688 



Read, 'Observations on Dicranum Dillenii, Taylor, MS.,' by Dr. Thomas Taylor. 



As Dillenius is the first author who directed the attention of botanists, seventy-five 

 years ago, by a separate figure, to the present moss, his name has been ascribed to it ; 

 and yet it is evident that Dillenius, as well as all subsequent muscologists, have con- 

 founded it with Dicranum scoparium, Linn. Nor is this without excuse, when we 

 consider the strong resemblance in the habit of both, their being nearly equal in size, 

 their very general occurrence in Europe, as well as the northern parts of America, and 

 particularly their frequently growing together in the same woods, or on the sarne banks, 

 in more open and mountainous situations. Besides, the present plant varies consider- 

 ably in appearance, so that the one state, well figured in ' English Botany,' t. 354, as 

 Dicranum scoparium, would scarcely be supposed to belong to the same species as 

 another state, equally well represented by Schwaegrichen in his Supplement, t. 42, under 

 the same name. It is the wide limits within which its aspect changes that probably 

 weighed with the editors of ' Muscologia Britannica,' to give both species, well-repre- 

 sented, as varieties only of Dicranum scoparium. 



Submitted however to a rigid scrutiny, Dr. T. apprehended that the following dis- 

 tinctive marks would be found to be constant, and if so, they would appear to be suf- 

 ficiently numerous and sufficiently grave to establish the present species. 



1. Dicranum Dillenii, though frequently difi'ering in size, is usually the smaller moss. 



2. Its leaves are not constantly, and but slightly, turned to one side, while in Di- 

 cranum scoparium they are more loosely set, and uniformly falcato-secund. 



3. In the present species the pedicels are solitary, in the other aggregated within 

 the same perichEetium. 



4. In the former the pedicels are opaque, even immediately below the capsule, at 

 the period of full maturity ; they are also reddish below and brownish above : while in 

 the latter, even when full grown, they are somewhat pellucid, and of a pale straw 

 colour. 



5. In the former, the capsule is erect below and slightly curved above, is nearly 

 equal, has no projecting struma, yet with an apophysis, pale brown when ripe : in the 

 latter, the capsule is curved, even long before the fall of the calyptra, is very unequal, 

 has a projecting struma, and is green when just ripe. 



6. In the former, the operculum is gradually acuminated, and falls after the ca- 

 lyptra ; while in the latter, the operculum, with a broad base, is suddenly acuminated, 

 and usually falls in and with the calyptra. 



7. In Dicranum Dillenii the teeth of the peristome are narrower and more opaque. 



8. The stem is often interruptedly leafy. 



9. The leaves are shorter, and have their points less curved. 



10. The parts of fructification are larger in proportion to the size of the plant. 



In the Museum of the Society occurs a Dicranum from Newfoundland, from the 

 late Mr. Lambert's collection, which, being barren, and consequently not admitting of 

 a comparison of the parts of fructification, Dr. T. would not venture to separate from 

 Dicranum Dillenii ; and yet its densely aggregated and shorter stems, its shining lus- 

 tre, and its less patent leaves, would demand the greatest attention, and would indi- 

 cate it as at least a very remarkable variety ; but when it is considered that its leaves 

 are shorter, wider in the lower half, with their points more canaliculate, and the nerve 

 serrated at the back, it must be confessed that its claims for separation are very strong. 

 — G. E. D. 



