78 



most brachial nerve, at its origin, a fine nerve on each 

 side runs outwards to innervate the muscles of the head 



(fig.ro, //,). 



V i s c e r a 1 N e r v o u s S y s I e in. 



Eledone, like all other Cephalopoda, possesses a 

 viscera] nervous system. There arc two ganglia, one 

 situated near the anterior end of the alimentary canal, 

 and one near the stomach. The two are united by a long 

 nerve which runs down the wall of the oesophagus. Each 

 of them gives oil several nerves to the neighbouring parts 

 til I lie alimentary canal. This system is connected with 

 the central nervous system by means of the buccal nerve 

 only. 



The Sub-oesophageal Ganglion represents the 

 anterior centre of the visceral system (fig. 72, Oes. </.). It 

 is a fairly large, bilaterally symmetrical, flattened 

 ganglion, situated in the acute angle between the buccal 

 mass and the oesophagus. To expose it properly, the 

 anterior salivary gland must be turned forward (PL VIII, 

 fig. 72, s. </.). Looked at laterally, the ganglion is 

 roughly triangular. The buccal nerves enter it at its 

 posterior external angles (fig. 72, B. N .). From the 

 anterior angle the ganglion gives off several nerves. (Jf 

 these, the lowest enters the buccal mass, the next runs to 

 the anterior salivary gland (fig. 72, a and h resp.), the 

 third enters the buccal mass (fig. 12, c), the uppermost 

 (fig. 72, d.) runs up to the oesophagus, and then 

 anteriorly along its wall to the buccal mass. The 

 posterior edge of the sub-oesophageal ganglion gives off 

 two nerves to the oesophagus. The anterior one is short 

 (tig. 72, /), but the posterior one is long and runs down 

 the side of the oesophagus as far as the crop (fig. 72, </). 

 Posterior to the crop the left and right nerves of this pair 



