372 THE MICKOSCOPIST. 



4 4. RytiphlcBa. Frond cylindric, inarticulate, trans- 

 versely striate. Tetraspores in podlike receptacles. 



5. Polysiphonia. Frond cylindric, articulate in whole 

 or in part, the branches longitudinally striate. Tetraspores 

 in distorted ramuli. 



6. Dasya. Frond cylindric, the stem inarticulate, ra- 

 muli articulate, composed of a single string of cells. Te- 

 traspores in podlike receptacles (stichidia) borne by the 

 ramuli. 



2. LAURENCIACE^. Frond cellular, continuous. Cera- 

 midia external. Tetraspores scattered, immersed in the 

 branches and ramuli. 



1. Bonnemaisonia. Frond solid, filiform, rose-red. 

 Much branched ; branches margined with subulate dis- 

 tichous cilia. 



2. Laurenda. Frond solid, cylindric, or compressed 

 (purple or yellowish), pinnatifid. The ramuli blunt. 



3. Chrysimenia. Frond hollow, filled with mucus, 

 neither constricted nor chambered. 



4. Chylodadia. Branches hollow, filled with mucus, 

 constricted at intervals and chambered. 



3. CORALLINACE^E. Frond calcareous or crustaceous, 

 rigid. Ceramidia external, containing the tetraspores. 



* Frond filiform, articulate. 



1. Corallina. Frond pinnated. Ceramidia terminal, 

 simple. 



2. Jania. Frond dichotomous. Ceramidia tipped with 

 two hornlike ramuli. 



* * Frond crustaeeous or foliaceous, opaque, not articu- 

 late. 



3. Melobesid. Frond stony, forming a crustaceous ex- 

 pansion, or a foliaceous or shrublike body. 



4. Hildebmndtia. Frond cartilaginous, not stony. 



