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Show 150 MR. P. CHALMEES MITCHELL ON THE [Jan. 14, down by the remnant of a primitive ventral mesentery. The last minor loop of the circular portion of the gut has the long caeca running forward alongside it. It is drained in the usual fashion by a branch of the mid-mesenteric vein and by short circuit branches from the duodenal vein. At first sight there is a striking similarity between the gut of the Rails and the gut of Fahnants(1ig. 7, p. 143); but this is due simply to the narrowness and regularity of the loops. The position of the yolk-duct vestige differs in the two, while the short caeca and the kinks immediately above them make absolutely distinctive characters in the Petrel. In the Dicholophida? and the Otididae the Ralline characters are still obvious, but the gut is still shorter and the loops more definite. Cariama cristata (fig. 14) shows the duodenum and the rectum identical with the Rails ; the last portion of the circular loop is Fig. 14. Cariama cristata ; intestinal tract, x, short-circuiting vessel divided. identical in its arrangement and veins, although the caeca larger. The rest of the mid-gut is reduced, the third loop being absent. The yolk-duct vestige is in the same place upon the second loop, but the first loop of the circular mid-gut is partly united with the second. In the Otididae the gut appears to be further modified in the direction in which Cariama differs from Crex. The duodenum, the rectum, and the last loop of the mid-gut are as in the Rails and Cariama ; but the remainder of the mid-gut is reduced to a single loop, corresponding to the second of that region in Crex, and bearing the yolk-sac vestige on its distal limb. CHARADRIIFORMES. The birds associated in this Order display a very varied series of divergences from the type. Among those Limicolae that I have |