318 BRYACE^. [Hypnum. 



13. Rhynchostegium. Stems more or less compressed. Leaves 



nearly entire, simply costate, rarely shortly bicostate; areolation 

 rhomboidal, somewhat loose, enlarged at base. 



14. Thamnium. Plants large, dendroid; stem woody. Stem-leaves 



scarious; branch-leaves strongly dentate; cells minute, round- 

 oval, the basilar longer. Capsules clustered. 



C. Plants variously divided. Capsules cernuous, rarely suberect; oper- 

 culum conic or rostrate. 



* Leaves thin, glossy, open, erect or spreading. 



15. Plagiothecium. Branches few, mostly simple, complanate. 



Leaves slightly unsymmetrical at base; costa none, or double 

 and very short; areolation rhomboidal-elongated, little enlarged 

 at base. Capsule suberect; operculum conic or rostrate. 



16. Amblysteg'mm. Stem creeping and widely spreading. Leaves 



mostly entire, opaque or glossy; costa simple, rarely none; areo- 

 lation distinct, rhomboidal. Capsule cylindrical-oblong; Jid 

 conical. 



17. Carapylium. Stem irregularly divided with pinnate or fastigiate 



branches. Leaves spreading, subsquarrose ; costa short or none; 

 areolation minute, flexuous. 



* * Leaves falcate-secund, of solid membranous texture. 



18. Harpidium. Stems pinnately ramulose. Leaves simply costate 



to the apex; areolation very narrow, linear, much inflated at the 

 concave basilar angles. 



19. Cratoneurum. Stems prostrate; branches erect, rigid, villous, 



pinnate. Leaves simply and strongly costate; areolation dense, 

 linear, oblong at the enlarged base and decurrent angles. Cap- 

 sule cylindrical, cernuous. 



20. Rhytidium. Stems large, prostrate, irregularly pinnate with short 



subuncinate branchlets. Leaves secund and subfalcato, undu- 

 late-rugose; areolation compact, linear. Capsule cylindrical, 

 arcuate. 



21. Ctenium. Branches in compact tufts, pinnately ramulose. Leaves 



hamate and circinnate-secund. Capsule cylindrical. 



22. Ctenidium. Plants cespitose; branches erect, appressed, regularly 



pinnately ramulose. Leaves soft, circinnate-secund. Capsule 

 short, cernuous, solid. 



23. Hypnum, proper. Plants variously divided; branches more or less 



densely pinnately ramulose. Leaves obscurely bicostate, mem- 

 branous, shining; areolation compact, narrowly rhomboidal, 

 distinctly quadrate at the angles. Capsule oblong, erect-cer- 

 nuous. 



» * * Leaves more or less closely imbricate, round or oblong, obtuse or 



pointed, deeply concave. 



24. Limnobium. Plants prostrate, irregularly branching. Leaves 



slightly unequal at the clasping and decurrent base, simply cos- 

 tate or obscurely bicostate. Capsule short, turgid-ovate, cer- 

 nuous. 



25. Calliergon. Stem erect, with few terete turgid branches. Leaves 



very concave, membranous; areolation very compact, narrow, 

 enlarged-quadrate at the angles. Capsule oblong, horizontally 

 cm"ved. 



