COMMON BRAKES. 
101 
accompanying membranes, together with the series of capsules 
between, are bent over towards the midvein, presenting an ap- 
pearance which I have attempted to repre- 
sent in the accompanying figure of the 
under surface of the apex of a lobe : h h 
is the marginal vein in its natural position ; 
c c, the indexed or convolute portion of 
the leaf ; d d the superior membrane par- 
tially covering the capsules, which are 
shown at e e projecting from beneath it ; f 
is the midvein of the lobe. The inferior 
membrane, although very similar to the su- 
perior, has some points of difference ; each 
consists of a disk divided into cells, and a 
marginal fringe of jointed hairs or capilla- 
ry segments, but the disk is somewhat differently marked. Mr. 
Jenner has taken great pains to obtain a view of both the mem- 
branes at once, and has favoured me with 
the annexed sketch, the accuracy of which 
1 have tested by examination. The 
marginal vein of the lobe is supposed to 
be presented to view^ edgeways at g, the 
capsules having been removed, in order to 
leave the view of the membranes unob- 
structed ; h represents the superior, and i 1 ^ \ 
the inferior membrane. 
It is highly probable that the great discrepancy betw^een the 
species of Pteris, as regards their mode of fructification, wdll 
eventually induce a more precise and natural grouping than any 
we are at present acquainted with. It seems to me that in this, 
as in other instances among the ferns, a single character has been 
somewhat arbitrarily selected, and considered of paramount im- 
portance, while the combination of other characters — for instance, 
those of habit, figure or texture — have been too much disregarded. 
The present work purposes to be a history of species, and it 
would be altogether foreign to such a purpose to make it an es- 
say on classification, yet I cannot with fairness to myself entirely 
w ithhold my opinion that the very basis of the classification of 
