THE PELVIS AND THE VISCERA 127 



supporting the body weight is not to be doubted, despite 

 some apparent contradictions, and it is to be remarked 

 that m animals in which the body weight is not borne at 

 all upon the hind-limbs (as in the Bats, etc.) no portion 

 of the pelvic girdle meets in the mid-ventral line, and 

 consequently no symphysis is developed. 



Fig. 45. — Purely Diagrammatic Eepresentation of the 

 Pelvis of an Orthograde Mammal. 



Note the way in which the sacrum articulates with the ilia at the 

 sacro-iliac joint, and the meeting of only a small area of the 

 pubes at the pubic symphysis. 



The pelvis has now, in its altered relation to the hiiid- 

 limb, an entirely different mechanical design. There i^ 

 a main w^eight-supj)orting arch behind, composed of the 

 ilia, with the sacrum as the keystone of this arch. A 

 subsidiary weight-supporting arch is developed in front, 

 and this is represented by the subpubic arch. The old 

 ventro-dorsal weight-sujDporting arch is superseded, and 

 now the cavity of the pelvis need no longer be moulded 



