Anacystis Meneghini. This name, dating irom 1837, has priority 

 (Drouet and Daily, in Daily 1942, p. 648). This greatly simplifies 

 the nomenclature and serves as a basis for assigning names to species 

 heretofore referred to both Aphanothece and Gloeothece. Some of 

 the species of these two genera not treated by Daily (I.e.) require 

 consideration. In the present study, type materal has been examined 

 for some of the species, but not for all. It is considered best, there- 

 fore, to retain the names commonly used for the plants referable 

 to these genera. The reader should see Daily (I.e.) for an analysis 

 of synonymy. In the following key the species which have been 

 transferred to synonymy in Anacystis are so indicated by the name 

 in parentheses. 



Key to the Species 



1. Colonies clatlirate, irregularly expanded, with large perforations - A. clathrata 



1. Colonies not clathrate; globular or amorphous 2 



2. Colonies globular or hemispherical, either free-floating or attached 3 



2. Colonies amorphous, gelatinous masses, usually 



adherent, becoming free-floating 4 



3. Cells short-cylindric, stout, ( 3.6 )-7/u in diameter; 



colony free-floating . (A. prasina — see A. stagnina) 



Anacystis rupestris var. prasina 



3. Cells cylindric with rounded ends, 3-5/u in diameter; colony 



adherent to bottom, sometimes free-floating .._ (A. stagnina) 



Anacystis rupestris 



4. Cells minute, 2/j, or less in diameter 5 



4. Cells larger than 2yu in diameter 8 



5. Cells 1-1. 5/u in diameter, about twice the diameter in length A. nidulans 



5. Cells larger, ( l)-1.8-2yu in diameter, slender, up to 



3 times the diameter in length A. saxicola 



6. Cells ovate to nearly spherical, not cylindric A. gelatinosa 



6. Cells cyhndrical, up to 3 times the diameter in length - 7 



7. Plant mass very pale, gray to light blue-green 8 



7. Plant mass brightly colored 9 



8. Cells 3.3-3.7-(4.5)m in diameter, up to 7/x 



long; densely arranged A. microscopica 



8. Cells larger, 4.5-5.6a<. in diameter, up to 



8.5/i long; loosely arranged (A. pallida — see Gloeothece rupestris) 



Anacystis rupestris 



9. Cells elongate-cylindric, 2.4Sfj. in diameter, up to 3 



times the diameter in length; loosely arranged A. microspora 



9. Cells short-cylindric, 2-3.5/x in diameter, up to 2 times the 



diameter in length; densely arranged (A. Castagnei) 



Anacystis marginata 



[466] 



