Anatomjf and Affinities o/IIypsobia nosophora. 407 



septum [cf. Robson (12)], which, as in the Paludesti-inidfe, 

 passes between the pedal ganglia and tiie cerebro-pleurul 

 complex. 



V. The Nervous System, (Figs. 4 & 5.) 

 (a) Sense-organs. 



1. Osphradium. — This is a small rod-shaped org-au lyin^, 

 as usual, on the left-hand side of the gill. It is 

 innervated by a conspicuous nerve rising from the 

 supra-intestinal ganglion. 



Fi-. 4. 



Jl. nosophora. Central nervous system (antei'ior aspect). 



/c=left cerebral ganjjlion; //j/=:left pleural ganglion; 7J = pedal ganglion ; 

 jyj/=rigbt pleural ganglion; pp= (sc.) parapodial and propodial 

 ganglia; ^/=suprainte8tinal ganglion; s6('=8ubintostinal gau- 

 glion ; o = ospbradial nerve ; rc = visceral commissure. 



