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 leaflet, 



