SHA-FISHERIES LABORATORY. 451 
’ * 
about midway between the mouth and the foot and abuts 
on the liver lobules at this point. It is rather flattened 
here, but from a point immediately below the foot it 
contracts considerably from side to side and becomes 
deeper. The deepest part is where the male abuts against 
the ovigerous portion, and the organ gradually tapers to 
a rounded point. Midway between this free end and the 
parieto-splanchnic ganglion it is attached to the adductor 
by the connective tissue that covers the under surface of 
the muscle and the adjacent organs of Bojanus. The 
whole of this mass is not gonad, for, as described above, 
part of the alimentary canal courses through it (fig. 1, 
Al.c. 3, Al.c. 4), and is thus surrounded by the sexual 
organs; but the intestine does not penetrate to the 
ovigerous part in P. opercularis, whereas in P. maximus 
it runs almost to the end of the mass. 
The ovigerous part occupies the hinder end, and can 
be easily distinguished from the male part when the 
products are ripe, for it has a beautiful vermilion-pink 
colour, becoming deeper as the eggs approach maturity. 
During the ripening of the products, the male part 
becomes cream coloured, and the junction of the cream 
and red is quite sharp though irregular in outline, and 
there may be islands of ovigerous tissue surrounded 
completely by the male organ, or the female part may 
extend a considerable way forwards into the centre of the 
seminal portion which then les on the exterior. After 
discharge of the contents, or when collected before the 
products have developed, the organ has a shrunken and 
flabby appearance, and is of a yellowish-brown colour, 
and the intestine may be seen through it. 
The male and female products of the one individual 
do not appear to be ripe at quite the same time, though 
there cannot be much difference in this respect. Fullarton 
