BAENES — NORTH AMERICAN MOSSES. 241 



PLAGIOTHECIUM, p. 362. ; 



I. Leaves complanate. 

 * Lid rostrate. 



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

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



* * Lid conic or convex. 



Capsule pendent or sub-pendent, seta arcuate . P. ele^ans, 366. 

 Capsule suberect, inclined or horizontal, often arcuate. 

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

 Smooth when dry. 

 Leaves serrulate, capsule sub-cylindric . P. SnlliTantiae, 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. denticalatniu,' 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. membranosum, 5I4. 

 Concave, point needle-like and recurved or pa- 

 tent P. acicnlaripun^ens, 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. 



•4— Capsule suberect, smooth when dry.^ 



Dioicous, cilia none, costa obsolete. 

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



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



1 See Appendix, nos. 512, 513. 



* P. pseudo-latebricola has an inclined capsule. 



