508 DR. P. CHALMERS MITCHELL ON THE 



the normal position, lies folded against the Meckelian mesentery, and a long and wide 

 rectal portion. The anterior mesenteric vein is nearly straight and is joined by a large 

 colic vein and a separate tributary from the colic loop. The large posterior mesenteric 

 vein, which drains the rectum, unites with the anterior mesenteric near the dorsal edge 

 of the mesentery. 



Family Lorisin^e. Perodicticus votto (fig. 42, p. 507). 



In the Potto there is no distinct duodenal loop. Meckel's tract is relatively short 

 and consists of a series of irregular loops occupying only about the anterior two-thirds 

 of the circumference of an oval expanse of mesentery. The caecum is long and 

 capacious. The hind-gut is extremely long, and consists of a colic region composed of 

 one or two short kinks and two very large loops, which, in the undisturbed condition, 

 are folded together and applied to the Meckelian mesentery, and a straight rectal 

 portion. The anterior mesenteric vein is nearly straight and receives a ceecal factor 

 and two large factors from the colic loops. It is joined by the posterior mesenteric 

 vein from the rectum. 



The gut-pattern of the Prosimise is fairly definite in character. The duodenum is 

 seldom well distinct from Meckel's tract ; the latter varies in length, probably in 

 relation to the diet. The caecum is always present and usually very capacious. The 

 hind-gut (except in Tarsius, where it is obviously reduced and still shows signs of 

 former differentiation) is relatively extremely long, sometimes being as long as, or 

 longer than, the fore-gut. It is, moreover, of greater calibre. It shows a well-marked 

 colic region, which may be a long narrow loop or a complex set of folds, and a distinct 

 rectum. 



Order SIMm 



Sub-Order PLATYRRHINA. 



Family Hapalid^e. Hapale penicillata, Midas rufimanus. 

 In the Hapalidae the whole intestinal tract is relatively short, although Weber's 

 (27) statement that it is only a quarter the length of the body is certainly an under- 

 estimate. The duodenal loop is not well separated. Meckel's tract consists of a 

 series of regular loops and a terminal straight portion arranged round the periphery 

 of a nearly circular expanse of mesentery. The caecum is long and very capacious. 

 The hind-gut is relatively long and capacious ; it consists of a wide colic loop which 

 passes insensibly into a straight rectal portion. The anterior mesenteric vein stretches 

 diametrically across the Meckelian mesentery, receives a large colic vein, and is joined 

 by a posterior mesenteric vein which drains both the rectum and colon. 



