PLATE XII. 



Nemodon brevifrons Courad 



Fig. 1. View of a specimen identified and labeled by Mr. Courad, from Haddoufield, N. J. 

 2. Eularged view of the hinge of the same. 



Nemodon Eufaulensis Gabb 



Fig. 3. View of a partial cast from the limestone nodules of the Lower Marls at Holmdel, 

 N.J. 



4. Enlargement of the hinge of the same. 



5. Enlargement (two diameters) of a specimen from Haddoufield, N. J., one of the 



types. 



Nbmodon angulatum Gabb 



Fig. 6. View of the type specimen, natural size. 

 7. Enlarged cardinal view of the same. 



Nemoarca Cretacea Conrad 



Fig. 8. Enlargement to two diameters of a cast from the iron nodules from Keyport, N. J. 



9. View of the exterior (tiiree diameters) of one of the type specimens. 



10. Diagram of the hinge of the same. 



Breviakca Saffordi Gabb 



Fig. 11. View of the exterior, natural size, of one of the type specimens, from Haddoufield, 

 N. J. 

 12. Enlargement of the hinge of the same. 



Arca (Trigonarca) transversa Gabb 



Fig 13. Left side of a specimeD from Mullica Hill, N. J. 



14. Right view of Mr. Gabb's type specimen. 



15. Cardinal view of the same. 



16. View of a small cast, more angular on the umbonal ridge than the others, and 



showing the hinge features. 



Tkioonarca cuneipormis Conrad 



Fig. 17. Enlarged view of the exterior of the type specimen, Haddoufield, N. J. (seven 

 diameters). 

 18. Outline view of the interior of the same equaJly enlarged. 



Idonearca Tippana Conrad 



Fig. 19. View of the cast of a left valve from the deep cut of the Holmdel and Keyport 

 ■ turnpike, N. J. 



20. Outline profile of the same, showing convexity. 



21. Inside of a valve from near Prairie Bluff, Ala., to show the hinge features. 

 Abca altirostris Gabb 



Fig. 22. Bight view of the original type of the species. 

 23. Cardinal view of the same. 



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