



Microns 



200 



Figure 202. — Two cross sections of the wall of the stomach of C. virginica under the gastric shield. A — the thickest 

 portion of the shield. Benin, hematoxylin-eosin stain. B — cross section near the periphery of the shield. Osmic 

 acid, iron hematoxylin. The surface of the shield is rough due to embedded and partially ground food particles. 

 Note cross striation of the shield visible in B. 



by Shaw and Battle (1957) in their work on the 

 microscopic anatomy of the digestive tract of this 

 species. 



The function of the shield is to provide a base 

 for grinding of food by the rotating head of the 

 crystalline style. 



ORGANS OF DIGESTION AND FOOD OF THE OYSTER 



CRYSTALLINE STYLE 



The posterior wall of the stomach leads to an 

 elongated outgrowth or sac which extends a con- 

 siderable distance along the ventral arm of the 

 visceral mass (fig. 197, cr.s., and fig. 203) on the 

 antero-ventral side of the adductor muscle. A 



223 



