98 INVERTEBRATE ZOOLOGY 



cerebro-visceral connective, which goes to the visceral ganglia, the 

 cerebro-pedal connective, which goes to the pedal ganglia, and 

 the pallial nerve, which passes to the mantle. Find them. 



The pedal ganglia form a nervous mass buried in the foot 

 near its base. Make a shallow longitudinal incision in the bot- 

 tom of the foot and gently pull the flaps apart; the pinkish 

 mass and the nerves radiating from it will be seen. In contact 

 with it is a sense-organ called the otocyst. 



Exercise 10. Draw a diagram representing the nervous system. 



Make several transverse sections with a razor through the 

 region of the heart of a mussel which has been previously 

 hardened. Identify all the organs which appear. 



Exercise 11. Draw a diagram representing a cross section ; care- 

 fully label all the organs. 



