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Show 306 PROF. HUXLEY ON THE A L E C T O R O M O R P H A E . [May Id, nineteenth bears ribs which are nearly as long as those of the first dorsal and possess verv deep, though short, unciform processes, un the right side, the rib "of this vertebra is connected with the sternum by an incompletely ossified sternal rib. , , The vertebral ribs of the dorsal region are remarkably broad ; ana in the three anterior pairs a considerable extent of the postenor margin is occupied by the unciform process, which is always shorter than the intercostal space. . ,, In the breadth of the ribs, and depth and relative shortness of the unciform processes, the ordinary Pigeons come nearest Opisthocomus. The ribs of Corythaix have a totally different character. Fig. 8. Fig. 9. Fig. 8, front, and Fig. 9, side view, of the sternum and shoulder-girdle of Opisthocomus cristatus. The sternum, as several observers have already pointed out, is one of the most anomalous parts of the organization of Opisthocomus. Its lateral edges remain nearly parallel for about two-thirds of its length, and then diverge, causing the transverse diameter to be considerably wider posteriorly than anteriorly. The external xiphoid processes are but little shorter than the middle xiphoid; and the posterior edge is evenly curved backwards. It presents two notches, of which the outer pair may be converted into foramina. The inner pair are deeper than the outer, but do not extend for a sixth of the |