146 PROCEEDINGS OF THE ACADEMY OF [March, 



the pharynx to a point about midway between the level of the central 

 nervous system and the first liver pouch. Here it divides, one branch 

 extending dorsally to enter the pleural gangUon or the base of P13, 

 while the ventral branch is directed to the ventral wall of the pharynx 

 where it breaks up into several branches. Both of these last-named 

 nerves give rise to a single offshoot, each of which continues backward 

 to the anterior border of the first liver pouch where they enter a 

 strong, ganglionated commissure, passing over the dorsal wall of 

 the pharynx. The lower of the two nerves just mentioned develops 

 a nerve, before entering the dorsal commissure, which is directed 

 posteriorly beneath the first liver pouch and branches over the 

 ventral wall of the stomach. Another nerve, having a similar 

 course, arises from the ganglion, and curving around the ventral 

 margin of the pouch becomes lost on its walls after branching two 

 or three times. 



As noted previously, the dorsal buccal commissure is ganglionated 

 at the point of union with the two nerves connected more anteriorly 

 with the buccal ganglion, and posteriorly this ganglionated section 

 extends along the sides of the stomach to the posterior border of 

 the first liver pouch. From it a clearly defined nerve arises, and 

 extending dorsally follows the bile duct into the liver proper, where 

 it breaks up and can be seen extending along some of the larger 

 follicles. At the posterior end of the liver pouch the buccal nerve 

 divides, the ventral branch supplying the liver pouch and the ventral 

 wall of the stomach. The dorsal branch extends posteriorly along 

 the sides of the stomach, and upon reaching the second liver pouch 

 forms several branches, all but one of which enter the liver pouch. 

 The exception is a distinct nerve (Bi) which continues along the 

 sides of the intestine, where it soon forms with its fellow a plexus 

 that has been followed to the anal opening. There are indications 

 that in the anal region this plexus becomes continuous with branches 

 from P13 or P2, which, as noted previously, are distributed to the 

 body wall about the anus. 



From the foregoing paragraphs it will be seen that the head, 

 tentacles and otocysts are innervated solely by nerves from the 

 cerebral gangUa. The neck region is suppHed with branches (PU, 

 P14) from the pleural ganglia. The entire ventral half of the body 

 proper and the posterior dorsal half is provided with nerves (PI, P2) 

 from the pedal ganglia. The remaining dorsal half is furnished with 

 offshoots from pleural ganglion nerves (P12, P13). The ventral 

 surface of the esophagus is innervated by nerves (Cx) from the 



