PLATE XXXVI 



PAGE 



Figs. 1, 2. MOUIOLUS SEDESCLARUS Gardner n. sp 616 



1. Exterior of right valve. 



2. Dorsal view of double valves. 



Monmouth formation, Brightseat, Prince George's County. 



Pig. 3. MODIOLUS TBIGONUS Gardner n. sp 616 



Exterior of left valve. X 2. Monmouth formation, Brooks' Estate 

 near Seat Pleasant, Prince George's County. 



Figs. 4-6. LITHOPHAGA RIPLEYANA Gabb 618 



4. Cast of double valves from right side. 



5. Front view of same. 



Matawan formation, Post 198-199, Chesapeake and Delaware 

 Canal, Delaware. 



6. Aggregation of casts. Matawan formation, Camp Fox, Chesapeake 



and Delaware Canal, Delaware. 



Figs. 7-9. LITHOPHAGA CONCHAFODENTIS Gardner n. sp 619 



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



8. Dorsal view of same. X 3. 



9. Left valve in situ. 



Monmouth formation, Brightseat, Prince George's County. 



Figs. 10, 11. LITHOPHAGA JUIXE (Lea) 620 



10. Double valves from right side. X 2. 



11. Front view of same. X 2. 



Monmouth formation, Brightseat, Prince George's County. 



Figs. 12, 13. LITHOPHAGA TWITCHELLI Gardner n. sp 622 



12. Double valves from right side. X 1%. 



13. Front view of same. X l 1 /^. 



Monmouth formation, railroad cut 1 mile west of Seat Pleas- 

 ant, Prince George's County. 



Fig. 14. LITHOPHAGA LINGUA Gardner n. sp 621 



Exterior of left valve. X 3. Monmouth formation, Brightseat, Prince 

 George's County. 



Fig. 15. LIOPISTHA PROTEXTA Conrad 636 



Exterior of left valve. Monmouth formation, Brightseat, Prince 

 George's County. 



Figs. 16-18. CRENELLA SERICA Conrad 624 



16. Exterior of left valve. X 6. 



17. Interior of same. X 6. 



18. Dorsal view of double valves. X 6. 



Monmouth formation, Brightseat, Prince George's County. 



Fig. 19. CRENELLA ELEGANTULA Meek and Hayden 625 



Cast of left valve. Monmouth formation, Brightseat, Prince George's 

 County. 



Figs. 20, 21. SOLYMA LINEOLATA Conrad 701 



20. Double valves from left side. 



21. Dorsal view of same. 



Chatfield, Navarro County, Texas, U. S. National Museum. 



932 



