PLATE LI I 



PAGE 



Figs. 1-4. DALMANELLA TIOGA (Hall) 569 



1. Small ventral valve. 



2. Cast of interior of ventral valve. 



3. Cast of interior of dorsal valve showing muscular scars. 



4. Portion of surface of preceding. X 4. 



Jennings formation, Chemung member, Ellerslie, Penna. 

 Figs. 1, 2, at 1316. Figs. 3, 4, at 1474. 



Fig. 5. DALMAXELLA CARINATA (Hall) 570 



Cast of interior of dorsal valve. Jennings formation, Chemung mem- 

 ber, west of Ellerslie, Penna. 



Fig. 6. DALMAXELLA sp 572 



Ventral valve. X 3. Jennings formation, Chemung member, National 

 Road, Polish Mountain. 



Figs. 7-11. RHIPIDOMELLA VAXUXEMI (Hall) 572 



7. Ventral valve. Hill south of Potomac River, 2% miles southeast of 



Cumberland. 



8, 9. Ventral and dorsal valves. Hinge line is shorter and cardinal 



angles more acute than in fig. 7. Same locality. 



10. Enlargement of interior of dorsal valve showing hinge. X 2. 



Williams Road, Polish Mountain, 1371. 



11. Cast of interior of ventral valve showing muscular scars. Base of 



Parkhead member, hill south of Turners Run Road, 9 miles 

 southeast of Cumberland. 

 Jennings formation, Parkhead member. 



Figs. 12, 13. RHIPIDOMELLA VAXUXEMI VAR. 



12. Ventral valve. 



13. Cast of interior of dorsal valve. 



Jennings formation, base of Parkhead member, B. & O. R. R. 

 cut, Rocky Run, 7 miles southeast of Cumberland. 



Figs. 14-18. SCHIZOPHOKIA STRIATULA (Schlotheim) 572 



14. Cast of interior of ventral valve of an unusually large individual 



showing deep muscular scars. Western Maryland Railroad, 2 

 miles west of Pawpaw, 1300. 



15. Cast of interior of ventral valve. Same locality as preceding. 



16. Cast of interior of dorsal valve, preserving striae. Yellow Springs 



Road, 3 miles east of Berkeley Springs, West Virginia, 660 feet 

 west of beginning of section. 



17. Cast of interior of dorsal valve. National Road, west of Tonoloway 



Ridge. 



18. Cast of interior of ventral valve of young individual. Same 



locality as fig. 16. 310 feet west of beginning of section. 

 Jennings formation, Woodmont member, Ithaca fauna. 



135 



