OF WESTERN PENNSYLVANIA 333 



c. Middle leaf-cells about 4-8 ^l; slender plants. 



1. B. cyrtophyllum. 

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



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



than 3:1. 3. B. oxydadon. 



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



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



non-plicate. 7. B. acutum. 



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



f. 

 f. Stem-leaves broad, a/bout 1 mm. at base. 



5. B. salebrosmn: 

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



6. B. flexkaule. 

 g. Seta rough only above. h. 



,^. Seta rough throughout. j. 



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

 h. Costa ending about in middle of the leaf. 



i. 

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



4. B. campestre. 

 !. Leaves non-plicate: cilia appendiculate. 14. B. flagellare. 

 j. Cilia appendiculate. k 



j. Cilia non-appendiculate. 1. 



k. Costa percurrent or sub-percurrent. 10. B. reflexum. 



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



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



9. B. rivulare. 

 1. Leaves gradually acuminate. m. 



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

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



8. B. rutabulum. 



I. Brachythecium cyrtopfiyllum Kindberg. 



(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 

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

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

 somewhat chlorophyllose ; perichastial 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 



