Figures 1-2. Stauroneis phoenicenleron (Nitzsch) Ehrenb. In figure 2 are shown 

 artifact structure caused by too rigourous cleaning (r/., Helmcke el al., 1961, plate 289 to 290) 

 for true structure of this species. Figure 1, X2500. Figure 2, X40,000. 



Figures 3-4. Stauroneis anceps Ehrenb. Figure 3, X2000. Figure 4, X40,000. 



Figures 5-6. Stauroneis smitliii Grun. These specimens are somewhat eroded but in 

 figure 6 it is shown that the slits in the outer membrane run across the striae, figure 5, 

 X2500. Figure 6, X 40,000. 



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