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Show 184 MR. W. A. FORBES ON THE KOALA. [Jan. 18, globular, and therefore less cylindrical in shape, the cardiac and pyloric openings being more approximated. The small intestine is villous, but otherwise smooth. It is not sacculated, and when spread out, after being cut, is 0'5 inch across. At its commencement it is dilated for about two inches; there are no Peyer's patches ; its length is 115 inches. The large intestine is very peculiar : for the first 2 8| inches or so of its length, which forms the ascending colon, it is very capacious, and internally longitudinally corrugated, like the caecum, which externally it much resembles, the rugae of the interior appearing through the walls of the intestine, and giving it a longitudinally striated appearance. These folds of the mucous membrane, which might be called longitudinal valvula? conniventes, where best developed are about '2 inch in depth; they are arranged longitudinally and are roughly parallel, though somewhat irregular in extent; they are separated from each other by intervals of about the same extent (0*2 inch). At the commencement of the colon, which here, when cut open and spread out, is 3'75 inches broad, and of the caecum, there are about a dozen of these folds very well marked. These continue throughout the ascending, caecum-like, colon ; but where it narrows to form the transverse and descending parts they converge, and become more or less blended with each other, forming linear elevations. They are continued downwards as far as the rectum, but are reduced by that time to fivel. In the caecum, which is also very capacious, the same arrangement of folds obtains till within 18 inches of its apex, when they gradually disappear, the rest of the organ being thence onwards quite smooth internally. The caecum, the curious position of the caput of which has already been described, measures 46'75 inches in length (nearly three times the length of the animal's body !) ; the large intestine 93-25 inches. In an adult female (20| inches long), preserved in spirit, the following were the intestinal measurements:- inches. Small intestine 111*15 Large „ 160-8 Caecum 66 0 Owen (Anat. Vert. iii. p. 420) gives 92, 125, and 77 inches respectively. On each side at the junction of the ileum and colon is a small patch of three glands. The liver of the Koala is of very remarkable form. It is repre- 1 Mr. Martin describes (I. c. p. Ill) both colon and caecum as sacculated "by a slight longitudinal (mesenteric) band of muscular fibres," with indications of a similar opposite band. I could find no traces of any such sacculation in the fresh Koala examined by m e ; nor are they mentioned by Prof. O w e n (Anat. Vert. iii. p. 418). It is also to be noticed that Martin does not in any way allude to tbe existence of the very remarkable folds of the interior of the cascuin and colon. In Phalangista and Phascolomys an examination of fresh specimens has completely failed to exhibit any traces in either caecum or colon of the longitudinal folds here described. In the latter genus the colon is capacious at its commencement, and sacculated transversely, in a way that does not obtain in either Phalangista or Phascolarctos. |