attaching fold of the peritoneum is frequently called the suspensory 

 ligament. The peritoneum, or coelomic epithelium, can be dis- 

 sected easily from the surface of the liver or the kidney and its 

 extreme thinness and delicacy noted. It consists of a single layer 

 of cells. 



Most of the abdominal organs are suspended from the dorsal 

 wall of the body cavity by delicate membraneous sheets, or mesen- 

 teries. Similar sheets between the organs are the ornenta. The 

 stomach is suspended by a mesogaster, which extends as a free fold 

 along the body as far as the anterior mesenteric and lienogastric 

 arteries. It encloses these, and is attached to the spleen, pancreas, 

 stomach, and anterior end of the intestine. 



The spleen is connected with the stomach by the gastro- splenic 

 omentum, formed by an extension of the peritoneal coat of the 

 stomach around the spleen. The liver is connected to the loop of 

 the stomach by the gastro-hepatic omentum in which are the hepatic 

 duct, portal vein, and hepatic artery. Near the stomach it is joined 

 by a fold of the peritoneum from the duodenum, the duodeno-hepatic 

 omentum, which also unites with the mesogaster. 



The rectum and rectal gland are supported by a second median 

 mesentary, the mesorectum. 



In Eugaleus the mesentery extends the entire length of the abdominal 

 cavity. It forms a broad sheet attached to the anterior end of the proximal 

 limb of the stomach (mesogaster) , to the anterior end of the intestine (mesen- 

 tery proper), and to the rectum (mesorectum). There is not the reduction of 

 the mesentery which there is in Squalus. The gonads are suspended from the 

 lateral faces of the mesentery above the stomach and intestine. The gastro- 

 hepatic omentum forms a broad sheet between the limbs of the stomach, join- 

 ing the mesogaster dorsal to the stomach and the mesentery above the intestine. 



A small division of the right lobe of the liver stands out be- 

 tween the main lobes. In this is located a long, narrow gall-bladder. 

 Open the bladder by a longitudinal ventral incision. The opening 

 into the bile-duct will be found near the anterior end of the bladder. 



In Eugaleus, which does not possess such a median lobe, the gall-bladder 

 lies hidden in the right lobe of the liver. It can be opened and explored, but 

 the connection with the duct can usually be demonstrated only by scraping. 

 Do this later. 



The bile-duct passes along the dorsal side of the gall-bladder 

 and the edge of the gastro-hepatic and duodeno-hepatic omenta to 

 the junction of the duodenum and large intestine, where it opens 

 into the alimentary canal. Trace its oblique course through the wall 

 of the intestine. The bile duct and the collecting (hepatic) ducts 

 of the liver will be traced in the liver at a later stage of the dissec- 

 tion. 



The pancreas consists of two lobes; a slender lobe lying dorsal 

 to and parallel with the stomach, and a flattened oval lobe lying 

 upon the ventral surface of the duodenum, connected with the dorsal 

 lobe by a slender bar of glandular tissue. 



The pancreatic duct passes from the extreme right end of the 

 duodenal lobe obliquely through the wall of the intestine, opening 

 into the anterior end of the large intestine. Free the edge of the 

 lobe from the peritoneum and follow the duct. 



Open the proximal limb of the stomach by a ventral incision 

 which shall not cut any large blood vessels. Wash out the in- 

 terior. Observe the three coats of the stomach; the outer peritoneal, 

 the middle muscular, and the inner mucous coats. In the anterior 

 portion of the stomach the mucous coat projects in the form of large 

 papillae (absent in Eugaleus). Posterior to these, observe the irreg- 

 ular folding of the mucous coat, depending upon the degree of con- 

 traction of the muscular coat. 



