THE ANTHOCEROTEJE 



141 



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

 pecuUarity being the more nearly equal diameter of the cover 

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

 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. 69, A). As 

 in A. fusifonnis, 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, and are 



Fig. 68. — Notothylas orbicularis (Sull.). Development of the antheridium. D, cross-section, the 

 others longitudinal sections; E, nearly ripe antheridium, X300, the other figures x6oo; f,. A, 

 the primary antheridial cells. 



larger than in Anthoceros. As in that genus, they are thrown 

 off when the archegonium opens. 



The youngest embryo found was composed of four cells, 

 and presented quite a different appearance from the corre- 

 sponding stage in Anthoceros. It is impossible from this stage 

 to tell whether the first wall in the embryo is vertical or trans- 

 verse. This embryo consisted of four nearly equal quadrants, 

 instead of having the two upper cells larger than the lower 

 ones. By comparison with the older stages there is little 

 doubt that here the first transverse wall separates the foot 

 from the capsule, as in SpJicerocarpus, and that the upper cell 



