322 Mr. Buown's Observations on the 



of the four species here described, I have had tl)e oppor- 

 tunity of removing the operculum without having been able 

 in an}"^ case to observe an external peristomium, which, from 

 the appearance of these plants, might be expected to exist, 

 and which Hedwig has figured in his Bryum macrocarpum. 

 Of this plant I have only seen specimens that had lost the 

 operculum : the mouth of the capsule, however, seemed to be 

 very perfect, and was furnished with a membrane, exactly as 

 in the species here described, but I could not- perceive any 

 remains of external teeth. In opposition to such authority, 

 however, I do not venture to add it to this genus, to which 

 in every other respect it seems to belong. 

 The character of Leptostomnm, derived from the undivided 

 annular process of the inner membrane of the capsule, may 

 to many appear too minute, and perhaps unimportant ; and 

 had it been observed in one species alone, I should not have 

 ventured on that account to distinguish it as a genus : but 

 finding it in four species, accompanied too with a habit 

 widely different from that of Gyumostomwn, to which these 

 plants must otherwise be referred, I have not hesitated to 

 employ it. As, however, Hedwig has actually figured and 

 described an external peristomium in his Bryum macro- 

 carpum, whose striking resemblance to Leptostomum has 

 been already noticed, there may be still some reason to 

 doubt the sufficiency of the generic character, and it may 

 seem somewhat improbable that Mosses of such a habit 

 should be really destitute of an outer peristomium. But, 

 without questioning the accuracy of Hedwig in this instance, 

 1 may be permitted to observe, that the outer peristomium 

 which he has figured in Bryum macrocarpum is extremely 

 unlike that of any other geuus where the fringe is double: 



and 



