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 y 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 6, 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 ¢, is 
somewhat inferior in size to the fifth infra-cesophageal, 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 & 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, y; 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 papille. 
In E. olivacea, E. coronata, Pl. VI. fig. 1, and EL. Drummondi, 
Pl. V. fig. 2, the central masses and the nerves emanating from 
