Mr. Brown on LycUia, Lepto.itomum, and Buxbaumia. 569 



P. undulatnm alone excepted, four longitudinal equidistant pro- 

 cesses, extending from the aperture to the base of the capsule; 

 and in many species projecting so far into its cavity as to come 

 in contact either with the salient angles or sides of the colu- 

 mella, and consequently to subdivide it into a determinate num- 

 ber of cells. 



The analogy of these longitudinal processes with the more nu- 

 merous and irregular plicae in Dawsonia and Lyellia is obvious; 

 and I have not myself met with similar processes of the inner 

 membrane in any other genus of mosses. They do not, however,, 

 afford an absolutely distinguishing character of this group, as they 

 seem to be altogether wanting in Poli/trichum undulatum ; and" 

 Hedwig, it must be admitted, has represented an apparently ana- 

 logous structure in Gymnostomum pyriforme*. 



The quadrangular or four- winged columella of Po/(/^n'c^j/;ncow2- 

 mtine is mcII figured and described by the accurate Schmidel-|-; 

 and I have found an equally regular form of this body in most 

 of the species of PolytricUum that I have examined ; though in 

 many it is less evidently winged than, in. P. commune and the spe- 

 cies nearly related to it. 



Mons. de Beauvois seems to consider the ala; of the columella 

 as themselves forming complete septa, and also that in this state 

 they exist only in such species as have quadrangular cap- 

 sules ; for to these he limits his genus Polytrichum, distinguished 

 by him from Pognnatum by its multilocular fruit. The cavity, 

 however, is completely subdivided in several of the species 

 with cylindrical capsules, as in P. urnigerum, and in a new 

 species very nearly related to it (P. microstomum, nob.) lately re- 

 ceived from Dr. Wallich : and the alae of the columella, as far as 



* Fundam. Hist. Nat, Muscor. Frond, pars ii. tab. 2. j3. 

 t. Iconespl. p. 236. tab. 59, fig. 15.. 



I have 



