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Show 140 MR. P. CHALMERS MITCHELL ON THE [Jan. 14, end-extension of gut-has been attained in different groups, would seem to offer a field of enquiry that may ultimately give important results bearing on the problem of divergent evolution. Dr. Gadow has shown that the modes of coiling the gut have systematic value: so far as m y material has been able to take me, it looks as if the divergencies were grouped indifferently around the common type. R A T i T m. In the Cassowary (fig. 3) the common type is retained with an almost diagrammatic simplicity. The duodenum is a short, very Fig. 3. Casuarius; intestinal tract. wide loop, and presents the peculiarity, which may have been an individual abnormality in m y specimen, that the hepatic and pancreatic ducts open on a wide diverticulum of the distal limb of the loop. The circular fold of mesentery has the very slightly folded gut suspended at its circumference, and the remains of the yolk-sac appear as a short ca?cum in the middle of the loop. The rectum is short and straight, and the ca?ca are in the typical position. The blood-vessels are absolutely typical. The E m u which I examined (Bromceus novce-hollandice) was identical in its main features wdth the Cassowary, and it is unnecessary to give a separate drawing. The duodenum was narrower and longer, and the hepatic and pancreatic ducts opened separately into the duodenum, not upon a common diverticulum. The Ostrich (fig. 4), which was the fine male known as the Queen's Ostrich, presented an important deviation. The first two parts of the intestine and the three great veins were according to type, the yolk-sac diverticulum being conspicuous on the circular loop opposite the end of the median mesenteric vein. The distal limb of the duodenum presented a short lateral diverticulum, and the ca?ca are relatively longer than in Casuarius and, as has been |