TRICIIOSTOMET. 265 



tions, or variously cleft and perforated ; often differing from 

 each other in the same peristome. 



2. D. luridus, Hornsch. ; dioicous; leaves ovato-lanceolate, 

 erecto-patent, keeled, straight and erect when dry ; margin 

 reflexed ; nerve strong, ending at the apex ; sporangium ob- 

 long or cylindrical ; lid conico-acuminate ; ring narrow, per- 

 sistent, teeth irregular. Hook. Wils. t. xli. ; (Moug. fy Nest, 

 n. 818.) 



On moist ground and stones. Ireland, Yorkshire, Kent, 

 and Sussex. Bearing fruit from December to April. 



Dioicous. Stems short, slightly tufted ; leaf-cells above 

 minute, crowded, those of the disk below the middle quadrate 

 and translucent, the very lowest only slightly elongated and 

 rectangular ; teeth of peristome very irregular and tender, 

 often rudimentary, simple or bipartite, inserted below the 

 orifice, with scarcely any basal membrane. 



3. D. cylindricus, Br. fy Schimp. ; dioicous; tufted; leaves 

 long, spreading, linear, somewhat undulated, crisped when 

 dry, slightly toothed at the apex ; wings opaque ; sporangium 

 cylindrical ; lid subulate ; ring narrow ; teeth fugacious, va- 

 riable. Hook. $ Wils. t. xxxiii. ; (Moug. fy Nest. n. 1006.) 



On stones and rocks, seldom if ever in limestone districts. 

 Bearing fruit in October. 



Forming loose, short, soft, yellow-green tufts. Leaves brittle 

 above ; margin granulated ; leaf- cells dense and minute above, 

 very slowly increasing to the base, those at the basal wings 

 hyaline and larger. This species has much the appearance of 

 Tortula tortuosa, but the leaf-cells are different, without ad- 

 verting to the peristome. 



4. D. flexifolius, Hook, ty Tayl. ; dioicous ; erecto-patent ; 

 leaves flexuous, crisped when dry, oblong or lingulate, apicu- 

 late, coarsely toothed ; margin plane above, reflexed below ; 



