J52 WISCONSIN PHYTOPLANKTON 



PLATE 54. 



All figures x 400. 



Page 



Fig. 1. Pleurotaenium trahecula yar. rectum (Delp.) W. & G. S. West.. 14 



Figs. 2-4. Pleurotaenium subcoronulatum var. detum W. & G. S. West 14 



Figs. 5-6. Pleurotaenium Elirenhergii (De Breb.) D. By 15 



Figs. 7-8. Pleurotaenium Ehrenbergii formae 15 



Fig. 9. Pleurotaenium Ehrenlergii var. undulatum Schaarsch 15 



Fig. 10. Pleurotaenium Ehr enter gii var. elongatum W. West 16 



Fig. 11. Pleurotaenium nodosum (Bail.) Lund 16 



