330 QN THE ALLIGATOR 



ting fluid. The parts composing this organ are two auricles, 

 two very distinct ventricles, a set of veins from the body, 

 the pulmonary artery, two veins of the same name, a branch 

 for the aorta on the left, anotlier for the right side, the right 

 subclavian, and the carotid artery. I shall now describe 

 these parts, beginning with the veins returning from the 

 body : 



The vena cava descendens follows for a time the right 

 subclavian artery ; it enters the upper part of the [)ericar- 

 dium, and is attached to the inner coat of this membrane 

 until it joins the vena cava ascendens, opposite to tlie right 

 auricle, where they unite. This vein runs along the right side 

 of the vertebrae, until it reaches the inner and lower part of 

 the large lolie of the liver ; there it enters this organ, run- 

 ning in a perfectly straight channel, formed near the edge of 

 this viscus, receiving from it a great number of veins, and 

 comes out a little above the gall-bladder, where, along with 

 four or five veme Aej^o^icee, it enters directly the pericardium. 

 This is closely attached to the liver, as M. Cuvier observes, 

 but more so in that part than any other. There is another 

 vein bringifig the blood from the left axilla, whicii pierces 

 the pericardium near and above the left pulmonary vein, and 

 enters the sinus venosns. This vein is anal igous to the left 

 subclavian (of the human subject.) differing only from this, 

 in its entering the right auricle separately: tliis, and several 

 important observations, I owe to Dr. Harlan, who has exa- 

 mined the heart witli me. These three veins empty them- 

 selves into the right auricle, which, rather larger than tlie 

 left, is situated above and on the riglit side of the heart. The 

 right ventricle, very muscular, has, like the left, thick pari- 

 etes ; it extends a little lower than the other, and is rather 

 more spacious ; it is furnished witii two large valves situated 

 near the orifice of the auricle to prevent the return of the 

 blood. Tliis ventricle has an opening into two arterial tubes ; 

 one on t)u^ left and superior part is furnished with two semi- 

 lunar valves opposed to each other, and opens into thesplanch. 



