56 WALTER K. FISHER, 



upper or rectal portion of the right nephridium, near the ureter. In 

 this connection it should be remembered that the rectal portion of the 

 kidney extends out into the pallial cavity, bounded on the forward 

 side by the rectum. Just before passing under the rectum, on its 

 course forward, the visceral nerve divides into two branches, one of 

 which supplies the right ureter. The other division, somewhat smaller, 

 keeps on forward under the rectum to the outer wall of the left 

 kidney, where another division into two nerves takes place. The left 

 one of these (act.n) leaves the wall of the kidney and enters the 

 afferent vein of the ctenidium which it follows, imbedded in the muscles 

 of the outer wall. This nerve is considerably smaller than the main 

 ctenidial nerve (Ct.N 1 ). Just before entering the sinus the nerve splits 

 and then joins again, forming a sort of loop. 



The right branch (lu. n) supplying the left kidney and its ureters 

 follows close under the left reno-pericardial canal, nearly to the ureter, 

 where it divides into two, one passing to either side of the ureter. 

 The lower of these branches then passes upward into the vein-net 

 over the kidney, and thence backward where it was soon lost. 



The prominent branch (ru.n) which innervates the right ureter 

 lies just under a thin layer of muscle in the floor of the rectal portion 

 of the kidney, and pursues a course almost direct to the ureter. The 

 branchings can be better understood from figure than by description. 

 Two divisions at the end of this nerve surround the opening of the 

 ureter and form a plexus. A prominent anterior division (ru. n') passes 

 upward, and enters the vein-net of the kidney. 



The third nerve from the visceral ganglion (Int.N) is smaller in 

 caliber than either of the others. Occasionally it arises by two roots, 

 one of which anastomoses with nerve Vn. It then passes backward 

 and to the right over the anterior-most loop of the intestine, branching 

 a number of times. The distribution of these divisions can best be 

 seen in Fig. 39. The nerve supplies, then, the right anterior portion 

 of the visceral mass. 



Resume of nerve supply of alimentary canal. It has 

 become evident from the foregoing account that the alimentary canal 

 is very plentifully supplied with nerves, arising from three centers: 

 the stomatogastric, visceral, and pleural ganglia. All the nerves of 

 the alimentary canal, particularly those of the stomach, anastomose in 

 a very intricate way, which can be better judged from the figure than 

 from the description. In working out these nerves it must again be 

 stated that only fresh specimens, carefully macerated, are of any 



