1886.] ON THE AIR-SACS OF THE CASSOWARY. 145 



3. Note on the Air-sacs of the Cassowary. By Frank E. 

 Beddard, M.A., F.R. S.E.J Prosector to the Society. 



[Received March 1, 1886.] 



The following note refers to a male Casuaritts 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 Icnow, 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 ' and Prof. 

 W. N. Parker's ' Note ' upon tlie same structures in Rhea ^. 



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 s.ic being situated 

 almost midway between the second dissepiment and the posterior 

 extremity of tiie pneumatic chamber. In the Duck, on the con- 

 trary, 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 tiian in Apteryx, its posterior wall has 

 been, apparently, driven out, like a hernial sac, between the peri- 

 toneum 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 inter- 

 mediate 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 



"■ P. Z. S. 1882, p. 560. « P. Z. S, 1883, p. 141. 



