A CRAB 45 



mass, in the shape of a ring, which occupies a central position 

 in the cephalothorax, and from which nerves radiate to the 

 different appendages. The dorso-ventral artery passes through 

 this ring. Expose the entire nervous system. 



Exercise 6. Draw a semidiagrammatic view of the nervous 

 system, being careful to represent accurately the nerves 

 radiating from the ganglionic ring and those going from 

 the brain to the eyes and to the antennae. 



