THE BRISTLE FERN. 
169 
part, the shape of which, from the point where 
the rachis commences, is somewhat acutely tri- 
angular. To the right and to the left of the 
rachis, and extending to the point of the frond, 
are a series of alternately-placed branches bear- 
ing leaflets deeply cleft, although not divided 
down to the midrib of the branches. The 
leafy expansion surrounding the veins of the leaf- 
lets is of a thin, pellucid, almost transparent 
texture. Indeed were the plant held up to the 
light it would seem to consist of a series of 
branched, wire-like veins, and the leafy texture 
surrounding these veins would have the appear- 
ance of delicate, filmy, semi-transparent wings. 
The spores of the Bristle Fern are produced 
under a curious arrangement. A sort of bristle, 
which is in reality placed in continuation of the 
veins of the leaflet, extends beyond the tip of 
the latter. At the point of the bristle, placed 
like a crown, is a little receptacle for seed ; and 
in this receptacle, as well as along the sides 
of the bristle, seed is also found. Just 
where the bristle passes beyond the tip of the 
