THE COMMON HARD FERN. 225 
communicated by that gentleman, and Mr. Clapham. It has also 
been found at Cat-holes-Clough, Todmorden, by Mr. Stansfield. 
22. serratum (Woll.). This is a vigorous form and somewhat vari- 
able. In the original plant, the barren fronds, often a foot in length, 
are more or less deeply serrated, and frequently forked at the tips. 
The fertile ones, as usual, are taller, broad lanceolate in outline, often 
three inches wide in the centre, with the lobes sharply serrated, and 
sometimes forked at the tips, the fronds themselves being also 
sometimes forked. In this form semi-fertile fronds without 
serratures are sometimes produced. This was found in 1853 by 
Mr. Wollaston near Tunbridge Wells, Kent, in a bogey ditch, and 
has since proved tolerably constant. In other forms the sterile 
fronds are more deeidedly and coarsely serrated in a variable degree. 
The plant has been found in—Devonshire : Ottery St. Mary, G. B. 
Wollaston ; Barnstaple, C. Jackson. Durham: Tanfield Dean, T. 
Wilcke. Lancashire: Todmorden, J. Fielden. 
23. tridactylum (M.). A curious dwarf form three or four inches 
high, the fronds coriaceous, nearly normal in character below, 
furnished with shortish blunt lobes throughout, except at the apex 
which, in a portion of the fronds, is remarkable for being developed 
into about three much larger segments, which not unfrequently 
are placed so as to resemble three spreading claws or fingers. 
Some of the fronds are entire or slightly caudate at the apex. 
The fertile fronds are not known ; but the sterile ones prove constant. 
It has been found in Towerclough near Portsmouth, by Mr. $. 
Nowell; and was communicated by Mr. Stansfield. 
24. trinervium (Woll). This very remarkable variety. may be 
described as a trifoliated Bleehnum. In its most usual condition, 
its fronds resemble those of the normal form, except that they are 
less tapered or diminished below, and at the base produce two 
lateral branches resembling small fronds. The fertile fronds have 
the same character. Both forms of frond are however occasionally 
produced with their apices forked; the lateral branches are also 
occasionally forked, and in some instances, the lower part of the 
central branch in the fertile fronds, has the segments irregularly 
and distantly placed, as well as enlarged and pinnatifidly lobed, or 
sometimes forked. The segments of the sterile fronds are also 
YOL. II. Q 

