332 ON LYELLIA, LEPTOSTOMUM, 



surface of the columella, which are noticed in my description, 

 and well expressed in Mr. Bauer's excellent figure. 



My principal object, in the present paper, is to establish 

 another genus of the same family, equally related to Poly- 

 trichmn in habit, which resembles Dawsonia in the remark- 

 able form of its capsule, but whose peristomium is of so 

 peculiar a structure as to require its separation from both 

 these, and readily to distinguish 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 par- 

 ticularly studied, and made several important discoveries in, 

 the natural order to which it belongs. 



Mr. Hooker has already intimated his intention of estab- 

 lishing a Lyellia in the same order, to consist of three species 

 of Leucodon 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 accompany the present com- 

 munication, I trust he will give the necessary illustration of 

 this interesting genus, in an early number of his excellent 

 Musci Exotici. 



LYELLIA. 



Stoma edentulum,clausum epiphragmate (crasso depresso), 

 cujus discus circularis a limbo (latiori) persistenti secedens, 

 cum columella remanenti inclusa cohseret. 



Capsula hinc plana inde convexa. 



Calyptra cucullata (apice pilosa). 

 663] Muscus (Nepalensis) habitu Polytrichi; capsulce fgurd 

 et structurd interiori Dawsonise similis; peristomio ab utroque 

 genere diver sissimus. 



' Musci Exotici, vol. i. 17. 



