PLATE LVI 



PAGE 



Figs. 1-3. CYRTINA HAMJ.LTONENSIS Hall 591 



1. Cast of interior of ventral valve. Chemung member, road from 



Oakland to Deer Park. 



2. Cast of interior of ventral cardinal area. Same locality. 



3. Dorsal valve. X 2. Woodmont member, Ithaca fauna, National 



Road, west of Tonoloway Ridge. 

 Jennings formation. 



Figs. 4-6. RETICULARIA L^EVIS (Hall) 592 



4. Cast of interior of dorsal valve. 



5. Interior of ventral valve. Portage formation, New York. 



6. Cast of interior of ventral valve showing muscular scars. 



Jennings formation, Woodmont member, Ithaca fauna, Na- 

 tional Road, east of Hancock, 690. 



Figs. 7-14. SPIBIFEB DISJTJNCTUS Sowerby 593 



7. Ventral valve. National Road, Polish Mountain. 



8, 9. Ventral valves. Near Deer Park. 



10. Ventral valve with extended cardinal angles. National Road, near 



top of Polish Mountain. 



11. Ventral valve with extended cardinal angles. Near Deer Park. 



12. Interior of dorsal valve. Near Oakland. 



13. Internal cast of ventral valve. National Road, Polish Mountain. 



14. Enlargement of cardinal portion of internal cast of ventral valve. 



X 2. Town Creek, 2122. 

 Jennings formation, Chemung member. 



139 



