OP NORTH AMERICA. 3U> 



auricle into the cell of the same side, has two courses to 

 take : — 1. That of the left deseiuling aorta ; and 2. That of 

 the pulmonary cell which forces it into tlic artery of the satne 

 name ; it may even take a third route, in filtrating through 

 numerous canals that traverse the partitions wliich separate the 

 two preceding. — the left and superior cell. Tiie left fiuricle 

 propels into tliis the Mood which it has received from the 

 pulmonary vessels. Its opening is bordered oti the right 

 side with a meml)ranous valve, to the right of which opens 

 the common trunk of the right descending aorta, the caro- 

 tids, ami the axiilaries ; which blood, passing into this trunk, 

 is distributed {)articuiarly to the head and to tlic extremities; 

 or it lihrates lluough the intervals of liie fleshy columns of 

 this coll. and penetrates into the two others. It results from 

 this, that the carotids and the axillaries carry to the anterior 

 portion of the body, the iliacs to the posterior portions, and 

 the median sacral to the tail, the blood which comes almost 

 entirely immediately from the lungs ; whilst a portion of that 

 wMiich takes its course for the viscera (l)y tlie left aorta) 

 comes from the right cell, and from the auricle of tlie same 

 side ; and consequently has not traversed the lungs in order 

 to be nmditled by the surrounding elrment. The jiidmo- 

 nary blood does not inix tiicn so well with that of the body, 

 as in the clielonicns. Such is the structure of the heart in 

 tlie crocodile of the Nile and the Caiman," Ciiv. Anat. 

 Comp. Vol. IV., p. 221. 



I shall now give the result of my dissection, which difters 

 very much from the preceding description : — 



The heart, in the alligator, is placed in the centre of the 

 thorax, exactly under the middle of tlie steriuim ; it occupies 

 a large space between the two lol»es of tlie liver and the 

 lungs. The heart itself however is not as large as might he 

 expected from the mere inspection of it, when contained in 

 the pericardium: the arterial tul)es. nearly as bulky as the au- 

 ricles and vmtiieles togethei', till a gieat space in the peri- 

 cardium, which contains besides a large quantity of lul)rica- 



