120 



WISCONSIN PHYTOPLANKTON 



five-) radiate, the angles bearing three (very rarely four) outwardly 

 divergent stout spines ; sides of cells deeply emarginate. 



Zygospores unknown. 



Cells 56-77 ja long with spines 43-51 /a long without spines ; breadth 

 with spines 65-99 /x, without spines 25-37 ju, (Nordstedt). 



Not found in the plankton of Wisconsin lakes. 



var. LuNDELLii W. & G. S. West. PI. 82, Figs. 3-5. 



Trans. Linn. Soc. 2nd. Set. Bot. 5: 259. 1896. 



Staurastrum hrasiliense Lundell (non Nordstedt), Nova Acta Reg. Soc. Sci. 

 Upsaliae 3 Ser., 8: 73, pi. 5, fig. 2. 1871. 



Cells (without spines) about twice the size of the type ; apex of semi- 

 cells straight or only slightly retuse. Vertical view five-sided (rarely 

 six-sided) ; emargination of sides subsemicircular. Cell wall smooth 

 or finely punctate. Chloroplast with a central mass and massive rays 

 towards each angle, rays each with several smaller laminate rays; 

 pyrenoids numerous, in both the central portion and the rays. (Fac- 

 ultative planktont.) 



Cells 145 [X long with spines, 74 fi long without spines ; breadth 

 with spines 148 yu., without spines 92 fi; breadth at isthmus 38 ju,; spines 

 27-37 IX long. 



Bass (rrr), Diamond (r). 



56. Staurastrum tohopekaligense WoUe. 



Bull. Torr. Bot. CI. 12: 128, pi. 51, figs. 4-5. 1885; Fresh w. Algae of TJ. S. 45, 

 pi. 59, figs. 4-5. 1887; W. & G. S. West, Trans. Linn. Soc. 2nd. Ser. Bot. 6: 180, 

 pi. 21, fig. 26. 1902. 



Cells of medium size, breadth (without processes) somewhat less 

 than the length, fairly deeply constricted, sinus widely open and 

 with apex acute, isthmus narrow; semicells with bases obsemicircular 

 and apices flattened; with three lateral processes arising about half 

 way from apex to the isthmus, lateral processes parallel; upper part 

 of semicells with six subapical processes arising just back of the lat- 

 eral margins, subapical processes markedly divergent ; all processes 

 hollow, with subparallel sides and length about equal to the diameter 



Fig. 16. Staurastrum tohopelcaligense Wolle (x500). Plankton specimens from 

 lakes in Ontario, Canada. Figs. A, C from Silver Lake, Fig. B from Gull Lake. 



