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NEW ARRANGEMENT OF 
said, to be a true inner peristome, and the epiphragma or 
tympanum only an expansion of the membrane, which (as 
in Hypnum) connects the bases of the inner teeth. Very 
different, indeed, is the structure which Mr James Sowerby 
first noticed, in P. subrotundum, and of which a dissection 
is given in Enghsh Botany, Tab. 1624., as also under the 
species alpinum and undulMum. This structure, which 
has been also observed by Mr Brown in P. urnigerum, 
and a Nepal species of his own, P. microstomum, is de- 
scribed by Sir James Edward Smith as an inner peri- 
stome; whereas it is nothing more than the transverse 
membrane which arises from the inner wall, or the lining 
of the theca, and is connected with the summit of the colu- 
mella. The true inner membranaceous peristome is re- 
markably evident in ripe capsules of P. alpinum. 
The membrane to which we have already alluded, as 
closing the mouth of the sporular bag, there is every reason 
to suppose, is stronger and more durable in all such as 
have a naked peristome. Whatever service it may per- 
form in them_, the membranaceous expansion of the inner 
peristome may assist to perform in Polytrichum, for the 
teeth of that genus afford but little protection to the mouth 
after the operculum has fallen: and although the mem- 
brane which closes the sporular bag also exists, something 
more may be necessary to effect a complete dispersion of 
the sporulae, which are obliged to escape by the orifices left 
between the teeth, by the elevation of the tympanum. 
It was not until after a very careful examination that we 
could determine whether the columella of Calymperes was 
furnished with the conical or opercular membrane. The 
horizontal epiphragma stretching across the stoma, which, 
in a young state, much resembles that of Polytrichum, in- 
duced us to think it could not be present ; while, on the 
Other hand, the epiphragma ultimately splitting into teeth, 
