AND BUX15AUMIA. 351 



by a circumstance that he does not seem to have noticed, 

 namely, that his outer peristomium, the corona of Hedwig, 

 consists of a double series of cilia. The number of cilia 

 in each series exceeds sixteen, but hardly amounts to thirty- 

 two ; it probably, however, corresponds with that of the 

 plicae in the membranaceous peristomium. 



We have here then a passage from a number still perhaps 

 definite, though disposed in a triple series, to the indefinite 

 number peculiar to, and so striking in, Dawsonia. 



My second observation relates to the inner membrane of 

 the capsule, of which I find the mouth to be quite entire 

 and open, though before the separation of the operculum it 

 is closed by the terminating process of the columella. 

 Hence Buxhaumia has some resemblance to Polytrichmi, 

 and a still greater to Lyellia, in this part of its structure. 



Buxbaumia aphylla is the only moss considered as being 

 entirely destitute of leaves ; and though it has been oftener 

 and more fully described than any other plant of the [sss 

 order, from the monographs of Linnaeus and Schmidel to 

 the excellent illustration recently published by Mr. Hooker, 

 there is no difference of opinion on this point. I have lately 

 ascertained, however, that Buxbaumia aphylla is always 

 furnished with perfect leaves, which more nearly resemble, 

 both in texture and division, those of a Juiigermannia than 

 of any species of moss properly so called; and consequently 

 are widely different from those of Bolytriclmdea, to which 

 this genus is in several respects related. 



The leaves in the barren plant, where I first observed 

 them, are lanceolate and but slightly divided. Those at 

 the base of the female perichgetium are even broader than 

 the former, but more deeply cut, both laterally and at top, 

 into several capillary segments ; while the leaves which 

 proceed from the surface of the perichsetium are still more 

 deeply divided, and their segments so much elongated that 

 the minute foliaceous base has been universally overlooked, 

 and the perichsetium consequently described as covered with 

 hairs. 



