578 
CVIII. P0LTP0DIACE7E. 
Ord. CVIII. POLYPODIACEJE R. Br. (Tab. IX. f. 1—4, 
X. and XI. f. 1.) 
Capsules dorsal or marginal, surrounded by a ring, reticulate 
and pellucid, opening transversely and irregularly. Fronds 
circinate in vernation. 
A. Capsules opening transversely, placed on the bach of the frond, but some- 
times close to its ma rgin ; their ring vertical, usually incomplete. 
* ’Sori neither furnished with a conspicuous involucre nor covered by the 
reflexed margin of the frond. 
1. Ceterach. Sori linear, on reticulate veins, covered with, chaffy 
scales. 
2. Gymnogramme. Sori oblong or linear, on forked veins, naked. 
3. Polypodium. Sori roundish. 
** Sori with an involucre, or covered by the reflexed margin of the frond. 
f Sori roundish. Involucres placed upon the back of the lateral veins. 
J Fertile fronds remaining similar to the barren ones. 
4. Woodsia. Sori roundish. Involucre below the sori, more or less 
cut at the margin. Veins forked. . 
5. Aspidium. Sori roundish. Involucre above the sori, circular 
( Polystichum ) or reniform (Licstrea). (Veins forked in British 
species ). 
G. Cystopteris. Sori roundish. Involucre cucullate at the base, 
attached below. Sorus on one side. 
Fertile fronds very dissimilar to the barren ones, each pinnule wrapt 
round the sori on it, and resembling a berry. 
(>. Onoclea. Sori much approximate, afterwards confluent. 
If Sori oblong or linear. Involucres attached by the one side to the lateral 
veins, opening at the other. 
7. Asplenium. Involucre single, linear or oblong-linear, or oblong- 
reniform, arising from lateral veins, opening towards the midrib. 
(Veins forked in British species.) 
8. Scolopendrium. Involucre linear and long, double, the two portions 
opening towards each other. 
Iff Sori marginal or parallel to the midrib, covered either by an involucre 
or by the reflexed margin of the frond. 
J Fertile and barren fronds similar. 
9. Pteris. Sori continuous, linear, at the margin of the frond. In- 
volucre consisting of the reflexed margins. 
12. Adiantum. Sori oblong or roundish, marginal. Involucre formed 
of the reflexed margins or lobes of the frond, and bearing the cap- 
sules. 
ft All or most of the fertile fronds dissimilar to the barren ones. 
10. Cryptogramme. Sori roundish at the margin of the frond, at length 
confluent and covered by the reflexed margins meeting in the 
middle. 
