1873.] ANATOMY OF AULACODTJS. 787 



few irregular rugae. No ridges of mucous membrane run along the 

 lesser curvature from the cardiac to the pyloric orifice. The pylorus 

 is large. 



In the duodenum the pyloric extremity is much dilated pyriformly 

 as in many Rodents. The mucous membrane becomes velvety, with 

 villi on the duodenal surface of the pyloric valve, and continues so 

 along the small intestine. The whole small intestine is 5| feet long. 

 The bile and pancreatic ducts open by an orifice 2 inches from the 

 pylorus and another a few inches further down. 



In the large intestine the caecum is 8 inches in length, and the 

 intestine itself an inch over 4 feet. It is peculiar amongst the allied 

 Rodents in that the caacum and colon are directly continuous, no 

 abrupt change of direction occurring at the junction with the ileum ; 

 and what is more, the sacculation on two longitudinal bands observed 

 through the whole length of the caecum is continued for some distance 

 along the colon, without any marked change of character, except size. 

 However, the two longitudinal bands which sacculate the caecum are not 

 those which do the same to the colon; for opposite the ileo-caecal valve, 

 which is a simple projection of thesmall into the large intestine forone 

 sixth of an inch, much like that in the horse, one of the caecal bands 

 splits into two, part going to join the other band, and part continuing 

 on as an independent band. The small intestine joins the large, not, 

 as is sometimes the case, at one of the bands, but in the middle of one 

 of the sacculi, halfway between two of them. The diameter of the 

 colon is less than that of the caecum, and diminishes gradually till it 

 becomes scarcely greater than that of the ileum. The sacculation 

 continues, getting less and less marked, for about a foot from the ileo- 

 caecal valve ; and the rest of the long colon is uniformly cylindrical, 

 presenting the well-known abrupt bend near the middle of its course. 



The caput of the caecum is situated in the right lumbar region, and 

 the base in the left lumbar, where an abrupt bend backward occurs 

 just before the small intestine enters. The omentum is not large, 

 and does not cover the viscera. There is little or no fat in the ab- 

 domen. 



On opening the caecum and large intestine along its non-mesenteric 

 longitudinal band, two strongly marked longitudinal ridges are seen 

 to run from the ileo-caecal valve along the colon, one on each side of 

 the inner surface of the mesenteric longitudinal band, which is the 

 compound one formed by one division of the bifurcate caecal longi- 

 tudinal band and the other caecal band. These ridges diverge at 

 first and are afterwards separated by an interval of two thirds of an 

 inch. For the proximal diverging 2 inches they are simple ; but after 

 that they are puckered regularly in exactly the same way as M. A. 

 Milne-Edwards has figured the gastric cardio-pyloric ridges in Lo- 

 phiomys, which they also resemble in general direction and arrange- 

 ment. These puckered ridges, after diverging, again approach till 

 within one fourth of an inch of one another, after which they con- 

 tinue parallel for a little more than 2 feet, where, just after the 

 sharp colic bend, they suddenly cease, joining one another just before 

 doing so. The puckering, however, does not continue the whole wav, 



50* 



