Abdomen- 



L ^V \\^^\^. Uropod 



out 



Figure 111. Crayfish, showing the external characteristic structures of most of the class 

 Crustacea. 



Tactile sefa 





Waxy layer 

 Rigid layer 



Flexible layer 



Epidermis- 



Flexible membrane of jo 



Basement membrane 



Figure 112. Diagram of the body wall of an arthropod, showing some of its modifications. 

 The rigid layer is replaced by a flexible membrane in places where movement occurs. 



200 



