OF WESTERN PENNSYLVANIA 307 



similar to stem-leaves but smaller and narrower, strongly 

 falcate to circinate-secund ; inner perichsetial leaves lance- 

 acuminate, plicate, faintly bi-costate, serrulate above ; median 

 leaf-cells linear- vermicular, about 1 : 15-20, rather incrassate, 

 sub-acute, median basal cells strongly incrassate, castaneous- 

 pellucid, porose, the alar portion with several oblong inflated 

 hyaline cells, above which is a patch of about 9-15 smaller, in- 

 crassate, quadrate to oblong-hexagonal cells often njore or less 

 castaneous-pellucid : seta 1.5-2.0 cm. long, dextrorse, castane- 

 ous, lustrous; capsule about 1.8 mm. long, oblong, inclined to 

 horizontal, arcuate, bright castaneous with a darker and 

 lustrous rim, when dry narrowed below the mouth and sub- 

 costate or smooth ; lid short, conic-acute ; peristome-teeth 

 lance-subulate, brownish-pellucid, more or less narrowly hya- 

 line-margined, dorsally cross-striolate below, the divistu-al line 

 and the lamellae fairly distinct, above hyaline and papillose, the 

 trabeculae numerous and strong; segments pale, about as long 

 as the teeth, carinately split between the articulations, the 

 basal membrane about two-fifths as high, the cilia usuall}' 2, 

 hyaline, nodose, somewhat shorter than the segments ; exothe- 

 cial cells rather thin-walled, quadrate-hexagonal to oblong- 

 hexagonal, at the mouth smaller and deeply castaneous ; 

 spores medium-walled, somewhat brownish, smooth or very 

 nearly so, about .015-.018 mm., mature in late summer. 



On decaying logs in moist and cool places, usually in hilly 

 or mountainous regions ; Europe, Asia, and, in North America, 

 from New Brunswick to British Columbia and southwards to 

 the northern United States. Rare in our region, and probably 

 only to be found in the northern portion. 



McKean : Leer's Run on decaying log, August 5, 



1895 (Figured), Langmade Hollow, Au- 

 £?ust 11, 1895, Gates' Hollow, October 27, 

 1895, and Bennett Brook, August 8, 1897. 

 D. A. B. 



3. Stereodon imponens (Hedwig) I.indberg. 



(Hypnum imponens Hedwig; H. cupressiformc Hooker). 



(Plate XLV) 



Robust in flat, thin, widely interwoven tufts of a yellow- 

 green color: stems rigid, reddish-brown, with numerous 

 paraphyllia, closely, rather regularly and more or less com- 

 planately pinnate, prostrate or sub-erect, sometimes reaching 

 more than 10 cm. in length ; stem-leaves usually somewhat 

 complanate-secund, from a triangular-oblong base gradually 

 long-acuminate, the base not excavate, scarcely decurrent, the 

 acumen strongly falcate-secund, the whole leaf about 2x0.5-0.7 

 mm., serrulate above, the margin often narrowly recurved 



