104 THE MARINE BOTANIST. 



planata never dies during" the recess of the tide." 

 The fourth species, R. fruticulosa, by its diffuse 

 and spreading" habit, may easily be distinguished 

 from the foregoing", which are all erect in their 

 g-rowth. 



GENERA OF THE RHODOMELA TRIBE. 



OdontJialia. Frond flat, serrated with a faint mid- 

 rib. Colour very dark red. 



Mhodomela, Frond cylindrical, inarticulate, opaque. 



Bostrychia. Frond cylindrical, inarticulate, dotted. 



Bytiplilcea. Frond cylindrical, inarticulate, trans- 

 versely striate. 



Polysiphonia, Fronds thread-like, articulate, long-i- 

 tudinally striate. 



Dasya, Fronds cylindrical, with inarticulate stems 

 and spreading jointed ramuli. 



ODONTHALIA. 



Name, a tooth and a branchy in allusion to the toothed frond. 

 Frond plane, between membranaceous and carti- 



