207 



EXPLANATION OF PLATE 4 

 Figure Page 



17. rteria colymbus (Roding) 41 



18. Pinctata radiata (Leach) 41 



19. Crassostrea virginica (Gmelin) 43 



20. Ostrea frons Linne 42 



21. Ostrea cristata Born 43 



22. Ostrea pemiollis Sowerby 43 



