98 NEW OR RARE BRITISH MOSSES. 
modon brachydontius, Wils. in Eng. Bot. Suppl. t. 2735), but which 
was figured and described in the ‘ Bryologia Europea’ as T. mutabile 
(Trichostomum, t. 5). From this species, however, it differs in its 
more tender, more obscure, and softer leaves, with an evident white 
base, in which the hyaline elongate cells ascend along the mar gins of 
the leaf higher than they do in the middle by the nerve. Although 
perfectly distinct in inflorescence and in the straight peristome, it is 
Tortula cespitosa, Schweegr. t. 31, that Trichostomum flavo-virens more 
nearly resembles than any other Moss, agreeing as it does in size, 
appearance, in the colour of its foliage, seta, and capsule; even in the 
areolation of the leaves it is almost exactly similar; and, it may be 
observed, that if the peristome of 7. flavo-virens had been ever so little 
twisted, it must have been placed in Tortula, from the absence of any 
difference of structure. 
There are some other British Mosses known hitherto in a barren 
state only, but which are evidently species very nearly allied to the 
more generally distributed Trichostomum mutabile; one of them has 
long been known, but it does not appear to be anywhere noticed. It 
may be thus characterized :— 
Trichostomum diffractum. Stems growing in compact tufts more or 
less elongated, and repeatedly dichotomously divided. Foliage densely 
inserted, green or yellowish-green, becoming when old brown and 
persistent, not interruptedly comose, when dry crispate. Leaves 
recurved from a short, erect base, patent, all except the very youngest 
uniformly broken off halfway up, when complete they are linear-lanceo- 
late, acute, slightly channelled, entire; the nerve thick, prominent on 
the back, in a dry state paler and shining, at the apex of the leaf it is 
excurrent into a short mucro; all the upper portion of the leaf is 
occupied by rounded, obscure cells, gradually towards the base be- 
coming more elongate and translucent, and at the base the hyaline, 
oblong, rectangulate cells ascend higher along the margins than they 
do in the middle.— Has. St. Vincent’s Rocks, Clifton (Dr. Thwaites) ; 
Carnelly, and St. Michael's Chapel, Torquay (the late Mr. Bormi 
on walls at Plymouth (Mr. Holmes). 
From 7. mutabile this differs in its more dense foliage not in- 
terrupted or comose, composed of leaves which are so generally broken 
off, as it would appear from their flexure, when passing from a wet to 
a dry state, that it is only on carefully-selected specimens that a single 
