83. 



together, on the inner, near tlie -ventral side, of the ganglion. 

 The origin of the corebro-pedal conunissure is entirely anterior 

 to tliis depression. The bulgings at the bases of the ner^re seem 

 sufficient to account for the irregularity. 



Each cerebral ganglion giv^es rise to several nerves. 

 A large herve passes forward, under the anterior adductor muscle, 

 branches^and supplies the anterior portion of the corresponding 

 inantl© lobe. Another large ner^.'-e passes dovm to the dorsal mar- 

 gins of the palps, follows them posteriorly and is finally continued 

 the whole length of the palp appendage. Of the smaller no37ves, 

 one supplies the anterior adductor muscle and another passes to 

 the body wal 1 . 



Each visceral ganglion gives rise anteriorly to a small 

 osphradial ner^.'-e, and posteriorly to a nerve that branches almost 

 immediately. Sometimes these branches originate as separate 

 nerves. One of them sends a small neirve to the posterior ad- 

 ductor muscle and another belo?/ the adductor muscle to the postero- 

 dorsal portion of the man.tle. The main nerve bends ventral ly and 

 is distributed to the siphons. The other nex^re passed ventrally, 

 Reside the ner^;-e just described, sends a large noirve to the siphon— 

 al tentacle^, on the side where this tentacle is present, and is 



contiraued to supply the postero-ventral margin of the mantle. 



