ALIMENTARY CANAL OF MARSUPIALIA. 417 



the inner secreting membrane, is further augmented by about 

 a dozen longitudinal parallel, or nearly parallel, plaits, which 

 are continued from the colon three-fourths of the way towards 

 the blind extremity. When we reflect that the Sloth, which has 

 the same diet and corresponding habits with the Koala, has 

 a singularly complicated stomach, but no caecum, the vicarious 

 office of this lower blind production of the digestive tube as a 

 subsidiary stomach is still more strikingly exemplified. In the 

 Marsupials Avith sacculated stomachs the caecum 

 coli is comparatively short and simple. In the 

 Potoroos, which scratch up the soil in search of 

 larvae and farinaceous roots, it is shorter than in 

 the great Kangaroos which browze on grass. 

 There is a slight tendency to sacculation at the 

 commencement of the crecum in the latter Mar- 

 supials, by the development of two longitudinal ca?cum of the 



bands, fio- 314. In the Wombat the caecum is 



' ~ 



extremely short, but wide ; it is remarkable for being provided 

 with a vermiform appendage, fig. 315. In this animal, how- 

 ever, the colon is relatively longer, larger, and it is puckered 

 up into sacculi by two broad longitudinal bands. In the speci- 

 men dissected by me, one of these sacculi was so much longer 

 than the rest as to almost merit special notice as a second caecum. 



The most interesting peculiarity which the Zoophagous Mar- 

 supials exhibit in the disposition of their simple intestinal canal, 

 consists in its being suspended from the very commencement of 

 the duodenum on a simple and continuous mesentery, like the 

 intestine of a carnivorous reptile. The duodenum makes the 

 ordinary fold on the right side, but it is not tied to the spine at 

 its termination; the commencement of the jejunum may, however, 

 be distinguished by a slight twist of the mesentery, and a fold of 

 peritoneum is continued from the lowest curve of the loop of the 

 duodenum to the right iliac region, as in the Kangaroos. The 

 intestine is a little narrower at its middle part than at its two 

 extremes ; the tunics increase in thickness towards the rectum. 

 There is a zone of glands at the commencement of the duodenum. 



In the Entomophagans ! the duodenum is tightly connected to 

 the spine, where it crosses to be continued into the jejunum : from 

 this part the mesentery is continued uninterruptedly along the 

 small intestines and colon to the rectum ; so that although the 

 caecum is generally found on the right side, its connections are 

 sufficiently loose to admit of a change of position. In the Carpo- 



1 See LXXIV', for characters of these families of Marsupialift. 

 VOL. III. E E 



