WISCONSIN PHYTOPLANKTON 113 



OOCYSTIS SUBMARINA Lagerheim. PI. 22, Fig. 10. 

 Bot. Not 1886: 45, fig. 1. 1886. 



Cells oblong-cylindrical, 2-3 times as long as broad, somewhat pointed 

 and with a nodule at each pole. Chloroplasts 1-2, laminate, parietal, 

 usually with a pyrenoid. Cells rarely solitary, generally in families 

 of 2-4-8-16 within the old mother cell wall. (Tychoplanktont). 



Cells 3-9 fji broad, 7-20 /* long. 



Camp (sss), Upper Nemahbin (rr). 



OOCYSTIS SOLITARIA Wittrock. PI. 22, Fig. 11. 

 Bot. Not. 1879: 24, figs. 1-5. 1879. 



Cells ovoid to ellipsoid, solitary or in families of 2-4-8. Cell wall 

 fairly thick and with conspicuous polar nodules. Chloroplasts numer- 

 ous (generally 12-25), parietal, discifonn to polygonal, with or with- 

 out pyrenoids. (Facultative Planktont). 



Cells 7-20 ^ broad, 14-35 p. long. 



Hooker (r), Sand (1) (rr). 



OOCYSTIS CRASSA Wittrock PI. 22, Figs. 12-13. 



Bot. Not. 188O: 117. 1880. 



Cells ovoid, length l 1 /^ times the breadth, with a nodule at each pole. 

 Chloroplasts 4-10 in number, fairly large, parietal, disciform to angu- 

 lar, generally with a pyrenoid. Cells solitary or in families of 2-4-8. 

 Old cell wall enclosing the colony greatly distended. (Tychoplanktont) . 



Cells 10-20 /* broad, 14-26 /t long. 



St. Croix (rr). 



OOCYSTIS EREMOSPHAERIA G. M. Smith. PI. 23, Figs. 1-2. 

 Trang. Wis. Acad. Sci., Arts, & Lett. 19 1 : 630, pi. 14, figs. 8-9. 1918. 



Cells ovoid, 1% to 2 times as long as broad. Solitary or in families 

 of 2-4. Chloroplasts numerous (40-60), parietal, lenticular, each con- 

 taining a single pyrenoid. Cell wall thick, with a conspicuous polar 

 nodule. (Facultative Planktont ?). 



Cells 23-31 ft broad, 35-45 //. long. 



Beaver dam (rr), Shell (sss). 

 8 



