PLATE XLIII. 



PAGE 



Figs. 1, la, 2, 2a. Coealliophaga (Oryctomya) bkyani Clark 183 



1. Exterior of right valA^e. 1 mile southeast of Mason Springs. 

 la. Interior of the same specimen. 



2. Exterior of right valve of the type specimen. Pomonkey 



Neck. U. S. National Mnseum. 

 2a. Interior of the same specimen. 



Fig. 3. Pholadomya maeylandica Conrad 184 



Exterior of left valve. Fort Washington. Acad. Nat. Sci. Phila. 



Figs. 4, 5, 5a. Modiolus alabamensts Aldrich 185 



4. Exterior of right valve. Mouth of Paspotansa Creek. 



5. Exterior of right valve. Potomac Creek. 

 5a. Exterior of left valve of same individual. 



Fig. 6. Modiolus maeylandicus n. sp 186 



Dorsal aspect of crushed specimen. Woodstock. 



Fig. 7. LiTHOPIIAGA MAEYLANDICA n. sp 186 



Exterior of left valve of tyj)e specimen. Clifton Beach. 



395 



