ANATOMY OF THE THREE-TOED SLOTH. 165 



The Duodenum (text-fig. 11, A). 



I have nothing to add to those descriptions of the macroscopic 

 appearances which have already been published. I must, how- 

 ever, record the conditions of the bile and pancreatic ducts 

 which differ from those mentioned by Francaviglia (4). The 

 pancreatic duct opens into the duodenum 2*9 cm. distal to the 

 pylorus ; it is situated on a papilla. At a point I'l cm. posterior 

 to the pancreatic papilla there is a large bile papilla, and 2*7 cm. 

 posterior to the latter there is a small papilla for the duct of an 

 isolated mass of pancreatic tissue. All the papillae lie on trans- 

 verse folds of mucosa. 



The entire duodenal mucosa is thrown into circular folds 

 which are large at the pyloric end, and small and numerous at 

 the jejunal end. 



The Jejunum and Ileum. 



Dr. Chalmers Mitchell (8) has described the macroscopic 

 appearances in B. inf meatus, and mentions the presence of a 

 large caacal pouch and a small rudimentary caecum opposite to it. 

 The latter Is not present in my specimen, but the remainder of 

 the intestine is the same as that described in Dr. Mitchell's 

 paper. There is no ileo- caecal valve. 



The mucosa exhibits alternating smooth and rugose areas 

 (Plate IV. B, A & b), and there is a strong development of rugae 

 at the posterior end of the ileum. 



The Large Intestine. 



In Plate IV. A, c & D, the entire large intestine is exhibited, 

 but the lower end of the ileum is also shown in the former. The 

 canal is, therefore, short, and maintains an almost uniform calibre 

 till the rectum is reached, but the latter gradually expands and 

 its walls become progressively thicker and more muscular. At 

 the anus the walls are exceedingly thick and strong. 



The whole of the colon and rectum are bile-stained, especially 

 in the posterior part of the latter, and these parts offer a marked 

 contrast to the pink ileum and anus. 



The interior of the large intestine presents several interesting 

 appearances. The colon has many circular folds of varying sizes, 

 but the two most posterior ones form complete diaphragms. In 

 the centre of each of these there is an opening surrounded by 

 a sphincteric valve, the anterior one being the larger'. In 

 Plate IV. B, d, a spicule of wood is passed through the two 

 openings. John Hunter (12) described three valves in the Two- 

 toed Sloth. 



The posterior septum separates colon and rectum, and the 

 appearances of the mucosa differ in these two divisions. In the 

 latter it is excavated into a number of pockets which contain 

 pellets of faecal matter. These are deepest in the posterior part of 



