88 A P L O P E R I S T O M 1. [Dicranum. 



rection of their leaves, that we were almost tempted to deviate 

 from the Linnsean rule of drawing the generic distinctions from 

 the fructification, and to employ those solely founded on the 

 difference of foliage. From this latter circumstance, however, an 

 admirable character for the primary division of the species may be 

 formed. Even in the true Dicrana, many vary from what we 

 must still regard as the most essential character of the genus ; viz. 

 the regularly cleft teeth of the peristome. D. virens has the cleft 

 often united at the apices of the segments. In D. rufescens the 

 segments are unequal ; in D. spurium frequently trifid. Those of 

 D. purpureum are so deeply divided, that we have had no hesita- 

 tion in removing it to the genus Didymodon, with which it likewise 

 accords full as well in habit. Mohr cautions us to distinguish 

 carefully between Dicranum longifolium, and the foreign Didy- 

 modon longirostrum, and between the likewise foreign Dicr. tortile 

 and Didymodon homomallum, and Weissia heteromalla. This last, 

 indeed, we believe, as we shall hereafter have occasion to mention, 

 to be nothing more than our Didymodon heteromallum, of which the 

 peristome had not been sufficiently examined. But there are other 

 true Weissitz, W. acuta in particular, which bear a very close 

 affinity to Dicranum, 



A. Leaves inserted in a bifarious manner, 

 (Fissidens. Hedw.) 



J. D, bryoides; fruitstalks terminal, perichsetial leaves resembling 



the cauline ones. (TAB. XVI.) 

 . stem short simple, capsule erect. 



Dicranum bryoides. Swartz, Muse. Suec. t. 2. f, 4k Smith, Fl. JBrit. 

 p. 1232. Engl Bot. L 625. Turn. Muse. Hib. t. 53. Drummond, Muse. 

 Scot. v. 2. n. 38. Hobson, Brit. Mosses, v. 1. n. 33. Hook. Fl. Scot. P. 

 II. p. 131. Arn. Disp. Muse. p. 27. 



Fissidens bryoides. Hedw. St. Cr. v. 3. t. 29. Schwaegr. Suppl v. 

 J. P. II. p. 7. Funck, Deutschl. Moose, t. 22. n. 3. 



Hypnum bryoides. Linn. Sp. PI. p. 1588. 



Dicranum viridulum. Swartz, Muse. Suec. t. 2. f. 3, Smith, Fl. 

 .Brit. p. 1230. Engl. Bot. t. 1368. 



Bryum viridulum. Linn. Dicks. Crypt. Fasc. 1. t. \. f. 5. Dill. 

 Muse. t. 34. /. 1. 



Fissidens exilis. Hedw. Sp. Muse, t, 38, / 710. Funek, Deutschl. 



