210 NERVOUS SYSTEM. 



tending backwards along the ventral surface of the abdomen, 

 like the great nervous axis of conchifera, meet with a large 

 compound quadrilobate ganglion (q,) behind the stomach (,) 

 and above the diverging muscles of the compressed pinniform 

 foot (n, o.} These two sub-ventral, detached and converging 

 columns (k, k,) extending from the cesophageal collar to the 

 middle or pedal ganglia (#,) can be traced backwards from 

 these ganglia along the lower surface (q, m,) of the abdominal 

 cavity and beneath the intestine (c, d } ) to near the caudal 

 extremity of the trunk. Another branch is described by 

 Chiaje as a sympathetic extending directly backwards from 

 the brain, or cesophageal collar, and spreading on the viscera 

 without passing to the quadrilobate ganglion (q.) Numerous 

 branches come off from the periphery of the pedal ganglia 

 (q,) to ramify on the muscles of the foot, and the surround- 

 ing parts. The pedal ganglia (q,) have been regarded as 

 sympathetic, but from their whole relations to the rest of 

 the nervous system, and from the form and position of the 

 great trunks (k, k, m,) connected with them, they appear 

 more analogous to the symmetrical sub-ventral ganglia of 

 conchifera, and of the articulated classes. The lateral ganglia 

 of the nervous cesophageal collar are generally the parts 



