106 AVES. 



tween the two lungs, and gives off large visceral trunks within the 

 thoracico-abdominal cavity to the stomach, liver, spleen, and mesen- 

 tery, a superior and inferior artery passing transversely to the 

 kidneys, and a small anterior or femoral with a much larger poste- 

 rior ischiadic artery to the leg ; the aorta is then continued along the 

 spine, as the arteria sacra media, and gives branches to the contents 

 of the pelvis. Several of the arteries, as the anterior tibial in the 

 Goose, Heron, and Crested Grebe, form here and there beautiful retia 

 mirabilia or vascular plexuses. 



The Veins of the body, as in Mammalia, have but few valves. 

 The blood of the superior half of the body is poured into the right 

 auricular sinus from the two distinct mouths of a pair of superior 

 vense cavse. They are formed by the junction of a jugular and 

 subclavian vein, of which the right jugular is generally three to 

 four times thicker and stronger than the left. The inferior or pos- 

 terior vena cava collects the blood from the posterior moiety of the 

 Jbody, and receives especially the large renal veins. The inferior 

 vena cava is very broad, especially in the Diving-birds. The Pul- 

 monary artery, single at its commencement, divides into two main 

 trunks for the two lungs ; in a similar manner, also, the pulmonary 

 veins enter the left auricular sinus by a single trunk. The vena 

 porta receives principally the blood from the viscera, but some also 

 from a large branch of 'the caudal vein and the veins of the poste- 

 rior extremities. The blood of Birds has the highest temperature 

 of all the Vertebrate animals (about 110 Fahr.), and the blood cor- 

 puscles are always of an elliptical form, and of very uniform diame- 

 ter, throughout all the orders. 



The Chyliferous or Lymphatic Vessels are numerous, and pro- 

 vided with valves, but do not form any conglobate glands upon the 

 mesentery, though in the neck these glands often occur, and are of 

 considerable size, as in the Heron, where there are from five to six 

 pairs. A receptaculum chyli is situated upon the origin of the 

 cffiliac artery, and the lymph of the body, as well as the chyle, is col- 

 lected into two lymphatic trunks, which enter the angles formed by 

 the junction of the superior vense cavse with the jugular and subcla- 

 vian veins. Lymphatic hearts have not as yet been satisfactorily 

 demonstrated to exist in Birds ; still, however, in the Cassowary a 

 lymphatic sinus has been found, situated beneath the integument, 

 upon the transverse processes of the second sacral vertebra, and 

 which, reasoning from the analogy of its position with that of the 

 Frog, may perhaps be regarded as a lymph-propelling organ. 



