196 



DR. P. CHALMERS MITCHELL ON THE 



is not sharply marked off, although in the diagram (text-fig. 8) * 

 this want of separation is exaggerated. Meckel's tract is com- 

 posed of a number of very closely packed minor loops suspended 

 at the periphery of an oval expanse of mesentery. Its distal 

 portion bends sharply up towards the dorsal line, and then 

 bends downwards as if it had been dragged out of place by 

 the enormous caecum. The ctecum is relatively, and in a full- 

 sized Koala possibly absolutely, the longest csecum of any 

 mammal. At its proximal end its cavity is directly, continuous 



Text-figure 8.- 



Intestinal tract of Fhascolarctos cinereus. 



S. Cut proximal end of duodenum. R. Cut distal end of hind-gut. C.C. Caecum. 

 C.L. 1. Colic loop {ansa coli dextra). C.L.2. Colic loop {ansa coli sinistra). 

 X.X. Cut ends of caecal blood-vessel. 



with that of the hind-gut, and is many times larger than the 

 cavity of the ileum. It tapers gradually towards its apex. The 

 ileum opens into the doi'sal wall of the CEecum, where the latter 

 is continuous with the hind-gut, by a small round aperture 

 protected by a raised lip. Dr. Mackenzie called my attention to 

 a pair of pouches placed symmetrically on the lateral walls of the 

 gut, jiist where the ciBcum joined the hind-gut. These could be 

 felt before the gut was opened as a paii- of thickenings which 



