PLATE XLVII—Continued. 
Nuculites triqueter. 
Page 326. j 
See Plate 93. 
Fig. 17. A cast of a left valve which is unusually acute at the post-inferior extremity. 
Figs. 18-22. A series of specimens presenting the usual characters of the species. 
Fig. 23. A cast of a left valve showing crenulations on the hinge-line. 
Hamilton group. Cumberland, Md. 
Fig. 24. A gutta-percha impression from the preceding, enlarged to two diameters. 
Figs. 25-28. A series of specimens presenting some variations from the typical forms. 
Nuculites Nyssa. 
Page 328. 
Figs. 29, 30. Left and right valves. 
Hamilton group. Eighteen-mile creek, N. Y. 
Leda diversa. 
Page 329. 
Figs. 31-37. A series of figures showing variation in form and size, enlarged to two diameters. 
Figs. 
Leda breyirostris. 
Page 329. 
38-41. A series of figures illustrating the varieties of form, enlarged to two diameters. 
Leda rostellata. 
Page 330. 
Figs. 42-46. Present the usual varieties of form in this species. The figures are enlarged to two diameters 
Fig. 47. A l-ight valve, enlarged to three diameters. 
Hamilton group. Pratt's falls, N. Y. 
Fig. 
Leda obscura. 
Page 331. 
48. A i-ight valve, enlarged to two diameters. 
Hamilton group. Fultonham, N. Y. 
Leda pandoriformis. 
Page 332. 
Fig. 49. A cast of a right valve. 
Fig. 50. A gutta-percha impression from the preceding showing the characters of the hinge. 
Wavei-ly g-roup. Newark, Ohio. 
Nucula UMBONATA. 
Page 321. 
Figs. 51, 52. Left and cardinal views of a cast. 
Chemung group. Mansfield, Pa. 
SOLEMYA (JANEIA) VETUSTA. 
Page 463. 
See Plate 94. 
Figs. 53-55. Right, left and cardinal views of a characteristic specimen. 
Hamilton group. Near Louisville, Ky. 
