KEY TO THE GENERA. 120 



5. Frond consisting of visibly articulated, or 

 jointed filaments. 

 Slender or robust, branching or forking; 

 filaments showing alternately white and 

 red, or light and dark bands. -^ 



Ceramium.- ^ 



6. Frond stiff, wiry, black. 1 

 Intricately and irregularly branched, some- 

 times bleached white. Ahnfeltia. 



7. Frond sto7iy and hard. 



Purple to white. Corallina. 



IV. Frond capillary. 



(Composed of a single series of cells 

 placed end to end). 



1. Cells long. 



Frond divided by regular, narrow forkings, 

 fan-shaped, level topped; color pale, 

 delicate pink. Griffithsia. 



2. Cells short. 



Plants mosdy small, often shaped like 

 a miniature shrub; much branched, 

 final divisions as fine as cobweb; color • 

 brilliant red or i)ink, the most beautifuM, 

 of plants. Callithamnion, 



"^©^^ 



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