SHA-FISIERIES LABORATORY. 417 
adductor having been suppressed and the foot reduced. 
Furthermore, the mantle, with its important muscles and 
seuse organs, 1s innervated chiefly by the visceral ganglia. 
The fused ganelia lie on the ventral surface of the 
adductor muscle, imbedded in a mass of connective tissue, 
and can be generally seen without any dissection (by 
reason of their yellowish brown colour), on the right side 
about 0°5 cm. from the last poimt of attachment of 
the visceral mass; that is, shehtly postero-ventral to the 
opening of the right renal organ. 
Its shape is very striking indeed (see fig. 28). There 
is a large central lobe, which is divided anteriorly by a 
transverse division into a light yellow posterior part, and 
an anterior portion which is more deeply pigmented 
yellow. ‘This anterior darker part is sub-divided into two 
lobes. laterally, the central lobe is connected by a 
depressed region with two crescent-shaped expansions or 
lateral lobes, practically without pigment. Thus there isa 
post-central lobe (fig. 28, G.c./.)—unpigmented except 
in-its anterior margin; two anterior lobes-—darkly pig- 
mented (G. ant.); and two lateral lobes—unpigmented 
0Glat.). 
These compound ganglia are connected with the 
cerebro-pleural ganglia by the cerebro-visceral connec- 
tives (fig. 28, Con.c.v.). ‘These arise, as we have already 
seen, from the lower end of the cerebro-pleural, and at 
once take a course slightly inward and away from each 
other. That on the left side passes to the left of the 
rudimentary retractor muscle of the foot, and then les 
along the base of the visceral mass at its sides, between it 
and the renal organs and closely apposed to the adductor 
muscle along the greater part of its course. The two 
connectives on reaching the visceral ganglion enter it just 
outside the anterior pigmented lobes, viz., by the anterior 
