40 



stows on these two plants, the more will he find they recede from 

 each other ; whereas all differences between the so-called C, fragilis, 

 angustata, and dentata, are speedily lost in cultivation." If there 

 be any value attaching to physiological facts of this kind, regarding 

 the determination of species, it must depend upon their corre- 

 spondence under all circumstances, and the above remarks do not 

 agree with my own experience. Of C. Dickieana I know but 

 little, indeed nothing beyond that which the examination of the 

 plant affords as to its general characters and structure, growing 

 specimens not having come into my possession until within the 

 last two or three years ; but of the others, cultivation from the 

 wild state for nearly thirty years has led to very different results. 

 The plants have retained during that period all their original 

 features, while their spore-scattered offspring have grown up as 

 types of the parent forms, except that fragilis has generally, but 

 not uniformly, produced angustata instead of its own : the latter 

 circumstance seems significant of the effect of difference of soil or 

 situation in the production of varieties among ferns, and may 

 account for the discrepancy of the two statements ; my own speci- 

 mens being chiefly grown in the open air, and never having any 

 other protection than a cold frame or occasionally a hand-glass, 

 while Mr. Newman's may have had the advantage of a closed case 

 or greenhouse. 



CYSTOPTERIS ALPINA. Alpine Bladder-Fern. TAB. XXIII. 



Fronds lanceolate, sub-tripinnate : pinnae ovate : pinnules con- 

 fluent, oblong-ovate, deeply pinnatifid; the lobes broadly and 

 shortly linear, obtuse, with two or three erect blunt teeth. 



Cystopteris alpina, Desvaux. Hooker and Arnott. Moore. Ba- 

 bington. Cyathea regia, Forster. Cyathea incisa, E. B. 163. 

 Cystea regia, Smith. Polypodium, Linnaeus. 



Though admitted by most botanical writers into the catalogue 

 of British Ferns, this species has no other claim to be regarded as 

 such, than the fact of its having at one time grown very plentifully 

 on a garden wall at Lojv Ley ton, near Walthamstow, Essex, where 

 it was first noticed by Mr. Forster : about thirty years back, the 

 wall needing repair and fresh pointing, it was obliterated from this 

 habitat, or nearly so, the occasional discovery of a specimen either 

 there or on other walls in the neighbourhood being of late vears 

 looked upon as a rarity. It has been recorded by some of the 

 older botanists as occurring both in Wales and Scotland, but as the 

 habitats mentioned by them have been searched in vain, it is now 

 generally considered that dwarf and deeply-divided specimens of 

 one or other of the preceding have been mistaken for it. It is 



