PLATE XLVIII 



PAGE 



Figs. 1-4. LEPTOSTROPHIA PEBPLAXA VAR. NERVOSA (Hall) 552 



1. The interior of a ventral valve. 



2. Ventral valve showing the character of the surface. 



3. Internal cast of an average ventral valve showing muscular scars 



and denticulate hinge. 



4. Interior of the dorsal valve showing the double cardinal process, 



muscular fulcra, and pustulose patches about the muscular area. 

 Jennings formation, Chemung member, from localities near 

 Deer Park and Oakland. 



Figs. 5, 6. LEPTOSTROPHIA PERPLANA VAR. ALTERNATA n. var 553 



5. Cast of exterior of ventral valve, hinge-line imperfect. 



6. Enlargement of striae. X 5. 



Jennings formation, Chemung member, Town Creek, 2391. 



Fig. 7. LEPTOSTROPHIA INTERSTRIALIS (Vanuxem) 554 



Ventral valve. Striae of shell are less regular than shown and some- 

 what nodose. Jennings formation, Woodmont member, Ithaca 

 fauna, National Road, east of Millstone, 795. 



Figs. 8-17. DOUVILLINA CAYUTA (Hall) 555 



8. A small ventral valve of average proportions. 

 9, 10. Two broader ventral valves. 



11. External cast of dorsal valve. 



12. Dorsal valve. 



13. Interior of ventral valve showing the clearly defined brachial de- 



pressions in front of the muscle scars. 



14. A characteristic internal cast of the ventral valve showing mus- 



cular scars and crenulate hinge. 



15. Internal cast of a larger ventral valve. 



16. Internal cast of ventral valve. 



17. Enlargement of the cardinal portion of the dorsal valve. 



Jennings formation, Chemung member, Deer Park, Oakland 

 and Altamont. 



131 



