PLATE LXXX. 
Mytilarca pyramidata. 
Page 256. 
Figs. 1, 2. Left side and anterior view of a cast of the interior. 
Schoharie grit. Schoharie, N. Y. 
Fig. 3. The right side of a specimen, somewhat smaller than the preceding-. 
Schoharie grit. Schoharie, N. Y. 
Leptodesma ? 
Fig. 4. An obscure right valve of undetermined relations. 
Chemung group. Salamanca, N. Y. 
SPHENOTUS (?) UNDATUS. 
Page 506. 
Fig. 5. View of a left valve as obtained from a gutta-percha impression in a natural mould. 
Chemung group. Mansfield, Pa. 
Orthonota rigid a. 
Page 181. 
Fig. 6. A rig-ht valve showing the form and surface markings. 
Chemung group. Near Elmira, N. Y. 
MODIOMORPHA ALTA. 
Page 278. 
See Plate 37. 
Fig. 7. The right side of a distorted specimen. 
Hamilton group. Pratt’s falls, N Y. 
PANENKA MOLLIS. 
Page 420. 
Fig-. 8. A specimen preserving- both valves in conjunction, showing the form and surface characters. 
Marcellus shale. 
Fig-. 9. Cardinal view of a small specimen retaining both valves in conjunction. Doubtfully referred to 
this species. 
Glyptocardia SPECIOSA. 
Page 426. 
See Plate 70. 
Fig. 10. View of a specimen retaining both valves, showing strongly developed surface ornaments, 
enlarged to four diameters. 
Byssopterta radiata. 
Page 252. 
See Plate 32. 
Fig. 11. A large right valve. 
Chemung group. Mansfield, Pa. 
Amnigenia Catskillensis. 
Page 516. 
See Plate 40. 
Fig. 12. The right valve of a very large individual. 
Oneonta sandstone. Pennsylvania. 
