THE COMMON BRAKES. 238 
entire or sinuate and adnate by their whole breadth, or more ovate 
pinnatifid and then with a narrower attachment and furnished with 
blunt linear oblong or shorter triangular lobes. In seedling plants 
or those grown in caves or in fissures of rocks or on walls, the fronds 
are peculiarly tender and delicate with an entirely different aspect. 
The same occurs when they spring up, as they sometimes do, acci- 
dentally in hothouses. 
Venation of the more entire pinnulets, consisting of a stoutish 
costa or midvein, from which the forked veins branch out in a curving 
or arcuate manner; these veins are one, two or three times forked, 
the venules extending to the margin. In the pinnatifid pinnulets the 
veins become secondary midveins to the lobes, and give off a series 
of once or twice forked veins; in these latter the lowest branches 
right and left of the secondary midveins sometimes meet and unite 
to form a series of costal areoles. "The edges of the fertile pinnulets 
produce a longitudinal submarginal vein, which becomes the 
receptacle. 
Fructification abundant on the back of the fronds. Sori linear, 
continuous, indusiate, marginal, the receptacle occupying nearly the 
margin of the pinnulets, and lying as it were in the axil of the 
indusium. Indusium linear, continuous, double, consisting of an 
outer and inner membrane, the former growing from the outer edge 
of the receptacle, thin, whitish, fringed, and folded inwards over 
the spore-cases, the latter growing from the inner edge of the 
receptacle, also thin, whitish, fringed, and lying beneath the spore- 
cases, the fructiferous margin being deflected so as to come in close 
contact with the under surface; the fringes of these. membranes, 
of which the inner is sometimes obsolete, consist of small jointed 
hairs. ` Spore-cases roundish obovate. Spores round oblong or 
angular, muriculate. 
Duration. The rhizome is perennial. The fronds are annual, 
growing up early in May, but they are very impatient of cold, being 
often cut down by late spring frosts and they are sered and killed by 
the early frosts of autumn, though from their rigid texture they 
retain their form through the winter. 
A common and well-known Fern, easily recognised technically 

