1883.] ON THE RESPIRATORY ORGANS OF RHEA. Ml 



3. Note on the Respiratory Organs of Rhea. By W. N. 

 ParkeRj Lecturer on Biology at the University College 

 of Wales, Aberystwyth. 



[Eeceived March 12, 1883.] 



In a paper read last year before this Society, " On the Respiratory 

 Organs of Apteryx,^' Prof. Huxley gave a clear and concise account 

 of the arrangement of the respiratory organs in Birds generally, 

 comparing more particularly those of Apteryx and the Duck. To 

 that paper the reader is referred for the explanation of the terms 

 used in the present note. 



Having had an opportunity of dissecting a specimen of Rhea 

 macrorhyncha and another of R. darwini while working at the 

 Society's Gardens, I examined the organs of respiration in these birds. 

 Owing to want of time, I was unfortunately not able to go into 

 this matter as fully as I could have wished ; but as so little has been 

 written on the subject, any facts relating thereto are worth recording. 

 I shall therefore content myself with giving a comparison of these 

 organs in Rhea with those of Apteryx and the Duck. 



As in the Duck, the lungs of Rhea are considerably larger abso- 

 lutely and relatively than in Apteryx, but the posterior ventral 

 margin is longer than the anterior. The pulmonary aponeurosis is 

 thick and strong as in Apteryx ; and its mesial attachment is some 

 distance from the median vertical septum, which, as well as the 

 superior facet, is not so deep as in the Duck. 



The oblique septum is stronger than in the Duck, hut apparently 

 not so strong as in Apteryx. I was unable to find any muscular 

 fibres in it. 



The general arrangement of the air-sacs in Rhea is much the same 

 as in the Duck, though in some points they more nearly resemble 

 those of Apteryx. 



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 backwards ; 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. 



This pushing-out has not taken place in Apteryx, the whole of the 

 posterior sac being enclosed between the oblique septum and the 

 pulmonary aponeurosis, and thus having the same relations as the 

 intermediates. 



The subbronchial sac presents an interesting intermediate condition 

 between that oi Apteryx and Carinate birds. The whole of this sac 

 in Apteryx is " floored by that part of the oblique septum which 

 lies at the side of the fore part of the pericardium," while in the Duck 

 the greater part of the sac extends forwards between the clavicles, 

 and then fuses with its fellow to form a large median reservoir. 



