WISCONSIN PHYTOPLA.NKTON 189 



PLATE 4. 



Page 



Fig. 1. Coelosphaerium Naegelianum (x 825) 35 



Figs, 2-3. Gomphosphaeria aponina (x 825) 37 



Fig. 4. Gomphosphaeria aponina var. cordiformis (x 825) 37 



Fig. 5. Gomphosphaeria lacustris (x 825) 36 



Fig. 6. Microcystis aeruginosa var. major (x 825) 40 



