CHAPTER VIII. 
THE BLADDER FERNS. 
Plate 4. 
HREE little Ferns only are comprised 
in this group : namely, — 1. The 
Brittle Bladder Eern ( Cystopteris 
fragilis). 2. The Alpine Bladder 
Fern ( Gystojpteris regia) : and 3. The Mountain 
Bladder Fern ( Gystojpteris montana). The common 
or popular name given to the delicate and beautif ul 
Ferns included under the genus Gystojpteris , has 
been suggested, as in the case of the Shield Ferns, 
by the shape of the spore-case covers. In this 
group these covers — the indusia as botanists call 
them — are raised somewhat in the form of hoods 
or bladders : and hence, as we have seen, the 
popular designation of the group. 
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