GENERA AND SPECIES. IOI 
PLATE XXXVII. 
CYSTOPTERIS. Bernhardi. 
BLADDER FERN. 
GEN. CHAR.—Fruit-dots roundish, on the back of the free veins; 
indusium inflated, attached by a broad base beneath the under side 
of the sorus, opening toward the apex of the segment; veins forked. 
This is a small genus of fragile ferns, chiefly confined to 
the temperate latitudes, though the C. fragilis has a very . 
wide range, and might almost be included in Mr. Red- 
field’s Cosmopolitan division. ‘The illustration, taken from 
Hooker and Bauer, gives a magnified view of the leaflet, 
showing the arrangement of the fruit-dots, the sorus, with 
the indusium laid open, and the sporange with its spore, 
all highly magnified. The indusium, or covering, of the 
fruit-dots is in the form of a small leaf, broad at the base 
and tapering to a point. This character can only be ob- 
served with the aid of a pocket lens. The sori are situ- 
ated on the veins a little short of the apex, while in most 
other ferns they are at the ends of the veins. 
The common name of Bladder Fern is given to plants 
of this genus on account of the peculiar inflated appear- 
ance of the indusium when fully mature. Only three 
species are found in this country—the C. montana, from 
Alaska, the C. fragilis and C. bulbifera; both of the latter 
being common. 
