148 THE STRUCT UEE OF THE HOESE. 



is immensely developed in the horse. It consists 

 mainly of a strong elastic cord, which is attached in 

 front to the upper part of the back of the skull (Fig. 

 22, O), and posteriorly to the elongated spines of the 

 dorsal vertebrae (S). Between this, the funicular 

 part of the cervical ligament, as it is called, and the 

 bones of the neck, fibers of the same material, pass 

 downwards and forwards, to be attached to the up- 

 per surface of all the different cervical vertebra?, ex- 

 cept the atlas, forming a lamellar part, which lies in 

 the middle line dividing the muscles of each side of 

 the neck. This structure, though called a ligament 

 for want of a better name, differs from the true liga- 

 ments, which connect bones together at the joints, in 

 being of a yellow color and in having in a very marked 

 degree the property of elasticity. It will bear con- 

 siderable stretching, and then will return again to 

 its normal length, which a true ligament composed 

 of ordinary white fibrous tissue will not do. 



Elastic material is often made use of in the animal 

 economy to great advantage mechanically, restoring 

 without effort to its proper position a part which 

 has been temporarily disturbed from it, and thereby 

 saving a vast expenditure of muscular power. The 

 valves of an oyster or a cockle-shell are opened by 

 an elastic hinge and closed by contraction of a mus- 

 cle placed between them. Under the ordinary con- 



