PLATE XXVIII. 



O^trfd xfrii/lUcuhi White. 



Figs. 1, 2, 5. — Views of variety I. 

 Figs. 3, 4. — Views of variety II. 

 Fig. 6. — View of variety III. 



0><trea dcn-sa, n. sp. 



Fig. 7. — View of fragment, the type. 



O^trea comociiHi.'i, n. sp. 



Fig. 9. — Interior view of valve. 



Ostrea sp. 



Fig. 8. — View of fragment. 



Avicula heedei, n. sp. 



Fig. 10. — Exterior view of valve. 



Tancredia bulbosa Whitfield. 



Figs. 11, 12. — Views of right and left valves. 



