Mr. Brown on Lyellia, Leptostomum, and Jiuxbaumia. 583 



described than any other plant of the order, from the monographs 

 of Linnaeus and Schniidel to the excellent illustration recently 

 published by Mr. Hooker, there is no difference of opinion on 

 this point. I have lately ascertained, however, that Buxhaumia 

 aphylla is always furnished with perfect leaves, which more nearly 

 resemble, both in texture and division, those of a Jungermannia 

 than of any species of moss properly so called ; and consequently 

 are widely different from those of Polytrichoidece, to which this ge- 

 nus is in several respects related-.. 



The leaves in the barren plant, where I first observed them, are 

 lanceolate and but slightly divided. 'I'hose at the base of the fe- 

 male perichaetiura are even broader than the former, but more 

 deeply cut, both laterally and at top, into several capillary seg- 

 ments; while the leaves which proceed from the surface of the 

 perichsetium are still more deeply divided, and tiieir segments 

 so much elongated that the minute foliaceous base has been uni- 

 versally overlooked, and the perichaetium consequently described, 

 as covered with hairs.. 



XXXVI. Ex- 



