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XXXV. Characters and Description of LYELLIA, a new Genus of 
Mosses, with Obserfations on the Section of the Order to which it 
belongs; and some/ Remarks on LE PTosroMuM and BuxBAUMIA. 
By Robert Brown, Esq. F.R.S. Libr. L.S. 
Read April 6, 1819. 
Ix the tenth volume of the Society's Transactions, I have given 
a description of Dawsonia, a genus of Mosses having entirely 
the habit of Polytrichum, but whose peristomium, instead of con- 
sisting of a single row of short teeth connected by a horizontal 
membrane, is composed of an indefinite number of capillary cilia. 
These cilia, originating both from the inner surface of the capsule, 
immediately within the orifice, and from the columella itself, form 
a loose pencil, of which the hairs are sufficiently distinct to allow 
of a gradual discharge of the seeds. 
The correctness of this account of Dawsonia, especially as to 
the origin of the peristomium*, and the nature of the supposed 
columella}, has been questioned by some of those authors, who 
have since adopted the genus. 
From a careful re-examination, however, I find no reason to 
alter in any respect the generic character formerly given; and to 
the description of the species I have only to add, that the upper 
surface of the leaves is furnished with parallel lamellæ, like those 
of Polytrichum ; and that the inner membrane of the capsule is, 
. * Bridel Meth. Nov. Muscor. p. 205. 
f De la Pylaie in Journal de Botanique appliq. iii. p. 134. Y 
in 
