FERNS. 31 



and top of the arch hung tufts of the Black-stalked Spleen- 

 wort, and of a light feathery Fern, more like a miniature 

 of the pinnatifid Lastreas. Eagerly gathering and 

 examining some of these fronds, I found the spoie-masses 

 covered by a bladder-like envelope. These spore-clusters 

 were round, and in many instances the white cover had 

 disappeared. The fragile nature of the plants, the delicacy 

 of their texture, and, above all, the peculiar spore-cover, 

 pointed the Fern out as Cystopteris fragilis. the Brittle 

 Bladder-Fern {Plate III., fig. 7). In the specimen in 

 my hand the rachis was dark-coloured, and had a few 

 scales towards the base. The frond was broadest in the 

 middle, and tapering above and below, though only 

 slightly decreasing in the latter direction. Each pinna 

 contained several pinnules, which were toothed at the 

 margin, and the spore-masses were borne on the branching 

 veins. The plants growing outside the bridge were laden 

 with spores ; those under the shade of the arch were but 

 scantily furnished with them. 



Afterwards we found a similar Fern of more elongated 

 form, and the pinnules were more sharply and decidedly 

 cut. This was the plant by some considered a variety of 

 C. fragilis, and by others accounted a separate species, C. 

 angustata. 



Another variety, rather toothed than cut — i.e., with 

 the points blunt and rounded, is also found among those 

 Yorkshire rocks and old walls, C. dentata. 



As we progressed higher and higher up the stream, 

 climbing upwards towards the hill-country, we found one 

 or other of these Bladder-Ferns anions; the rocks and 

 boulders by the brooksicle. The fernery supplied another 



