
7. Athyrium. Sori oblong-reniform. Indusium opening 
towards the central nerve or midrib. 
8. Asplenium. Sori elongate straight. Indusium opening 
towards the central nerve or midrib. 
9. Scolopexdrium. Sori elongate straight, 2 together. In- 
dusia of each pair opening towards each other. 
Tr. IV. GRAMMITWEsE. Sori elongate without an indu- 
sium. 
10. Ceterach. Lateral veins anastomosing, sori attached 
to their middle. Whole back of the frond covered with 
chaffy scales. 
Tr. V. ADIANTARIjE. Thecae covered by a marginal or 
submarginal elongated part of the frond, or by a separated 
portion of the cuticle resembling an indusium. 
11. Blechnum. Thecre in a continuous line parallel to the 
midrib upon the transverse anastomosing veins, and covered 
by a continuous scarious indusium. 
12. Pteris. Thecce in a continuous marginal line covered by 
a continuous indusium formed of the indexed margin. 
13. Adiantum. Sori marginal, oblong or roundish, covered 
by distinct reflexed portions of the margin of the frond. 
