In the next five chapters the Crustacea are classified 

 according to their habitats, and those living in the 

 shallow waters, the depths, and the surface of the 

 ocean, in the fresh waters, and on land, are discussed 

 in turn ; while a separate chapter is devoted to the 

 curious forms that live as parasites on, or as associates 

 with, other animals. The last two chapters deal 

 respectively with the Crustacea as they affect man, 

 and with the past history of the group as revealed 

 by fossil remains. 



