OF WESTERN" PENXSYLVAXIA 109 



d. Slender small plants in dense cushions; central strand in 



stem; teeth decidedly cribrose. 2. G. conferta. 



d. More robust, loosely cespitose; no central strand; teeth slight- 

 ly cribrose. I. G. afocarpa. 

 e. Leaf-cells without sinuose walls: capsule oblong. 



(G. ambigua [Sullivant] 



Sullivant.) 



e. Leaf-cells with somewhat sinuose walls: capsule oblong-ovate. 



3. G. Pennsylvania. 

 f. Capsule distinctly ribbed; seta curved; leaf-margins of a single 



layer of cells. (G. olncyi Sullivant.) 



f. Capsule smooth, seta straight: upper leaf-margins of more than 



one layer of cells. g. 



g. Leaves lanceolate, tapering: basal leaf-cells thin-walled and elon- 

 gate-rectangular, about 1:4 to 1:8. alpine. (G. obtnsa Schwaeg- 



richen : G. doniana 

 Smith.) 



g. Leaves oblong-lanceolate, the long apex rough, piliferous; basal 

 leaf-cells more or less quadrate. 4. G. laevigata. 



1. Grimmia apocarpa [Linnaeus] Hedwig. 



( Plate XIV) 



Loosely cespitose, more or less erect, branching rather 

 freely, about 2 cm. high, dull olive-green, drying stiff and non- 

 crisped : leaves ovate-lanceolate, erecting-spreading, strongly 

 costate and usually more or less carinate, margin narrowly re- 

 curved, apex narrowly obtuse, leaves about 2 mm. long; 

 perichsetial leaves similar but somewhat longer and thinner; 

 costa ending in or just below the apex, terete dorsally ; basal 

 cells rectangular, about .008-.010X-015-.030 mm., upper 

 basal cells quadrate, and in our specimens usually sinuose- 

 \valled. the median and upper cells rounded and .005-.009 mm. 

 in diameter, all cells incrassate and more or less opaque: seta 

 erect, stout, about 0.5 mm. long; capsule immersed, oval- 

 oblong, about 1 mm. long, reddish-brown, rather thick-walled, 

 smooth ; calyptra short, lobed ; operculum low-conic, rostrate ; 

 peristome single, teeth 16, lance-linear, trabeculate, somewhat 

 cribrose. reddish-brown, faintly papillose, when dry reflexed- 

 revolute : spores reddish-brown, in our specimens about .012- 

 .018 mm. in diameter; columella falling away with the opercu- 

 lum and remaining attached to it; spores mature in late spring. 



On stones, hard earth, etc., with a wide distribution over 

 the colder regions of the earth. In America occurring from 

 Alaska and Newfoundland to the Northern States and south 

 in the mountains to Georgia. 



Fayette : Cheat Haven. September 3-6, 1910. O. 



E. T. and G. K. J. 



McKean : D. A. B. (Porters Catalogue). 



Washington : Linn and Simonton. (Porter's Cata- 

 logue). 



