EXPLANATION OF PLATE XLVII. 



EXOGYRA COSTATA Say, p. 45& 



1. View of a nearly perfect valve. 



Navesink marl; Cross-wicks Creek, (146"). 



EXOGYRA PONDEROSA Roemer, p. 458 



2. View of a nearly perfect valve. 



Marshalltown clay-marl; near Sivedesboro, (/77). 



EXOGYRA sp., T p. 460 



3. View of an internal cast of a lower valve. 



Merchantville clay-marl; Lenola, (163). 



OSTREA CONGESTA Con., p. 435 



4. View of the internal cast of an attached valve. 



Cliffivood clay; Cliffwood, Point, (105). 



976 



