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 alono; 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 Acrostic/mm, but when the structure of this race of 



