152 
BRITISH FERNS, 
stones, as well as from among the decaying mortar of 
old towers and bridges. In the rocky dales of the north 
of Yorkshire the Brittle Bladder-fern meets you at every 
turn, its frail leaflets quivering over the well-head, as 
well as from the dizzy height of the Scar, or the crum- 
bling arch of the ruin. It is equally common in similar 
districts in other counties of England and Scotland, but 
much less frequent in Ireland. 
Yar. dentata . This form of C.fragilis is smaller than 
the one just described, less decidedly bipinnate, — indeed, 
the pinnae are only divided into pinnules on the lower 
parts of the most luxuriant fronds ; the leaflets are egg- 
shaped, and their colour is pale green. This is only a 
variety of the preceding, and is much less frequently 
met with than the normal form. 
Yar. Dickieana. This is another form of C.fragilis , 
and here the fronds are broader and less pointed, the 
pinnae beset with broad, ovate, lobed leaflets, overlapping 
one another. On the upper part of the frond the pinnae 
are crowded, often overlapping each other just as the 
leaflets do ; on the lower part they are distant and op- 
posite. The fronds measure from 6 to 9 inches, and the 
stem occupies about a third of its length ; the few scales 
at the base of the stem are very narrow. The only au- 
thentic wild habitat of this fern is Cove, near Aberdeen, 
where it was found by Mr. Dickie, and it is named after 
him. 
Var. angustata. Sir W. J. Hooker considers this 
variety of C . fragilis unworthy of notice, but it is both 
described and figured by several high authorities. It 
grows taller than the simple form of fragilis ; its fronds 
are more pointed, and the pinnae are more tapering. 
The leaflets are cut into sharp teeth, and are of a bril- 
