WISCONSIN PHYTOPLANKTON 159 



var. LONGISPINA (Chodat) G. M. Smith. PI. 40, Figs. 12-14. 

 Trans. Wis. Acad. Sci., Arts, & Lett. 18 2 : 480, pi. 31, figs. 159-161. 1916. 



Cells ovoid-cylindrical. Length of cells 2.5 times the breadth. (Fac- 

 ultative Planktont). 



Cells 3.5-5 p. broad, 8-11 p. long. 4-celled coenobia 8-11 p. broad, 

 12-20 p, long. Spines 7.5-10 p. long. 



Horse (rr), Lost (rr), Mendota (sss), Palmer (r). 



var. WESTII G. M. Smith. PI. 41, Figs. 3-7. 

 Trans. Wis. Acad. Sci., Arts, & Lett. 18 2 : 480, pi 32, figs. 177-180. 1916. 



Cells 4.5-8 p. broad, 16-22 p long. 4-celled coenobia 16-22 p. broad, 

 25-35 p. long. Spines 12-16 p long. (Facultative Planktont). 



Bear Trap (rrr), Blake (rr), Camp (rr), Cochrane (rr), Crawling Stone 

 (rr), Grassy (rr), Horse (rrr), Lac Court Oreilles (rr), Loon (rrr), Meta 

 (rr),, Silver (2) (rr). 



var. MAXIMUS W. & G. S. West. PI. 41, Figs. 1-2. 

 Trans. Linn. Soc. 2 Ser. Bot. 5: 83, pi. 5, figs. 9-10. 1895. 



Cells much larger and spines proportionally longer. (Facultative 

 Planktont). 



Cells 9-11.5 p, broad, 27-36 p. long. 4-celled coenobia 27-36 p. broad, 

 35-40 p. long. Spines 20-30 p. long. 



Eagle (rr), Nicaboyne (rr), Pine Tree (rr), Poor Farm (rr), Tenderfoot 

 (rrr), Travis (r). 



SCENEDESMUS OPOLiENSis P. Eichter. PL 41, Figs. 8-11. 

 Zeits. f. angw. Mikr. 1: 7, figs. A-E. 1896. 



Coenobia flat, of 2-4-8 (generally 4) cells in a single linear series. 

 Interior cells naviculoid, outer margin of terminal cells straight or 

 slightly convex. Cells in lateral contact in median third only. Termi- 

 nal cells with a long spine at each pole ; interior cells with or without 

 long or short spines. Polar spines greatly reduced at times. (Faculta- 

 tive Planktont). 



Cells 5-8 p. broad, 12-28 p. long. 4-celled coenobia 12-28 p. broad, 

 15-30 p. long. Spines 5-28 p. long. 



Palmer (rr). 



The navicular shape of the cells, their lateral contact in the median 

 third only, together with the beak-like instead of rounded apex sepa- 

 rates this species from S. quadricauda. 



