Fig. 12 Modiolus modiolus; surface of inner wall of the stomach opened 

 from the right side; long arrows indicate direction of ciliary currents on the 

 ridges artd exposed surfaces of the mucosa, short arrows show direction in the 

 furrows and grooves, ct, ciliated tract leading to mouth of caecum; civ, ciliated 

 whorl from which this tract originates; gs, gastric shield; ig, intestinal groove; 

 mc, mouth of caecum; oe, oesophagus; sis, style sac; t ma, major typhlosole; 

 t mi, minor,typhlosole. 



Fig. 13 Lampsilis anodontoides; enlarged view of the secreting cells of the 

 dorsal wall of the style sac. gl, globules of secreted material; mg, mucous 

 gland; st, style. 



Fig. 14 Anodonta grandis; optical section of freshly removed style showing 

 inner spiral core of food materials, and the solution of the head of the style. 



72 



