Woodsia.] FILICES. 515 



3-5 on each lobe— Distrib. Arctic, K and Alps of Mid. Europe, N". Asia, 



Himalaya, N. America. 

 W. hyperbo'rea proper ; frond linear-lanceolate, pinnae ovate-cordate, lobes 



few broad. — N. Wales, Forfar, Perth. 

 Sub-sp. W. ilven'sis, Br. ; frond broadly lanceolate, pinnae deeply pinnatifid 



with oblong subcrenate lobes. — N. Wales to Forfar. 



lO. CYSTOP'TERIS, Bernh. Bladder-Fern. 



Delicate flaccid ferns. Rootstock short or creeping. Fronds tufted or 

 scattered, 1-4-pinnate ; veins pinnate or forked, venules free. Sori small, 

 dorsal on the middle of a venule, globose ; involucre membranous, attached 

 by a broad base to the venule below the sorus, ovate, convex, acute, at 

 length refiexed. — Distrib. Cool damp regions ; species 5. — Etym. Kvaris 

 and Tnepis, from the bladder-like involucre. 



1. C. frag'ilis, Bernh. ; rootstock tufted, frond ovate-lanceolate 1-2 

 pinnate, pinnse deltoid-ovate. 



Rocks and walls in mountain districts, Orkney to Cornwall and Sussex ; 

 absent in E. half of England, S. of York and N. of Middlesex ; ascends to 

 4,000 ft. in the Highlands; Ireland; frt. July- Aug. — Rootstock densely 

 clothed with pale brown lanceolate membranous scales. Stipes 2-4 in., 

 brittle. Frond 4-8 in. ; rachis slightly winged above, larger pinnae 1-1^ in., 

 lobes or teeth obtuse or acute. Sori 2-12 on each segment. — Distrib. 

 Arctic, N. and S. temp regions. 



C. fraq'ilis proper; frond tripinnatifid, pinnules generally incised half-way to 

 the rachis, ultimate division contiguous. — Var. C. denta'ta, Hook. ; pinnae 

 ovate-lanceolate obtuse obtusely toothed, sori submarginal. — Var. C. Dick- 

 ie'ana, Sim ; frond ovate-oblong obtuse membranous, pinnae ovate obtuse 

 subdeflexed segments broad crowded obtuse crenate. 



Sub-sp. C. alpi'na, Desv. ; frond quadripinnatifid, pinnules incised nearly to 

 the rachis, ultimate divisions not quite contiguous. — Teesdale. 



2. C. monta'na, Link ; rootstock creeping, frond deltoid 3-4-pinnate, 

 pinnae and pinnules spreading. 



Alpine wet rocks, alt. 2,300-3,600 ft., very rare, Perth, Forfar, and Aberdeen ; 

 frt. July- Aug. — Rootstock widely creeping, sparingly scaly. Stipes 6-9 in., 

 very slender. Frond 4-6 in., as broad as long, lowest pinnae 1-1| in., seg- 

 ments cut to the rachis, deeply sharply toothed, especially towards the tip. 

 Sori small, 18-24 on the lowest pinnules. Involucre cut at the edge. — 

 Distrib. Arctic and alpine regions, Europe, Asia, America. 



11. aspid'ium, Sw. Shield-Fern. 



Habit various. Sori dorsal, globose ; involucre superior, orbicular, 

 peltate. — Distrib. All regions ; species 55. — Etym. aavis, a shield, 

 from the form of the involucre. — The British species belong to the section. 

 Polystichum, having free veins, 



1. A. Lonchi'tis, Sw. ; frond linear-oblong pinnate 



LL 



