OF WESTERN* PEXXSYLVAXIA 129 



spores large, papillose, mature in late autumn to early spring. 

 On moist earth, often in swamps, eastern Xorth America. 

 Occurs in Central Ohio and Eastern Pennsylvania and is. prob- 

 ably, the plant referred to as follows : 



Indiana : James. (Porter's Catalogue). 



2. ACAULON C. Mueller. 

 ( Sphaerangium Schimper). 



Dioicous : minute, bud-like, brown, gregarious : stem very 

 short and few-leaved, without central strand, unbranched, 

 green protonema persistent ; leaves erect-spreading, broadly 

 ovate, keeled or concave, above with revolute and sinuate- 

 denticulate margin, or plane and entire ; costa more or less ex- 

 current-cuspidate ; upper cells short-rhombic, below rhom- 

 boidal. dorsally strong thickened, smooth, rarely with a few 

 high papillae, the lowest thin-walled, hvaline and rectangular: 



C5 



seta very short : capsule sub-globose, cleistocarpous, immersed ; 

 calyptra very small and delicate, conic-mitriform 3-5-cleft ; 

 spores small, brown, subglobose, minutely granulose. 



A widely distributed genus, on soil, mostly in the temper- 

 ate zone. Fifteen species in all, 4 in Xorth America, 2 in our 

 region. 



Key to the Species. 



a. Uppermost and perichsetial leaves sharply carinate and with re- 

 flexed margins. i. A, triqiietnini. 

 a. Uppermost and perichjetial leaves concave: and with margins plane. 



2. A. ntfcscens. 



}. Acaulon triquetrum (Spruce) C. Mueller. 

 (Sphaerangium triquetrum Schimper) . 



Plants minute, about 1 mm. high, bulbiform. pale green 

 or yellowish, distinctly triquetrous; protonema green, persist- 

 ent; lower leaves small, rounded, the middle leaves larger, 

 broadly ovate, deeply concave, convolute, the upper largest 

 (perichaetial) broadly ovate, deeply carinate. triquetrous, all 

 upper leaves w r ith retiexed margins, erose-denticulate above ; 

 costa strong, in upper leaves excurrent in a recurved apiculus ; 

 basal leaf-cells elongate-hexagonal, lax, thin-walled, hexagonal 

 to oblong-hexagonal : seta about as long as capsule, arcuate ; 

 capsule globose, smooth ; calyptra minute, niitrate, cleft-lobed, 

 covering only very apex of capsule; spores papillose, about 

 .025-.030 mm., mature in early spring. 



On clayey or sandy soil in fields or on banks, Europe, 

 Algeria, and, in Xorth America, from western Canada to 

 Xew England south to the Carolinas ; occurs in Ohio and in 

 Pennsylvania but not yet reported from our range. 



