;54 



MUSCI. 



which overlap at the ends are jtnrcnchymatous. Their outer surface niaj' be smooth or produced 

 into siniph; or forked papilhe. These cliaracteristies of h-af-structure are largely relied upon in 

 the definition of tlie, trilics, as well a.s freiiueiitly of genera and species. The syM.iuatic arrange- 

 ment of tlie nuissis is slill to ^sonle exteul unsettled. 'I'he lunits of genera vary vt ry nuuth witli 

 dilferent authorities, and the principh's which govern tlieir disposition vary as wid.ly. In tlie 

 following urrungenient, while lulopting esicntially the method dcveloiied by Scliiiiiper most fully 

 in the second edition of his Synopsis iMuscoruin Europa^orum, his groupings are niodilied by a con- 

 solidation of some of the tribes, while less prominence is given to the numerous minor divisions 

 jiropo.sed by him. Under the last tribe Hiipuctx it has .seemed advisable to deviate fre(|uently 

 from his order. It has not been found always easy to express clearly and definitely the distinc- 

 tions which determine the several tribes and genera, but it is hoped tliat the key w-ill in most 

 cases serve satisfactorily its intended purpose. The descriptions of the genera and species are 

 drawn almost wholly from published works, and are intended only as a temporary aid to the study 

 of the western species pending the publication of the more critical and authoritative Manual of 

 North American Mosses, by Messrs. Leo Les(iuereux and Thomas P. James, which is now in 

 course of preparation. Acknowledgments are due to ilr. James for assistance in questionable 

 cases of synonymy, range, etc. 



I. Capsule without operculum, dehiscing irregularly. Fruit terminal on the main stem. 



Tribe I. PHASCE^^E. Minute terrestrial plants, stemless and bud-like or with a short mostly 

 simple stem. Capsule rarely e.xserted, globose to ovate-oblong. Flowers monoecious or 

 sometimes bisexual. 



* Prothallus filamentose, persistent : leaves coarsely serrate or incised, the areolation loose and 



uniform : columella none. 



1. Ephemerum. Very minute, annual. Calyptia campanulate. Capsule glolio-^e-ovate, api- 



culate, siibsessile. 



♦ • Prothallus not persistent : leaves entire or nearly .so, the areolation narrower toward the 



apex : ci)liimella present. 

 +- Leaves broadly lanceolate, crowded, more or less jiapillose. 



2. Sphaerangium. Acaulescent, bud-like, with deeply concave subscarious If.ives. Capsule 



globose, not apiculate, immersed. Calyptia mitrilbrin. 



3. Phascum. Stouter, more caulescent. Leaves broadly lanceolate. Capsule subglobose to 



ovate-oblong, apiculate. Calyptra cucullate. 

 4- +- Leaves narrowly lanceolate, the lower remote, not papillose, shining : stem at length 

 branching below the summit. 



4. Pleuridium. Capsule ovate-globo.se, without collum, apiculate, .shortly pedicellate. Calyp- 



tra cucullate. Male flowers axillary or hypogynous. 



5. Bruchia. Capsule ovate-oblong, with large thick collum, rostellate, exserted. Calyjitra 



mitriform. Male flowers terminal, bud-like. 



II. Capsule dehiscing by a deciduous opercuhim. Fruit terminal on the main stem or rarely 

 on short lateral branches. 



Tribe II. POTTIE.E. Caulescent perennials (or annuals in Pottia), with the areolation 

 round-hexagonal above, mostly looser and hyaline and more rectangular at the base of the 

 leaves. Flowers bud-like. Calyptra cucullate (mitriform in a species of /W//*/), long- 

 beaked. Capsule without collum, erect or nodding, on an exserted pedicel. Peristome 

 simple, of 1(J teeth, entire or bifid or more or less completely divided, sometimes iiii))ei I'ectly 

 developed or wanting. 



* Leaves alternate, in several ranks. 



-f- Peristome none (except in a species of Pidtia) : capsule subglobose to oblong : operculum 

 obli(piely rostrate or obtuse. 



6. Gymnostomum. Low perennials, on rocks. Leaves lanceolate or linear-lanceolate, of 



close linn texture, creiiulate or subserrate. Capsule long-pedicellate, and conic opercu- 

 lum long-rostrate. 



7. Pottia. Very small terrestrial annuals or biennials. Leaves soft, oblong or oblong-obovate, 



rarely senate. Capsule immersed or exserted, and the plano-convex ot conic operculum 

 more or less rostrate or obtuse. 

 +■ +- Peiistome-teeth entire or bifid at the apex or unequally cleft to or below the middle : cap- 

 sule more or less oblong or cylindrical, long-pedicellate : leaves lanceolate. 



8. "Weissia. Teeth entire or bifid at the apex only. Capsule oval or oblong, erect. Leaves 



entire, involute ami crisped when dry. 



9. Dicranum. Teeth unequally cleft to the middle. Capsule nodding or erect, often incurved. 



Leaves frequently sen-ate toward the apex, often large. 



