112 Mosses — Grimmia and Schistidium. 



species are obtuse pointed, and destitute of the bristle, with a 

 margin so inflexed that the upper part of the leaf might be 

 called seini- cylindrical, and having a broad nerve which reaches 

 to the apex, and so predominating as scarcely to be distin- 

 guished from the laminar substance of the leaf. The capsule 

 is ovate, smooth, yellowish-brown, erect, or slightly oblique, 

 and having a lid with a straight or inclined beak half as long 

 as the capsule, annulus large and dehiscent, calyptra dimidiate 

 and rather oblique. 



Grimmia atrata, or the black-tufted Grimmia, somewhat 

 resembles the last, growing to about the same height, but in 

 more compact tufts, with blackish glossy leaves, rather less 

 rigid than in unicolor, less obtuse, with a thinner nerve, though 

 more distinctly defined, and carinate, which the leaves of 

 nnicolor are not. The fruit-stalk is rather thicker and longer, 

 the capsule longer, and becoming blackish when old • the lid < 

 has a shorter beak, and the calyptra is fugacious. The inflo- 

 rescence in both is dioicous, but Grimmia atrata is the more 

 rarely met with, Snowdon and the rocks above Glen Callater 

 have been given as its habitats. It fruits in spring and 

 autumn. 



The three other British species of Grimmia have been 

 arranged under the head of Schistidium. They differ from 

 those already described in very little more than having im- 

 mersed and almost sessile capsules, whose columella adheres to, 

 and falls away with their lid. 



The term Schistidium is derived from aytCps, I split, or 

 shiver to pieces, in allusion to the lacinated base of the calyptra, 

 which is also so small as scarcely to cover the lid. 



Scldstid/ium confertum, or the close-tufted Grimmia, is densely , 

 csespitose, with- ovate lanceolate acuminate leaves, of an intense 

 green colour above, blackish below, the upper ones only shortly 

 hair-pointed, erect and lurid when dry, deeply and acutely 

 channelled above, and with a strong nerve dilated at the back; 

 the capsule oval or roundish, with a shortly rostcllate lid, no 

 annulus, and teeth much, perforated. It is found on trap or 

 Bandstone roclgs, and fruits in February and Maroh. 



ScMsUdivM (ijiornr/iinii, or the sessile Grimmia f has con- 

 siderable resemblance bo 8. confertiim; the capsule is, how- 

 ever, larger, of darker hue and thicker texture, that of 

 confertum being almost pellucid. N. (ijxx-nrpvin, too, is taller, 

 more loosely csespitose j in fche larger varieties diehotomously 

 branched, and often procumbent; and the firm, opaque, 

 fcened capsule has a wide mouth in the dry state: fche 

 teeth of tlie peristome are rather long, and of a dark red, 

 those of confertwty of a pule m\ or orange colour. The lid 

 is convex, with a short inclined beak, and the calyptra 



