2 54 



THE TANGANYIKA PROBLEM. 



up over the oesophagus, and carries the supra-intestinal 

 ganglion. From the left pleural ganglion there passes a fine 

 nerve towards the supra-intestinal ganglion, which appears 

 to form a dyaloneurous connection with a derivative of the 

 supra-intestinal nerves. Towards the right the sub-intestinal 

 connective passes from the left pleural ganglion beneath the 

 oesophagus straight to the sub-intestinal ganglion. This 

 ganglion is directly connected with the right pleural ganglion 



^ 



Fig. 37. — The nervous system of Nassopsis nassa. 

 P. g., Pedal ganglia. 



c. g., Cerebral ganglia. 



by a thick cord, and the nervous system is therefore strongly 

 zygoneurous on the right. Above, the cerebral ganglia 

 give off a number of anterior nerves, which are distributed 

 to the buccal mass and the parietes of the head. Among 

 these there are conspicuous the tentacular nerves, which pass 

 separately to the tentacles and ocular papillae. The buccal 

 ganglia are situated on the lateral walls of the buccal mass, 

 and are united to the cerebral ganglia by connectives. Near 

 the origin of the buccal nerves there arise two fine nerves, 

 one from each cerebral ganglion, which pass forward along 



