AJYATOMY OF THE GAT. 565 



The abdominal cavity contains the principal reproduc- 

 tive, excretory, and digestive organs. The a3sophagus ter- 

 minates in the stomach almost immediately below the dia- 

 phragm. The stomach {St) occupies a transverse position, 

 its larger {cardiac) end, which receives the esophagus, lying 

 on the left, the smaller {pyloric) end on the right. The 

 pylorus is furnished with a sphincter muscle, a ring of 

 fibres, which can completely close the orifice by their con- 

 traction. The stomach is followed by the long, coiled 

 small intestine {In). The posterior portion of the intestine 

 is somewhat dilated, and is called the colon, which passes 

 into the wide terminal rectum {R). The whole abdominal 

 portion of the intestinal canal is suspended from the me- 

 dian dorsal line by a thin membrane, the mesentery, which 

 forms several folds, the most striking of which is the omen- 

 tum or grand epiploon {Om.). This fold, when in situ, 

 hangs down from the stomach like an apron, covering over 

 the intestines ventrally. Upon opening the walls of the 

 abdomen, it is the first structure met with. It usually con- 

 tains a great deal of fat. Its principal function is supjDosed 

 to be to prevent the loss of heat. The omentum is present in 

 all mammals, but is least developed in Cetaceans, being most 

 prominent in Carnivora and ruminants. Connected with 

 the intestine are two glands, the liver {Li) and pancreas 

 {Pan). The liver is large and lies directly underneath 

 the diaphragm. One part of it has been cut across and 

 left in situ to show the oblong gall-bladder {G). The 

 pancreas is very much elongated and lies upon the upper 

 part of the intestine, the. so-called duodenum. The spleen 

 {Sjj) is closely connected with the stomach, and is of an 

 elongated shape, as in the majority of the Mammalia mono- 

 delpJt ia. 



The kidneys {K) are large and oval, and lie on either 

 side of the vertebral column ; the aorta passes between 

 them, giving off a renal branch to each gland. A delicate 

 ureter passes from each kidney obliquely across the rectum 

 to the large flask-shaped bladder {B). A urethra, not 

 shown in the figure, arises from the bladder posteriorly and 



