PI, ATE XXVIII. 



Figures 3, 7, 10, 12 miignl-fied l.~>0 diameters ; others ooo diameters. 



I'AC.K. 



Fig. 1. EUASTRUM CRASSUM, . . . . . . 10(i 



" 2. " semi cells of very large form, . 10(i 



" 3. " transverse view of semi-cell, . . 100 



" 4. EOASTRCM ORNATUM, a form of " E. orassnm," . . 100 



Figs. 5, 6. ETTASTRUM OBLONOUM, two forms, .... 100 



Fig. 7. . transverse view of semi-cell, . 100 



Figs. 8, 9. ECASARUM ANSATUM, two forms, .... 109 



Fig. 10. transverse view of semi-cell, . 109 



Figs. 11, 12. EUSASTRUM AFFINE, front and transverse views, . . 110 



