STRUCTURE OF BIRDS. 



65 



<7, /^, is of very largo size, situated between the heart and the 

 intestines, generally formed of two lobes, of which the left is the 

 largest, and filling a great portion of the thoracic and abdominal 

 cavities. The bile is carried directly into the intestine by the 

 hepatic duct, and by the hepatico- cystic into the gall-bladder, 

 whence it issues by the cystic duct. 



Fig. 16. represents the heart, 

 «, h ; the liver, c, d ; the gall- 

 bladder, e\ the hepatic duct, 

 /; the hepatico-cystic duct, g\ 

 the cystic duct, h ; and a portion 

 of the intestine, /,/, of theSnow^y 

 Owl. The gall-bladder is want- 

 ing in the Pigeons, in which, as 

 in many other respects, they dif- 

 fer from the Gallinaceous birds. 

 The heart, Plate IV, Fig. 4, 

 g, /^ and Plate V, Fig. 1, /, 

 occupies the anterior part of tho 

 Fro. iG. thorax, and is of a conical form, 



its apex passing between the two lobes of the liver, these organs 

 not being separated by a diaphragm, as in the Mammifera. 

 It is invested with a strong pericardium, Plate IV, Fig. 4, /«, 

 wdiich is prolonged between the lobes of the liver. There is 

 little perceptible distinction between the auricles and ventricles; 

 the auriculo-ventricular apertures are secured by an oblique 

 fleshy band ; the left ventricle has its parietes of from three 

 to five times the thickness of the left, which is much larger, 

 and is curved round it, and there are scarcely any indications 

 of columnae carnese. The aorta divides at its very base into 

 three principal branches, Plate V, Fig. 1, a, /5, 7 ; of which one 

 on each side is for the anterior extremity or wing, and the head, 

 while the branch forming the aorta proper, y, curves backward 

 to the right, over the bronchus of that side. The consideration 

 of the distribution of the arteries, veins, and lymphatics, must 

 be deferred to another opportunity, as it would occupy much 

 space, and is not essential to my descriptions, which cannot 

 comprehend the entire anatomy of the species. 



