Annulata. 



at the posterior end is 

 the anus. These are the 

 two ends of the digestive 

 tube, which runs straight 

 through the body, being, on 

 the average, about half the 

 diameter of the body. The 

 body, then, consists of two 

 tubes,the outer wall,or body 

 wall, and the digestive tube; 

 the outer tube, or body wall, 

 narrowing till it joins the 

 inner tube. Between these 

 two tubes is a space, the 

 body cavity, or celom. In 

 most of the higher animals 

 we find a similar space 

 around the digestive tube 

 and within the body wall. 

 In the earthworm the body 

 cavity is divided into many 

 compartments by the par- 

 titions that extend between 

 the inner and outer tubes 

 at the constrictions, seen 

 on the outside, between the 

 successive segments. 



The Body Wall. This 



consists of two coats, each 

 of which is made up of two 

 or more layers. Outside is 

 the skin, and within this 

 the muscular coat. 



