WISCONSIN PH7TOPLANKTON 151 



Wall variously sculptured or ridged, at times with terminal teeth, or spines. 

 Longitudinal ridges on sides of the cells. 



Without terminal teeth or spines S. ACUTTFORMIS 



With terminal teeth or spines. 



Terminal cells with long spines at poles S. ABMATUS 



All cells with short teeth at poles S. BRASILIENSIS 



Longitudinal ridges not present on sides of the cells. 



Teeth-like spines covering entire wall S. HYSTBIX 



Teeth or spines confined to poles, outer face of terminal 

 cells, or middle of all cells. 



Cells with short teeth at poles S. DENTICTJLATUS 



Cells with long spines. 

 Spines on both median and terminal cells. 

 Poles of cells only region bearing spines. 



Cells ovoid to ovoid-cylindrical S. LONGUS 



Cells naviculoid S. OPOLTENSIS 



Poles and median part of cells bearing spines S. ABUNDANS 



Spines confined to terminal cells. 



Cells ovoid to ovoid-cylindrical S. QTJADBICAUDA 



Cells naviculoid S. OPOLIENSIS 



SCENEDESMUS OBLJQUUS (Turpin) Kiitzing. PI. 37, Figs. 12-14. 

 Linnaea 8: 609. 1833; G. S. West, Brit. Freshw. Algae 220, fig. 92A. 1304. 



Cells of 2-4-8 cells arranged in a single linear or sublinear series. 

 Cells fusiform, with acute apices ; interior cells with straight sides, outer 

 face of terminal cells slightly' concave, straight, or convex. Cell wall 

 smooth, without terminal teeth or spines. (Tychoplanktont). 



Cells 3-9 fjL broad, 10-21 p. long. 4-celled coenobia 10-21 /* broad, 

 12.5-24 /* long. 



Balsam (rrr), Bear (1) (rrr), Blake (rr), Bone (rr), Grassy (rr), Hill- 

 man (rrr), Horseshoe (2) (rrr), Lindy (rr), Little Bear (rrr), Little Doctor 

 (rr), Little Rice (2) (rrr), Loon (rr), Mendota (rrr), Pewaukee (rrr), Poor 

 Farm (rrr), Pope (rrr), Rice (2) (rr), Sand (3) (rrr), Sand (4) (rrr), Up- 

 per Nemahbin (rrr), White Ash (rrr). 



SCENEDESMUS DIMORPHUS (Turpin) Kiitzing. PI. 37, Figs. 15-17. 



Linnaea 8: 608. 1833; G. M. Smith, Trans. Wis. Acad. Sci., Arts, & Lett. 18 2 : 

 434, pi. 32, figs. 185-189; pi. 33, figs. 190-195. 1916. 



Coenobia of four or eight cells arranged in a linear or alternating 

 series. Cells fusiform with apices attenuated to delicate points. In- 

 terior cells erect, outer erect or markedly lunate. Cell wall smooth, 

 without terminal teeth or spines. (Facultative Planktont). 



Cells 2-5 ft broad, 18-23 ^ long. 4-celled coenobia 18-23 ^ broad, 

 12-25 p. long. 



Dunham (rrr), Horse (r), Pine Tree (sss), Poor Farm (ss), Travis (sss). 



