GENERAL REMARKS. 



381 



exists in some Weissiae and Didymodons. I believe that Mr. 

 Brown was the first to direct attention to the composition of 

 the teeth of the peristome in the above instances. One of 

 the most curious peculiarities in Polytrichum exists in the in- 

 flection of the inner membrane, forming, as it were, a ring 

 opposite the neck of the capsule. This is quitef distinct from 

 the inflection that occurs in some other genera, in which the 

 inflected portion is the termination of the membrane. 



The outer peristome of Buxbaumia is obviously of analo- 

 gous origin with the peristome of Polytrichum ; neither do 

 I see any reason for not adopting the opinion of Bridel, that 

 the inner peristome of Buxbaumia and Diphyscium is analo- 

 gous to the epiphragma of Polytrichum. Bridel in his gene- 

 ric characters of Catharinea, Pogonatum and Polytrichum, 

 describes the teeth of the peristome as seizing, by their 

 apices, the epiphragma. This is incorrect ; the teeth are 

 seized by the epiphragma, which, in the dry state alone by 

 contraction, leaves the interstices open ; in the wet sate it 

 expands, covering the whole of the teeth as well as their in- 

 terstices. 



I have referred a species, which, with almost every charac- 

 ter of Dicranum, has the peristome of Didymodon, to the 

 former genus. Schwaegrichen however refers a nearly allied 

 species with a similarly anomalous peristome to Didymodon ; 

 this however appears to be sacrificing a number of cha- 

 racters to a solitary one. But if such views are correct, my 

 Fissidens neckeroides must be incorporated with Didymodon. 



Fissidens has, I think, without doubt, terminal setae, for in 

 those cases in which they are axillary, they frequently become 

 elongated, which, so far as 1 know, is never the Case with 

 those which have truly lateral setae. Judging from the first 

 developed leaves both of the stem and perichaetium, it would 

 seem that the i: duplicatura" of Hedwig is the true lamina, 

 and that they differ only from highly carinate leaves in the ex- 

 current vein being as it were alate, the dorsal ala being pro- 

 longed down the carina to its base. The only objection to 

 ^' ; ? view is the frequent inequality of the two lamella?.. 



