79 



the pubis-bones, and as immovably connected be- 

 hind by another bone called the sacrum,'^ These 

 bones, though seemingly one mass with the pelvis 

 in the full-grown animal, are originally distinct. 



The sacrum is evidently an analogue of the 

 spinal vertebrae, and we shall, further on, attempt 

 to show that the puhis-hones represent a continua- 

 tion of the breast-bone, the hip-bones standing for 

 the ribs. 



The sacrum is a direct continuation of the spine, 

 and this, in quadrupeds, is again continued by the 

 tail. 



The pelvis is not connected with the spine by a 

 free joint as is the head, but by the same sort of 

 juncture that exists between the several vertebrae 

 of which the spine is made up. 



The whole pelvis, thus moving in one piece, an- 

 swers, in locomotion, the pui-pose of an exagge- 

 rated vertebrae belonging to the trunk of the 

 body as a whole, and furnishing an extended 

 sweep for the thigh-bone sockets which it carries. 

 The trunk of the body may thus be considered as a 

 COMPOSITE SPINE, of ivMch the legs and J for a certain 

 -share in their motion, thefoi^e-limhs are tlie ribs. 



* The pubis-bones are. at their rear ends, keyed to the hip-bones by 

 other two bones (one on each side), called the ischium-boues, which in 

 4nan form the seat bones. 



