PLATE L. 



PAGE. 



Figs. 1-4. AnomalodonTa GIGanTEa, Miller 637 



1. Very good cast of the interior of a left valve, showing the large posterior ad- 



ductor muscle scar, the pallial line, and the impression of a pedal muscle a 

 short distance behind the beak. The pallial line continues uninterruptedly, as 

 in all the genera of the family, to the inner side of the beak, and there is no an- 

 terior adductor scar unless it be a very small one in the rostral cavity. The liga- 

 mental area is wanting in the specimen, but has been restored, perhaps too nar- 

 rowly, in the drawing. 



2. Anterior view of an unusually complete testiferous example, showing the ab- 



ruptly impressed byssal opening. 

 3 and 4. Internal views of the original types of the genus and species, kindly loaned 

 by Dr. S. A. Miller. Figure 3 shows about one half of the anterior margin and 

 nearly all of the hinge of an old right valve, while figure -1 shows the greater 

 part of a left valve. Upper beds of the Cincinnati group, Versailles, Indiana. 



Figs. 5-9. Anoptera miseneri, n. gen. et. sp.... 650 



5 and 6. Dorsal and lateral views of a cast of the interior. 



7 and 8. Anterior and lateral views of another cast of the interior. Both specimens 

 show the pallial line very distinctly, and rather faint impressions of the posterior 

 adductor muscles. Upper beds of the Cincinnati group, Richmond, Indiana. 



9. Gutta percha impression from a natural mold of the exterior of a small left valve 



in the base of a parasitic bryozoan. The mold is imperfect at the apex. Clarks- 

 ville, Ohio. 



Figs. 10-12. Lyrodesma inorkatum, u. sp 682 



10. A small right valve. 



11. A larger right valve that may be considered as of the average size. This species is 



without the radiating strise usually found on the posterior cardinal slope in 

 shells of this genus. 



12. Hinge of a right valve, natural size. Middle beds of the Cincinnati group, Coving- 



ton, Kentucky. 



Fig. 13. Lyrodesma Grande, n. sp 683 



The left side of a complete cast of the interior. Middle beds of the Cincinnati group, 

 Cincinnati, Ohio. 



Figs. 14-15. Ctenodonta retrorsa, n. sp 679 



Eateral and cardinal views of a cast of the interior. "Middle Trenton, near Burgin, 

 Kentucky. 



