38 POLYTRICHACEiE. 



rather thick seta, which is f-i inch long ; ovate-cylindrical, erect 

 or somewhat inclined, somewhat plicate when dry, and contracted 

 below the mouth ; lid shortly rostrate, oblique, often falling off 

 with the calyptra ; columella four-winged ; peristome teeth short, 

 unequal. 



Var. /6. laxum Braithw. Stem taller, 2.-4 inches high, slender. 

 Leaves more distant, spreading, pellucid, with fewer lamellae, and 

 much larger cells, more distinctly toothed. Barren. 



Hab. Sandy and stony ground on or about mountains. The var. $ rare ; Ben 

 Nevis ; Bangor, Snowdon, and other places in Wales. Fr. late summer. 



In this species, as in Polytrichum, the axis of the male plant is produced and 

 continues growing beyond the first year's perigonium ; producing another in the follow- 

 ing year, so that two or three perigonia may be found one above the other on the 

 same stem. 



A few stomata are to be found on the neck of the capsule. 



Although the lamina of the leaf is not spinose at back, a few short, toothed 

 lamella may frequently be found ; principally near the apex. A very curious form 

 which I gathered near Llyn Dinas, Beddgelert, somewhat intermediate between the 

 type and the variety, has stems 2-4 inches long, frequently branched, with the leaves 

 much crisped when dry, pellucid and with few lamellse as in var. laxum, but with 

 cells quite as small as in the type, and numerous short lamellae scattered over the 

 back of the lamina near apex, principally near the margin. 



6. POLYTRIOHUM Dill. 



Plants varying in size, often tall and showy, the stems 

 innovating from creeping underground rhizomes, occasionally 

 branched above. Leaves large, suddenly narrowed above the 

 membranous, sheathing base, not bordered ; the nerve broad, 

 sometimes toothed but not lamellate at back, covered on the upper 

 surface with numerous straight lamellse, occupying the greater 

 part of the width of the limb, and rendering the leaf rigid and 

 opaque ; lamellae entire or crenulate along the upper margin, not 

 coarsely toothed. Dioicous (in the European species). Calyptra 

 covered with a thick felt of deflexed hairs reaching far below its 

 base and usually covering the greater part of the capsule, or the 

 whole. Capsule erect or cernuous, cylindrical or angular, with or 

 without apophysis. Lid plane or convex, with a subulate beak. 

 Teeth of peristome 32 or 64. 



A large genus, exhibiting much variety in size, but very 

 uniform in the general arrangement and form of the leaves. 

 Stomata are usually to be found on the neck of the capsule, just 

 above or on the apophysis. The character of the apical cell of 

 the lamellae when seen in section is of great value in distinguish- 

 ing the species, especially when barren. 



