PLATE LIX 



PAGE 



Figs. 1, 2. SPIBIFEB (DELTHYRIS) MESACOSTALIS Hall 601 



1. Cast of interior of large dorsal valve with greatly extended cardinal 



angles. 1 mile southeast of Sunnyside. 



2. Cast of interior of ventral valve of usual size. X 2. National Road, 



Polish Mountain. 

 Jennings formation, Chemung member. 



Figs. 3-7. AMBOCCELIA UMBONATA (Conrad) 602 



3. Ventral valve. X 2. Polish Mountain. 



4. Dorsal valve. X 2. Same locality. 



5. Internal cast of dorsal valve. X 2. Same locality. 



6. Exterior of ventral valve. X 2. Same locality. 



7. Internal cast of ventral valve. X 2. Near Deer Park. 



Jennings formation, Chemung member. 



Figs. 8-10. ATHYRIS ANGELICA Hall 604 



8. Dorsal valve. 



9, 10. Ventral valves. 



Jennings formation, Chemung member, Allegany Grove, 2941. 



Figs. 11, 12. GRAMMYSIA EIXIPTICA Hall 606 



Two views of a right valve. Jennings formation, Chemung member, 1 

 mile east of Barrelville. 



Fig. 13. GRAMMYSIA SUBARCUATA Hall 606 



Left valve. Chemung formation, New York. 



Figs. 14, 15. GRAMMYSIA COMMXTNIS Hall 607 



Right and left valves. Jennings formation, Woodmont member, Ithaca 

 fauna, Yellow Springs Run Road, 3 miles east of Berkeley 

 Springs, W. Va., 1124. 



Figs. 16, 17. PAL^ANATINA ANGUSTA 609 



16. A small right valve. 



17. Cast of interior of right valve. 



Jennings formation, Chemung member, Town Creek, 4596. 



Figs. 18, 19. SPHENOTUS CONTRACTUS Hall 610 



18. Sculpture cast of left valve. Chemung formation, New York. 



19. Right valve doubtfully determined. Jennings formation, Chemung 



member, Wills Creek Station, Penna. 



142 



