582 Mr. Brown on Lyellia, Leptostomutfi, and Buxhaumia. 



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 striae 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, though consisting 

 of several and even of dissimilar series, be regarded as analogous 

 to that portion of the pencil of Dazsz^so/u'a which arises from the same 

 part of the capsule. This analogy is suggested by Mr. Hookerj 

 and is confirmed by a circumstance that he does not seem to 

 have noticed, namely, that his outer peristomium, the corona of 

 Hedwig, consists of a double series of cilia. The number of cilia 

 in each series exceeds sixteen, but hardly amounts to thirty-two; 

 it probably, however, corresponds with that of the plicae in the 

 membranaceous peristomium. 



We have 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 Buxbaumia has some 

 resemblance to Polytrichum, and a still greater to Lyellia, in this 

 part of its structure. 



Buxbaumia aphylla is the only moss considered as being entirely 

 destitute of leaves ; and though it has been oftener and more fully 



described 



