Botanical Society of London. 129 



BOTANICAL SOCIETY OF LONDON. 



July 7th.— J. E. Gray, Esq., F.R.S. &c.. President, in the Chair. 



Read " Observations on Dicranum Dillenii (MSS. T. T.)," by Dr. 

 Tliomas Taylor. 



As Dillenius is the first author who has directed the attention of 

 botanists, seventy-five years ago, by a separate paper, to the present 

 moss, his name has been ascribed to it, and yet it is plain that he, 

 as well as all subsequent muscologists, have confounded it with 

 Dicranum Scoparhim (Linn.). Nor is this without excuse, when we 

 consider the strong resemblance of the habit of both, their nearly 

 equal size, their very general occurrence in Europe as well as in the 

 northern parts of America, and particularly their frequently growing 

 together in the same woods, or on the same banks, in more open 

 and mountainous situations. Besides, the present plant varies very 

 considerabl}' in appearance, so that the one state well figured in 

 'English Botany,' t. 354, as Dicranum Scoparhim, would scarcely be 

 supposed to belong to the same species as another state equally well 

 represented by Schwregrichen 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 the ' Muscologia Britan- 

 nica' to give both species, well represented, as varieties only of Di- 

 cranum Scopnrium. Submitted, however, to a rigid scrutiny. Dr. Tay- 

 lor apprehended that the following distinctive marks would be found 

 to be constant ; and if so, they would appear to be both sufficiently 

 numerous and sufficiently grave to establish the present species, 



1 . Dicranum Dillenii, though frequently differing in size, is usually 

 the smaller moss. 2. Its leaves are not constantly and but slightly 

 turned to one side, while in Dicranum Scoparium they are more 

 loosely set and uniformly falcato-secund. 3. In the present the pe- 

 dicels are solitary, in the other aggi-egated within the same perichrE- 

 tium. 4. In the former the pedicels are opake, even immediately 

 below the capsule at the period of full maturity ; they are reddish 

 below and brownish-yellow 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 ai^ophy- 

 sis 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 opercu- 

 lum is gradually acuminated and falls after the calyptra ; while in 

 the latter the operculum, with a broad base, is suddenly acuminated, 

 and usually falls on and with the calyptra. 7. In Dicranum Dillenii 

 the teeth of the peristome are narrower and more opake. 8. The 

 stem is often interruptedly leafy. 9. The leaves are shorter, and have 

 their points less curved. 10. The parts of fructification are greater 

 in proportion to the size of the plant. 



In the museum of the Society occurs a Dicranum from Newfound- 

 land, from the late Mr. Lambert's herbarium, which being barren, 

 and so not admitting of a comparison of the parts of fructification, 



Ann. ^ Mag. N. Hist. Vol. xii. K 



