Mr. Bnoww on Lyellia, Leptostomum, and Buxbaumia. 365 
Spongy texture of the base of the capsule. Butby thus removing 
support from the columella and inner membrane, they may con- 
tribute to the greater shortening of the former, and consequently 
in increasing the dispersion by the mouth of the capsule ; or, from 
the same cause, the inner membrane being at length ruptured, the 
seeds may be in part discharged by the pores themselves. 
It seems then not improbable, from what we at present know 
of the structure of Lyellia, that for the dispersion of the seeds in 
this genus there are two distinct contrivances, both of which, 
however, in the only species yet known, are apparently imperfect. 
But hence it is perhaps allowable to conjecture, that either other 
species of Lyellia, or a nearly-related genus may exist, in which 
while the mouth of the capsule remains absolutely shut, the pores 
of the base may be sufficiently enlarged for the complete per- 
formance of this important function. 
Pores exactly resembling those of Lyellia crispa have not hither- 
to been found in any other moss. I have observed, however, in 
several specimens of Polytrichum alpinum still more minute pus- 
tules, not very different in appearance, and similarly situated on 
the base of the capsule. 
In establishing this new genus of Mosses, it is of importance to 
determine its more intimate affinities in the family to which it 
belongs. Its place is unquestionably between Polytrichum and 
Dawsonia; and it will I believe be admitted, that these three ge- 
nera, in the natural method, cannot be separated ; though they will 
necessarily form or be referable to distinct sections of an artificial 
system founded chiefly on modifications of the peristomium. 
In attempting to discover characters by which this group of 
PorvrnicHoiprz may be distinguished from other Mosses, it is 
in the first place necessary to determine the whole structure of 
Polytrichum; for this genus, though one of the most common of 
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