The structure of the ctenidia in the Japanese scallop Patinopecten yessoensis was examined anatomically. The ctenidium was fixed on the adductor muscle with the suspensory membrane of filament. The outer lamina of inner ctenidium and the inner lamina of outer ctenidium were reinforced by the dorsal respiratory expansion. The fused border of inner lamina of inner ctenidium and the fused border of outer lamina of outer ctenidium have detachably structure from the attachment parts when the water pressure to the ctenidium is too high. The mouth was covered with the well developed lobe of lipapparatus. The gill type showed the heterorhabdic filibranch: The primary filaments between inner and outer lamina were connected with the inner-filament connecting membrane, and the primary filament and the ordinary filament, and each of the ordinary filaments were connected with the ciliary disk.
Japanese scallop
ciliary disk
fused border of lamina
heterorhabdic filibranch
inner-laminar connecting membrane
lobe of the lip-apparatus