Adiantum.] XCIV. FILICES. 569 



stalk of a shining brownish-black. Segments obovate or fan-shaped, 

 4 to 8 lines broad, all narrowed at the base into a short, slender stalk, 

 more or less divided into wedge-shaped, obtuse lobes, thin, and of a 

 . bright green, without any midrib, but numerous forked veins converg- 

 ing at the base. Sori conspicuous, occupying the extremities of most 

 of the lobes of the segments. 



In the fissures of moist rocks, at the entrance of caves and wells, and 

 other situations sheltered from cold, as well as from sun and drought, 

 in most of the tropical and warmer parts of the globe, common in 

 southern Europe, extending northward over the greater part of France, 

 but scarcely into Germany. In Britain, only in the southern and western 

 counties of England, in South Wales, the Isle of Man, and Ireland. 

 Fr. all summer. 



XIV. CYSTOPTERIS. BLADDERFERN. 



Delicate Ferns, with twice or thrice pinnate fronds. Sori small 

 circular, on the under surface, enclosed, when young, in a very thin, 

 globular, or hood-shaped membrane, which opens out irregularly into a 

 cup under one side, and often disappears early. 



A small genus limited to the colder or mountainous regions of both 

 hemispheres. 



Fronds oblong-lanceolate, the lowest pinnas decreasing in size . 1. C. fragilis. 

 Fronds broadly triangular or rhomboidal, the lowest pair of pinnas 



the largest 2. C. montana. 



1. O. fragilis, Bernh. (fig. 1310). Brittle B.— Rootstock shortly 

 creeping. Fronds tufted, usually under a foot long, oblong-lanceolate 

 in their general outline, twice pinnate ; the longest primary pinnas 

 towards the middle of the frond, 1 to 1\ inches long, decreasing 

 towards both ends. Stalks slender, without scales. Segments lanceo- 

 late, deeply pinnatifid, or the lower ones pinnate, with small, oblong, 

 more or less crenate lobes, all obtuse, not pointed as in Asplenium 

 fontanum, to the larger specimens of which this plant bears some 

 resemblance. 



On rocks and old walls, spread over the greater part of the globe, 

 especially in mountainous districts, extending far into the Arctic 

 regions. Dispersed over all Britain, and common in the hilly districts. 

 Fr. summer and autumn. A variety from the Alps and Pyrenees, C. 

 alpina, Desv.. with a 3- 4- pinnate frond, is found in Teesdale. [Another 

 variety is C. dentata, Sm., with ovate-lanceolate obtuse segments, and 

 submarginal sori.] 



2. C. montana, Bernh. (fig. 1311). Mountain B. — Rootstock creep- 

 ing. Fronds growing singly, twice or thrice pinnate, broadly triangular 

 or rhomboidal in general outline, the pinnas of the lowest pair being 

 considerably larger and more divided than the others, as in Poli/podium 

 Dryopteris, which this plant much resembles. It is, however, of a more 

 delicate texture, only 6 or 8 inches or rarely a foot high, including the 

 long slender stalk ; the pinnas are mostly alternate, with more divided, 

 smaller segments, and the slender indusium over the sori is easily seen 

 under a magnifying-glass when young. 



