150 



MOSSES AND FERNS 



CHAP. 



The full-grown antheridium is more flattened than in either 

 species of Anthoceros examined by me, and the stalk shorter 

 and thicker, but otherwise closely resembles it, although the 

 extremely symmetrical arrangement of the cells, especially of 

 the wall, is much less noticeable. 



The archegonia correspond very closely, both in position 

 and structure, with those of the other genera, the most marked 

 peculiarity being the more nearly equal diameter of the cover 

 cell and central cell, and a corresponding increase in the breadth 



Fig. 8i. — Notothylas orbicularis. Development of the archegonium, X6oo; x, 



the apical cell. 



of the neck canal cell. Subsequently the central cell becomes 

 much enlarged and the appearance of the fully-developed arche- 

 gonium is very much like that of Anthoceros (Fig. 8i, A). 

 As in A. fusiformis, the usual number of neck canal cells seems 

 to be four, and in no case did the number exceed five. The 

 cover cells were four in number in all the archegonia studied, 



