MARSUPIAL! A. 





a fold of peritoneum continued from the con- 

 vexity of its depending curve. I found the 

 ccecum in this species disposed in a spiral 

 curve in the left lumbar region : the colon 

 ascended a little way in front of the stomach, 

 receiving a branch of the superior mesenteric 

 artery, and was then continued straight down 

 to the anus; thus we are again reminded of the 

 oviparous character by the shortness of the 

 large intestine. 



In the Pet. taguanoides the duodenum is 

 tied down to the iliac region, as in the Da- 

 syure ; the ccecum is four inches long, and 

 the colon is relatively longer than in the Aero- 

 bates ; it makes the tour of the abdomen much 

 as in man, but is continued into the rectum 

 without forming a sigmoid flexure. 



In the Phalangers the duodenum winds round 

 the root of the mesentery, descending pretty 

 low down on the right side, and becoming a 

 loose intestine or jejunum on the left side. 

 The long ccecum is suspended by a broad du- 

 plicature of peritoneum continued from the 

 mesocolon ; and the colon is closely attached 

 at its transverse arch to the duodenum and root 

 of the mesentery. 



In the Koala the coecum and large intestines 

 arrive at their maximum of development. The 

 duodenum commences with a small pyriform 

 sacculus nearly an inch in breadth, and soon 

 contracts to a diameter of five lines, which is 

 the general calibre of the small intestines. The 

 large intestines, where the ilium terminates, 

 have a diameter of two inches. The end of 

 the ileum (a, jig. 129) protrudes for the extent 



Fig. 129. 



Ileo-ccccal valve, Koala. Half its natural size. 



of a quarter of an inch within the ccecum, 

 forming a very effectual valve : near this part 

 there are two wide and deep glandular fossae : 

 the longitudinal valvulse conniventes of the 

 large intestines have already been noticed. 



In the Potoroos the small intestines are dis- 

 posed nearly as in the Phalangers : the short 

 and wide ccecum lies in the right hypogastrium: 

 the colon makes the usual tour of the abdomen, 



but is disposed in long convolutions through 

 its whole course, being suspended on a broad 

 mesocolon. The diameter of both small and 

 large intestines is nearly the same : in Hyps, 

 setosus I found this to be half-an-inch. 



In the great Kangaroo the descending por- 

 tion of the duodenum is attached posteriorly, 

 by means of a thin peritoneal duplicature, to 

 the spine, and anteriorly to the ascending co- 

 lon : it makes an abrupt turn upon itself, and 

 a fold of peritoneum is continued from the con- 

 vexity of the curve to the right iliac region. 

 The small intestines are strung in short folds 

 on a rather narrow mesentery. The coecum is 

 in part suspended from the same mesenteric 

 fold. The colon, besides its posterior con- 

 nexions with a mesocolon, is attached, as be- 

 fore observed, to the duodenum ; and also, by 

 means of the great omentum, pretty closely to 

 the stomach, whence it passes down, forming 

 many large and loose convolutions to the rec- 

 tum, being attached by a broad mesocolon to 

 the left hypochondriac region. 



The zone of glands at the commencement of 

 the duodenum has been already noticed ; 

 they are present in other Marsupials, even in 

 the most carnivorous species ; but I have not 

 met with a similar structure in the placental 

 Mammalia. The villi of the small intestines 

 in the Kangaroo are of moderate length, com- 

 pressed and close-set. Glandulae aggregatae 

 are arranged in narrow patches in the ileuin. 

 There are seven groups of similar follicles in 

 the ccecum; and a few long and narrow patches 

 of glands occur in the colon intermingled with 

 numerous glandule solitariaa; the surface of the 

 rest of the lining membrane of the large intes- 

 tine is disposed in a very fine net-work. 



Two faint longitudinal bands extend along 

 the first ten inches of the colon and are con- 

 tinued along two-thirds of the ccecum : the 

 sacculi produced by these bands are but very 

 feebly marked. I have not met with any ex- 

 ample in the Macropus major of a ccecum, 

 which, either naturally or when inflated and 

 dried, presented the sacculated structure repre- 

 sented by Cuvier in jig. 8, pi. xxxix. of the 

 Lemons d'Anat. Comparee. 



The contents of the ccecum in the great Kan- 

 garoo are of a pultaceous consistence, and the 

 mass continues undivided along the first two feet 

 of the colon, gradually becoming less fluid and 

 then beginning to be separated into cubical 

 faeces about an inch square. The diameter of 

 the large intestine in this species exceeds very 

 little that of the small intestines. 



In all the Marsupials two sebaceous follicles 

 open into the termination of the rectum. The 

 anus has its proper sphincter, but is also sur- 

 rounded, in common with the genital outlet, 

 by a larger one. When the penis is retracted, 

 the faecal, urinary, and genital canals all ter- 

 minate within a common external outlet; so 

 that in the literal sense the Marsupials are mo- 

 notrematous. 



The following is a table of the length of the 

 intestinal canal, and its parts in a few species 

 of the different families of Marsupiaha. 



