

A CepJialopJiorous Mollnsk. 69 



teriorly in a line nearly parallel to the course taken by the 

 digestive tract. This posterior band forms one half of the 

 so-called visceral loop and leads to the abdominal gan- 

 glion, located far up in the substance of the body near the 

 nephridial opening. 



The left visceral or sub-intestinal ganglion lies on the right 

 side of the oesophagus, below the right pleural ganglion, and 

 posterior to the right pedal ganglion. A broad band, the 

 left viscero-pleural commissure, will be observed to lead from 

 the left visceral ganglion to the left pleural ganglion, passing 

 below the oesophagus just back of the pedal ganglia. The 

 left visceral ganglion gives rise to the left half of the visceral 

 loop, which passes posteriorly to join the abdominal ganglion 

 already noted. On its course it gives off a branch to the 

 columellar muscle. 



The pleural ganglia give off nerves which pass to the 

 lateral walls of the body and to siphon and collar. 



Make a series of drawings of the nervous systems. 



K 



