PLATE XXXVII 



PAGE 



Figs. 1-3. PHOLADOMYA OCCIDENTALIS Morton 630 



1. Cast of double valves from left side. 



2. Same from right side. 



3. Dorsal view of same. 



Matawan formation, Post 218, Chesapeake and Delaware 

 Canal, Delaware. 



Figs. 4, 5. CUSPIDARIA CUCURBITA Gardner n. sp 641 



4. Cast of double valves from right side. X 3. 



5. Dorsal view of same. X 3. 



Matawan formation, % mile southwest of Ulmstead Point, 

 Anne Arundel County. 



Figs. 6, 7. CUSPIDARIA AMPULLA Gardner n. sp 640 



6. Cast of double valves from left side. X 3. 



7. Dorsal view of same. X 3. 



Monmouth formation, Brightseat, Prince George's County. 



Figs. 8-11. DREISSENA TIPPANA Conrad 628 



8. Exterior of left valve. 



9. Exterior of right valve. 



10. Anterior view of double valves. 



11. Interior of left valve. 



Monmouth formation, Brightseat, Prince George's County. 



