TRICHOSTOMEI. 261 



On calcareous or gritty, moist rocks. Bearing fruit in 

 winter and early spring. 



Stems of a dull deep-green ; leaves rather twisted when 

 dry ; teeth as in the last, very variable, sometimes reduced to 

 sixteen, in both springing from a narrow basal membrane ; 

 nerve always shorter. 



3. T. mutataile, Bruch; leaves spreading, crisped when 

 dry, lanceolate, acute; margin plane, slightly undulated; 

 nerve excurrent, forming a short point; sporangium ovate; 

 lid rostrate ; teeth very short. — Hook, fy Wils. t. xli. ; Eng. 

 Bot. t. 2735. 



In crevices of rocks and on the ground in calcareous dis- 

 tricts, mostly near the sea. Wales, Ireland, and Sussex. 

 Bearing fruit in summer. 



Stems short, bright-green ; leaf-cells dense and punctiform 

 above, then exactly quadrate, rectangular and hyaline at the 

 base; teeth unequal from a narrow membrane, very fuga- 

 cious. 



4. T. crispulum, Bruch ; leaves spreading, crisped when dry, 

 lanceolate or linear-lanceolate, concave and almost cucullate 

 at the tip ; nerve excurrent, forming a short point ; sporangium 

 oval ; lid obliquely rostrate ; ring none ; teeth in unequal pairs. 

 —Hook, if Wils. t. xli. ; Eng. Bot. t. 2734. 



On limestone rocks and banks near the sea. Bearing fruit 

 in summer. 



Forming dense, flat, yellow patches. Leaf-cells very minute 

 and crowded above, larger in the narrow-leaved variety (Moug. 

 if Nest. n. 915) ; teeth of peristome much longer than in the 

 last species. 



5. T.convolutum, Brid.; pulvinato-csespitose; leaves spread- 

 ing, twisted when dry, oval-oblong, apiculate; nerve strong, 

 thickened above and slightly excurrent; margin revolute; 



