126 SWISS FEBNS. 



6. Cystopteris. — Bladder-Fern. 



A delicate fern, tufted, with oblong-lanceolate pointed and 

 twice or thrice pinnate fronds, sori small, circular. 



C. montana. Fronds deltoid, ternate, tripiunate. Lower 

 pinnas larger and more divided than the others. Alps and 

 Jura. 



C. Alpina. Fronds almost thrice pinnatifid, with broadly 

 and shortly linear segments partly cloven and toothed at 

 the end. Alps. 



C. fragilis. Fronds twice pinnate, the longest pinnas in 

 the middle of the frond from one to two inches long, 

 decreasing towards both ends. Segments oval, oblong, or 

 lanceolate, crenate or toothed. A variable plant. Walls 

 and rocks. 



7. Aspidium.— Shield-Fern. 



Fronds once or twice or thrice pinnate. Sori circular, 

 covered by the indusium, which is attached by the centre — 

 plants are then called Lastrea ; or by the margin, by a kind 

 of fold which gives it a kidney-shape — plants then called 

 Polystichum. This distinction is often difficult to see. 

 Stems generally scaly, at least at the base. 



