PLATE LIII. 



PAGE, 



Figs. 1-2. Modiolodon oviformis, var ampujs, n. var 653 



1. The left side of a nearly perfect cast of the interior. 



2. Mold of the exterior of a right valve. Trenton group, Frankfort, Kentucky. 



Figs. 3-4. Modioeodon deceivis, n. sp 654 



The right side and a cardinal view of a cast of the interior of the average size. Upper 

 beds of the Cincinnati group, Richmond Indiana. 



Figs. 5-6. Modiolodon subrecTus, n. sp. 653 



The left side and a dorsal view of a small but characteristic cast of the interior of this 

 species. Upper beds of the Cincinnati group, Richmond, Indiana. 



Figs. 7-8. Modioeodon oviformis, Ulnch 652 



7. A perfect impression of the interior of a left valve. The specimen is of the usual 



size and from the Trenton at Frankfort, Kentucky. 



8. Gutta percha impression from the preceding to show the character of the hinge, the 



anterior adductor scar and the pallial line. 



Figs. 9-18. Ortoneela hainesi, Miller sp 670 



9. The right side of a perfect though rather small specimen of the typical form. 



10. Antero-dorsal view of same, showing the lunule and escutcheon. 



11 . Interior of a left valve. 



12. Almost entire mold of the interior of a right valve, showing impressions of the 



posterior lateral teeth. 



13. The left side of a large and complete cast of the interior. 



14 and 15. The right side and an antero-dorsal view of a small cast of the interior be- 

 longing to a variety that is shorter than the typical form. 



16. A small cast of the next variety. - 



17 and IS. The right side and a dorsal view of an excellent cast of the interior of an 

 unusually long variety. The small pedal muscle scars are shown very distinctly 

 in figure 18. Upper beds of the Cincinnati group Richmond, Indiana. 



