PLATE XLVII. 



PAGE 



Fig. 1. Eridonychia apicaeis, n. sp 639 



Interior of a left valve as shown in a gutta-percha impression of a cast of the in- 

 terior. Middle beds of the Cincinnati group, Newport, Kentucky. 



Fig. 2. Eridonychia paucicostata, n. sp 640 



An average left valve of this species. Middle beds of the Cincinnati group, Coving- 

 ton, Kentucky. 



Fig. 3. Eridonychia crenata, n. sp 640 



A left valve showing the greatly attenuated beaks and the wavy character of the ventral 

 outline. Upper beds of the Cincinnati group, Waynesville, Ohio. 



Figs. 4-5. Bysonychia? byrnesi, n. sp 635 



4. Gutta-percha impression of a natural mold of the exterior of a right valve. The 



outline of this specimen is a little unusual in the post-dorsal region. 



5. A left valve of the usual size and form. Lower beds of the Cincinnati group, Cov- 



ington, Kentucky. 



Fig. 6. Opisthoptera eaTicostata, n. sp 646 



The right side of a somewhat imperfect cast of the exterior. Upper beds of the Cin- 

 cinnati group, ne^r Waynesville, Ohio. Collection of the Ohio State Uni- 

 versity. 



Fig. 7. Opisthoptera ampla, n. sp 647 



View of the imperfect specimen described. It is a cast of the interior of a left valve. 

 Middle beds of the Cincinnati group, Cincinnati, Ohio. 



Fig. 8. Lyrodesma subpeanum, n. sp 683 



Partial cast of the interior of a large right valve. Eower beds of the Cincinnati, 

 group, Covington, Kentucky. 



Fig. 9. Lyrodesma conradi, n. sp ' 684 



Sharply defined cast of the interior, showing the muscular scars and the sinuate 

 pallial line very clearly. Lower beds of the Cincinnati group, Covington, Ken- 

 tucky. 



Figs. 10-12. Technophorus punctostriatus, n. sp 685 



10. Right valve of the natural size. 



11. Cast of the interior of a left valve. 



12. The original of Fig. 10 magnified two and one-half diameters to show the regular 



puncto-lineate surface marking. Middle beds of the Cincinnati group, Cov- 

 ington, Kentucky. 



Figs. 13-14. Technophorus yoediiformis, Ulrich 685 



13 The original type of this species, x 2. The specimen is preserved in soft shale as 



a partial cast of the interior. 

 14. The same valve together with a right valve found in the same block of shale. Eower 



beds of the Cincinnati group, Covington. Kentucky*. 



