Scenedesmus bijuga var. alternans (Reinsch) Hansgirg 1888, p. 114 



PL 63, Figs. 3, 4 



Cells ovate or elliptic, regularly arranged in 2 alternating series; 

 cells 4-8/A in diameter, 7-16/x long. 



Widely distributed; common in the plankton of many lakes and 

 in the tychoplankton of ponds and swamps. Mich., Wis. 



Scenedesmus bijuga var. flexuosus (Lemm.) Collins 1909, p. 168 



A variety differing from the typical by having the cells arranged 

 in a single series only, as many as 32 in one colony; cells broader 

 than in the typical plant. 

 Wis. 



Scenedesmus bijuga var. irregularis ( Wille ) 

 G. M. Smith 1916a, p. 448 

 Cells very irregularly arranged, occurring either in alternate or 

 double series; 3.5-6^ in diameter, 7.5-10/a long. 

 Wis. 



Scenedesmus brasiliensis Bohlin 1897, p. 22 

 PI. 63, Figs. 5, 6 

 Colony composed of 2-8 subcylindric or ovate-ellipsoid cells 

 arranged in a single series; apices of cells with 1-4 short teeth and 

 with a longitudinal median ridge extending between the apices of 

 each cell; cells (3)-5-7/x in diameter, 10-22/x long. 

 Common in many lakes. Mich., Wis. 



Scenedesmus denticulatus Lagerheim 1882, p. 61 

 PI. 63, Figs. 10, 11 



Colony composed of 4 or 8 ovate cells arranged in a single 

 series (rarely alternating); apices of cells with 1-4 short teeth; 

 free walls of cells smooth; cells 6-^10/^, in diameter, 8-15/x long. 



Very common and almost always accompanying other species of 

 Scenedesmus. Mich., Wis. 



Scenedesmus denticulatus var. linearis Hansgirg 1888, p. 268 



Colony composed of 4 or 8 ovate cells arranged in a single, 

 straight series, poles of the cells rounded and furnished with 2 

 small teeth; cells 4-5/a in diameter, up to 15/^ long. 



Wis. 



Scenedesmus dimorphus (Turp.) Kuetzing 1833, p. 608 



PI. 63, Figs. 8, 9 

 Colony composed of 4 or 8 fusiform cells arranged in a single 

 or alternating series; the inner cells with straight, sharp apices; the 



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