CYSTOPTERIS 



137 



Rotundatum (Fig. 134.) — Found by Mr. Clift ; pinna round and 

 very small at base, fronds narrow, with occasional elongated pinnae. 

 A similar form, but with more even pinnae for entire length, was 

 found by the writer near Aberfeldy. 



Serratum (Fig. 135). — Found by Mr. G. B. Wollaston and others ; 

 a very fine form, with close-set, curved, and saw-toothed pinnae. 



S. Airey No. 1.- — The parent of ■plumosum Airey ; a markedly 

 serrate form, but not tripinnate. 



Serrulatum (Fig. 136) . — A prettily saw-toothed dwarf form. 



Strictum (Fig. 137.) — This has been repeatedly found, and is 

 distinguished by saw-toothed side divisions, which are usually 

 extra short near the base, and occasionally 

 somewhat irregular in length ; not so robust 

 as the normal. 



Subserratum (Fig. 138 and Plate XII). — 

 Found near Castle Howard by Mr. Monkman 

 and near Todmorden by Mr. Stansfield ; 

 in this the pinnae are prettily blunt-toothed, 

 especially on the lower side, the upper being 

 often smooth. 



Trinervio-coronans. — Seemultifurcatum. 



Trinervium. — Found in Wicklow by Dr. 

 Kinahan and subsequently in considerable 

 numbers in the Mourne mountains by Mr. 

 W. H. Phillips ; the two lowest pinnae are 

 considerably elongated. 



T. Hodgson^. — Found on Kirkley Moor 

 by Mr. Hodgson ; the two lower pinnae are 

 developed into secondary fronds, so as to 

 form a trident ; extremely distinct. 



Fig. 138. 

 B. s. subserratum. 



CYSTOPTERIS FRAGILIS (The Brittle Bladder Fern) 



(Plate XIII) 



The Bladder Ferns (Fig. 139) derive their'names, both popular 

 and botanical, which are synonymous, from the fact that their 



Cyslopteris fragilis (pinnre). 



small round spore heaps are covered by thin, domed skins, looking 

 like little bladders, while the term brittle is well applied, since the 



