MUSCI 



149 



In most Bryaceae the tissue of the leaf is nearly homogeneous, with the 

 exception of the margin and an elementary midrib composed of elongated 

 prosenchymatous cells; but in Leucobryum (Hpe.) the small chloro- 





FIG. 117. Sporange of Polytrichum commune, showing 

 epiphragra. A, covered by calypter ; B, with calypter 

 removed ; C, with opercule removed (magnified). 



FtG. 118. Sporange of Hypnum 

 populeum, showing peristome 

 (magnified). 



phyllous cells interlace among large empty cells with circular orifices in 

 their walls, as in Sphagnum. 



The very numerous genera of Bryaceae are further classified as under. 



Acrocarpi. Fructification produced at the extremity of the branches. 

 Illustrative genera : Weissia (Hedw.), Dicranum (Hedw.), Leucobryum 

 (Hpe.), Pottia (Ehrh.), Tortula 

 (Hedw.), Bartramia (Hedw.), 

 Encalypta (Schreb.), Fissidens 

 (Hedw.), Grimmia (Ehrh.), Or- 

 thotrichum (Hedw.), Zygodon 

 (H. & T.), Tetraphis (Hedw.), 

 Buxbaumia (Hall.), Polytri- 

 chum (Dill.), Aulacomnion 

 (Schw.), Bryum (H. & T.), 

 Mnium (B. S.), Funaria 

 (Schreb.), Splachnum (B. & S.), Tayloria (Hook.), Barbula (Hedw.), 

 Ceratodon (Brid.). 



Pleurocarpi. Fructification lateral, not at the extremity of the prin- 

 cipal branches. Illustrative genera : Hedwigia (Ehrh.), Fontinalis (L.), 

 Hookeria (Sm.), Hypnum (Dill), Leucodon (Schw.), Neckera (Hedw.). 



LITERATURE (in addition to the papers already quoted). 



Philibert (Peristome) Rev. Bryol., 1884-1888. 



Vaizey (Polytrichacese) Journ. Linn. Soc., xxiv. (1888), p. 162. 



FIG. 119. Peristome ot 

 A irichum undulalum 

 (magnified). 



FIG. 120. Peristome of 

 Cinclidium stygium 

 (magnified). 



