THE WOODSIA. 
Genus XIV: WOODSIA, R. Brown. 
Gen. CHar.=@Sori involucrate i.e. with inferior indusia, globose ; 
the receptacles medial or terminal. Involucre soft membranaceous, 
pateriform and fimbriately crinite, or calyciform with the margin 
lobed, or subglobose with the mouth contracted. Veins simple or 
forked, or pinnate from a central costa ; venules free. 
Fronds membranaceo-herbaceous, small, pinnate-pinnatifid, or 
bipinnate. 
Caudex tufted, erect or decumbent. 
This small genus is found to be very distinct in character when its 
fructification is rightly understood, although at first sight no very 
prominent distinction is apparent. It is one of those ferns in which 
the fructification, dorsal on the frond, and medial on the veins, is 
punetiform or dot-like ; but instead of the sorus being naked as in 
the Polypodieœ, or indusiate as in the Aspidieœ and Cystopterideœ, it 
is here involucrate: in other words, instead of the investing mem- 
brane being placed over the spore-cases as in the truly indusiate 
groups, it is here placed beneath them, assuming a more or less cup- 
shaped or calyciform character. In Cystopteris the indusium being 
concave and attached behind the spore-cases, becomes semi- 
calyciform, and indicates an approach to the structure observable 
in Woodsia; but the truly calyciform indusia of the latter, keeps 
it quite distinct from all other British genera. Regarded in this 
light, Woodsia is a very well-marked genus, distinguished by the 
coincidence of three characteristics :—the presence of an involucre or 
an involucriform indusium, sessile sori, and free veins. 
There are some differences in the nature of the involucre among 
the species referred to Woodsia, and some botanists prefer to 
separate under distinct generic names the species possessing these 
peculiarities, but we have preferred to regard the differences, which 
certainly do exist, rather as modifications of one type of structure, 

