Genus Polytrichum; with fome E:mendations. 65 
“merely in the number of minute dents, and general ftructure at 
the orifice of the capfule. 
This author’s ftricét 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 fhall therefore in the following arrangement be obliged 
to exclude thefe two fpecies of Hedwig: nay, I muft go further; 
many authors, and thofe too of great re{pectability, have placed the 
Bryum frriatum 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 poffibly be ar- 
ranged under it. Hedwig has, I think, very properly defcribed thefe 
varieties as diftinct {pecies, and placed them under a new genus, 
which he calls Orthotrichum; and though I am not at prefent much 
inclined to adopt his minute diftinétions, 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 {pecies. 
Having thus excluded thefe feveral {pecies, and feemingly muti- 
lated the genus, it now remains for me to eftablith its characteriftic ; 
and this | 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 publifhed in the year 1775, 
in Leers’s Flora Herbornenfis, where, after defcribing ‘the Poly- 
Vor. IV. K trichum 
