PLATE XL. 



Figures magnl^ed :Wo diameters. 



Page. 

 Fig. 1. MicRASTERiAS riMBKiATA, semi-cell, typical form, . 121 



" 2. '' " other semi-cell, Var. apiculata, . 121 



" 3. " ' one-fourth cell, Var. Elephantina, . 121 



" 4. " " Var. nuda, . , . 121 



Figs. 5, 0. " " two varieties of polar lobes, . .121 



Fig, 7. MiCEASTERiAS suBFiMBRiATA, has the form of lobelets, bnt not 



the specific number, . . 121 



" 8. MicRASTERiAS SIMPLEX, Unlike all other forms in the simple, 



acute, ultimate division of the lobules, 121 



