178 Descri])tion of the Plates. 



mosis with the left jugular, attaining, as is usual in birds, 

 a larger size than that vessel. 



n. Right jugular vein in thorax. The junction of the subclavian 

 with the jugular vein is not effected until some way below 

 the point on which this line terminates ; a portion of the 

 former vein is seen in connection with the very short vena 

 cava superior just above the right bronchus. 



0. Vena cava inferior, entering the auricle to the right of and 

 posteriorly to the entrance of the vena cava superior of the 

 right side. 



p. Lung, showing on its exterior surface indentations correspond- 

 ing with the ribs. 



q. Right bronchus entering the lung. The right pulmonary 

 artery and the pulmonary veins which held the same relation 

 to the bronchus on this side which in the mammal they 

 hold on the left have been cut away, together with a con- 

 siderable portion of the spongy tissue of the lung on its 

 internal aspect. The aorta is seen arching over the bron- 

 chus, in its singleness contrasting with the aorta of Reptiles, 

 and in its dextral flexure with that of Mammals. Between 

 the bronchus and the vena cava inferior we see a portion 

 of the glandular proventriculus, and immediately above the 

 bronchus and below the arch of the aorta, which has been 

 a little displaced upwards, the junction of the fragment 

 of vein left to represent the subclavian trunk with the 

 jugular. 



T. Right innominate artery, which is seen to break up into three 

 main divisions, the common carotid, the axillary and the 

 pectoral arteries. 



8. Great pectoral muscle, the main depressor of the humerus and 

 wing seen in section on the right side as it arises from the 

 lower portion of the keel of the sternum and from the 

 clavicle. Its origin from the external lateral portion and 

 processes of the sternum is not seen, those parts having 

 been removed in the dissection; its main tendon is seen 

 turned back at x; two other tendons which it gives, one 

 to the long extensor, the other to the short extensor of the 

 alar membrane, are not shown in this figure. 



t. Second pectoral, the main elevator of the humerus, seen in 



