22 



MOSSES AND FERNS 



dichotomous, and as this is rapidly repeated, it often causes the 

 thallus to assume an orbicular outline. Some forms, however, 



Fig. 1. — Marchantiales. A, B, Male plants of Fimbriaria Californica. A, from above; 

 B, from below; ^, antheridial receptacle; /, ventral lamellae, X4; C, Riccia glauca, 

 X6; sp, sporogonia; D, Conocephalus conicus, X4; E, Targionia hypophylla, X2; 

 ^1 antheridial branch. 



e.g., Targionia (Fig. i, E), may fork comparatively seldom, 

 and the new branches are for the most part lateral. The thallus 



