MOSS HABITATS. 51 



capsule, and narrower leaves than the last-named variety, 

 with no membranous processes on the upper surface. 



Tortula muralis is one of our most frequent mosses, often 

 filling up the interstices between the bricks of an old wall 

 from its base to its top, growing in hoary, bluish-green tufts ; 

 the leaves are oblong with blunt tips, terminated by white 

 hair-like points, very hoary in some of the varieties ; the 

 leaf-margin is recurved, leaf-cells minute and opaque in 

 upper part, transparent and elongated below ; the capsule 

 is erect ; lid shortly beaked ; fringe of thirty-two teeth, 

 beautifully twisted. 



Tortula marginata is a more local species, partial to damp 

 stone walls, and usually growing on the surface of the stone. 

 At first sight not unlike the foregoing, but has narrower 

 leaves, with the margin thickened, not recurved, and ter- 

 minated by a minute green point. The fruit-stalk, too, is 

 yellow in this species ; reddish in muralis. Fruit characters 

 similar to the last. 



Grimmia apocarpa is a not unfrequent denizen of wall 

 tops, forming deep-green loose tufts. The upper leaves are 

 hair-pointed, with recurved margins. The capsules are 

 sessile among the surrounding (perichaetial) leaves. Lid 

 slightly beaked ; fringe of sixteen teeth, dark red, marked 

 with transverse bars, and sometimes perforated. 



Grimmia pulvinata is a very common species, growing on 

 walls, and often in great masses on thatched roofs, forming 

 round, hoary, cushion-like masses (fig. 19). The leaves are 

 densely crowded, and suddenly terminated by long white- 

 hair points. Fruit-stalk longish and bent downwards, so 

 that the capsule is often hidden among the leaves. The lid 

 has a straight beak \ the teeth of the fringe sixteen, deep 

 red and sometimes cloven at the tips. Calyptra mitriform, 

 five lobed at the base. 



Bryum capillare is very fond of old walls, and is very 

 frequent; often occurs in large dense dark-green masses. 

 The leaves are spreading when moist, but strongly twisted 

 when dry, somewhat oblong and abruptly hair-pointed. 

 Capsule somewhat pear-shaped, and pendulous ; lid conical, 

 with a minute point ; fringe double ; outer fringe reddish 



