PLATE XVI. 



(Figures 1-16, 18-33, 21-30, 32-U by H. P. Wiittfield ; 17, 31 by F. B. Meek ; M copy.) 



Legend. D. Deltidium, pedicle- valve. j. Cai'dinal process. 



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



St. Cardinal tubes. a'. Posterior adductors, 



t. Teetli. r. Anterior diductors. 



b. Dental sockets. r'. Posterior diductors. 



8. Septum. V. Brachial ridges. 



Genus CHONETES, Fischer de Waldheim. 



(See Plate XVb.) 

 I'agc 303. 



Chonetes cornuta, Hall. 



Fig. 1. A view of the pedicle-valve. X 2. 



Clinton group. Sodiis Bay, JV. Y. 



Chonetes setigera, Hull. 



Fig. 2. A view of the pedicle-valve. X 2. 



Waverly group. PeiifieM, Ohio. 

 Fig. 5. Pedicle-valve of a larger specimen with finer striiE. X 2. 

 Fig. 19. An enlargement of the surface strice of this specimen. 



Marcellus shales. Near Caledonia, N. T. 



Chonetes scitula, Hall. 



(i)Fig. 3. A pedicle-valve, with somewhat moi-e circular outline and longer cardinal spines than usual. X 2. 



Fig. 4. A view of the brachial valve ; showing the cardinal area and deltidium. 



Fig. 27. The interior of a brachial valve ; showing the structure of the cardinal process and the faint 



brachial ridges. X 2. 

 Fig. 32. The interior of the pedicle-valve ; showing the cardinal area and teeth. X 2. 



Hamilton group. Canandaigua Lake, N. T. 

 Fig. 40. An enlargement of the cardinal portion of the valves; showing the hollow spines and the curving 

 coui'se of the spine-tubes through the substance of the cardinal area of the pedicle-valve. X 8. 

 Hamilton group. Westei'n New York. 

 Fig. 44. An internal cast of the pedicle-valve, retaining the filling of the spine-tubes and showing their 

 convergence toward the bealv before reaching the upper margin of the area. X 8. 

 Chemung gi-oup. Cattaraugus county, N. Y. 



Chonetes mucronata, Hall. 



Fig. B. A pedicle-valve with very coarse plications and apparently destitute of spines. X 2. 

 Fig. 7. A pedicle-valve with long, extremely divergent spines. X 2. 

 Marcellus shales. West Avon, N. Y. 



Chonetes acutiradiata, Hall. 



Fig. 8. The pedicle-valve. 



Corniferous limestone. WiUiamsviUe, N. Y. 



Chonetes Logani, Norwood and Flatten, var. Aurora, Hall. 



Fig. 9. Pedicle-valve, enlarged to show the fine concentric strise. X 3. 

 Fig. 18. An enlargement of the surface. 



Tnlly limestone. Tully. N. Y. 



