104 BRYACE^. [Didymodon. 



Var. pilifera, Muell. Apex of the leaves prolonged into a 

 flexuous hair. — Hryum piliferum, Dicks. PI. Cryjit. iv. 10. 

 Pottia pilifera, Linclb. Trichost. 223. 



Hab. Naked ground in alpine districts; Colorado (Downie, Wolf, 

 Rothrock); Uinta Mountains i Watson); British America, (Drummond). 



40. DIDYMODON, Hedw. (PL 2.) 



Plants repeatedly dichotomous, fastigiate, radiculose at base. 



Areolation of the leaves narrower than in the preceding genus, 



hyaline at base, chlorophyllose and densely papillose in the 



upper part. Flowers polygamous and dioecious, gemmiform. 



Calyptra long, cucullate. Teeth of the peristome plane, 



slender, linear-lanceolate, confluent at base, nearly entire or 



split either partly or sometimes their whole length, distantly 



articulate, punctulate, not papillose, often irregular. Auuulus 



distinct. 



Distinguished from Trichostomum by the peristome composed of a flat 

 double lamina, and by the softer and more papillose leaves. 



1. D. rubellus, Bruch & Schimp. Plants in reddish tufts, 



slender, about two cm. long: leaves erect at base, open, 



flexuous above, crispate when dry, the lower lanceolate, shorter, 



the upper linear-lanceolate, acuminate, half-clasping at base, 



the borders revolute above, minutely papillose on both faces ; 



costa narrow, percurrent ; perichaetial leaves with a longer 



clasping hyaline very thin base : capsule oblong-cylindrical, of 



thin texture, dusky green when filled ; lid short or long-rostrate, 



inclined ; teeth linear, more or less strongly articulate, entire or 



perforated along the divisural line, soft, pale red; annulus 



large, fragile. — Bryol. Eur. t. 185. Brymn rulellum, Hoffm. 



Weisia recurvirostris and curvirostris, Auct. Trichostomum 



ruhellum, Rabenh, ; Muell. Syn. i. 581 ; Lindb. Trichost. 226. 



Hab. On stones or on the ground, on or near the water; plains and 

 mountains ; not uncommon on both the eastern and western slopes. 



2. D. luridus, Hornsch. Dicecious: tufts green when 

 moist, dirty brown when dry, half to one cm. long, simple or 

 sparingly branching: leaves open when moistened, imbricate 

 when dry, the lower broadly ovate-lanceolate, the upper longer, 

 ovate at base, lanceolate above, blunt or acute, concave, with 

 borders reflexed and surface nearly smooth; costa stout, 



