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Figs, la, lb. OsTREA trigoxalis Conrad 381 



la. Exterior of lower valve. Greensboro. x % 

 lb. Interior of the same valve. X % 



Figs. 2-4. OsTREA cAEOLiNENSis Conrad 381 



2. Interior of lower valve. Governor Run. X % 



3. Interior of upper valve. Same locality. X % 



4. Exterior of lower valve. Same locality. x % 



