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Show 886.] ON THE AIR-SACS OF THE CASSOWARY. 145 3. Note on the Air-sacs of the Cassowary. By F R A N K E. B E D D A R D , M.A., F.R.S.E., Prosector to the Society. [Keceived March 1, 1886.] The following note refers to a male Casuarius uniappendiculatus which died in the Society's Gardens on February 15th of the present year. Since no description of the respiratory organs of this bird has, so far as I know, been published, I have thought it worth while to bring a note upon the subject before the Society, to supplement Prof. Huxley's paper upon the respiratory organs of Apteryx 1 and Prof. W . N. Parker's « Note ' upon the same structures in Rhea 2. As regards its air-sacs the Cassowary appears to resemble Apteryx much more closely than Rhea, though differing slightly from the former. In Apteryx the main difference in the air-sacs from those of Carinate Birds is in the small extent of the abdominal air-sac. " In Apteryx the whole of this sac is enclosed between the oblique septum and the pulmonary aponeurosis, the dissepiment between its loculus and that of the posterior intermediate sac being situated almost midway between the second dissepiment and the posterior extremity of the pneumatic chamber. In the Duck, on the contrary, the dorsal end of this dissepiment is attached close to the posterior extremity of the lung, and thence slopes very obliquely backwards. The capacity of the posterior intermediate air-sac thus becomes greatly increased. But, as the capacity of the posterior air-sac is also vastly greater than in Apteryx, its posterior wall has been, apparently, driven out, like a hernial sac, between the peritoneum and the parietes, and projects into the abdominal cavity." {Loc. cit. p. 566.) In Rhea " the anterior and posterior intermediate and the posterior air-sacs are almost precisely similar to those of the Duck. The dorsal end of the dissepiment between the posterior intermediate and the posterior sac slopes backward ; and the posterior wall of the latter has been, as Prof. Huxley describes it, * apparently driven out like a hernial sac, between the peritoneum and the parietes' projecting almost to the posterior end of the abdomen." (Parker, loc. cit.) In Casuarius uniappendiculatus the anterior and posterior intermediate air-sacs are of about the same size and are separated from each other and from the posterior sac by erect, almost vertical dissepiments, which are entirely parallel with each other ; the dissepiment which separates the posterior air-sac from the one in front does not slope backwards any more than does the dissepiment in front of it. The posterior air-sac is entirely shut off from the abdominal cavity by the oblique septum ; there was no trace whatever of any prolongation of its walls among the coils of the intestines ; the whole of the sac, as in Apteryx, is enclosed between the oblique septum and the 1 P.Z. S. 1882, p. 560. 1 P. Z. S. 1883, p. 141. |