PISCES 165 



is produced into the submucous layer to form numerous, 

 simple, tubular gastric glands (fig. 83). The walls of the 

 stomach are strongly muscular. The opening between the 

 stomach and intestine is tightly closed by a constricting 

 ring of muscle, a sphincter muscle. Beyond the pylorus the 

 intestine is narrow for a short distance, and this part of the 

 intestine receives the bile duct from the large trilobed liver and 



Spiracle 



Cer. I Coeliac Post. Rectal 



Rostrum Olf. lobe hem] Gill Sp. cord \ Ant. mes. Tes. mes. gland Kidney 



Mouth Thyroid Heart Liver Stomach Spleen Int. Pel. Cloaca 



Vent, aorta Pancreas 



FIG. 84. Raia. General dissection from left side. 



the pancreatic duct from the pancreas. A gall bladder is 

 situated between the right and middle lobes of the liver and 

 serves as a reservoir for the bile. The pancreas is light yellow 

 in colour and is placed around the pylorus. Beyond this 

 region the intestine expands into a wide tube which leads 

 to the short rectum. Internally the wall is folded in the 

 form of a spiral valve which serves to increase the absorptive 

 area and to give time for digestion and absorption. The 

 terminal end of the intestine, the rectum, is produced into a 

 distinct cylindrical body supported by mesentery, the rectal 

 gland. 



