560 FROF. HUXLEY ON THE RESPIRATORY [June 20, 
2. On the Respiratory Organs of Apteryx. By Tuomas 
H. Hoxiey; PBS, EAS. 
[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 Apterya presents any real approximation to 
mammals in the structure of its breathing-apparatus is of consider- 
able 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 preserva- 
tion) 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 Carinatze and Ratitze 
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 * supplemented this 
by the important discovery of the existence of intercapillary air-pas- 
sages; and, more recently, Campana® has contributed a very elaborate 
study of the respiratory organs of the Common Fowl. It is not diffi- 
cult 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 
vertebre, 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. 
2 “On the minute Structure of the Lung of the Bird,” Medico-Chirurgical 
Transactions, xxxii. 1849. 
3 Les lois de ’Hyolution animale.—La respiration des Oiseaux: 1875. 
