228 MOSSES AND FERNS ciiap. 



Bryales, and not through the cleistocarpous forms. These 

 latter would then all have to be considered as degraded forms 

 derived from a stegocarpous type, unless, with Leitgeb, we 

 consider them as a distinct line of development leading up to 

 the higher Bryales, entirely independent of the Sphagnaceae, 

 and with Archidium and Ephemerum as the simplest forms. 

 His comparison of these forms with Notothylas, however, can- 

 not be maintained with our present knowledge of that genus, 

 and more evidence is needed before his view can be accepted; 

 but the possibility of some such explanation of the cleistocarp- 

 ous Bryales must be borne in mind in trying to assign them 

 their place in the system. 



The objections to considering Buxbaumia a primitive type 

 have been already given, and it is not necessary to repeat them. 



