OF WESTERN PENNSYLVANIA 333 



c. Middle leaf-cells about 4-8:1; slender plants. 



1. B. cyrtophylhtm. 

 c. Middle leaf-cells about 9:1: rather robust. 2. B. acuminatiun. 



d. Capsules sub-erect, narrowly cylindric-oblong; usually more 



than 3:1. 3. B. oxycladon. 



d. Capsules cernuous, less than 3:1. e. 



e. Stem-leaves narrowed gradually from base to acuminate apex, 



non-plicate. 7. B. acutiun. 



e Stem-leaves ovate-lanceolate, more or less plicate. 



f. 

 f. Stem-leaves broad, about 1 mm. at base. 



5. B. salebrosum. 

 f. Stem-leaves narrow, about 0.5-0.6 mm. at base. 



6. B. fle.ricaule. 

 g. Seta rough only above. h. 



g. Seta rough throughout. j. 



h. Costa percurrent or very nearly so. 13. B. populeiim. 

 h. Costa ending about in middle of the leaf. 



i. 

 i. Leaves more or less plicate: cilia non-appendiculate. 



4. B. campestre. 



i. Leaves non-plicate: cilia appendiculate. 14. B. flagcllarc. 

 j. Cilia appendiculate. k 



j. Cilia non-appendiculate. I. 



k. Costa percurrent or sub-percurrent. 10. B. refle.rum. 



k. Costa distinctly incomplete. 11. B. starkii. 



1. Leaves very short-acuminate, non-decurrent. 



9. B. rivulare. 



I. Leaves gradually acuminate. m. 



m. Slender; leaves lanceolate, often secund. 12. B. velutinum. 

 m. Robust: leaves ovate to lance-ovate, not secund. 



8. B. nitabuluin. 



or 



1. Brachythecium cyrtophyllum Kindben 

 (Plate XLVIII) 



Cespitose, lustrous, dark green : stems irregularly branch- 

 ing to sub-pinnate, creeping, up to 4 to 6 cm. long; stem- 

 leaves lance-ovate, up to 1 or 1.5 mm. long; branch-leaves 

 similar but narrower and smaller, lance-ovate to ovate, acute 

 to short-acuminate. 0.6-0.8x0-3 mm., rather close, loosely ap- 

 pressed when dry, serrulate at least in the upper half, mar- 

 ginally reflexed at base, not plicate, not decurrent, when moist 

 more or less spreading: costa stout, reaching about two-thirds 

 the length of the leaf; median leaf-cells rhomboid-fusiform, 

 about 4-8:1, the alar sub-quadrate, numerous, sub-inflated, 

 somewhat chlorophyllose : perichsetial leaves ecostate, half- 

 sheathing : seta about 2-2.5 cm. long, dextrorse above, erect, 

 flexuous ; capsule erect, cylindric, sometimes slightly curved, 

 from 1.5 to 3 mm. long, castaneous, smooth; annulus none; 

 peristome-teeth slender, pale castaneous, confluent at base, 

 hyaline and papillose above, the dorsal lamellae closely cross- 

 striolate below, the trabeculse close and strong ; segments 

 nearly as long as the teeth, slender, pale yellowish, more or 

 less carinately split, the cilia rudimentary or none; basal 



