242 



THE TANGANYIKA PROBLEM. 



intestinal and visceral nerve cords, and to the right pallial 

 nerve, Fig. 23. From the right pleural ganglion a nerve 

 passes out to the mantle, and a branch from this anas- 

 tomoses with a branch on the pallial nerve just described. 

 In like manner, on the left, the pleural ganglion gives birth 

 to a nerve on that side, Fig. 23, which passes out and 

 probably anastomoses with a twig given off from the 

 supra-intestinal ganglion, but I was not able to trace this 

 nerve throughout its entire course. 



Unlike the sub-intestinal ganglion, the supra-intestinal 



Fig. 24. — Bythoccras minor shell front and back. The right-hand figure 

 showing the characters of the operculum. 



is carried on a very long supra-intestinal connective, Fig. 

 23, exactly as it is in Cerithwm or Aporrhais. Viewed 

 from the side, the cerebro-pedal and pleuro-pedal con- 

 nectives are seen to be of considerable length, rather 

 longer than the same structures in Voluta, but not so long 

 as those in Nassopsis or in Strombtis. The pedal ganglion 

 has the bulbous form encountered in the true Cerithiidse, 

 and in like manner there pass from the lower extremity 

 of each pedal ganglion two predominent foot nerves. 



