188 Messrs. Hancock and Embleton on the Anatomy of Eolis. 



is then subdivided among the testis, the oviduct, the mucus- 

 gland, &c. It seems more than probable that the penis receives 

 a twig from this nerve, and that the spermatheca and ovarium 

 are also supplied from it, though we have not traced branches so 

 far. If any branches pass from this nerve to the heart, which 

 we are inclined to believe is the case, they probably run along 

 the anterior aorta. 



We think it only right to remark, that not having traced this 

 nerve with the same precision as the rest, we do not feel our- 

 selves competent to speak so decidedly of its distribution as we 

 could wish. 



The nerve 7 arises from the third or hindermost collar at the 

 side, passes backwards to the aperture previously noticed as ex- 

 isting in the buccal mass, and therein is applied to the surface 

 of the nerve that issues from the opening, and further we have 

 been unable to follow it. 



In addition to these we have the nerve marked S, which ap- 

 pears to be single ; it comes off from the inner margin of the pos- 

 terior segment of the middle slender collar near the median line, 

 and has been traced to the under surface of the anterior portion 

 of the stomach. There appears to be a small fusiform swelling 

 on this nerve. 



The last nerve to be mentioned, and which is designated s, is 

 somewhat inferior in size to the fifth infra-oesophageal, and as 

 before stated emerges from the aperture among the muscular 

 bundles of the posterior part of the buccal mass. On attempting 

 to follow this nerve more deeply, we find it to end in what seems 

 to be a ganglionic swelling f, from which nervous branches ap- 

 parently radiate throughout the muscular tissue of the buccal 

 mass. If this nerve be traced in the opposite direction from the 

 intermuscular aperture, it is found to pass forwards, inclining at 

 first inwards, and as it approaches the outermost collar receives 

 obliquely from it, near the union of the collar with the buccal 

 ganglion, a branch of communication, »; ; it next runs under that 

 collar, and then under the middle one ; after this still passing 

 forwards and approaching the posterior margin of the lateral 

 supra-cesophageal ganglia, it turns outwards, hooking round 

 over the two outer collars, but having no connexion with either 

 at this part, and reaching the skin at the side of the buccal 

 mass, it bifurcates, one branch passing forwards, the other back- 

 wards ; they both send off numerous twigs which have been fol- 

 lowed to the ramifications of the gastric system at the bases of 

 the papillae. 



In E. olivacea, E. coronata, PL VI. fig. I, and E, Drummondi, 

 PL V. fig. 2, the central masses and the nerves emanating from 



