REPORT OF COMMISSIONERS OF INLAND FISHERIES. 163 



The Pyloric Sac. 



The pyloric sac is irregularly ovate and is considerably flattened 

 laterally. Its cavity is a narrow vertical slit which is partially 

 divided by ridges and pads into an upper and lower chamber and an 

 upper, a middle, and two lower canals. 



The opening from the pyloric sac into the intestine is guarded by 

 four valves: The dorsal pyloric valve or "funnel"* is a pen-point 

 shaped plate which reaches far into the intestine and partly separates 

 the intestinal caecum from the remainder of the intestinal cavity. 

 The right and left lateral pyloric valves are triangular plates fringed 

 with bristles and attached to the sides of the gastro-intestinal open- 

 ing. They enclose a narrow passage which leads upward into the 

 concavity of the dorsal valve. The ventral pyloric valve is a broad 

 triangular horizontal plate which is separated from each lateral valve 

 by a deep sinus and whose upper surface is covered with bristles. 

 The wall of the intestine is attached to the bases of the dorsal and 

 lateral valves, to the edge of the sinus between the lateral and 

 ventral valves, and to the edges of the ventral valve. The intestinal 

 caecum is a broad pear-shaped evagination of the intestinal wall. It 

 extends upward and forward over the posterior part of the dorsal 

 wall of the stomach. The tubular duct of each half of the liver or 

 digestive gland, an immense compound tubular gland, opens into the 

 intestine between the ventral and the corresponding lateral pyloric 

 valve. Jordan has shown that the finely comminuted food from 

 the lower canal of the pyloric sac passes into the liver and is there 

 digested and absorbed. 



The dorsal surface of the pyloric sac is directed upward and back- 

 ward, and is divided into two convexities and one concavity. The 

 anterior convexity is formed by the pyloric and the anterior dorso- 

 lateral pyloric plates, and it forms the roof of the upper pyloric 



*That the funnel is not an essential structure is shown by the fact that a perfectly well, actively 

 feecUng lobster examined by us had lost the funnel. It probably acts as a valve to prevent the 

 return of material to the stomach as is shown by the fact that it is sometimes found 'drawn 

 down across the mouth of the middle canal. 



