260 HANDBOOK OF BRITISH MOSSES. 



On walls, especially in calcareous districts, chalk pits, etc. 

 Bearing fruit in winter. 



Very like the last two, but distinct in the form of the spo- 

 rangium, which is half covered by the veil, which in those 

 species is much shorter. 



82. TRICHOSTOMTJM, Br. fy Schimp. 



Sporangium erect or more rarely curved; veil cucullate, 

 smooth ; peristome single, of thirty-two more or less perfect, 

 straight teeth, disposed in pairs, composed of a single series of 

 elongated cells, sometimes so united or perforated as to look 

 like sixteen, connected by a narrow basal membrane ; leaf- 

 cells punctiform above, minutely papillose, rectangular and 

 hyaline below. Perennial, terrestrial Mosses, with the habit of 

 Tortula. 



1. T. rigidulum, Smith; tufted; leaves spreading and re- 

 curved, elongato-lanceolate, keeled ; margin recurved ; nerve 

 subexcurrent ; sporangium subcylindrical ; ring narrow ; teeth 

 in pairs or free, sometimes connected by transverse bars. — 

 Hook. # Wils. t. xx.; Eng. Bot. t. 2178.; (Moug. # Nest. n. 

 612.) 



On moist rocks or upon dry, exposed, calcareous walls. 

 Bearing fruit in autumn and winter. 



Loosely tufted. Stem straight, about an inch high, of a 

 brownish or dull green; leaf-cells distinct, punctiform; lid 

 obliquely rostrate. When growing on dry walls it is shorter, 

 the sporangium more elliptic, and the lid longer. 



2. T. tophaceum, Brid. ; stem branched, elongated ; leaves 

 spreading from an erect base, lanceolate, obtuse ; nerve ceasing 

 below the tip, keeled, concave; sporangium oblong, subcylin- 

 drical ; ring none ; lid obliquely rostrate ; teeth irregular, in 

 pairs.— Hook. 1$ Wils. t. xx. ; Eng. Bot. t. 1598, 1707, 2295. 



