186 Messrs. Hancock and Embleton on the Anatomy «/Eolis. 



mass to the skin. It then passes forwards and m wards, and is 

 lost upon the sides of the channel of the mouth. 



The tenth and eleventh pairs are small, come off from the same 

 ganglion still further back and just in front of the eye, and pass 

 directly outwards into the skin. 



The twelfth and thirteenth arise from the junction of the an- 

 terior and lateral cerebral ganglia, and passing outwards and 

 downwards first, then incline downwards and backwards and run 

 half-way down the body, one above the other, in the skin between 

 the border of the foot, and the rows of branchial papillae. 



The fourteenth and fifteenth, very minute pairs, emerge from 

 the line of union of the anterior and' the lateral ganglia, and 

 are then placed directly under the eye. The former of these 

 nerves goes to the skin of the side of the head between the oral 

 and the dorsal tentacles, the latter to the skin immediately be- 

 hind the situation of the former. 



The sixteenth or optic nerves are stout but very short, and 

 have the organ of vision at their extremity. They are inclined 

 forwards and upwards from the line of union of the anterior and 

 lateral ganglia. 



The seventeenth or auditory are mere rudiments of nerves, and 

 are attached to the anterior ganglia quite close to the bases of 

 the optic nerves, and immediately behind them. The auditory 

 capsule and the eye will be described further on with the other 

 organs of special sense. 



The eighteenth pair, one of the largest, issues from the outer 

 borders of the lateral ganglia, rather in front of the middle, 

 passes outward and bifurcates very soon after ; each of these 

 branches again bifurcates and is distributed by many twigs to 

 the muscles and skin of the foot, both anteriorly and posteriorly 

 (thepedial nerve). 



The nineteenth, also of considerable size, come out of the ex- 

 ternal borders of the lateral ganglia, behind the middle, separated 

 by a considerable interval from the eighteenth, and passing 

 slightly outwards take a backward course, and can be traced in 

 the skin for a long way down the sides of the back, giving off 

 chiefly externally numerous branches that supply the skin. This 

 we presume is the respiratory nerve. 



The twentieth are seen to come forth from the posteriov mar- 

 gins of the anterior ganglia, and are of a size little inferior to the 

 last. They can be traced in the skin of the back between the 

 last-described nerve and the dorsal median line nearly as far as 

 the tail, giving off twigs from their outer sides like the nineteenth 

 pair to the skin. 



The twenty-first, twenty-second and twenty-third pairs arc all 

 small nerves coming out successively from the posterior borders 



