308 



MAMMALS 



lun_2;s to he purified. Tlie blood is returned from the lungs 

 through the puhiionaiy veins to tlie left auricle. From 



„ .„ . here it flows into the left 



Capillaries . , , 



■ ""' ventricle whence it is ex- 



pelled tlii'ough a system 

 of arteries to all parts of 

 the body (Fig. 204). 



Excretory system. — The 

 carbon dioxide and other 

 waste materials gathered 

 from the body by the 

 blood is exchanged in the 

 lungs for ox}'gen ami ex- 

 pelled through the \Aind- 

 pipe. 



A pair of bean-shaped 

 kidneys attacheil to the 

 (loisal side of the abdo- 

 men gather the nitroge- 

 nous A\ aste matters of the 

 body and discharge them 

 through the ureters into 

 the urinary bladder. 



Brain and spinal cord. 

 — Tlie surface of the brain 

 is not greatly com'oluted 

 like that of the human 

 brain, thus indicating a 

 low order of intelligence. 

 The brain consists of several distinct jiarts. In front is 

 the cerehrvm, made u]i of two large hemis]iheres, on the 

 antei'ioi' extremities of which arc Ihe two club-shaped 



Cn]nltaric. 



Fig. 204. — CirtulalH.iii.r 



ing the course of the M I. 



vessels contain inijmi'e bluocl 

 light vessels pure blood. 



bbit 



show- 

 e dark 

 id the 



