The Framework of the Bird 71 



Let us suppose that we have strung a wire through 

 the hollow centre of the back-bone of our chicken, to 

 which the ribs are still attached, and that we have be- 

 sides the skull and the bones of one wing and one leg. 

 Compare them with those in the illustrations and we will 

 see if they can tell us aught of interest. 



The bones of the neck are all separate, and slide back 

 and forth on the wire, like beads on a string. How unlike 



FIG. 47. Front and rear views of seventeenth and eighteenth cervical vertebrae 

 of Ostrich, showing complicated saddles and sliding surfaces, giving great 

 freedom of motion. 



the long smooth ribs are these vertebrae, bristling with 

 spines and projections! How is it that a bird can be 

 comfortable with a string of such irregular-looking ob- 

 jects run through its body? But fit two of these bones 

 together and see how beautifully they saddle end to end, 

 every convexity or projecting knob exactly adjusted to 

 a corresponding concave portion of the neighbouring bone. 

 These saddles are characteristic of birds alone. Every 

 one of the sixteen bones of the neck is different from its 



