PLATE XXVIII. 



Figures magnified 500 diameters. 



P \ r; E . 



Figs. 1. 'J. K> \- 1 1:1 m i [rculabe, fronl and transverse view of semicell, KM 



Fig. 3. EUASTROM 'IMMAITM. ...... KM 



I. transverse view "i semicell, . 1 < ' 1 



" .">. EUASTRUM EVERETTKNSE, ..... 102 



Figs. 6, 7. "' transverse and lateral aspect of semi- 

 cell, ..... 102 



8 10. Euastbum \miti.i.\i i rM. three forms, . . 100 



I 'ig. 11. transverse view of semicell, . 100 



" 12. I SO \-i BUM BUM] aosuM, .... 99 



13. " basal view of Bemicell, . 99 



Figs. 14, L5. Euastri m i-i\n\m m. ..... 98 



Fig. L6. " " basal aspecl of semicell, . . . 98 



