KEr TO THE GENERA. 133 



(f .) Stem branched and forked ; end of 

 branches beset with many short, stout, 

 oval or obtuse ramuli. Chylodadia. 



. Frond finer and more elaborately divided. 

 (a.) Stem robust, branches irregular ; ultimate 

 ramuli, clustered in bunches ; black. 



Rhodomela. 

 ((5.) Frond delicate, many times finely and 

 pinnately divided; color, brown or black. 

 Polysiphonia. 

 (r.) Frond delicate, finely piilnated, brilliant 

 pink. Callithamnion. 



