BARNES — NORTH AMERICAN MOSSES. 249 



Plants small (usually less than 5 cm.). 

 Perichsetial leaves plicate. 

 Inner periclisetial leaves costate. 



Alar cells not distinct ^ H. fertile, 391. 



Alar cells large, hyaline . . . H. Waghornei, 665. 



Inner perichsetial leaves ecostate . . . H. hamulosnm, 391. 



Perichaetial leaves not plicate. 



Alar ceUs not enlarged . . . . H. snbimponens, 393. 



Alar cells quadrate or vesicular, enlarged. 



Leaves narrowly acuminate, faintly bicostate H. depressalnm, 391. 



Leaves long subulate, ecostate . . . H. circinale, 392. 



2. Plants irregularly branched, 

 [-H. callichroum maybe sought here.l 



* Leaves quite entire. 



Alar cells not different H. pscudoarcticnm, 5S4. 



Alar cells enlarged, oblong rectangular. 



Teeth hyaline margined, cilia appendiculate H. arcuatlforiue, 576. 



Teeth not hyaline margined, cilia nodose . . H. pratense,^ 397. 

 Alar cells quadrate. 



Plants erect, fastigiately branched . . . H. Bainbergeri, 397. 



Plants prostrate, irregularly pinnate . . H. IncnrTatum, 600. 



* * Leaves serrulate or denticulate above. 



[EC. pseudo-arcHcuTii and H. incwrvatum may be sought here.] 



Perichsetial leaves costate, and plicate or sulcate. 

 Costa geminate, reaching middle . . . . H. reptile, 390. 

 Costa geminate, short. 



Middle leaf cells long. (1 : 12-15) . . H, cupressiforme,» 394. 



Middle leaf cells shorter (1 : 6-8) . . . H. Vaucheri,* 570. 



Costa single, or wanting. 



Inner perichsetial leaves long subulate (1 : 12) . H. Moseri, 559. 



Inner perichaetial leaves lanceolate (1:5) . H. fastl^iatnni, 564. 



1 "BlattflUgelzellen aehr gross, aufgeblasen, wasserhell bis gold gelb," sec. Milde, Bry. 

 Siles. 359. Not according to Bryol. Eur. pi. 591, from which this character is taken. 



' See Appendix, no. 578. 



' See Appendix, no. 569. 



* The character of the perichsetial leaves is unknown to me, but since the species is 

 so closely related to H. cupressi/orTne, it is placed in this position. 



