214 



THE VOYAGE OF H.M.S. CHALLENGER. 



inspiration. Of these apertures, one is situated about half-an-inch in front of tlie point 

 of entrance of the bronchus, a second is placed close to and in front of that tube, the third 

 is situated behind the point of entrance of the bronchus, and the fourth is placed on the 

 inferior border of the lung. By means of the first of these air is transmitted from the 

 lung to the cervical, by means of the third to the inter-clavicular, and by means of the 

 fourth to the hepatic air sac. The superior border of the lung is almost straight. It is 

 thick and rounded, and is marked by six oblique fissures, which, as above observed, are 

 likewise visible on the external surface of the organ, and indicate the position of the six 

 anterior ribs. The inferior border is thin, sharp, and convex, from before backwards. 

 It comes into relation with, and overlaps the lateral surface of the liver, heart, and 

 pericardium. Behind it is continuous with, and forms an angle with the posterior margin 

 of the lung, which rests against the anterior border of the kidney. About the middle 

 of the posterior border of the lung there is a single oval aperture. By means of this, the 

 fifth orifice, the largest or abdominal air sac is brought into communication with the 

 bronchial tube, through which it is supplied with air. The apex or anterior extremity of 

 the lung is pointed, and rests against the lower surface of the first rib. 



The accompanying table shows the measurements of the lung of different species 

 in inches : — 



Variations. — Except in respect of size, the lung of every species of Penguin agrees 

 with that described above of Euchjptes chrysocome. 



