LEPUS. 385 



fast as they are worn away by use. Just behind the upper 

 incisors is a pair of little peg-like second incisors. Behind 

 the incisors is a part of the jaws with no teeth, forming a 

 space or diastema^ and further back is a row of six flat teeth 

 on each side of each jaw. These are the molar teeth 

 with flattened ridges which serve to crush and masticate 

 the food (various vegetables). The cheeks can be pushed 

 together across the diastema ; and in this way the incisors 

 may be used on occasion for gnawing without the products 

 passing into the oesophagus. 



This peculiar type of dentition is characteristic of the 

 order Rodentia to which the rabbit belongs. 



The oesophagus (see Plate XI.) passes down the neck as a 

 soft tube and emerges through the diaphragm, opening into 

 the large stomach towards the left side. The duodenum forms 

 the usual loop, in which is a diffuse pancreas with a single 

 pancreatic duct passing into the distal limb of the duodenum. 

 The liver is very large and has five lobes. Partially em- 

 bedded in it is the gall-bladder^ from which there passes a 

 bile-duct opening into the proximal limb of the duodenum. 

 After the duodenum, the ileum forms an enormously long 

 (8 feet) and coiled tube of small calibre. It terminates in 

 the sacculus rotundus^ a swollen sac v/hich opens distally into 

 the ccecum. The ccecum is a blind tube of large calibre which 

 terminates in a small process, the vermiform appendix. It 

 is continued, in the opposite direction, into the colon with 

 sacculated walls and is about 18 inches long. It gradually 

 loses its sacculation and passes into the rectum^ a thin- walled 

 tube about two feet long terminating in the anus. 



The large size of the caecum (about two feet long) and 

 great length of the intestine are usually correlated with a 

 herbivorous diet. 



The duodenum and ileum are the two portions of the 

 small intestine, the colon and rectum forming the ** large 

 intestine." The spleen is, as in other types, a dark-red body 

 lying near the pancreas and beside the stomach. 



The portal vein, as in preceding types, should be noticed 

 before removal of the alimentary canal. It is formed of a 

 lienogastric from the stomach and spleen, a duodenal and 

 anterior and posterior mesenteries. The organs drained by 

 the portal are supplied with arterial blood by the coeliac, 

 M. 26 



