CYSTOPTERIS MONTANA, BERNHARD, IN STIRLINGSHIRE, 217 
(4) They may still be on the back (dorsal), but unprotected 
by any involucre, as in Polypodium and Gymno- 
gramme. 
From the foregoing, which is based on the classification given 
by Sir J. D. Hooker in “The Student’s Flora,” Cystopteris is 
seen to belong to the third group. Its involucre, membranous in 
substance, ovate, convex and acute in form, and eventually 
becoming reflexed, is attached by a broad base to the back of a 
veinlet, and, arching forward closely over the cluster of spore 
capsules, presents the appearance of a little sac, hence the name 
Cystopteris, Bladder Fern, from ktoris, a sac or bladder. 
The genus Cystopteris, of which there are five species known to 
science, has in Britain (excluding the doubtful C. alpina of 
Desvaux) two representatives, viz., the subject of this communi- 
cation, and C. fragilis, Bernh. The latter, as we know, is common ; 
I have taken it near Glasgow under the shade of a hawthorn 
hedge, between Possil Marsh and Cadder “ Wilderness” in Lanark- 
shire. The altitudinal range of ©. fragilis is from the sea-level 
to 4,000 feet, contrasting in this with C. montana, which latter, 
however, though an “alpine,” grows well from its creeping 
rhizome in our gardens under cultivation. 
[For permission to use the figure I am indebted to the courtesy of 
Messrs. Swan Sonnenschein & Co., publishers of ‘British Ferns, and 
_ where found.”] 
