46 SPECIES OF 



b. Filaments dividing longitudinally; mucous; 4 in. long, floating, 



Lenormandi, 138 



b. " not dividing longitudinally (c\ 



c. Joints often constricted; diameter of cells 9-10/1 . rivularis, 136 

 c. Joints not constricted; aquatic; variable; diameter of cells 5-50/4, 



sub t His, 135 

 c. " " " " filaments tortuous, very long, 



muralis, 137 



c. " " " On damp walls, pavements, exposed rocks, etc., (*) 

 *. Cells 6-7/4 in diameter; on walls, pavements, etc. . mitens, 137 

 * " 7~9-5/* " " cell contents usually at one side; on ex- 

 posed rocks, etc flaccida, 137 



d. Cells 12-14^ in diameter cequalis, 134 



d. Cells about 7/4 in diameter; on moist clay or sand . . varia, 138 

 c. Green, cell contents usually on one side, hemispherical, flaccida, 137 



e. Green, dark, bright or pale; contents diffused (/). 



f. Joints often constricted; cells 9-10/4 in diameter . rivularis, 136 



f. " not constricted; filaments attached, 17-25/1 in diameter, 



tennis, 1 34 

 /. " " " filaments not attached (g). 



g. In brackish water, filaments 1-3 in. long, 10-30/4 dia., 



Younganum, 135 



g. In fresh water subtilis, 135 



h. Filaments dividing longitudinally, 4 in. long, floating, 



Lenormandi, 138 

 h. not dividing (/'). 



/. Joints often constricted, cells 9-10/4 in dia.. . . rivularis, 136 

 i. " not constricted in sterile filaments (/). 

 j. Filaments 10/4 or more in diameter (/). 

 j. " less than io/* in diameter (m). 



k. In brackish water; filaments 20-36/4 in dia. . Younganum, 135 

 k. In brackish and in fresh water; filaments 38-50/4 in dia., 



speciosa, 135 

 k. In fresh water only or on the grpund (/). 



/. On shaded ground; flexuous, interwoven ^arietina, 138 



/. Aquatic; filaments IO-T 2/4 in dia oscillarina, 137 



/. " " 14-40/4" " Zonata, 133 



m. Bright, grass green; filaments tortuous, very long, interwoven, 



muralis, 137 

 m. Yellowish green, mucous; cells shorter than wide . compacta, 136 



