PLATE 54. 



Rensselaerina medioplicata var. lalior Dunbar (?) 

 Page 197. 



Fig. 1. Ventral view of a portion of a shell. 



Fig. 2. A portion of a ventral valve. 



Fig. 3. Interior of a fragment of a dorsal valve. 



Fig. 4. Interior of a part of a ventral valve. 



Pteronitella (?) sp. 

 Page 205. 



Fig. 5. Internal cast of a portion of a left valve — the only specimen observed. 



Conocardium sp. 

 " Page 205. 



Fig. 6. The one specimen — an internal cast of a part of a left valve. 



Aviculopecten (?) umbonata (Hall) (?) 

 Page 205. 



Fig. 7. An incomplete left valve that retains portions of the shell. 

 Fig. 8. A portion of a left valve. 



Cypricardinia distincta Billings (?) 

 Page 206. 



Fig. 9. The single specimen — an imcomplete left valve. 



Platyceras pentalobus Hall. 

 Page 207. 

 Fig. 10. Ventral view. 

 Fig. 11. Upper view. 

 Fig. 12. Upper view. 



Figs. 13-15. Upper, lower, and ventral views. 

 Figs. 16, 17. Upper and lower views. 

 Figs. 18-20. Upper, lower, and ventral views. 



Platyceras sp. 

 Page 207. 



Figs. 21, 22. Upper and dorsal views of the partially exfoliated individual. 



Platyceras (?) sp. 

 Page 207. 



Figs. 23, 24. Dorsal and ventral views of the specimen. 



Diaphorostoma sp. 

 Page 207. 



Figs. 25, 26. Upper and ventral views of the single representative — an internal cast. 



Goldius barrandii Hall 

 Page 208. 



Fig. 27. The sole specimen — -a portion of a pygidium. 



