This type is encountered among the herbivorous Marsupials, such as the opossums, kangaroos and wallabys. Fig. 348 shows the structures in _Didelphis virginiana_, the common opossum, Fig. 349 in a small species of opossum from Trinidad, and Fig. 350 the same parts in _Halmaturus derbyanus_, the rock wallaby. [Illustration: FIG. 348.--_Didelphis virginiana_, opossum. Ileo-colic junction and caecum. (Columbia University Museum, No. 1533.)] [Illustration: FIG. 349.--_Didelphis sp._? opossum. Ileo-colic junction and caecum. (Columbia University, Study Collection.)] [Illustration: FIG. 350.--_Halmaturus derbyanus_, rock kangaroo. Ileo-colic junction and caecum. (Columbia University Museum, No. 727.)] 2. _Forms with enormously developed sacculated caeca, coiled spirally, with or without additional convolutions of the proximal colon; the terminal portion of the caecal pouch diminishes in caliber to form a pointed appendage._ This type of caecum characterizes the _Phalangeridae_ or Phalangers and the _Phasolarctidae_. [Illustration: FIG. 351.--_Trichosurus vulpinus_, vulpine phalanger. Ileo-colic junction and caecum. (Columbia University Museum, No. 1800.)] [Illustration: FIG. 352.--_Phascolarctos cinereus_, koala. Ileo-colic junction and caecum. (Drawn from preparation.) (Columbia University Museum, No. 1528.)] Examples are shown in Figs. 351 and 352, representing the structures in _Trichosurus vulpinus_, the vulpine phalanger, and _Phascolarctos cinereus_, the koala. 3. _Forms with simple caeca of moderate size._ The _Peramelidae_ or bandicoots. Fig. 353 shows the ileo-colic junction, caecum and proximal segment of the colon in _Perameles nasuta_, the bandicoot. [Illustration: FIG. 353.--_Perameles nasuta_, bandicoot. Ileo-colic junction and caecum. (Columbia University Museum, No. 1481.)] 4. _Forms with sacculated short caeca, whose terminal portion is reduced to constitute a typical vermiform appendix._ The caecum of the _Phascolomyidae_ or wombats, resembles, in its general structure and in the presence of a typical vermiform appendix, very closely the corresponding parts of the alimentary canal in man and the anthropoid apes. Fig. 354 shows these structures in _Phascolomys wombat_, the common wombat. [Illustration: FIG. 354.--_Phascolomys wombat_, wombat. Ileo-caecum and appendix. (Columbia University Museum, No. 1508.)] 5. _Forms with simple direct ileo-colic junction without caecum._