PLATE XXX 



PAGE 



Figs. 1, 2. GRYPH^EA (PYCNODONTE) VESICULARIS (Lamarck) Race B 576 



1. Exterior of left valve. 



2. Exterior of right valve of same individual. 



Matawan formation, Camp Fox, Chesapeake and Delaware 

 Canal, Delaware. 



Figs. 3, 4. GRYPH^EA (PYCXODONTE) VESICULARIS (Lamarck) Race indet. 



3. Exterior of immature right valve. X 2. 



4. Interior of same, showing excentric posterior adductor of young. 



Monmouth formation, Brooks' Estate near Seat Pleasant, 

 Prince George's County. 



926 



