14 DR. E. LONNBERG ON DIGESTIVE [Jan. 14j 



fed, and thus been swallowed together with the vegetable matter. 

 Trichosurus and Pseudochirus are thus chiefly phyllophagous, 

 and so also is the Koala (^Phascolarctos), which feeds on Eucalyptus- 

 leaves. Of the latter I have had only scant material — the dried 

 caecum of a grown animal and the intestine of a foetus. It may, 

 however, also be considered in this comparison because its anatomy 

 is known from the descriptions of Owen ^ and Forbes ^. 



For the purpose of illustrating the length of the difterent pai-ts 

 of the intestine, the measurements are given in the following 

 table ^ : — 



Tricliosurus. PseudocJiirus. Flialanger. Petaurus. 

 Length of animal 



without tail ... 39 cm. 28"5 cm. 58 cm. 14 cm. 



Small intestine... 213 „ 139-5 „ 198 „ 48 „ 



CaBcum 23 „ 42-5 „ 69 „ 5-5 „ 



Large intestine... 122 „ 87-2 „ 261 „ 11 „ 



To make the comparison easier it is, however, convenient to 

 express the relation between the length of the different parts of 

 the intestine and the length of the animal itself (withovit tail). 

 This is done in the following table, in which the numbers indicate 

 percentages of the length of the animal without tail. The 

 numbers under the head of Phascolarctos are calculated from the 

 measurements of this animal recorded by Forbes [l. c. p. 184). 

 There are also added measurements taken by myself from a 

 specimen of the small insectivorous Acrohates jiygmceus. 



A glance at this table reveals that in the Koala all parts of 

 the intestine are very much more lengthened than the corre- 

 sponding parts of the intestine of the animals at the other end of 

 the series. The caecum and the large intestine are considerably 

 larger even than in the likewise chiefly phyllophagous Trichosunts 

 and Pseudochirus. On the other hand, all three phyllophagous 

 animals have the small intestine developed in comparatively the 

 same degree but a good deal longer than in the others. The 

 reason why the caecum and the large intestine in Trichosurus 

 and Pseudochh'us are comparatively shorter than the same organs 

 in the Koala may be seen from the description further on. If 

 the digestion of the cellulose takes place chiefly in the caecum, 

 as has been supposed by the authors quoted above and with 



1 'Anatomy of Vertebrates.' 



2 " On some Points in the Anatomy of the Koala (Pliascolarctos cinereus)." 

 P.Z.S. 188],p. 180. 



3 All measurements are taken by means of a thread laid along the middle of the 

 intestine while adherent to the mesentery. 



