582 Mr. Brown on Lyellia, Leptostomum, and Buabaumia. 
to this view would perhaps be obviated by rejecting the outer pe- 
ristomium of Hedwig, as I have formerly proposed, and which 
Mr. Hooker has since done; as there would then be nothing either 
in the origin or texture of this part essentially at variance with 
the supposition; the principal remaining difference being its 
greater length; for the cilia of the peristomium of Buxbaumia may 
be compared with the striæ or divisions existing in the annulus, 
Which seem to be equally determinate in number, and in some 
cases also disposed in a double series. | 
On the second supposition, the peristomium of Buxbaumia ori- — 
ginating entirely from the outer membrane, may, thou gh consisting 
of several and even of dissimilar series, be regarded as analogous 
to that portion of the pencilof Dawsonia which arises from the same 
part of the capsule. This analogy is suggested by Mr. Hooker, 
and is confirmed by a circumstance that he does not seem to 
have noticed, namely, that his outer peristomium, the corona of - 
Hed wig, consists of a double series of cilia. The numberof cilia 
in each series exceeds sixteen, but hardly amounts to thirty-two; 
it probably, however, corresponds with that of the plicæ in the 
membranaceous. peristomium. 
. . Wehave here then a passage from.a number still perhaps defi- 
nite, though disposed in a triple series, to the indefinite number 
peculiar to, and so striking in, Dawsonia. — 
My second observation relates to the inner membrane of the 
capsule, of which I find the mouth to be quite entire and open, 
though before the separation of the operculum it is closed by the 
terminating process of the columella. Hence Burbaumia has some 
resemblance to Polytrichum, and a still greater to Lyellia, in this 
part of its structure. crm 
Buxbaumia aphylla is the only moss considered as being entirely 
destitute of leaves; and though it has been oftener and more fully 
described 
