PLATE XVII. 



(Figures 1-15, lS-29, 33-46 by K. P. VVhitfikm); 16, 31, 3-2 by F. B. Meek; 47-51 copies.) 



Legend. A. Cardinal area. j. Cardinal process. 



D. Deltidiiim, pedicle-valve. . v. Brachial ridges. 



C. Deltidium, brachial valve. a. Anterior adductors, 



t. Teeth. a'. Posterior adductors, 



b. Dental sockets. r. Diductors. 



Genus PKODUCTELL.'V, Hall. 



Page 323. 



Pkoductella subaculeata, (Murchibon) Hall. 



Fig-. 1. The exteiioi" of a pedicle-valve. 



Corniferous limestone. Falls of the Ohio. 

 Fig-. 2. The interior of a brachial valve ; showing the cardinal process. 



Corniferous limestone. East Vkior, N. Y. 



Pkoductella spinulicosta, Hall. 



Figs. 3, 5. Two views of a pedicle-valve. 



Corniferous limestone. Limisville, Kentucky. 

 Fig. 4. The exterior of a pedicle-valve. 



Marcellus shales. Western Neio York. 

 Fig. 6. A pedicle-valve referred with doubt to this species. 



Yellow san<lstoneg. Burlington, lovxi. 



Pkoductella Shumardiana, Hall. 



Fig. 7. A pedicle valve with distinct spinfei-ous costa;. This figure is from one of the original specimens 

 of the species.  • 



Yellow sandstones. Burlington, lovM. 



Pkoductella navicella, Hall. 



Figs. 8, 9. Views of the interior and exterior of the pedicle-valve. 

 Hamilton group. Westen-n Nno York. 



Genus STROPHALOSIA, King. 



(See Plates XVb, XVI.) ' 

 Page 314. 



Stkophalosia truncata, Hall. 



(See Plate XVb, fi-s. 24-26.) 

 Fig. 10. The interior of a brachial valve ; showing the cardinal process. 

 Fig. 11. The exterior of a brachial valve ; showing the convex umbo corresponding to the truncation of the 



apex of the opposite valve. X 2. 

 Figs. 12, 13. Two views of a pedicle-valve ; showing the truncation of the l)eak. X 2. 



Marcellus shales. Westein New York. 



Fig. 14. An impression of the external surface of the brachial and part of the pedicle-valve ; showing the 

 cardinal ai'eas and minute deltidia. X 2. 



Hamilton group. Near Tally, N. Y. 

 Pig. 15. An enlargement of the carilinal process; showing its simple, uncoalesced lobes. X 6. 



Marcellus shales. Western New York. 



Genus PKODUCTELLA, Hall. 



Page 328. 



Pkoductella subalata, Hull. 



Fig. It5. Exterior of the pedicle-valve; from one of the original specimens. 

 Hamilton group. Sock Island, Illinois. 



