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Show 696 PROF. OWEN ON THE STERNUM OF NOTORNIS. [Nov. 28 of baked eggs in the stone ovens exposed beneath several feet of superficial soil, that the great wingless birds supplied the immigrant Polynesians with their staple animal diet, until that source was exhausted through such extirpation. Returning to m y more usual field of work (the skeleton), I would remark that the sternally-reduced Rallines do not offer in the rest of their organization a much greater degree, if any, of difference from Struthio than Apteryx presents. In Dinornis, as in Apteryx, the breast-bone has shrunk in length rather than in breadth, and the postmarginal notches, /, with the corresponding processes, g, are retained. Rudiments of these notches and processes are visible in Struthio, with a relative breadth of the keelless breast-bone approaching that in Dinornis. In the less broad, longer, triangular shape of the sternum, devoid of both notches and processes, Rhea comes nearest to Aptornis, and there is no trace of a manubrial process in either. The non-articular portion of the anterior border of the sternum is relatively greater in Aptornis than in Notornis (fig. \,e); in this respect the larger extinct Coot more resembles both Apteryx and Dinornis. In Struthio and Dromaius the coracoid cavities, b, almost meet upon the fore border of the sternum. In Casuarius the tripartite character of that border is the same, as regards the relative lateral extent of the articular (b) and non-articular (c) portions, as in Notornis (fig. 1). In tbe young Coot the sternum is ossified from two transversely parallel centres. These first harden the primitive cartilaginous expanse near the costal borders, c; and it may be remarked that the respiratory movements pressing thereon precede the muscular actions of flight. In the Gallina the keel, which forms the chief part of the breast-bone, is ossified from a separate centre, and the pair of slender bifurcate bony tracts beyond the costal borders have each a centre of ossification, distinct from the parial centres, common to the class, from which the main sternal plate is ossified. But these five points of ossification are exceptional in the class of birds, and relate to adaptive peculiarities of form in a particular group. They have been viewed as the rule of avian sternal development, and the two pairs of centres in the Common Fowl have been homologized with the hyo- and hyposternals of Chelonia; but this only shows how an embryology misconceived may mislead in the quest of homologies. The New-Zealand birds afford instructive examples of the progressive loss of the volant faculty, with concomitant modifications of the parts of the skeleton giving origin to the pectoral muscles'. The keel progressively shrinks from Porphyrio to Tribonyx, thence to Notornis, Aptornis, Stringops, Apteryx, Dinornis. But the modifications are adaptive, and accompany a sum of organic characters truly indicative of natural affinity ; which sum, as it forbids the Kivi to be associated in the same order with the Wood-hen, or Stringops with either, equally removes Apteryx from Aptornis, and the latter B nSeen^ ^dmjra£le J?^8 on the Eirds of New Zealand, by Walter L. BuUer, O.M.G., Sc.D., F.R.S.; especially his 'Manual' on the subject, 8vo, |