52 PHYSIOLOGICAL SERIES. 



oesophagus to (ii.) a large compound Buboeeophageal mass 

 formed by the fusion of pedal and pleural ganglia with 

 the four centres of the short untwisted (orthoneurous) 

 visceral loop. 



The two halves of the cerebral ganglion are united by a 

 short eoniniissure : each is indistinctly tabulated, the mM 

 conspicuous lobe forming a conical projection (tentacular 



Fig. 17. 



P. G 



CRC. 



CPL.C S 



Diagrammatic reconstruction of the Pleura-pedal mass of Helta- 



xao, 



C.P.C. Cerebro-pedal connective. C.PJj.O. Cerebro-pleural connective. 

 !'.<;. IVdal ganglion. PL.G. Pleural ganglion. V.L. Visceral loop. 



lobe) on its anterior surface, from which arises a large 

 nerve for the optic tentacle and eye and a smaller one for 

 the otocyst. From tin- Bntero-lateral margins of th<> 

 ganglion, m-rves an- "iven off to the lips and anterior 

 tentacles, and from its ventral surface a pair of delicate 

 buccal connectives. The siih.-tance of the suboBSOphageol 

 mass (fig. 17) is traversed hetwi-en the pleuro-visceral and 

 pedal centres by the anterior aorta. The pleural ganglia 

 off no nerves. Four large nerve- riae from the 

 of the visceral loop ; three of them innenate 



