THE CHAIN FERNS. 221 
pinnule, and another series of larger sori parallel with the 
midribs of the pinnae. They appear as if partly sunk. 
in the tissues of the frond and are covered with a 
leathery indusium as witha lid. It does not require 
avery lively imagination to seein the oblong sori 
placed end to enda resemblance to the links in a chain 
and the common name is therefore quite appropriate. 
From its delight in mud and water, it is sometimes 
called the bog fern. This species is also illustrated in the 
Key to the Genera. 
The chain fernis found from southern Canada to 
Florida, Louisiana and Michigan and also in Bermuda. 
‘It is frequently found growing in several inches of water 
near the coast where it is often so abundant as to al- 
most fill the swamp, like a field of grain. Inland it is 
likely to be found in sphagnum swamps among 
Pogonias, pitcher-plants and other semi-aquatic vege- 
tation. According to Eaton, the fronds may face in any 
direction in bushy swamps, but when they are exposed 
to the sun, all face toward the south. It is an excellent 
species for cultivating on the borders of artificial lakes 
in the fern garden. On the western coast of America, 
there is a tall and robust species—IV. radicans—which is 
much like ours in general appearance, but is darker 
green in colour. This is the only western species and is 
widely distributed in other parts of the world. 
The Narrow-Leaved Chain Fern. 
Like its relative, the narrow-leaved chain fern (JVood- 
wardia angustifolia) has the misfortune to resemble a 
more plebeian species. This species is the sensitive fern 
and the resemblance. as in the case of the other, extends 
