346 



MANUAL OF ZOOLOGY 



SECT. 



Inspiration and expiration of air 

 Rabbit take place through the 

 Oe 



-Tr 



Bt, 



B^^* 



FIG. 203. Lizard (Lacerta agilis). General 

 view of the viscera in their natural rela- 

 tions. BL urinary bladder ; Ci, postcaval 

 vein ; ED, rectum ; GB. gall-bladder ; H. 

 heart ; Lg. Lgf. th^ lungs ; M. stomach ; 

 MD, small intestine ; Oe. oesophagus ; Pn. 

 pancreas ; Tr. trachea. (After Wieders- 

 heim.) 



in the Lizard and in the 

 nostrils. The nasal 

 chambers into which 

 the nostrils lead com- 

 municate internally with 

 the mouth cavity or the 

 pharynx through a pair 

 of apertures known as 

 the internal or posterior 

 nares. On the floor of 

 the pharynx behind the 

 root of the tongue is a 

 slit-like aperture, the 

 glottis, opening behind 

 into a chamber known 

 as the larynx, the wall 

 of which is supported 

 by cartilages. From the 

 larynx the air passes 

 backwards along a tube, 

 the trachea, the wall of 

 which is supported by 

 numerous rings of car- 

 tilage. The trachea bi- 

 furcates when it enters 

 the body-cavity, each of 

 the two branches, or 

 bronchi as they are 

 termed, passing to the 

 corresponding lung. In 

 the Lizard the lung is in 

 essence a thin-walled 

 sac with elastic walls. 



