The structure of the ctenidium of the Razor-shell Sinonovacula constricta was examined. Each space between the principal filament of the outer laminae and one of inter laminae was connected at the base with the inter-laminar connecting vessel, and was connected with the inter-laminar connecting membrane which spread triangularly from the food groove to the vessel. Each semicircle space surrounded with the principal and the ordinary filaments was connected with the inter-filament connecting membrane. From the results, the gill type of the Razor-shell was identified as a Homorhabdic eulamellibranch.
Razor-shell
ctenidium
food groove
Homorhabdic eulamellibranch
inner-filament connecting membrane
inner-laminar connecting membrane