WOODSIA. 
185 
Genus XIV. WOODSIA. 
The Woodsias form a family group consisting of two 
diminutive kinds, which, however, possess much interest 
among the British species on account of their extreme rarity. 
These Ferns are furnished with indusia, and by the peculiar 
construction and position of this organ, they may readily be 
known. The peculiar nature of the indusia consists in 
their being placed not as a cover to the sori, but attached 
underneath them; when very young they indeed enclose 
them, but subsequently they split from above into narrow 
scale-like segments not easily distinguished, without optical 
assistance, from the hairs which occur along with them on 
the fronds. In the full-grown state, the sori are conse¬ 
quently seated in the centre of a spreading tuft of hair-like 
scales, which are formed of the lacerated margins of the in- 
dusium—the latter being attached to the frond at the point 
beneath the capsules. No other native Ferns possess a 
structure at all approaching to this. 
These Ferns were formerly ranked with the Polypodies 
and Acrostichum, but when the structure of this race of 
