100 . BRITISH MOSSES: 



Plate XIII. 



TRICHOSTOMB^. Part III. 



T O R T U L A. 



Fig. 1. Generic Charactee. 



Much resembling Trichosiomum, but the stems are generally shorter, and the 

 leaves proportionately large. The chief characteristic of the genus is the peris- 

 tome. This is single, composed of thirty-two teeth, bright red, twisted round each 

 other (ft) , whence the name of the genus, Tortula or Screw Moss. The capsule 

 (b) is cylindrical, and furrowed lengthwise. 



The Screw Mosses are among the most abundantly distributed of all the 

 species ; they may be found upon almost every wall, and hardy and brave, they 

 venture nearer to the smote of London than any other. No Mosses add more to 

 the beauty of our every-day sights. Their round green and grey cushions, with 

 red " clumps of spears"* rising from them, shining in. the sun, glisteniag in the 

 rain, fill the same home-place among Mosses as daisies do among flowers, and 

 robins among birds. 



I. Leaves rigid, covered on the upper side with filaments rising from 

 the nerve ; nerve broad. 



Fig. 2. Tortula rigida. 



Rigid Screw Moss (a) . 

 Colour. Yellow green. 



Stems. Short. 



Leaves (6) . Oblong, margin reflexed. 



Flowers and Fruit. Dioicous. Capsule elliptic, erect; peristome very much 



twisted; calyptra half covering the capsule. Winter. 



Locality. On walls, in limestone and chalk, 



* " Could call up Ai'thur and his peers 



By some low moss's clump of spears." — Lowell. 



