EXPLANATION OF PLATE III. 



Fig. 7a. — External structures of Anodontoides ferussacianns (Lea). 9 

 (Nat. size). 



1. — Ventral extremity. 6. — Rest lines of growth. 



2. — Dorsal extremity. 7. — Beak. 



3. — Anterior extremity. 8. — Post-dorsal ridge. 



4. — Posterior extremity. 9. — Post-umbonal ridge. 



5. — Minor lines of growth. 



Fig. 7b. — Internal structures of shell of A. ferussacianus. 9 . 

 — Ventral extremity. 6. — Mantle line. 



— Dorsal extremity. 7- — Ant. add. scar. 



— rAnterior extremity. 8. — Post. add. scar. 



— Posterior extremity. 9. — Beak cavity. 



— Rest lines of growth showing 10. — Apex of beak, 



through shell. 



Fig. 8a. — Dorsal view of A. jerussarianns shell showing Anodoiitiiie beak 

 sculpture. 



Fig. 8b. — Dorsal view of P. coccinciim shell showing Uuioninc beak 

 sculpture. 



Fig. 8c. — Dorsal view of E. (C.) parva shell showing Lampsilinc beak 

 sculpture. 



