450 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
The first kind of cells, those lining the coelomoducts, 
have been found in Lamellibranchs to contain Urea or 
Uric Acid, whilst in Pecten maximus the excretory cells 
of the auricle have been found to contain Hippuric Acid 
(18). In both cases the contents are extruded, in the 
former into the cavity of the coelomoduct and in the 
latter into the pericardium (at least by the cells of the 
auricles), from whence they pass by the renal-pericardial 
openings into the coelomoducts, and so outwards. 
Finally, there are granular eosinophilous cells, which 
are found in numbers along the mantle edge. In places 
they can be seen exiruding their contents, and they 
probably also perform some excretory function, though 
since none are found in the connective tissue it is not easy 
to determine their origin. 
REPRODUCTIY Ee ORGANS: 
The genus VPecten is interesting because both 
unisexual and hermaphrodite species exist. 2. tenut- 
costutus (Mighels), the giant scallop of America, 1s 
unisexual. P. opercularis and P. maaimus are both 
hermaphrodite. In the two latter species the reproduc- 
tive organs are posterior and ventral to the rudimentary 
foot, forming a tongue-like mass attached to and 
depending from the adductor muscle (fig. 1, Go. o. and 
Go. s.). ‘They do not extend into the mantle or encroach 
upon other organs, even when expanded to their greatest 
extent in the spawning season. 
When the sexual products are nearly ripe the organ 
is at its largest, and is firm in consistency as if the 
contents were pressing against their walls. At this time 
the male portion of the gland (fig. 1, Go.s.), which is 
situated most dorsally and anteriorly, extends to a point 
