REPORT OF COMMISSIONERS OF INLAND FISHERIES. 167 



mediate pyloric plate to the corresponding edge of the lower inter- 

 mediate pyloric plate. 



The inferior pyloric dilator muscle has a double origin and a double 

 insertion. One head arises from the cephalic apodeme near the oeso- 

 phagus ; the other head arises from the lower ventro-lateral cardiac 

 bar. These bands, passing backward, unite, and then the muscle 

 divides : One branch is inserted on the anterior surface of the lower 

 intermediate pyloric bar; the other, uniting with the corresponding 

 muscle from the other side, is inserted upon the median portion of 

 the ventral pyloric plate. 



Before attempting to explain the action of this extremely com- 

 plicated stomach it is well to summarize briefly the facts described 

 in detail above. 



The bristles of the cardiac sac are all directed toward the gastric 

 mill with the apparent exception that those of the lower part of the 

 side walls are directed downward and backward. 



All the bristles of the pyloric sac except those of the lower and 

 middle canals are also directed toward the gastric mill. 



The alternate contraction and expansion of the anterior, posterior, 

 and postero-lateral gastric muscles (assisted feebly by the cardio- 

 pyloric muscle and the elasticity of the stomach wall) cause the 

 median tooth to move back and forth across the surfaces of the 

 lateral teeth and also cause the lateral teeth to move inward. 



The contraction of the lower lateral constrictor pushes the lower 

 lateral pad inward and backward. 



The cardio-pyloric valve is practically hinged upon the posterior 

 ends of the ventro-lateral cardiac bars, and we believe that it is driven 

 forward and upward by the contraction of the upper and middle 

 lateral cardiac constrictors. 



Again, we must remember that the upper cardiac canal leads 

 along the base of the cardiac sac to the beginning of the lower pyloric 

 canal. This canal passes along the base of the pyloric sac to the 

 lateral pouches, where the coarser particles of the food are separated 

 from the remainder. 



