PERNS OP GREAT BRITAIN. 35 



4. Wood SI A (Woodsia). 



1. W. Ilvensis (Oblong Woodsia, or Ray's Woodsia). 

 — Frond lanceolate or oblong, pinnate, bairy beneath. 

 The only two species which we possess in this country 

 of this genus of Ferns, are both very rare plants. They 

 have some peculiarities which readily distinguish them 

 from any other species. Their indusia, instead of cover- 

 ing the clusters of spore-cases, as in other genera, are 

 attached beneath them, enclosing them while young, 

 but tearing as they grow older into numerous little 

 chaffy segments, which look like tufts of slender hairs 

 placed around the clusters. This species grows on the 

 most elevated and bleak mountainous places, among the 

 fissm-es of rocks. It' has been found on Clogwynn-y- 

 Garnedd, Snowdon, and Llynn-y^cwn, on Glyder Vawr, 

 Wales; on the Clova mountains, Scotland, as Well as 

 in Durham, where Mr. Backhouse found it growing at 

 the base of some basaltic rooks on the Durhanl side 

 of the river Tees, about 200 yards below Cauldron 

 Snout. It is said also to have been found formerly in 

 Westmoreland, where a single frond was gathered from 

 the old walls of Crosby Ravensworth Church ; but these 

 walls have now been taken down. The fronds of this 

 species are about two or three inches high, and are 

 covered on both sides with shining hairs, which are, 

 however, on the upper surface invisible to the naked 

 eye. The clusters of seed-cases lie among these, on the 

 under-surface, and are almost hidden by them. A few 

 chaffy scales are scattered on the stalk, and this has 

 a joint at a short distance from its base, at about threfi- 



