1902. J ADAPTATIOXS IX DIPROTODOXT MARSUPIALS. 23 



mesenteric bands of muscular fibres which are most often longi- 

 tudinally, but sometimes obliquely, arranged. Svich bands are 

 found on both sides of the ceecunii The interior of the c?ecum 

 shows at the constricted places slight longitudinal folds, which, 

 however, probably are of a temporary nature. They are thus 

 not to be compared with the longitudinal folds described in the 

 Koala by Owen and Forbes (I. c). 



In the large intestine of Phcilanger there are some longitudinal 

 folds near the upper sphincter. They are, however, quite short 

 and continue but a few centimetres from the ileo-ctecal valve, 

 and are therefore quite unlike the longitudinal "w<fo?6fe co^im- 

 venies" described in the Koala by the authors just mentioned. 

 The colon tapers abruptly from the width of the caecum 4| cm. 

 to 2g and then to 14 cm. In places where it is much distended 

 its width may reach 3 cm., but as a rule it is less than that of 

 the small intestine, usually 2-1 1 cm.^ The rectum attains a 

 width of 2| cm., and is provided with about half a dozen longi- 

 tudinal folds, plainly conspicuous, but not much developed. 

 They may, however, be regarded as homologous with those of 

 the Koala in a corresponding situation and of nearly the same 

 number, according to Forbes. The non-digestible remains in 

 the colon of Phalange?' consist of pieces of epiderm of fruit, pro- 

 senchymatous fibres and vessels. The main mass of the fruit- 

 pulp is, however, so decomposed that its particles cannot be 

 identified. 



The duodenum of Fetaurus is very densely beset with flattened 

 more or less tongue-like villi which are transversely arranged 

 and partly form thin denticulated lamellae. They lie so close 

 together that the contents of the intestine probably only, or 

 at least chiefly, come into contact with the tips of the villi — 

 a condition found by Oppel (1. c. pp. 288-9) in Trichositrus. 

 In Petaurus the small intestine is beset with villi through its 

 whole extent, although they decrease in size posteriorly. The 

 condition found in Acr abates seems to be essentially the same. 

 In Petaurus the duodenum forms a much more distinct loop than 

 in Phalanger ; it is 3 cm. in length, the ascending branch being 

 closely connected with the descending one and returning along 

 the same to the pyloric tract. In the latter the duodenal loop is 

 less pronounced because the ascending branch is only half as long- 

 as the descending one. 



In Petaurus the connection between the large and small intes- 

 tine takes place in such a manner that the ileum opens into the 

 colon, into which the valvula ileo-ccecalis (the name is thus not 

 quite suitable in this case, more correctly v. ileo-colica) protruded 

 about 2 mm, Close to this valve there is between the csecum and 

 the colon a strong sphincter, partly like a valve protruding into 

 the cavity of the colon and only leaving a very narrow opening 

 (which, of course, also can be closed) between the same and that 

 of the ceecum. 



I All .such measui'emeiits are taken across die empty but not opened intestine. 



