PLATE XLIX 



PAGE 



Figs. 1, 2. DOUVILLINA CAYUTA (Hall) 555 



1. Interior of dorsal valve. 



2. Enlargement of internal cast of dorsal valve. X 2. 



Jennings formation, Chemung member, Oakland and Deer 

 Park. 



Figs. 3-13. DOUVILLINA CAYUTA VAR. GBACILIORA n. var 556 



3. Ventral valve. X 3. 



4. Ventral valve represented somewhat too concave at the umbo. 



5. Ventral valve. 



6. Dorsal view of shell. X 3. 



7. 8. Internal casts of ventral valves. 



9. Dorsal view of a larger specimen. X 2. 

 10. Ventral valve similar to fig. 1. 



11, 12. Upper and profile views of a characteristic ventral valve. X 2. 

 13. Profile view of ventral valve. 



Jennings formation, Chemung member, Deer Park and Oak- 

 land. 



Figs. 14-17. DOUVILLIXA ARCUATA (Hall) 557 



14, 15. Upper and profile views of a typical ventral valve. X 2. From 

 Upper Devonian of Lime Creek, Iowa. (Introduced for com- 

 parison with following.) 



16, 17. Upper and profile views of a ventral valve believed to be of this 

 species. 



Jennings formation, Chemung member, National Road, 6 

 miles west of Frostburg. 



Fig. 18. STROPHOXEIXA CF. REVEKSA (Hall) 557 



The interior of a dorsal valve showing the reversed convexity, cardinal 

 process, hinge and median sinus. Jennings formation, Che- 

 mung member, Trout River, near Oakland. 



Figs. 19-22. SCHUCHERTELLA CHEMUNGENSis (Conrad) 559 



19. Interior of small dorsal valve. Deer Park. 



20. Dorsal valve. Wills Creek Station. 



21. 22. Upper and cardinal views of a ventral valve. Two miles east 



of Oakland. 



Jennings formation, Chemung member. 



132 



