442 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.56. 



Figs. 44-47. Platystrophia elegantula, new species, p. 410. 



44. Pedicle valve. The multiplicate sinus is characteristic. 



45. Cardinal view showing the short hinge. 



46. Brachial valve. The outer plications are shown to curve. 



47. Anterior view. This species has a low rounded fold and broad sinus. Thes** 



specimens show the characteristic multiplicate sinus. 

 Trenton group (Bigby limestone), Frankfort, Kentucky. 

 Fig. 48. Platystrophia elegantula triplicata, new variety. p. 411. 



48. Pedicle valve showing the presence of only three plications in the sinus. 

 Trenton limestone, Ellisburg, New York. 



Fig. 49. Platystrophia elegantula aniplisulcata, new variety, p. 411. 



49. Pedicle valve with seven plications in the sinus. 

 Trenton group (Bigby limestone), Frankfort, Kentucky. 



Fig. 50. Portion of the outer surface of a Platystrophia morrotvensis James, showing 

 the granular character. 



Pl,.\TE 44. 



All tigures on this plate are natural size. 

 Figs. 1-4. Platystrophia precursor Foerste, p. 415. 



1. Brachial valve. This figure shows the subequal plications on the fold. 



2. Pedicle valve. The broad sinus is typical. 



3. Anterior view showing the broad, moderately deep sinus. 



4. Cardinal view showing the equiconvex valves. 

 Trenton group (Catheys formationV Nashville, Tennessee. 



Figs. 5-7. Platystrophia precursor latiformis, new variety, p. 415. 



5. Cardinal view showing the long hinge line. 



6. Pedicle valve. The triplicate plication pattern is well shown. 



7. Brachial valve. 



Trenton group (Catheys formation^ Nashville, Tennessee. 

 Figs. 8-11. Platystrophia colhiensis Foerste, p. 414. 



8. Brachial valve of an average individual. 



9. Pedicle valve of an average individual. 



Trenton group (Catheys formation), Edgefield Junction, Tennessee. 



10. Pedicle valve of a large specimen. 



11. Brachial valve of same specimen. 



Trenton group (Catheys formation), Nashville, Tennessee. 

 Fig. 12. Platystrophia colhiensis mutata Foerste, p. 414. 



12. Pedicle valve showing five plications in the sinus. 

 Trenton group, 4 miles east of Mount Pleasant, Tennessee. 



Figs. 13-16. Platystrophia precursor angusta, new variety, p. 416. 



13. Brachial valve of a specimen which is referred to this variety. 

 Trenton group fProsser limestone^ TIader, Goodhue County, Minnesota. 



14. Pedicle vahe showing the typical narrow form. 



15. Brachial valve of another specimen. 



16. Anterior \aew. The figure shows the thick valves. 

 Trenton group (Catheys formation), Nashville, Tennessee. 



Figs. 17-20. Platystrophia precursor profunda, new ^•ariety, p. 415. 



17. Pedicle A^alve. The figure shows a deep sinus. 



18. Brachial valve. The broad fold is characteristic. 



19. Cardinal view showing the brachial valve to be deeper than the pedicle valve. 



20. Anterior view. The deep sinus is characteristic. 

 Trenton group (Catheys formation), Nashville, Tennessee. 



