SYNOPSIS OP BEITISH MOSSES. 27 



double, outer a filmy, narrow, whitisli ring, quite 

 rudimentary, internal an elongate, conical, 16-plicate 

 membrane. 



Tribe xxii. PolttrichacEjB. 



PI. firm, more or less rigid, varying in size. L. solid, 

 areolae thick and dense, tbe nerve often forming the 

 greater portion, lamellate on upper surface. Calyptra 

 narrow, cucuUate, spinulose at apex, rarely smooth, 

 generally covered with long hairs. Caps, on an 

 upright or cernuous seta, round or angular, more or 

 less elongate. Perist. single, rarely absent, generally 

 of very short Ungulate teeth, rarely prolonged into 

 cilia. 



Fam. 1. Polytriohss. 



Perist. of 16, 32, or 64 shortly Ungulate teeth, united 

 below by a membranous tympanum covering the mouth 

 of the capsule. 



82. Oligotriehum, De Oand. St. simple, with sub- 

 terraneous stolons. L. very concave, scarcely undulate, 

 elongate and linear-lanceolate, margin incurved, almost 

 tubulose at apex, remotely serrate, nerve terete and 

 naked below, dilated and lamellate above. Caps, erect, 

 ovate-oblong, rounded. Calyptra large, with a few 

 upright hairs". Perist. of 32 short, rigid, obtuse teeth. 



83. Atrichum, P. Beauv. PI. gregarious or csespi- 

 tose. L. Ungulate, scarcely sheathing, more or less 

 undulate, crisped when dry, margin acutely serrate, 

 nerve narrow, slightly lamellate. Caps, oval or cylin- 

 dric, cernuous, straight or slightly arcuate, lid hemi- 

 spherical, with a long slender beak. Perist. as in last. 

 Calyptra narrow, spinulose at apex only. 



84. Pogonatum, P. Beauv. St. short and simple, or 



