OF WESTERN PENNSYLVANIA 181 



persistent; stem without central strand, mostly very short, 

 erect, thickly foliate to almost leafless: seta ranging from al- 

 most none up to 5-20 cm. long, erect ; capsule proportionally 

 large, sub-erect to inclined, often finally more or less horizontal, 

 dorsiventrally unsymmetric, flattened above, ovate to oblong 

 or ovate-conic, narrowed to a very small mouth ; annulate ; 

 peristome double or, apparently, single, the inner consisting of 

 a membraneous plaited cone with an apical opening, the teeth 

 originating from one to four concentric rows of cells, faintly 

 barred ; operculum conic, glabrous, smooth ; spores very small. 

 A very small and rather primitive family of mosses, grow- 

 ing on earth or decayed wood. Two genera, as follows : 



Key to the Genera. 

 a. Seta almost none; capsule immersed in the fringe of the perichattial 



leaves. 1. Dipliyscium. 



a. Seta 5-20 cm. long, thick, red or reddish-brown ; leaves none at 



the time of ripening. 2. Buxbaumia. 



1. DIPHYSCIUM [Ehrhart] Mohr. 

 (Webera Ehrhart, not Hedwig). 



Autoicous or dioicous : perennial, mostly low and densely 

 gregarious; protonema long-persisting; stem without central 

 strand, short, erect, radiculose, thickly-leaved, simple, rarely 

 longer and branched ; leaves twisted or crispate when dry, 

 spreading when moist, the lowe;- Ungulate or elongate-spatu- 

 late, obtuse or acuminate, entire ; costa strong, without guides, 

 ending below apex; lamina 2-(3-) stratose; leaf-cells on both 

 sides mamillate to smooth, rounded to 4-6 sided, incrassate, 

 often widened transversely, in the basal portion uni-stratose, 

 pellucid to hyaline, lax, elongate 4-6-sided with the transverse 

 walls incrassate, smooth ; perichsetial leaves much larger, erect, 

 membranaceous, elongate, lanceolate to linear, the apex usual- 

 ly fringed and the costa long aristate-excurrent : seta very 

 short, without central strand ; capsule immersed, obliquely 

 ovate-conic, gibbous, without collum, mouth very small; 

 annulus present; outer peristome rudimentary or none, when 

 present consisting of 16 triangular teeth ; inner peristome pale, 

 membranaceous, 16-plaited, papillose, short-conic; operculum 

 small, acute-conic, falling away attached to the upper part of 

 the fleshy columella ; calyptra very small, conic, glabrous. 



A genus of 10 species, only one in North America. 



1. Diphyscium foliosum [Weber] Mohr. 

 (Buxbaumia foliosa Weber; Webera sessilis Lindberg). 



(Plate XXV) 

 Small, widely cespitose, very short-stemmed (1-2 mm.), 

 the general appearance being that of a grain of wheat sitting 

 in a tuft of bristles: stem-leaves minute, the largest being 



