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Show 148 MR. P. CHALMERS MITCHELL ON THE [Jan. 14, deviation among the Pelargi, although Dr. Gadow has laid some stress on the existence of such a resemblance. In some ot the Vultures and Falcons there are spirals formed by the subsidiary loops, just as occurs, for instance, in Ciconia (fig. 9). On the other band, members of both groups exhibit a much simpler method of attaining increased length, and this seems to imply that the spiral formation is a convergent resemblance. When the simplest members of the groups are taken-I am speaking of them only from the point of view of gut-formation-the special spiral formation disappears and the relations between the groups are only their relations to the common type. The White-tailed Sea-Eagle (fig. 12) shows the general character of the group. Its gut is very long, and if the spiral twists were a character of the Haliaetus albicilla ; intestinal tract, x, short-circuiting vessel divided. group one would expect the increased length to be displayed in the formation of complicated spirals. This does not occur. The duodenum is thrown into a complicated set of subsidiary loops, thus recalling the similar modification in the Penguin. _ Among the Accipitrines generally the duodenum is a very wide irregular loop, but I have not found it thrown into secondary loops in other cases. The circular loop forms a very extended set of minor loops, some of which, especially on the lower side, are slightly twisted into spirals. In other Accipitres it is more often the upper loops of this series that are twisted. The vestige of the yolk-duct occurs at the end of the median mesenteric vein in the typical fashion, but is situated rather nearer the proximal end of the loop. The last loop of the circular system is very long and usually, as in Haliaetus, spirally twisted. It gives a short-circuiting vein to the duodenal vein. The part of the hind gut between the caeca and the circular loop is thrown into a complicated set of folds, |