The Framework of the Bird 71 



Let us suppose that we have strung a wire tlirou^li 

 the hollow centre of the back-bone of our cliickcn, lo 

 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 vertcliru' 

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

 freedom of motion. 



the long smooth ribs are these vertebra^, bristling with 

 spines and projections! How is it that a bird can l)e 

 comfortable with a string of such irregular-looking ob- 

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

 together and see how beautifull}' they saddle end lo cud, 

 every convexity or projecting knot) exactly adjusted to 

 a corresponding concave portion of the neighlx)uring bone. 

 These saddles are characteristic of birds alone. Eveiy 

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



