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- 



FlG. 117. — Sporange of Polytrichunt commune, showing 

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

 removed ; C, with opercule removed (magnified). 



Fig. 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 Bryacese are further classified as under. 



Acrocarpi. — Fructification produced at the extremity of the branches. 

 Illustrative genera : — Weissia (Hedw.), Dicranum (Hedw.), Leucobr3aim 

 (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.). 



Fig. iig. — Peristome ot 

 A irichum undulaumt 

 (magnified). 



Fig. 120. — Peristome ot 

 Cinclzdium. stygitt7jt 

 (magnified). 



Literature (in addition to the papers already quoted). 



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



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



