ON MONOPYLEPHOEUS LIMOSUS. 



19 



always roundish in cross section, the dorsal part being mostly 

 occupied by the ganglionic cells. 



A second pair of nerves branch off from the root of the lateral 

 prostomial nerves on the outer side and after running out for a short 

 distance enter the body wall and become connected with the 

 lateral lines of the body. 



The pharyngeal nerve commissures run out from the ventral side 



l.p.n 



bw 



Fig. 14. 

 Brain and anterior portion of 

 ventral nerve cord ; reconstructed 

 from cross sections of a well nar- 

 cotised specimen. xl50. l.p.n— 

 lateral prostomial nerve, 1.1 — late- 

 ral line, br — brain, n.r — periphar- 

 yngeal nerve, 1 — 2g— first and 

 second ventral ganglia. 



Fig. IS. 



Brain and pharyngeal glands from 

 a much contracted, living specimen. 

 xl50. bw — body wall, sp— septum 

 III/IV, l.p.n — lateral prostomial nerve, 

 br — brain, mg — median pharyngeal 

 gland, lg — lateral pharyngeal gland. 



of the posteriormost part of the lateral prostomial nerves, and 

 proceed downwards in a nearly straight line. After reaching the 

 ventral body wall and giving rise to a pair of nerves, they turn 



