198 



ZOOLOGY. 



Fig. 137.* 



* This theoretical figure is intended to indicate the relative position of the 

 great organic apparatuses in the class mammals : b, buccal cavity forming the 

 entrance of the alimentary tube, the exit is at the posterior extremity of 



the body ; t, the intestine ; f t the liver ; t, trachea ; p, lungs ; c, the heart ; 

 e, encephalon (brain, &c.) ; ra, 



t , 



ra, spinal marrow. 



