riLMT FEENS. 



107 



spore-cases are attached. The receptacles or capsules are 

 not at all flattened, and consist of two valves, the edges 

 of which are smooth, and not toothed or jagged. The 



characters which separate this species from the last are 

 not such as will be at once appreciated by the unscientific. 



BBISTLH FEBNS. 



Spore-cases contained in an urn-shaped receptacle, which is borne on 

 the edge of the frond. 



The Bristle Ferns are closely allied to the Tilmy Perns 

 in structure, appearance, and habit. In both, the fruit 

 is borne at the edge of the frond in certain special re- 

 ceptacles. In both, the veins of the leaves are prolonged 

 into a kind of columella, or little column, which stands up 

 in the middle of the receptacles, and in both the spore- 

 cases are attached to this column. Eut in the Bristle 

 Ferns the column is lengthened out so as to extend like a 

 bristle beyond the mouth of the receptacle, giving a 



