WISCONSIN PHYTOPLANKTON 



KEY TO THE SPECIES. 



Outer face of marginal cells without projections. 



Wall smooth p. INTEGEUM 



Wall reticulate p. ABANEOSUM 



Outer face of marginal cells with 1, 2, or 4 projections. 

 Marginal cells with more than one projection. 



Cells on margin with four projections and a deep linear incision. .P. TETBAS 

 Cells on margin with two projections. 

 Coenobe entire. 

 Cell wall smooth or punctate. 



Projections side by side in front view of cell P. BORYAJTOM 



Projections above one another in front view P. KAWRAISKYI 



Cell wall reticulate. 



Wall covered with coarse reticulations P. ABANEOSTTM 



Wall covered with fine reticulations P. ScuipTATtrM 



Coenobe perforate. 



Ends of projections truncate P. DUPLEX 



Ends of projections incised P. BESADIATUM 



Marginal cells with one projection P. SIMPLEX 



PEDIASTRUM SIMPLEX var. DUODENARIUM (Bailey) Rabenhorst. PL 45, 



Figs. 2-6. 



Fl. Eur. Algarum 3: 72. 1868. 



Monactinus duodenarius Bailey, Smithsonian cont. to knowl. 7, Art. 3: 14, 

 pi. 1, fig. 37. 1855. 



Monactinus octonarius Bailey, ibid. p. 14, pi. 1, fig. 36. 1855. 



Pediastrum simplex var. clathratum (Schroter) G. S. West, Jour. Linn. Soc. 

 Bot. 38: 134. 1907. 



Coenobia circular to oval, of 4-8-16-32-64-128 (generally 8-16-32) 

 cells. Inner face of marginal cells concave, outer face produced into 

 a single, delicately tapering, concave process frequently furnished with 

 a tuft of delicate hyaline setae. Interior cells as those of the periphery 

 but with shorter processes. Interstices between cells large. Cell wall 

 smooth or finely punctate. (Facultative Planktont). 



Cells 10-24 n broad, 20-45 p. long. 



Balsam (rr), Bear (1) (r), Bear Trap (rrr), Blake (r), Camp (rr), Green 

 (1) (rrr), High (rr), Hillman (rrr), Kegonsa (rr), Little Bass (rr), Little 

 Butternut (r), Little Crooked (rrr), Lost (rr), Loveless (rrr), Mary (rr), 

 Monona (r), Mud (2) (rr), Palmer (rrr), Pokegama (1) (sss), Rice (1) (r), 

 St. Croix (rr), Silver (1) (rr), Spirit (rr), Upper Turtle (r), Vermilion (cc), 

 Wapagossett (r), White Ash (rr), Winnebago (rr), Wolf (rrr). 



This alga is one that has been given a number of names by various in- 

 vestigators, but for the reasons stated elsewhere (Trans. Wis. Acad. Sci., 

 Arts, & Lett. 19 1 : 642. 1918) I consider the one given above the proper 

 name. 



