PLATE IvV. 



PAGE 



Figs. 1-5. Cymatonota Typicalis, n. sp 662 



1. Left side of a nearly complete cast of the exterior. The specimen is a large one but 



its thickness has been so-mewhat reduced by pressure. 



2. Dorsal view of same in outline, to show gaping extremities and the oblique dorsal 



furrows. 



3. Dorsal view of an incomplete cast of the exterior. The length of this specimen has 



been reduced by pressure, bringing the dorsal furrows a little closer together 

 than is normal for the species. 

 4 and 5. The left side and a dorsal view of an incomplete but otherwise well preserved 

 cast of the interior, showing faint traces of the anterior muscular scar. Upper 

 beds of the Cincinnati group, Waynesville, Ohio. 



Figs. 6-7. CymatonoTa semistriata, n. sp 663 



6. The anterior half of the left side of a nearly complete cast of the exterior, x2, show- 



ing the fine, equal, threadlike surface markings of this part. 



7. The entire left side of same, natural size. The length of the specimen has been re- 



duced probably from the outline restored in the figure. Upper beds of the Cin- 

 cinnati group, Clarksville, Ohio. 



Figs. 8-9. Cymatonota recta, n. sp 662 



8. Cast of the interior of a small left valve, preserved in a limestone matrix. A few of 



the concentric lines on the flanks of the shell should be stronger than represented 

 in the figure. Middle beds of the Cincinnati group, Newport, Kentucky. 



9. Cast of the exterior of a large left valve, preserved in soft shale. Cincinnati, Ohio. 



Figs. 10-11. Cymatonota constricta, n. sp 664 



The left side and a dorsal view of a nearly perfect cast of the interior, showing the 

 gaping extremities, the obtuse anterior end, and the constriction of the shell be- 

 neath the beaks. Upper beds of the Cincinnati group, Butler county, Ohio. 



Figs. 12-14. Cymatonota aTTEnuata, n. sp 664 



12 and 13. The right side and a dorsal view of a small specimen, preserving very nearly 



the shape regarded as normal. 

 14. A peculiarly distorted large specimen believed to belong to this species. Upper 



beds of the Cincinnati group, Waynesville, Ohio. 



Figs. 15-16. Corallidomus concentricus, Whitf. 493 



The right side and a dorsal view of a partial cast of the interior of this boring shell ; 

 natural size. The specimen shows a gape between the edges of the valves at 

 each end, and a strong anterior muscular scar precisely as in Modiolopsis 

 and Orthodesma. 



Figs. 17-18. Cymatonota productifrons, n. sp 665 



The right side and a dorsal view both restored — of a slightly distorted cast of the ex- 

 terior. The unusual length of the anterior end is the principal peculiarity of 

 the species. Lower beds of the Cincinnati group, Covington, Kentucky. 



Figs. 19-20. Orthodesma parvum, n. sp 660 



The left side and a dorsal view of the type specimen. It is a nearly complete cast of the 

 interior. Middle beds of the Cincinnati group, Cincinnati, Ohio. 



Figs. 21-22. Orthodesma subangulatum n. sp 660 



The left side and a dorsal view of a cast of the interior. Upper beds of the Cincinnati 

 group, Richmond, Indiana. 



