V. 



MOSSES (MUSCI): SPHAGNALESANDREJEALES 181 



young embryo from the venter of the archegonium, this muci- 

 laginous mass adheres to it and forms a more or less complete 

 envelope about it, in which are often found the remains of 

 spermatozoids. 



The species of Sphagnum are either monoecious or dioecious, 

 but in no cases do archegonia and antheridia occur upon the 

 same branch. 



THE ANDREW ALES 



The second order of the Mosses includes only the small 

 genus Andrecea, rock-inhabiting Mosses of small size and dark 



A. 



FIG. 94. Andre&a petrophila. A, Plant with ripe sporogonium, Xio; B, median sec- 

 tion of nearly ripe capsule, X8o; ps, pseudopodium ; col, columella. 



brown or blackish colour. In structure they are intermediate 

 in several respects between the Sphagnales and the Bryales, 

 as has been shown by the researches of Kiihn (i), and Wald- 

 ner (2), to whom we owe our knowledge of the life-history of 

 Andrccea. They all grow in dense tufts upon silicious rocks, 



