PLATE LXXIV 



PAGE 



Figs. 1-4. MERISTELLA PR^ENUNTIA Schuchert n. sp 443 



I. Dorsal view. 



2-4. Dorsal, side, and ventral views of a large and gibbous specimen. 

 Helderberg formation, Keyser member, Keyser, W. Va. 



Figs. 5-8. MERISTELLA ARCUATA (Hall ) 444 



5, 6. Dorsal and side views. 



7. Anterior view to show depth of ventral sinus. 



8. Small ventral valve. 



New Scotland formation, New York. 



Figs. 9-11. MERISTELLA LATA (Hall) 445 



9, 10. Ventral view of different specimens. 



II. Dorsal view of another specimen. 



Oriskany formation, Ridgely member, Warren Point, Penna. 



Figs. 12, 13. MERISTELLA LENTIFORMIS Clarke 446 



Dorsal and side views of type. Oriskany formation, New York. 



Figs. 14, 15. MERISTELLA ROSTELLATA Schuchert n. sp 447 



Dorsal and ventral views of type. Oriskany formation, Ridgely mem- 

 ber. Cumberland. 



Figs. 16-19. MERISTELLA SYMMETRICA Schuchert n. sp 448 



16, 17. Dorsal and side views of a small individual. 



18. Ventral view of a large specimen. 



19. Ventral view of an unusually large specimen. 



Oriskany formation, Ridgely member, Cumberland. 



Figs. 20-24. MERISTA TYPA (Hall) 449 



20. Dorsal view. 



21. 22. Interiors of ventral valves. 



23. A longitudinal section of fig. 22. 



24. Internal cast of ventral valve. 



Helderberg formation, Keyser member, Cumberland.* (After 

 Hall.) 



