322 
Mr. Brown’s Observations on the 
of the four species here described, I have had the oppor- 
tunity of removing the operculum without having been able 
in any 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 Leptostomum, 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 Gymnostomum, to which these 
plants must ótherwise 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, 
I may be permitted to observe, that the outer peristomium 
which he has figured in Bryum macrocarpum is extremely 
unlike that of any other genus where the fringe is double: 
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