32 TETRAPHIDACE/E. 



more regularly rectangular ; capsule on a smooth, brown, much 

 shorter and more rigid pedicel, very small, ovate, firm, dark 

 brown, solid ; calyptra darker, more deeply cleft at base ; mouth 

 of the capsule more or less sinuosely notched between the 

 peristome teeth, which are much shorter, broadly triangular, of 

 broader and shorter, rectangular cells. Perigonial bracts fewer, 

 nerveless. 



Hab. — Sandstone or gritstone rocks, frequently growing downwards from the 

 roof of caves or clefts. Frequent in some parts of Scotland and the North of England, 

 but not a common moss. Fr. summer. 



A minute plant, best distinguished in the field by the plicate calyptra and the 

 peristome, from Seligeria, Brachyodus, etc. ; under the microscope it presents no 

 resemblance to any other moss. 



T. repanda Funck, a species or variety not found in this country, but known in 

 France and elsewhere on the continent, differs only in the frondiform leaves being 

 replaced by minute flagelliform shoots bearing extremely microscopical nerveless leaves. 



Order IV. POLYTRICHACE^E. 



Plants usually of a large size, growing on earth, the simple or 

 slightly branched stems growing from a creeping subterranean 

 rhizome. Leaves usually narrow, the nerve more or less ex- 

 panded on the ventral surface, and producing on that surface 

 longitudinal strips of tissue (lamellse) in the form of thin laminae 

 standing on edge and running parallel to one another along the 

 nerve, sometimes in great numbers and crowded, or few and lax, 

 usually formed of a few rows of cells in height and a single cell in 

 thickness, so as to appear in transverse section of a single row of 

 superposed cells, the uppermost or external cell being often of a 

 different form from the lower ones. Upper areolation generally 

 hexagonal, with thin walls. Inflorescence nearly always dioicous, 

 the male flower terminal, large, discoid. Capsule on a long seta, 

 large, cylindrical, or prismatic with 2-6 angles. Calyptra narrow, 

 cucullate, spinulose at apex, or with few or many erect or deflexed 

 hairs. Peristome (in the European species) of 32 or 64 short, 

 ligulate, unbarred teeth, triangular in transverse section ; 

 columella expanded at apex into a shield-shaped membrane, the 

 epiphragm, or, as it is sometimes rather inaccurately called, the 

 tympanum, covering the mouth of the capsule and united at its 

 edges with the teeth of the peristome. 



The larger species of this order, being very noticeable plants 

 and also common, are among the first which come under the notice 

 of the student of mosses, and will be easily referable to their right 

 natural order by the lamellose face of the leaf, which in 



