350 DESCRIPTION OF 



ovata, per lentem reticulata, areolis subrotundis, sordide 

 fusca, laevis, iionnitens, supra plana marginibus acutis, 

 subtus modice convexa ore coarctato, marginato. Apophysis 

 nulla. 



Operculum conico-cylindraceum, capsula brevius, apice 

 lateris superioris in mucronem levissirae incurvum producto, 

 basi incrassata, cum calyptra ssepissime deciduum. 



Perisfomium penicillum densum album referens, longi- 

 tudine circiter dimidii capsulse, formatum Ciliis indeter- 

 minatim numerosissimis (200 et ultra) capillaribus inarti- 

 318] culatis sequalibus rectis albis opacis, pluribus e capsulse 

 parietibus ortum ducentibus, centralibus (circiter 50) colu- 

 mellam terminantibus ! 



Memhrana interior capsulse maturae exteriori approxi- 

 mata, vasculisque numerosis connexa. 



Columella longitudine capsulse maturse, in qua latiuscula, 

 corrugata, colli brevis margine incrassata, intra cilias 

 desinens in processura filiformem solidum indivisum apicem 

 operculi attingentem eique arctiiis adhcerentem. 



Semina minutissima, Isevia, in cumulo viridia, seorsum 

 hyalina. 



Obs. I. I have named this remarkable genus in honour 

 of my esteemed friend Dawson Turner, Esq., a gentleman 

 eminently distinguished in every part of cryptogamic botany, 

 and from Avhom, after he has finished the incomparable 

 work on Fuci, in which he is now engaged, we may expect 

 a general history of mosses. 



Obs. II. The strict relationship between Dawsonia and 

 PolytricJiimi in most respects, and the striking dissimilarity 

 of their peristomiums, may tend, perhaps, in some degree 

 to lessen our confidence in the characters derived from that 

 part ; for there seems in this case but little analogy between 

 the two structures. The better to understand that of 

 Polytriclmm, I was induced along with Mr. Turner to 

 examine it in the unripe capsule : in this state the cavity of 

 the operculum was found completely filled with a cellular 

 pulp, similar to that composing the columella, of which it 

 appeared evidently to be a continuation ; to the surface of 

 this pulp the teeth of the peristomium were closely pi-essed, 



