118 BRITISH FERNS. 
but plants are not of unfrequent occurrence which 
produce only barren fronds; and these are larger and 
greener, and have the pinnules more deeply toothed 
than when fertile. The fronds vary from five to ten 
or more in number; their position is nearly erect, or, 
the Mountain Fern: all the pinne are nearly linear, 
but acute at the tip; they are regularly pinnate: the 
Pinnules are rather blunt, toothed at the tips, and 
notched at their edges. The lateral veins are 
after the fork, the anterior branch bears a nearly 
circular mass of seeds; these are covered by a smooth, 
lead-coloured, kidney-shaped involucre, which is at- 
veins do not quite reach the edges of the pinnules, 
_ and the anterior branch of each ig not quite so long 
_ as the posterior. ; ny 
