LESSON 79.] NERVOUS SYSTEM IN LAMELLIBKANCHIATA, 



261 



glion connects with its fellow, by the agency of the commissural 

 nerve, i. 



The demonstration of the figure is as follows : 

 FIG. 878. 



a. 



5. 



c, c. 



*,*. 



1,1. 



m, m. 



n, n. 



o, o. 



P- 



Nervous system of Mytilus edulis (common Mussel). 



Cephalic, or labial ganglia. 



Commissure, or nervous chord, passing behind the oasophagus, uniting them. 



Nerves, derived from the cephalic ganglia. 



Their termination in ganglia at the base of the foot. 



Bilobed pedal (pes, foot) ganglia. 



Nerves from the pedal ganglia distributed to the foot. 



Nerves which originate in,the cephalic ganglia, and terminate in 



The branchial ganglia. 



Commissure, or nervous chord connecting branchial ganglia. 



Branches from the branchial ganglia, which are distributed to the inner margin of the 

 mantle. 



Nerves derived from .?,.;, and the branchial ganglioa, and distributed to the outer mar- 

 gin of the mantle. 



Branch from branchial ganglion, distributed to the posterior part of the mantle. 



Nerves distributed to the gills, forming the branchial plexus. 



Terminal nerves from the branchial plexus, ending in the cephalic ganglia. 



The gills. 



Sympathetic nerves, derived from the cephalic ganglia, and distributed to the stomach. 



Nerves distributed to the anterior adductor muscle. 



