Scenedesmus quadricauda var. Westii G. M. Smith 1916a, p. 480 



PL 64, Figs.7,9 



Colony composed of 4-8 ovate cells with broadly rounded apices; 

 cells S-Sjx in diameter, 10-18-(22)^ long; spines relatively short, 

 often strongly reflexed. 



Rare, but found in the plankton of a great variety of lakes, ponds, 

 and swampy habitats. Mich., Wis. 



Scenedesmus serratus ( Corda ) BohUn 1901, p. 44 

 PI. 64, Fig. 8 



Colony composed of 4 oblong-ovate cells arranged in a single 

 series; the outer cells with one, the inner cells with two longitudinal 

 rows of small teeth; apices of all cells bearing 3-4 small teeth; cells 

 4.5-7/i in diameter, 15-20ju. long. 



Plankter; in several lakes. Wis. 



ACTINASTRUM Lagerheim 1882, p. 70 



Colonial, planktonic, composed of 4-16 ti'uncate-fusiform or 

 basidia-like cells, sometimes cigar-shaped with subacute poles, 

 radiating in all planes from a common center, not inclosed by a 

 colonial envelope; chloroplast a parietal, elongate plate covering 

 about % of the wall in circumference and nearly as long as the 

 cell; 1 pyrenoid present. 



Key to the Species 



Cells 7-10 times as long as wide, about as wide at the poles 



as in the median part of the cell A. gracilimum 



Cells 3-6 times as long as wide; median part of the 



cell about twice as wide as the poles A. Hantzschii 



Actinastrum gracilimum G. M. Smith 1916, p. 480 

 PI. 64, Fig. 5 

 Cells cylindrical, with very slightly narrowed to abruptly truncate 

 poles, forming colonies of individuals with the long axes of the 

 cells radiating in all planes from a common center; cells 1.7-3/a in 

 diameter, 14-21/a long; colonies 30-45/i, in diameter. 

 Rare; in the plankton of several lakes. Mich., Wis. 



Actinastrum Hantzschii Lagerheim 1882, p. 70 

 PL 64, Figs. 10, 11 

 Cells spindle-shaped or cylindrical, narrowed toward the apices, 

 arranged in simple or compound colonies of 4 or 8 with the long 



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