INTESTINAL TEACT OF MAMMALS. 469 



simplicity of the gut of P/toccena, therefore, as being secondary. I hope that some 

 anatomist who has an opportunity will make a careful examination of the gut-pattern 

 in some of the Mystacoceti, as it is quite possible that thereby some clue to the 

 affinities of the group would be given. Flower (5) states that in the Whalebone 

 AYhales a short conical caecum is present, and that, unlike the Toothed Whales, the 

 former display a differentiated hind-gut, with a distinct colic loop. 



Order ARTIODACTYLA. 



Sub-Order NON-RUMINANTIA. 

 Family HiproPOTAiiiDJi;. 



I have had no opportunity of dissecting a Hippopotamus, but Flower (5) and 

 Garrod (6) have published some information, from which it appears that the general 

 pattern is not unlike that of the Swine. The duodenum and Meckel's tract, which 

 are not sharply marked off from each other, are enormously long and with a narrow 

 calibre. There is no caecum. The hind-gut displays first a series of irregular loops, 

 corresponding in position to the spiral coil of the Pig, and somewhat similar to that 

 when the latter, as in the figure (fig. 18), has been dissected out; then follows a 

 " transverse and descending colon," and then the rectum. The literature, however, on 

 this subject is scanty, and more information is much wanted. 



Family Suid^e. Stis scrofa (fig. 18, p. 470), Phacochcerus cethiopica, Babirussa 

 babirussa, Porcula salvania. 



In the Domestic Pig the duodenum is a well-separated loop or occasionally a double 

 loop. Meckel's tract is extremely long and disposed in a number of closely-packed 

 simple folds. The caecum is single, wide, relatively short and tapering to a point. 

 The hind-gut exhibits, first of all, an enormous double loop, more or less coiled into a 

 spiral. In the drawing, which was made from an embryo Pig, the relative size and 

 capacity of this loop is much less than in an ordinary adult example. The growth of 

 the loop has caused the rupture of the mesentery, the loop with its very large blood- 

 vessel being supported by a special fibrous band with some muscular fibres. In the 

 figure the thinner distal limb of the loop is represented as partly dissected away from 

 the main mass, and the edge of the mesentery supporting the rectum is torn. 



There is a single, large, anterior mesenteric vein draining the duodenum and Meckel's 

 tract. The caecum is drained by a separate branch, which enters the anterior mesen- 

 teric vein near the edge of the mesentery. The huge vessel from the great loop 

 of the hind-gut is immediately proximal to the last-named vessel. The posterior 

 mesenteric or rectal vein is slight and insignificant ; in the diagram, owing to the 

 displacement caused by dissecting out the great loop, it is represented as cut across 

 at X and X. 



vul. xvii. — part v. No. 5. — December, 1905. o r 



