OF THE CLASS MAMMALIA. 



235 



manner with the sacrum (sa), and reuniting inferiorly, form 

 a girdle or pelvis, thus surrounding the lower portion of the 

 trunk. The form and dimensions of this girdle vary much, 



Fig. 184. The Chamois. 



and, cceteris paribus, the erect position on the lower limbs is 

 easier as the pelvis is larger. It must also be remarked, that 

 in the opossums and other marsupial animals, the muscles of 

 the abdomen assisting in the formation of the pouch of these 



Fig. 185.- The Mole. 



