Messrs. Hancock and Eniblcton on the Anatomy i/Eolis. 187 



of the anterior ganglia between the last-described nerve and the 

 median line. They all pass a good way backwards to the dorsal 

 skin on each side of the median line. 



The origin, course and distribution of the six pairs of infra- 

 oesophageal nerves are as follows : — 



The lirst pair come from the upper surface of the roots of the 

 pedicles that support the gastro-cesophageal, and close to the 

 buccal ganglia. The nerves are rather small, run forwards and 

 apply themselves to the oesophagus, along which they are con- 

 ducted to the stomach, the greater part of which organ they sup- 

 ply with branches. 



The second, third and fourth arise from the margins of the 

 gastro-oesophageal ganglia, are very small nerves, but can be 

 traced to the oesophagus and neighbouring parts of the stomach. 



The fifth pair come out of the external ends of the buccal 

 ganglia in conjunction with the third or outermost oesophageal 

 collar, to which they are slightly inferior in size. The nerves and 

 the collar separate at once; the nerves passing backwards and 

 outwards give oiF each a branch that bendy forwards and outwards 

 and becomes lost among the muscles of the buccal mass external 

 to the ganglion. The trunk then inclines towards an opening 

 between the muscular bundles of the back part of the buccal 

 mass, and enters that opening lying in contact with another large 

 nerve that is observed to issue from the same. 



It is difficult to follow the trunk far into the intermuscular 

 aperture, but as far as we have been able to trace it, it appears 

 to be destined iov- the buccal mass and tongue. 



The sixth pair is given off from the posterior margin of the 

 buccal ganglia, and shortly after becomes lost among the mus- 

 cular bundles of the back part of the buccal mass. 



Of the five pairs of nerves from the commissures, two have 

 already been described, viz. the first and second supra-oesopha- 

 geal j the three that remain come off from the oesophageal collars 

 in the following manner. 



The pair marked a come off from the outer margin of the first 

 or innermost collar near the median line. They are very minute 

 nerves, and we have not succeeded in tracking them to their 

 destination. 



That marked ^ is the genital and probably the cardiac nerve, 

 and is an offset from the middle or slender collar, which it nearly 

 equals in size, at a short distance behind its attachment to the 

 anterior cerebral ganglion. It runs from this origin backwards 

 and outwards to the generative organs, guided partly by the an- 

 terior aorta, gains the fissure where the confluence of the ducts 

 from the diftercnt parts of the generative apparatus exists, and 



