TABLE OF BKITISH FERNS 9 



valves, bursting by an irregular and transverse cleft, 

 the elastic ring vertical and nearly complete ; and 

 TricJiomaninecB, without valves ; and bursting irregu- 

 larly, but surrounded by urn-shaped involucres, the 

 ring horizontal or oblique, complete. The second 

 division has only one tribe, or group : Osmtrndinece, 

 spore-cases two-valved, opening vertically or at the 

 top, the ring merely rudimentary. 

 OPHIOGLOSSACEJE are Ferns whose young fronds are 

 folded up straight, and whose spore-cases have no 

 ring. They are two-valved like the Osmundineae. 



POLYPODIACE^]. 



1. Polypodinese ; 2. Trichomanineae ; 3. Osmun- 

 dinese. 



POL YPODINE^] fructification dorsal, that is, the 

 spore-cases borne on the back of the frond. Com- 

 prising the sub-groups Polypodiece, Qymnogrammece, 

 Aspidiece, Aspleniece, Lomariece or Blechnece, Pter- 

 idece, Adiantecs, Cystopteridece, Peranemeae, 



POLYPODIES Sori (or clusters of spore-cases) round, 

 and with no special indusium (or covering) : compris- 

 ing two genera Polypodium, Attosorus. 



* GTMNOGBAMME^: Sori linear, no indusium : one 

 only genus Gymnogramma. 



* Of GYMNOGEAMMEJE genus Gymnogramma there is only 

 one British species, the Small -leafed Gymnogram & leptophylla, 

 lately found in Jersey, hardly therefore a British fern at all. Of 

 ADIANTE.S: again its one British genus, Adiantum, has only one 

 species, the Common Maiden-Hair Fern A. Capillws Veneris, not 

 found in the Lake District. Neither is the one British species of 

 the genus Trichomanes, the Bristle Fern T. radicans. 



