36 

 PAET IT. 



APPLICATION TO THE MOVEMENTS OF THE SNAKE. 



§ 36. The actions and reactions which we have: 

 described for the rod are, we concei-ve, those which 

 take place in the body of the snake, and which pro- 

 duce its locomotion. 



The two pairs of antagonistic forces, as then 

 brought into play, represent and are the resultants 

 of the general muscular action of the animal, ad- 

 ded to the elasticity of its ribs. 



The various articulations of the spine, head and 

 ribs allow the discharge of the different alternating 

 twists. 



§ 37. The head of the snake is coupled to the 

 back-bone by a perfect ball and socket joint. Of 

 the two parts of this joint, the ball is carried by 

 the head, and the socket by the head-end of the 

 back-bone. 



In descriptions of the snake's action we must 

 change the terms upper and lower used in relation 

 to the rod, to anterior and posterior. 



The head-joint then being a ball and socket, the 

 equivalents of the " points of application " and the 

 results of the " winding lines " in the rod, would, 

 as represented at the head-joint, in its actual or 



