EXPLANATIONS AND REFERENCES, 

 PLATE LVIII. 



Figures magnified 500 diameters. 



PAGE. 

 Fig. 1-3. EUASTRUM VENTRICOSUM, zygo^pore, lateral and end views of cell, 38 



Figs. 4, 5. EUASTRUM CRASSUM, Var. SCROBICULATUM, front and lateral views,3S 



Fig. 6-8. EUASTRUM MAGNIFICUM, front, lateral and end views, . . 37 



9-11. EUASTRUM PURUM, two front and one lateral view, . . 37 



Figs. 12, 13. EUASTRUM CUNEATUM, front and lateral views, . . 37 



