34 



GENERA. 



FIRST CLASS.— SECOND ORDER. 



Dynamena. Not much branching. Cells opposite. 



Sertularia. Stem or branches flexible. Cells al- 

 ternate. 



Idia. Branches pinnated and alternate. Cells al- 

 ternate, nearly awl-shaped, and curved. 



Clytia. Stem filiform, twining or climbing. Cells 

 campanulated and pediculated; pedicles long and 

 cur\^ed. 



GENERA. 



FIRST CLASS.— SECOND ORDER. 



Laomedea. Plant-like. Cells dispersed ; peduncu- 

 lated, or almost sessile. 



Thoa. Stem formed of numerous interwoven tubes. 

 Ovaria in clusters. 



Salacia. Cells long, cylindrical, and in united for- 

 mation to the number four ; side and verticillated 

 openings. 



