APPENDIX E. 
417 
illustrate it by some additional observations on its structure, and by a very per- 
fect drawing, for which I am indebted to the friendship of Mr. Francis Bauer. 
The character distinguishing Woodsia from all other genera of Ferns hi- 
therto established, consists in its involucrum being inserted under the group of 
capsules, or, as it is technically called, the sorus, which it completely surrounds 
at the base, while it is in every stage open at the top, having its margin divided 
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 unnoticed, 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 cap- 
sules, and the marginal hairs, which alone are visible, exactly resembling the 
pubescence 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 remarks already quoted, its existence has been 
doubted by a botanist 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 frequently repeated, were they 
not so distinctly confirmed by Mr. Bauer’s excellent drawing. 
I first observed the involucrum six years ago in living plants of Woodsia 
hyperhorea, and have since repeatedly ascertained its existence in dried speci- 
mens 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. 
(E, p. 158). 
Descriptions of European species of Cistopteris, By Roth. 
(From the Flora Germaiiica, iii. 94), 
1. Cyathea fragilis. C. frondibus &c. 
Frondes plures ex una radice crassiuscula, fusca, csespitosa, digitales, spi- 
thameae et semipedales, tenues, debiles, molles, oblongae, e pallide luteo virides, 
glabrae, subpellucidae, bipinnatae : pinnis per paria approximatis, suboppositis, 
remotis, cordato-oblongis, obtusiusculis, patentibus, pinnatis : in injimo pari re- 
motiore plerumque sterili brevioribus, basi latioribus, vix semiunciam longis ; 
mediis longioribus, circiter uncialibus ; superioribus angustioribus et in apicem 
frondis lanceolatum, obtusum, pinnatifidum decrescentibus. Pinnulce alternae, 
2 E 
