Pteroffonium.] APLOPERISTOMI. 73 



Grimmia unicolor. Hook. Fl. Scot. ed. 2. MSS. Drummond, 

 Muse. Scot. v. 2: n. 32. Grev. Scot. Cr. FL t. 123. Arn. Disp. Muse. 

 p. 21, 



HAB. Abundant on the steep, almost perpendicular, faces 

 of bare exposed rock, above Bachnagairn, a hunting 

 Lodge belonging to the Hon. D. Ogilvie at the head of 

 Clova, Angusshire. Mr. Drummond. 



This rare moss has much the habit of Trichostomum ellipti- 

 cum ; the leaves are of an equally dark brown colour, and 

 obtuse ; but they are even more rigid, and their margins are 

 much incurved. The capsule is longer, of a softer texture, and 

 the peristome, which is deep red, is decidedly that of a Grim- 

 mia. Mr. Drummond mistook it at first for a variety of Tri- 

 ckostomum microcarpum, but independent of the difference in 

 the generic character, the leaves in the latter are far more pa- 

 tent and more attenuated at their points. 



The plant grows in veiy dense and broad tufts, and upon 

 rocks so dry and so exposed to the sun, that in the summer it 

 appears to be burned up and destroyed. The stems are from 

 one to three inches long, sometimes throwing out, as Dr. 

 Greville observes, slender, filiform, barren shoots, clothed with 

 snfall ovate, imbricated leaves ; all the leaves have a strong nerve 

 reaching to the point. The seta is erect, straight or slightly 

 flexuose. Capsule reddish brown ; the lid conico-subulate. 

 The Calyptra, at first, truly mitriform, afterwards, as in some 

 Trichosfoma, bursts on one side as it were by the enlargement of 

 the capsule, and thence becomes dimidiate. Teeth quite entire. 



XVI. PTEROGONIUM. 



GEN. CHAR. Fruitstalks lateral ; Peristome single, of 16 en- 

 tire, equidistant teeth ; Calyptra dimidiate. (TAB. II.) 



Mohr has, we think, contrary to nature, united this genus with 

 Weissia and Grimmia. It bears the same affinity to Weissia 



as Hypnum does to Bryum ; being distinguished by its branched 



10 



