INTESTINAL TRACT OF MAMMALS. 195 



that the ceecum consists of two portions. There is an upper 

 elongated papilla (text-fig. 7, V.) attached to the ileum by a 

 mesenteiy which is not shown in Owen's figure. This is the 

 so-called "vermiform appendage" of the Wombat. The free 

 portion is a solid mass of tissue closely similar to the tissue 

 composing the human appendix ; but the proximal portion, 

 beginning just at the point (text fig. 7, X.) where the appendage 

 blends or is embedded in the wall of the gut, is hollow. Owen 

 regards this as the tip of the large caecum indicated by the 

 letter C. in text-fig. 7. 



In Flower's figure the wide pouch marked C. in text-fig. 7 is 

 lettered caecum. The author expresses doubt as to whether or 

 no the vermiform appendage of Owen is to be regarded as 

 a remnant of an originally expanded caecum, but does not 

 refer to the fact that only the proximal portion of the vermiform 

 appendage is hollow. He describes and figures, however, the 

 relations of the appendage to the ileum in precisely the form in 

 which I found them. The apertures of the ileum and of the 

 colon into the dorsal side of the colon lie close together on 

 a projection enclosed by a raised lip in such a fashion that it is 

 impossible to regard the so-called vermiform appendage as a 

 continuation of the globular proximal end of the colon. The 

 interjjretation that seems to be least doubtful is to regard the 

 projection marked Y. as the true caecum, the greater part of 

 which has become transformed to a solid vermiform appendage. 

 On this view, the ca?cal jDouch G. is merely one of the sjiccu- 

 lations into which the colic loop is constricted, as Owen pointed 

 out, by two parallel bands. Owen states that he found another 

 of these sacculations, close to the terminal one, so well marked 

 as almost to be regarded as another caecum. In one of the two 

 examples of the Common Wombat that I dissected, I found 

 another extremely well-marked sacculation forming a caecal 

 pouch towards the distal extremity of the colic loop. In 

 dissecting the intestines I came upon it first, and until the 

 whole pattern was? unfolded, and the true caecum in its proper 

 morphological position displayed, thought that I had found a 

 Wombat in which the caecum had no vermiform appendage. 



The length and complexity of the gut-pattern of the Wombat 

 is in relation with the rough unnutritious diet of the animal. 

 The pattern, however, is seen to be a simple elaboration of 

 the primitive type. Apart from the peculiarity of the caecum, 

 the most interesting feature is the elaboration of the first 

 portion of the hind-gut into a colic loop. This loop corresponds 

 with the similar loop in Phascolarctos (text-fig. 8), and, like it, is 

 an ansa coli dextra, and differs from the expansion on the hind- 

 gut of other large Diprotodonts, e. g. Deiulrolagus (text-fig. 9), 

 which is an ansa coli sinistra. 



By the kindness of Dr. Colin Mackenzie, I have been able to 

 examine the intestinal tract of two well-preserved examples 

 of the Koala [Phascolarctos cinereus). The duodenal region 



13* 



