CLASSIFICATION. 



parenchymatous, quadrate-hexagonal, papillose, and chloro- 

 phyllose above (i.e. filled with green granules), and transparent 

 at the base ; capsule erect, oval, or cylindrical ; peristome of 

 usually sixteen flat membranous teeth, sometimes simple 

 and rudimentary, mostly 

 split to the base into 

 thirty-two thread-like, ob- 

 scurely jointed segments ; 

 in some of the genera the 

 peristome is absent. 



This is an important 

 tribe, comprising Pottia, 

 Trichostomum, Barbula 

 (fig. 32), etc. 



Tribe IV. Grimmiece. 

 Plants tufted, or growing 

 in cushion-like masses ; 

 leaves short, solid, often 

 tapering to a point, with 

 hair-like tips ; cells dense, 

 obscure, dot-like, minutely 

 round- quadrate, and filled 

 with green granules above ; 

 capsule on a straight or 

 curved fruit-stalk ; teeth, 

 sixteen, with transverse 

 markings, cleft or pierced, 

 rarely absent ; calyptra 

 generally lobed at the 

 base, or split on one side 

 (dimidiate). 



This comprises the ge- 

 nera Grimmia (fig. 19) 

 and Racomitrium (fig. 33). 



Tribe V. Orthotrichea. Plants tufted ; leaves of close 

 texture; calyptra lobed at the base, mostly plaited, often 

 hairy ; peristome of eight or sixteen flat, short, lance-shaped 

 outer teeth, and eight or sixteen simple, thread-like inner 

 teeth. 



FIG. 33. Racomitriutn canescens. T, 

 fruit ; a, peristome ; b, capsule. 2, subu- 

 late operculum or lid. 3, mitriforme 

 calyptra, which is lobed at the base. 4, 

 papillose leaf ; 4 a, section of same to show 

 revolute margins. 



