REP(3RT OF COMMISSIONERS OF INLAND FISHERIES. 161 



prevents it from going too far down between the lateral teeth. A 

 little in front and outside of this cusp there is another elevation, 

 the anterior dorsal pad, which is covered with downwardly directed 

 bristles. A deep longitudinal groove extends backward from the 

 lower side of the gastrolith into the lateral tooth. Just below the 

 anterior end of the lateral tooth a deep tubular invagination, whose 

 walls form the upper lateral pad, extends upward in front of the 

 tooth. Behind the infero-lateral tooth, below tlje lateral tooth, and 

 below and behind the preceding pit, is a larger, but shallower, pit, 

 the middle lateral pad. 



The oesophageal opening is guarded by a median and a pair of 

 lateral valves. The median valve is formed by a triangular broaden- 

 ing of the upper end of the vertical ridge of the oesophagus. The 

 lateral walls of the oesophagus are prolonged upward into a ridge-like 

 valve which nearly encircles the oesophageal opening and which is 

 higher on each side than behind the opening. The three valves are 

 covered with a thick pile of long slender bristles which point towards 

 the stomach. 



The anterior constrictor muscle arises from the middle of the man- 

 dibular sternum and, passing backward and slightly upward, is in- 

 serted upon the upper edge of the median oesophageal valve. Its 

 contraction pulls down the anterior wall of the stomach and causes 

 it to fold inward. 



The anterior wall of the stomach is covered with a similar coat of 

 bristles which are inclined in various directions in such a manner 

 that when the anterior folds are pushed inward the bristles point 

 toward the gastric mill. The upper wall of the stomach is smooth, 

 as also is the inner face of the gastrolith. 



Upon the inside of the stomach we find the anterior two thirds of 

 the upper part of the side occupied by the smooth surface of the 

 gastrolith and the posterior one-third by the upper and middle lateral 

 pads. The lower part of the side is formed by a large lateral plate 

 which is bounded below by the upper ventro-lateral cardiac bar, 

 above by the lower intermediate cardiac bar, the infero-lateral tooth, 



