MOSSES AND LIVERWORTS 75 



borne in a drooping fashion. The leaves of 

 this moss are decidedly large and are lance- 

 shaped. Growing amongst rocks we shall find 

 certain of the small Fringe Mosses [Grimmia). 

 Some of these species grow in dense cushions, 

 and one [G. pulvinata) is readily distinguished 

 by the circumstance that when young the 

 fruit stalks are arched in such a way that 

 the spore cases touch the leaves. The Screw 

 Mosses {Tortula) are also common on rocks and 

 walls. One, the Wall Screw Moss [T. muralis), 

 is almost certain to be found in such places, 

 and its little cushions look quite downy by 

 reason of the hairy points on the leaves. The 

 spore cases are long and narrow and the 

 curious teeth-like processes at the mouth of 

 the case are spirally coiled. As the weather 

 becomes quite dry, the teeth uncoil to an 

 extent, and thus allow the spores to escape. 

 The Apple Mosses {Bartrammia) grow upon 

 dry banks, walls, or rocks. These are chiefly 

 found in more or less mountainous districts, 

 though some of the kinds have a wide distri- 

 bution. The young spore cases are rounded, 

 and, being a bright green colour in the spring, 

 bear a resemblance to miniature apples. 



