ae 
it 
4 
234 RANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
then cut through in the middle line, and the two sides 
reflected outwards from below upwards, the attachments 
of the transverse muscle bundles being cut through as close 
to the body-wall as possible. The whole course of each 
cerebro-pedal connective is then exposed from the point 
where it perforates the muscular body-wall to its ending 
in the ganglion. The latter, with its nerves, is further 
exposed by picking away the transverse muscle fibres and 
the tubules of the gonad. 
The ganglion (Ga.p.) is elongated in a transverse direc- 
tion, and is rather oblong in shape. The cerebro-pedal 
connectives (Con. cp.) leave its upper and external borders. 
Half-way between the pedal and cerebral ganglia each 
connective gives off a small branch from its internal 
surface, which enters into the viscero-pedal mass. 
Exclusive of the connectives four pairs of nerves radiate 
out from the ganghon. These enter into the surrounding 
tissue. One nerve, however, which is very thick, and 
which leaves the lower border of the ganglion, can be 
traced as far as the tip of the foot. 
The pallial plexus is formed by the three pallial nerves 
described above. The anterior common pallial nerve, it 
has been stated, bifurcates on leaving the anterior adduc- 
tor muscle; the inner of the two branches so formed gives 
off a very fine nerve on its internal side, and thus three 
pallial nerves, as in the case of the posterior common 
palhal trunk, are formed. These three nerves are, of 
course, identical with the three formed from the posterior 
trunk, and so each pallial nerve has a double origin, one 
extremity proceeding from the cerebral ganglion, the other 
from the visceral. At about the centre of the mantle 
margin, the middle and external nerves, which have 
hitherto kept widely apart from each other, come together 
and separate again, and at this point of contact a gangli- 
4 
