THE SKELETON 



253 



brae are so united as to form a column of bones with graceful 

 curves (Fig. 121), an arrangement which in itself has more of 

 the qualities of a spring 

 than are possessed by a 

 straight column. 



In order that the legs 

 may firmly support the 

 heavy body, strong con- 

 nection of the " hip bones" 

 to the spine is necessary. 

 To make this junction 

 solid, five of the vertebrae 

 in that region are enlarged 

 and grown together, form- 

 ing the sacrum; Figs. 121 



FIG. 122. ONE OF THE DORSAL VERTA 

 VIEWED FROM THE SIDE 



for Stood vesse) 



trum 



Neural Process 



and 124. Below this are 

 four much smaller ver- 

 tebrae, partially grown 

 together and called the 

 coccyx. It is the con- 

 tinuation of this which 

 forms the ' tail in some 

 animals. 



The Ribs and Sternum. 

 The ribs are a series 

 of slender arching bones, 

 attached at one end to 

 the twelve dorsal verte- 

 brae, and bending outward 

 and forward to enclose 

 the thorax or chest cav- 

 ity. The lower ribs afford 

 some protection to the 

 upper part of the abdo- 

 men also. After arching around the chest the ribs are 



Centrum 



FIG. 123. ONE OF THE DORSAL VERTE- 

 BRA VIEWED FROM ABOVE 



