548 APPENDIX. 



quadruped, as also the blood-vessels, more espe- 

 cially the veins. 



The heart is inclosed in its pericardium, which 

 is attached by a broad surface to the diaphragm, 

 as in the human body. It is composed of four 

 cavities, two auricles, and two ventricles : it is 

 more flat than in the quadruped, and adapted to 

 the shape of the chest. The auricles have more 

 fasciculi, and these pass more across the cavity 

 from side to side than in many other animals ; 

 besides, being very muscular, they are very elas- 

 tic, for being stretched they contract again very 

 considerably. There is nothing uncommon or 

 particular in the structure of the ventricles, in 

 the valves of the ventricles, or in that of the ar- 

 teries. 



The general structure of the arteries resembles 

 that of other animals ; and where parts are nearly 

 similar, the distribution is likewise similar. The 

 aorta forms it usual curve, and sends off the ca- 

 rotid and subclavian arteries. 



Animals of this tribe, as has been observed, 

 have a greater proportion of blood than any 

 other known ; and there are many arteries ap- 

 parently intended as reservoirs, where a larger 

 quantity of arterial blood seemed to be required 

 in a part, and vascularity could not be the object. 

 Thus we find, that the intercostal arteries divide 

 into a vast number of branches, which run in a 

 serpentine course between the pleura, ribs, and 

 their muscles, so as to form a pretty thick sub- 

 stance. Those vessels, every where lining the 



