RHODOPHYCE^E, OR FLORIDE.E 233 



the cortical layers, and the fruit cavity is of similar 

 character to that of the Delesscriecc. The gonimo- 

 blast is a copiously branching tuft of filaments 

 of which the terminal cells bear large club-shaped 

 carpospores. 



Bonnemaisonia asparagoides is the only British 

 form. Asparagopsis Delilei occurs in the warm North 

 Atlantic ; and of the other noteworthy genera 

 Ptilonia and Delisea occur in southern seas. 



Rhodomelece. 



This is one of the most natural and best defined 

 families of Rhodophycece, not only from its repro- 

 ductive characters but to a considerable extent its 

 vegetative structure as well. The thallus in most 

 cases consists of tiers of cells in series, a central 

 one with smaller pericentral cells of the same length 

 grouped round it. Branching, commonly of a mono- 

 podial type, occurs, and the whole shoot is clothed 

 more or less with fine hair-leaves if they may be so 

 termed. Both antheridia and procarpia are formed 

 on these hair-leaves, and are in the great majority of 

 cases stalked. The cystocarps are therefore rarely 

 sessile. In Polysiphonia, which may be taken as 

 fairly typical of the rest of the family, the carpo- 

 gonial branch is four or five-celled. The lowest 

 of these cells becomes the auxiliary cell and the 

 carpogonial branch so bends round that the car- 

 pogonium itself touches the auxiliary cell (Fig. 

 77). The other joint-cells adjoining the one 

 which gave origin to the carpogonial branch 



