BARNES NORTH AMERICAN MOSSES. 241 



PLAGIOTHECIUM, p. 362. 



I. Leaves complanate. 



* Lid rostrate. 



Leaves transversely undulate, serrulate at the apex P. undnlatnm, 369. 

 Leaves not undulate, quite entire . . .P. sylvaticum, 368. 



* * Lid conic or convex. 



Capsule pendent or sub-pendent, seta arcuate . P. elegans, 366. 



Capsule suberect, inclined or horizontal, often arcuate. 

 Sulcate and constricted below the mouth when dry P. tnrfaceum, 366. 

 Smooth when dry. 



Leaves serrulate, capsule sub-cylindric . P. Sullivantise, 368. 

 Leaves quite entire. 



Capsule obovate, campanulate when dry P. Mnellerianum, 367. 

 Capsule oblong, constricted under the mouth when dry. 

 Costa bipartite, vanishing half way to the mid- 

 dle ...... P. denticnlatum, 1 367. 



Costa simple, short, or none . . . P. brevipungens, 515. 



II. Leaves equally spreading, straight. (Ill) 



* Alar cells abruptly enlarged. 



Leaves acute or short acuminate. 



Flat, point broad and straight ... P. membra nosum, 514. 

 Concave, point needle-like and recurved or pa- 

 tent . ... . . .P. aeicular ipungens, 516. 



Leaves filiform acuminate. 

 Cilia none . . . . . . . . P. pilifernm, 364. 



Cilia 2-3. 



Branches erect, leaves serrate ... P. Mnhlenbeckii, 370. 

 Branches intricate, leaves nearly entire . . P. Fitzgeraldi, 370. 



* * Alar cells scarcely different, quadrate or oblong, not abruptly 



enlarged. 



i- Capsule suberect, smooth when dry. 9 



Dioicous, cilia none, costa obsolete. 



Inner perichaetial leaves ovate lanceolate . P. latebricola, 363. 

 Inner perichaetial leaves abruptly acuminate . P. Passaicense, 363. 



1 See Appendix, nos. 512, 513. 



2 P. pseudo-latebricola has an inclined capsule. 



