216 THREE CRUISES OF THE " BLAKE." 



nelids and starfishes, or crabs and actiniae. Finally, we come to 

 those communities among invertebrates where the subdivision of 

 labor is carried out so far that the different individuals possess 

 special functions. These cases belong to the same phenomena : 

 they illustrate the interdependence of the animal and vegetable 

 kingdoms, and the influence of special conditions of existence 

 upon the development of the animal and vegetable life of our 

 shores, continental slopes, and deep-sea basins. 



