156 THE MARINE BOTANIST. 



when once dried they preserve their rich tints 

 unaltered for a length of time. The genus Nito- 

 phyllum is distinguished from Delesseria by its 

 being without a midrib, which is usually very dis- 

 tinct in the latter. Plocamium coccineum, a well 

 known feathery plant, common on our shores, and 

 found in all cool waters extending, according to 

 Dr. Harvey, within some 34° of the line in both 

 hemispheres, is the only British filiform species of 

 the tribe ; other species of the genus Plocamium are 

 natives chiefly of the shores of South Africa, and 

 New Holland. 



GENERA OF THE DELESSERIA TRIBE. 



Delesseria. Frond leaf-like of definite form, with 



a midrib running through it. 

 Nitophyllum. Frond without a midrib, delicate, 



expanded ; sometimes marked with vague veins. 

 Plocamium. Frond linear, or filiform; much 



branched; distichous. Ramuli secund. 



