OF WESTERN PENNSYLVANIA 323 



McKean : On sandstone rocks, Rutherford Rocks, 



altitude 2000 feet, July 7, 1894, Divide be- 

 tween Hawkins and Rutherford Hollows, 

 April 25, 1893, and March 12, 1894, and 

 Langmade, May 9, 1896. (Figured). All 

 near Bradford. D. A. B. 



Lawrence : Slippery Rock Creek, 1906. Miss Susan 



Gageby. 



2. Plagiothecium roeseanum (Hampe, mss.) Bryologia 

 Europaea. 



{Hypnnm sullivanUae Schimper; H. roeseanum 'Ha.xn'ps.). 



Compactly cespitose, pale green to yellowish-green, shin- 

 ing: stems more or less erect, sparsely branched, radiculose at 

 base; leaves crowded, sub-imbricate, ovate-oblong, abruptly 

 and shortly filiform-acuminate, serrulate towards the apex; 

 thin, concave, glossy, the leaves hardly complanate but the 

 branches appearing julaceous; costa bifid, rather long and 

 strong; median leaf-cells narrowly linear, about 15 :1, the basal 

 scarcely different, a little broader and shorter ; perichsetial 

 leaves erect, the inner oblong, narrowly acuminate: capsule 

 cylindric-oblong, erect to sub-inclined, smooth when dry, con- 

 stricted at the neck ; lid conic, obliquely short-rostrate ; annulus 

 large, simple : peristome hypnoid, the 2 cilia strong and about 

 as long as the entire segments ; spores mature in summer. 



On stones and earth in moist or swampy woods ; Europe, 

 Asia, and from Nova Scotia to Alaska and south to Florida. 

 Not yet found in our region. 



3. Plagiothecium sylvaticum [Hudson] Bryologia Europsea. 

 {Hypnnm sUvaticuin Hudson; H. denticulatum C. Mueller). 

 (Plate XLVII) 

 Both this and P. roeseanum are perhaps but varieties of P. 

 denticulatum, but until better known should probably be kept 

 apart as separate species. Tufts large, dull or but slightly 

 glossy, deep olive-green to yellowish-green ; stems prostrate, 

 stoloniferous ; leaves rather soft, large, concave about 2-3 

 mm. long, not very regularly complanate, widely spreading, 

 shrinking and somewhat twisted when dry, broadly ovate- 

 lanceolate, narrowed considerably towards the decurrent base, 

 tapering abruptly to the acute, entire or obsoletely denticulate 

 apex, plane-margined ; costa rather faint, double, often reach- 

 ing one-third the length of the leaf; median leaf-cells about 

 8-10:1, about .016 mm. wide, large, hexagonal-rhomboid, the 

 alar cells numerous and quadrate-oblong, sub-inflated, hyaline 

 and decurrent ; perichastia bearing rhizoids at base, about 3 mm. 

 high, the leaves sheathing with a flexuous acumen, non- 

 costate ; seta castaneous, slender, about 2—4 cm. long, dextrorse 



