172, Mr. Brown on Woodsia, a new Genus of Ferns. 
into a number of capillary segments, which from their length and 
incurvation entirely conceal the young capsules, and in a great 
measure the full grown. | . 
That so singular a structure should have been hitherto unno- 
ticed, even though both species of the genus have been described 
and figured since the publication of Dr. Smith’s memoir, is not 
perhaps to be wondered at: for the membranaceous base of the 
involucrum is completely concealed by the capsules, and the 
marginal hairs, which alone are visible, exactly resembling the pu- 
bescence of the frond, have been universally confounded with it. 
The difficulty, too, of separating the membrane entire from the 
frond, to which, by the pressure of the capsules, it is closely 
applied, is so considerable, that, since the publication of my: 
remark already quoted, its existence has been doubted. by a bo- 
tanist, whose opinion, especially in whatever regards this order of 
plants, is of peculiar weight, and in opposition to. which I should 
not retain full confidence in my own observations, though fre- 
quently repeated, were they not so distinctl y confirmed. by 
Mr. Bauer's excellent drawing. 
I first observed. the involucrum six years ago in living plants 
of Woodsia hyperborea, and have since repeatedly ascertained its 
existence in dried specimens of the same species, and of Woodsia 
ilvensis. These two plants are indeed so nearly related, that I 
find myself unable to construct for them clear specific characters ; 
and therefore, in proposing them here as distinct species, I am, 
from want of sufficient materials to determine the question,, 
rather following the prevailing opinion than my own. 
To the characters and ‚synonyms which follow, I have not 
thought it necessary to add descriptions of the two supposed spe- 
cies, these having been given by several of the authors referred to; 
and in every respect correctly,except what regards the involucrum. 
WOODSIA. 
