186 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



Filaments without a gelatinous sheath, spores next to the hetero- 

 cysts •- Sphcorosyga. 



12. Filaments with a gelatinous sheath . . : 15 



Filaments without a gelatinous sheath > 13 



13. Filaments spirally twisted Spirulina. 



Filaments not spirally twisted 14 



14. Cells bluish or purplish green Oscillaria. 



Cells colorless or containing opaque granules Beggiatoa. 



15. Filaments free Lyngbya. 



Filaments adherent in meshes Symploca. 



Filaments united in bundles and surrounded by a general gelatinous 



sheath Microcoleus. 



16. Filaments free Calothrix. 



Filaments imbedded in a dense mass of jelly 17 



17. Filaments nearly parallel, fronds forming a thin expansion. . .Isactis. 

 Filaments diverging from the base of the hemispherical or somewhat 



flattened fronds Rivularia. 



Filaments simple at the surface and forking in the interior of the 

 vesicular fronds Hormactis. 



18. Fronds unicellular 19 



Fronds multicellular 20 



19. Cells small, ovoidal, prolonged into a long, root-like process at the 



base Codiolum. 



Cells large, filamentous, pinnately branching Bryopsis. 



Cells large, with few, erect, alternate branches, some of which swell 



at the end and bear numerous spores Derbcsia. 



Cells very long, cylindrical, with irregular or subdichotomous 



branches, spores large, solitary, in special lateral or terminal cells. 



Vaitcheria. 



20. Fronds membranaceous 21 



Fronds filamentous 22 



21. Fronds formed of a single layer of cells Monostroma. 



Fronds composed of two layers of cells, wdiich in some cases sepa- 

 rate so as to form tubular fronds ZFlva. 



22. Filaments simple 23 



Filaments branching 24 



23. Small alga?, filaments soft and flaccid JJlothrix. 



Father coarse algre, filaments more or less rigid, often twisted to- 

 gether CJuctomorpha. 



24. Some of the cells bearing long, hyaline hairs Bulbocoleon. 



Hairs wanting , 25 



25 Branches small and root-like Rhizoclonium. 



Branches distinct Cladophora. 



26. Fronds irregularly globose, hollow, gelatinous Lcathesia. 



Fronds forming crusts or expanded pellicles 27 



