378 Wilson's notes on British muscology- 



After having completely dissected a number of the finest 

 specimens, 1 feel satisfied that this Moss ought to be removed 

 to the genus Didymodon. It is only in starved specimens 

 that I find sixteen simple teeth, and even some of these under 

 a good doublet or triplet lens, exhibit sufficient traces of di- 

 vision into geminate processes. In those peristomes, which 

 are perfect, there are sixteen decidedly geminate slender teeth, 

 by no means horizontal, as represented in Muse. Brit., but 

 nearly erect, at least twice as long as the diameter of the 

 mouth of the capsule, and surrounding that conical prolonga- 

 tion of the columella (termed the metula by Mr Valentine, 

 opercular membrane of Arnott,) which fills up the cavity of 

 the operculum. In old specimens the peristome appears to 

 be less erect, but the teeth can scarcely in any instance be 

 regarded as horizontal, and their remarkably slender form is 

 very unlike the figure referred to. 



My remarks would terminate here if doubts concerning the 

 identity of this Moss with Tor tula torluosa had not been frequent- 

 ly entertained, and if the Moss last named had not recently 

 been by Dr Taylor himself placed in the genus Didymodon. 

 In JVeissia (Didymodon) termirostris, I find the innovations 

 or barren shoots very different from those of Tortula tortuosa, 

 the leaves being much shorter, more linear in form, more 

 obtuse at the extremity, and less crisped in a dry state; they 

 are widely-spreading, recurved, and by no means crowded. 

 The operculum presents no mark whatever of spiral arrange- 

 ment of its cellular tissue ; nor does the peristome exhibit any 

 tendency to take a spiral, or even an incHned direction. I 

 conclude therefore that the Moss is distinct from Tortula tor- 

 tuosa, although circumstances having hitherto prevented me 

 from rigorously comparing the two together, it may not be 

 altogether safe to insist much upon their diversity. 



In addition to what has already been said, I may state the 

 following particulars : — JVeissia tenuirostris has a very obscure 

 annuluSf adiierent to the margin of the operculum, and some- 

 what more deeply coloured. — Capsule narrowly lanceolate, 

 tapering towards the base, often somewhat bent, and the 



