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Show 560 FROF. HUXLEY ON THE RESPIRATORY [June 20, 2. On the Respiratory Organs of Apteryx. By T H O M AS H. HUXLEY, F.R.S., F.Z.S. [Received June 2, 1882.] I am not aware that the structure of the respiratory organs of Apteryx has been investigated since the publication of Professor Owen's Memoirs on the Anatomy of the Southern Apteryx, in the second and third volumes of the ' Transactions' of this Society. Professor Owen gives a detailed description of a structure which he terms the diaphragm, and compares it with that organ in mammals ; the account of the anatomy of the lungs and of the air-sacs, on the other hand, is less full. The important fact that no air-sac extends into the abdomen is noted ; but only four air-sacs on each side are mentioned, and no attempt is made to identify these with the air-sacs of other birds. The question whether Apteryx presents any real approximation to mammals in the structure of its breathing-apparatus is of considerable interest, from its bearing upon the general problem of the affinities of birds to other groups of vertebrated animals. Having recently examined a specimen of Apteryx (which, although it had been many years in spirit, was still in a very fair state of preservation) with reference to this point, I have come to the conclusion that its respiratory organs differ in no essential respect from those of other birds-though they exhibit those peculiarities which are peculiar to and characteristic of the class Aves in a less developed condition than that which obtains in all those Carinatae and Ratitae which have been carefully studied. The admirable monograph by Sappey *, chiefly based on the study of the respiratory organs of the Duck, contains the most complete and accurate account extant of the general disposition of these organs in their highest condition of development. Rainey 2 supplemented this by the important discovery of the existence of intercapillary air-passages; and, more recently, Campana3 has contributed a very elaborate study of the respiratory organs of the Common Fowl. It is not difficult to verify the chief statements of these anatomists. Nevertheless it is any thing but easy to find a succinct and precise account of the facts; and the terminology at present employed appears to me to be for the most part cumbrous and inappropriate. I make no apology, therefore, for endeavouring to amend this state of matters. The lungs of birds lie, one on each side of the vertebral column, between the first thoracic rib in front and the anterior end of the kidney behind. On the dorsal aspect they rise, on the sides of the vertebrae, as high as the tubercular transverse processes of the ribs. On the ventral aspect they descend to a variable distance towards the 1 Recherches sur l'appareil respiratoire des Oiseaux: 1847. * " O n the minute Structure of the Lung of the Bird," Medico-Chirurgical Transactions, xxxii. 1849. 3 Les lois de l'Evolution animale.-La respiration des Oiseaux : 1875. |