444 PROCEEDINGS OP THE NATIONAL MUSEUM. vol. 56, 



Fig. 3. Brachial valve. The low spreading fold is typical. 



4. Brachial valve -with nine plications on the lateral slopes. 

 Richmond group (Waynesville formation), Warren County, Ohio. 



Figs. 5-8. Platystrophia acuminata (James) p. 420. 



5. Brachial valve showing the slightly elevated fold. 



6. Brachial valve. The acuminate cardinal extreme are characteristic. 



7. Pedicle valve. The plications on the slopes of the sinus have almost disap- 



peared. 



8. Posterior view of the shell. 



Richmond group (Arnheim formation), Waynesville, Ohio. 

 Figs. 9-12. Platyslrophia foerstei, new species, p. 420. 



9. Posterior view showing the long hinge-line. 

 Richmond Group Waynesville, Ohio. 



10. Pedicle valve. The somewhat extended cardinal extremes are well illus- 



trated. 

 Richmond group (Liberty beds), just east of Eastwood, Jefferson County, 

 Kentucky. 



11. Pedicle vah^e of a narrow specimen. 



12. Brachial valve. The broad fold is typical. 



Richmond group (Arnheim formation), 1 mile east of Seatonville, Kentucky. 

 Figs. 13-1o. Platystrophia foerstei ampla, new variety, p. 421. 



13. Brachial valve of an aA^erage specimen. 



Richmond group (liberty), Ravine East of Floyd's Fork, Jefferson County, 

 Kentucky. 



14. Posterior view showing the ventricose form. 



Richmond Group (Waynesville formation), Long Run near mouth of Tates 

 Creek, Jefferson County, Kentucky. 



15. Pedicle valve. 



16. Brachial valve. 



Richmond group (Waynesville), H miles southeast of Thixton, Jefferson 

 County, Kentucky. 

 Figs. 17-19. Platystrophia elkhornensis, new species p. 426. 



17. Pedicle valve. The figure shows the strong growth varices. 



18. Cardinal view showing the short hinge line and globose form. 



19. Brachial valve. 



Richmond group (Elkhorn Division), Elkhorn Creek, Richmond, Indiana. 

 Figs. 20-24. Platystrophia annieana Foerste, p. 423. 



20. Anterior view of a narrow specimen. The even convexity is characteristic. 

 Richmond group (Whitewater formation), Richmond, Indiana. 



21. Pedicle valve. . A mutation with five plications in the sinus. 



22. Brachial A^alve of an average specimen. 



23. Brachial valve. (Same specimen as fig. 21.) 



Richmond group (Waynesville formation), Waynesville, Oliio. 



24. Anterior view. This specimen has a higher fold than the average. 

 Richmond group, 1 mile east of Bradstown, Kentucky. 



Figs. 25-28. Platystrophia moritura Cumings, p. 424. 



25. Brachial valve. 



26. Anterior view showing the deep sinus. 



Richmond group (Whitewater beds), Ripley County, Indiana. 



27. Anterior view of a robust specimen. The slightlj' compressed fold is charac- 



teristic. 



28. Pedicle valve. This figure represents a mutation with five plications in the 



sinus and six on the fold. 

 Richmond group (Liberty beds), railroad cut just northwest of Eastwood, 

 Kentucky. 



