The typical pericardium is well developed.
A, Pericardium opened dorsally a, Ventricle of the heart.
The pair of renal organs of Anodonta, called in Lamellibranchs the organs of Bojanus, lie below the membranous floor of the pericardium, and open into it by two well-marked apertures (e and f in fig.
The glands secrete hippuric acid which passes from the pericardium into the renal organs.
It contains a closed vesicle regarded by Schepotieff as a right probosciscavity and in any case representing the pericardium of Balangolossus, the glomerulus of which is also probably represented.