Mr. Brown on Lyellia, Leptostomum, and Buxbäaumia. 561 
in the early stage at least, connected by numerous plice with 
those elevations of the surface of the columella, which are no- 
ticed in my description, and well expressed in Mr. Bauer's excel- 
lent figure. 
My principal object, in the present paper,.is to establish 
another genus of the same family, equally related to Polytrichum 
in habit, which resembles Dawsonia in the remarkable form of 
its capsule, but whose peristomium is of so peculiar a structure 
as to require its separation from both these, and readily to di- 
stinguish it from all other genera of Mosses. 
This new genus I shall name Lyellia, in honour of Mr. Charles 
Lyell, an accurate English Botanist, who has particularly studied, 
and made several important discoveries in, the natural order to 
which it belongs. 
. Mr. Hooker has already intimated his intention of establishing 
a Lyellia in the same order, to consist of those species of Leuco- 
don that have a mitriform calyptra*; but he has readily agreed 
to transfer the name of our friend from a genus, respecting which 
there is still some uncertainty, to one so unquestionable as that 
here proposed ; and.as I have not a drawing prepared to accom- 
pany the present communication, I trust he will give the necessary 
ilustration of this interesting genus, in an early aumher of his 
excellent Musci fune | T AE 
 LYELLIA. 
Stoma edentulum, clausum epiphragmate (crasso depresso), cujus 
discus circularis a limbo (latiori) persistenti secedens, cum colu- 
mellà remanenti inclusà cohzret. 
Capsula hinc plana inde convexa. | 
Calyptra cucullata (apice pilosa). 
* Musci Exotici, vol, i. 17. 
Muscus 
