446 PROCJJEDINGS OF THE XATIOXAL MUSEUM. vol.56. 



Plate 48. 

 All iigures on this plate arc natural size. 

 Figs. 1-3. Platysirophia cypha arcta, new ^•arifty, p. 437. 

 l.^Pediclo valvo. 



2. Anterior view showing tlic deep sinus. 



3. Brachial valve. (Same specimen as fig. 2.) These figures show the charac- 



teristic narrow form. 

 Richmond group (Arnlieini formation), Greenwell Ford Section, Bullitt 

 County, Kentucky. 

 Figs. 4-7. Platystrophia unicostata (Jumiugs, p. 433. 



4. Pedicle valve. The specimen has only two plications in the sinus. 

 Maysville group (Bellevue member), Madison, Indiana. 



5. Cardinal A-iew showing the somewhat extended cardinal extremes. 

 Mays\ille group, Southeastern Indiana. 



6. Brachial valve. The high compressed fold ln-aring weak lateral plioations is 



typical . 

 Maysville group, Lebanon, Kentucky. 



7. Anterior view showing the characteristic profound sinus. 

 Corryville, Cincinnati, Ohio. 



Figs. 8-10. Platystrophia unicostata crassiformis, new variety, p. 434. 



S. Anterior view. Showing the presence of one strong and two weak plications 

 in the sinus. 



9. Brachial valve. The high compressed fold is characteristic. 



10. Pedicle valve. 



These specimens show the typical narrow valves. 

 Mayesville group (Bellevue member), Madison, Indiana. 

 Figs. 11-13. Platystrophi'a laticosta (Meek), p. 432. 



11. Anterior view. The high fold and profound sinus are typical. 

 Maysville (Bellevue), Oldham County, Kentucky. 



12. Pedicle valve. 



13. Brachial valve showing weak plications on the slopes of the fold. 

 Maysville (Corryville beds), Cincinnati, Ohio. 



Figs. 14-16. Platystrophia cypha, variety. 



14. Anterior \'iew. 



15. Pedicle valv(\ 



16. Brachial valve. 



Richmond group (Waynesvill< ), Madison, Indiana. 

 FiG.s. 17-20. Platystrophia cypha tumida, new variety, p. 436. 



17. Brachial valve. 



18. Pedicle valve. 



19. Anterior view showing the great depth of the sinus. 



20. Cardinal view. The tumid appearance is characteristic. 

 Jiichmond group (Arnheim formation). Southeastern Indiana. 



Plate 49. 



All ligures on this plate are natural size. 

 Figs. 1-5. Platystrophia ponderosa Fo< rste, p. 427. 



1. Cardinal view of an immature specimen. 



3. Pedicle valve of an immature specimen. 

 5. Pedicle valve of a mature specimen. 



Maysville group (Bellevue). Madison. Indiana. 



2. Brachial valve of a specimen which is referred to this species. 

 Maysville group (Leipers formarion), I>eipers Creek, Tennessee. 



4. Interior view of pedicle valve. 



Maysville group, Oldham County, Kentucky. 



