PLATE 98. 



Page 



Fig. 1-8. Spibifbb arenosds. 425 



1 & 2. Two views from the same specimen, whicli is slightly distorted and the shell partially 

 removed. 



3. Ventral valve of a large specimen. 



4. A dorsal view, showing the area and foramen. 

 6. View of a ventral valve. 



6. The dorsal side of a specimen where the shell is worn from the mesial fold, and partially 



from the sides of the valve, 

 fi a, b. Front and profile views of the same specimen, the ventral side being a cast of the 

 interior. 



7. The interior of a large ventral valve. 



8. Enlargement of the plications, showing fine concentric strise. 



Fig. 8 a, b. Cyrtia rostrata. 429 



8 a, b. Ventral and cardinal view of an imperfect cast of this species. 



