71 



June 12, 1838. 

 The Rev. F. W. Hope in the Chair. 



Mr. OAven communicated to the Meeting another portion of the 

 results attending his examination of the body of the Aptcryx, em- 

 bracing a description of the parts connected with the function of re- 

 spiration, and their general relations, as shown in this extraordinary 

 bird, to that structure of the respiratory organs which is so eminent- 

 ly characteristic of the entire class. 



Mr. Owen remarks, that the system of respiration in birds is so 

 obviously framed with especial reference to the faculty of aerial pro- 

 gression, and the peculiarities in the former exhibit so marked a phy- 

 siological relation to the lattei', that in the A])teryx, where the wings 

 are reduced to the lowest known rudimentary condition, the exami- 

 nation of the accompanying modifications in the respiratory apparatus 

 presented a most interesting subject for inquiry. 



Upon carefully removing the viscera from the abdomen, Mr. Owen 

 was both gratified and surprised at finding no trace of air-cells in 

 the abdominal cavity ; the diaphragm being entire, and pierced only 

 for the transmission of the asopkagus and larger blood-vessels, as in 

 the Mammalia. 



The position of the diaphragm was almost horizontal, like that of 

 the Dugong, differing from it principally in relation to the heart and 

 pericardium, which projected into the abdominal ca^'ity, as through a 

 hernial aperture, the aponeurosis of the diaphragm being continuous 

 over the pericardium ; an approach towards the oviparous type in the 

 disposition of the viscera being thus preserved. 



In the origins of the diaphragm Mr. Owen found the crura of the 

 lesser muscle exhibiting a gi-eater degree of development than is 

 known to exist in any other bird ; the crura were entirely tendinous, 

 and arose from slight projections at the sides of the last costal ver- 

 tebree, their fibres expanding and being lost in the large aponeuro- 

 tic centre ; at the point of their expansion to join the aponeurosis a 

 small proportion of muscular fibre was observed. 



The abdominal surface of the diaphragm, as in the Mammalia, was 

 principally in contact with the convex surface of the liver, but the 

 thoracic surface of the former was separated from the lungs by a se- 

 ries of small but well-marked air-cells, one of w'hich projected 

 slightly through the anterior aperture of the thoracic-abdominal 

 cavity at the base of the neck ; the Apteryx thus still retains the 

 ornithic type of structure, although presenting us with the only 

 known instance, in the feathered race, of a species in which the recep- 

 tacular portion of the lungs is not extended into the abdomen. 



The lungs were each of an irregular sub-compressed triedral fi- 

 gure, broader anteriorly and contracted towards the posterior ex- 

 No. LXVI. — Proceedings of the Zoological Society. 



