VII THE BRYINEJL 215 



form, the ends of the crescent pointini^ up, and united with the 

 adjacent end of the bundle next it. The tops of the teeth thus 

 formed are connected by a layer of cells stretching across the 

 opening like the head of a drum. This membrane is known 

 technically as the " Epiphragm " (Fig. 1 06, C). 



The BuxbauniiacecB 



The last group of Mosses to be considered is the very 

 peculiar one of the Buxbaumiaceai. In these Mosses the 

 gametophyte is extraordinarily reduced, although the sporo- 

 gonium is large and well developed. So simple is the sexual 

 plant, that Goebel ^ has concluded that these ought to be taken 

 away from the rest of the Mosses, and removed to a distinct 

 order. According to Goebel's account, the antheridia, which 

 are long stalked, are borne directly upon the protonema, and 

 subtended by a single colourless bract. The female branches 

 are also very rudimentary, but less so than the male. On the 

 strength of the extreme simplicity of these, Goebel thinks 

 that Biixbauniia is a primitive form allied to some alga-like 

 progenitor of the Mosses. There are, however, two very strong 

 objections to this. First the sporogonium, which is extremely 

 large, and complicated in structure, and essentially like that of 

 the other stegocarpous Mosses ; secondly, Bnxbauniia has been 

 shown by Haberlandt " to be distinctly suprophytic in its habits, 

 and the extreme reduction of the assimilative tissue of the 

 gametophyte is quite readily explicable from this cause. 



Fossil MuscinecB 



The remains of Muscineae in a fossil condition are exceed- 

 ingly scanty ; so much so indeed as to practically throw no light 

 upon the question of their origin and affinities, as nearly all of 

 the forms discovered belong to the later formations, and are 

 either indentical with living species or closely allied forms. 

 No doubt the great delicacy of the tissues of most of them, 

 especially the Hepaticae, accounts in great measure for their 

 absence from the earlier geological formations. 



1 Goebel (16). - Haberlandt (4), p. 4S0. 



