OF WESTERN' PENNSYLVA\riA 153 



strongly appendiculate, slightly shorter than segments, basal 

 membrane one-half height of teeth; spores yellowish-pellncid, 

 smoothish or minutely roughened, about .014— .016 mm.; 

 exothecial cells incrassate, rectangularly quadrate or hexa- 

 gonal, the upper three or. four rows much smaller and rounded 

 to transversely elongate and darkly reddish-pellucid : gonio- 

 autoicous, — antheri-dia in apex of the lateral innovations : ma- 

 ture in May or June. 



In crevices of walls and sandstone rocks. Europe, Asia, 

 northern Africa, North America from Greenland to British Co- 

 lumbia and south to the northern United States. Rare in our 

 region. 



Allegheny : On debris in rock-crevices along sand- 



stone cliff facing the Alleghen}' River at 

 Power's Run, April 28, 1907. O. E. J. 

 (Figured). 



7. Bryum caespiticium [Linnseus] Hedwig. 



(Plate XX) 



Densely cespitose, yellowish-green : stems erect, rarely 

 more than 1 cm. high with us, branching by lateral innovations, 

 brownish-tomentose below, reddish above ; leaves remote and 

 small below, the upper densely tufted, ovate to lanceolate or 

 narrower within, concave, narrowly acuminate, borders re- 

 curved, the apex slightly denticulate or sometimes entire, the 

 base often reddish, the comal reaching 3-3.5X1 mm., when dry 

 but Httle shrunken or twisted ; cosfa strong, reddish, long-ex- 

 current; leaf-cells narrow-rhomboid, becoming larger and 

 rectangular at base, the marginal in one to three rows of linear- 

 prosenchymatous incrassate cells but not forming a very pro- 

 nounced border : set erect, slender, flexuous, lustrous-castane- 

 ou=, about 2-4 cm. long, rarely more ; capsule oblong-pyriform., 

 3-3.5 mm. long, yellowish-brown to darker with age, the neck 

 comprising almost one-half the capsule, horizontal, to pendu- 

 lous, sometimes unsymmetrically up-curved, constricted below 

 the mouth when dry and empty ; the mouth darker colored ; 

 peristome-teeth yelLowish-pellucid below, paler and minutely 

 papillose above, linearrlanceolate ; segments of inner peristome 

 almost as long, somewhat yellowish, carinately split and gap- 

 ing, cilia as long as segments or almost so, strongly appendicu- 

 late, basal membrane about two-fifths the height of teeth ; 

 spores about .012-.017 mm., smoothish, yellowish-pelkicid ; 

 exotheciaJ cells incrassate, rectangular below to irregularly 

 iiuadrate-hexagonal above, the upper three or four rows much 

 smaller and rounded-quadrate to laterally elongate and 

 colored; operculum, usually orange-brownish, mamillate to 

 conic-apiculate : dioicous: mature in Maj' to June or July. 



