7(5 



bucco-splaiuhnic^ connectives and a lar^e nerve which supplies tlie liver, the 

 pancreas, and I't-iliaps the intestine. The innervatiim of the systemic heart has 

 not been discovered but there is little doubt that the splanchnic ganglion also 

 supplies it. 



The visceral ganglion is the most dorsal of the oesophageal ganglia and fits 

 into a shallow depression in the skull above the statocysts. It is bound down 

 to the cartilage by a tent-shaped sheet of fascia whose top is attached to the 

 oesophagus and to the anterior half of the great foramen of the skull and whose 

 edges are attached to the rim of the depression that lodges the ganglion. The 

 ventral portion of this sheet is perforated laterally by openings for the viscero- 

 pedal and viscero-pleural connectives. These connectives arise together in the 

 ganglion and diverge as they pass backward , the pedal turning downward , and 

 the pleural outward. Four pairs of nerves arise from this ganglion. Two arise 

 from the dorso-external region of the ganglion : one passes directly outward to 

 the lateral siphonal valve : and one downward over the dorsal surface of the 

 skull close to the attachment of the cephalic retractor, then thru this muscle 

 into the upper surface of the siphon. From the dorsal surface of the visceral 

 ganglion arise two pairs of nerves which are united to two pairs of connec- 

 tives : the visceral nerve with the viscero-branchial connective . and the pleural 

 nerve with the viscero-stellate connective. The pleural nerves and the associated 

 connectives arise from the sides of the dorsal surface of the ganglion. Each 

 bundle of fibres passes obliquely outward and backward thru a deep groove in 

 the liver to the dorsolateral edge of the nuchal cartilage , turns over this edge , 

 and passes thru the nuchal I'etractor which is attached to it. As the bundle 

 emerges from this muscle it divides ; the pleural nerve passes backward and 

 the viscero-stellate connective at once enters the stellate ganglion. The pleural 

 nerve gives off a small branch to the nuchal retractor as it leaves that muscle 

 and forms the greater part of the nerve which innervates the fin. 



The two stellate ganglia are oval and flattened and lie under the skin of 

 the inner surface of the mantle near the dorsal end of the nuchal cartilage and 

 close to the shaft of the pen. Each ganglion sends off eight or ten nerves which 

 radiate from its ventral edge. The dorsal part of the ganglion projects back- 

 w^ard like the tail of a comma and contains the majority of the large nerve cells 

 of the ganglion. The stellate ganglia are connected by a small commissure which 

 leaves each ganglion with the viscero-stellate connective and which passes under 

 the dorsal end of the nuchal cartilage. All but two of the nerves arising from 

 the stellate ganglion enter the mantle within five or six millimeters of the gang- 

 lion and pass at once to the middle of its wall and are distributed to all parts 



