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Show 1902.] ADAPTATIONS IN DIPROTODONT MARSUPIALS. 13 substances (amylum, fat, proteine), the digestion of which may take place in the small intestine without the help of any caecum and without any specialization of the colon. Yegetable food may thus, just as well as a carnivorous diet, lead to the loss of the caecum. He also draws attention to the condition found in the peculiar Phalangerid Tarsipes, in which the caecum is entirely wanting, and thinks that this depends upon the fact that this animal feeds chiefly on honey. This last statement is of special interest because Tarsipes belongs to the same family as the animals which are to be considered here; and it might, with regard to the development of its intestine, be put at one end of the series described below. The chief material for this little study was afforded by some specimens of Phcdanger macidatus and Petaurus breviceps, collected in N e w Guinea by the late Dr. E. Nyman; a specimen of Pseudochii-as occidentalis brought home from Western Australia by the late Captain Forsstrom; and a specimen of Trichosurus vulpecula from an unknown locality. In addition to these I have, with the kind permission of m y friend Professor T. Tullberg, had the opportunity of using other available material in the Zoological Museum of the Royal University at Upsala, and I beg to offer him m y best thanks for these new proofs of his never-ceasing liberality. M y first attempt was to try to find out on what kind of diet the above-mentioned animals lived, by carefully examining the contents of the stomach and the intestine. The stomach of the Petaurus contained pieces of the chitinous integument of various insects and larvae, some whole Podurids, and hair of the animal itself. Among the Podurids m y friend E. Wahlgren was able to distinguish specimens of Isotoma palustris and of an Achorutes. It seems accordingly to be certain that this animal may be termed entomophagous, although perhaps also berries etc. may enter into its diet. The stomach and the intestine of the Phalanger macidatus were completely filled with fruit-pulp, and there is thus reason to regard this Cuscus as chiefly carpophagous. The stomach in m y specimens of Pseudochirus and Trichosurus was empty ; the contents of the intestine and especially the caecum indicated, however, a vegetable origin. In the caecum of Tricho-surus comparatively large pieces of the fibrous skeleton of leaves could be found, but the parenchymatous substance was digested or, at any rate, loosened from the " nerves." This agrees well with Lydekker's words-"the highly aromatic leaves of the Peppermint-gum form the favourite food of these animals."1 The caecum of Pseudochirus was filled with a substance in which, under the microscope, various parts of leaves, upper and lower epiderm, bundles of vessels, etc. could be discerned. There was also a good deal of fine sand, which, probably as dust, had once covered the leaves and sprouts on which the Pseudochirus had 1 Lydekker : ' A Handbook to the Marsupialia and Monotremata.' London, 1894. |
