The structure of the ctenidium in the Japanese razor-shell Solen strictus was examined. The outer laminae and the inter laminae were connected at the base of the primary filaments opposing at regular intervals by the inter-laminar connecting vessel, and were connected triangularly from the food groove to the inter-laminar connecting vessel by the inter-laminar connecting membrane. The primary filaments and the ordinary filaments were jointed by the inter-filament connecting membrane which spread semicircularly. From the results, the gill type of the Japanese razor-shell was classified with the heterorhabdic pseudolamellibranch.
Japanese razor-shell
ctenidium
food groove
heterorhabdic pseudolamellibranch
inner-filament connecting membrane
inner-laminar connecting membrane