158 WISCONSIN PHYTOPLANKTON 



PLATE 57. 



All figures x 600. 



Page 



Figs. 1-2. Euastrum gemmatum De Breb 26 



Pig. 3. Cosmarium circulare Reinsch 29 



Fig. 4. Cosmarium depressum (Nag.) Lund 29 



Figs. 5-6. Cosmarium depressum var. achondrum (Boldt) W. & G. S. West 30 



Figs. 7-8. Cosmarium Moculatum De Breb 30 



Figs. 9-11. Cosmarium contractum Kirclm 30 



Figs. 12-13. Cosmarium contractum var. papiUatum W. & G. S. West 31 



Figs. 14-17. Cosmarium coritractum var. papiUatum forma minor .31 



Fig. 18. Cosmarium granatum De Breb 31 



Figs. 19-20. Cosmarium cyclicum var. N ordstedtianum (Reinsch) W. & G. S. 



West 32 



Fig. 21. Cosmarium amoenum var. mediolaeve Nordst 32 



Fig. 22. Cosmarium Botrytis (Bory.) Menegh 33 



Fig. 23. Cosmarium reniforme (Ralfs) Arch 33 



Fig. 24. Cosmarium Portianum Arch 33 



Fig. 25. Cosmarium ornatum Ralfs 34 



Fig. 26. Cosmarium commissurale var. crassum Nordst 35 



Fig. 27. Cosmarium protractum (Nag.) De Bary 35 



Fig. 28. Cosmarium quinarium Lund 36 



Fig. 29. Cosmarium punctulatum var. subpunctulatum (Nords.) B0rg. . . 37 



