THE BRITTLE BLADDER FERN. i 263 
are some forms which may be conveniently associated and distin- 
guished by names, and certain plants referred to these are constant 
under cultivation, though perhaps variable forms are sometimes 
wrongly associated with them. The most remarkable variations 
are the following :— 
1. angustata (Smith). The variety to which this name has been 
given is one of the taller forms of the species. According to Sir 
J. E. Smith it is the same as the Polypodium rheticum of Dick- 
son and of Bolton (Fil. Brit. t. 45). This plant of Dickson's has 
slender fronds nearly or quite a foot high, and almost caudate at 
the apex; it is bipinnate; the pinne end in a long taper point; the 
pinnules are generally oblong-lanceolate acute, the lowest only being 
somewhat acutely ovate, and the larger ones are deeply lobed with 
sharp-toothed segments, the smaller ones acutely toothed. What 
appears to be the same form is sometimes more vigorous, and then 
the pinnules are larger, broader, and divided into secondary pinnules 
resembling the lesser primary ones of Dickson's plant; the margin 
is always acutely toothed, and we include those forms in which 
the edges of the smaller pinnules, and of the lobes of the larger 
ones, are deeply and rather evenly incised into conspicuous longish 
narrow teeth. The spores in Dickson’s plant are roundish and 
echinate. Mr. Wollaston and others think it is not very constant, 
and probably the name may have been given to some plants which 
have reverted under culture to the ordinary state; but we have seen 
others somewhat smaller indeed than Smith's description seems to 
point out, but otherwise according with it, which are quite perma- 
nent under pot-culture in a cool fern house. Those to which we 
refer are more narrowed and elongated in the frond and the pinn® 
than the usual form, the points being as it were drawn out, and the 
pinnules are generally oblong and somewhat decurrent: these being 
its chief characteristics. [Plate CII C.] 
Besides Dickson's plant, said to be from “Shadow Rocks" 
in Scotland, we refer here specimens from the following habitats :— 
Peninsula.—Devonshire: Marwood, Rev. F. Mules. 
Trent.—Derbyshire: Matlock; Castleton, W. Christy. 

