Genus Poly trichum; with fome Emendations. 65 



merely in the number of minute dents, and general ftruaure at 

 the orifice of the capfule. 



This author's ftri6t adherence to thefe very minute characters 

 has made him regardlefs of others more confpicuous, and induced 

 him to place another plant under this genus, viz. the Polytrichum 

 hircinicum, which, from its fingle calyptra with upright hairs, more 

 obvioufly, and perhaps more naturally, belongs to one of his new 

 genera. I {hall therefore in the following arrangement be obliged 

 to exclude thefe two fpecies of Hcdwig : nay, I muff, go further ; 

 many authors, and thofe too of great refpectability, have placed the 

 Bryum Jlriatum of the Species Plantarum, and its varieties, under this 

 genus, although they have not the moft diftant affinity, and, accord- 

 ing to the generic character I have adopted, cannot poflibly be ar- 

 ranged under it. Hedwig has, I think, very properly defcribed thefe 

 varieties as diflinft fpecies, and placed them under a new. genus, 

 which he calls Orthotrichum ; and though I am not at prefent much 

 inclined to adopt his minute diftinclions, or follow him in his revo- 

 lutionary career through this natural order, yet I cannot help con- 

 fidering this genus as a real improvement, and (hall endeavour at a 

 future opportunity to lay fome account of it before the Linnean 

 Society, as my late peregrinations have enabled me to enrich it with 

 a confiderable number of new fpecies. 



Having thus excluded thefe feveral fpecies, and feemingly muti- 

 lated the genus, it now remains for me to eftablifhits characteristic ; 

 and this I am happily enabled to accomplifh by means of that in- 

 genious difcovery of the double calyptra, made upwards of twenty 

 years ago, and nearly about the fame time, by two celebrated Na- 

 turalifts, who were then unacquainted with each other's labours, 

 and confequently may both be confidered as equally entitled to the, 

 merits of this improvement. It was firft publiihed in the year I775> 

 in Leers' s Flora Herborncnjis, where, after defcribing the Poly- 



Vol. IV. K irichum 



