The structures of exhalent orifice, ctenidium and labial palp of the purplish bifurcate mussel Septifer virgatus were examined. The exhalent orifice was the single structure with elliptical form. The ctenidium showed the homorhabdic filibranch type. The inner and outer laminae, and each gill filament were connected with the inter-laminar connecting membrane and the ciliary disk, respectively. Each labial palp stretched in wing-shape to the outer side of the ctenidium. The labial palps were not jointed to the ctenidia.
purplish bifurcate mussel
ctenidium
exhalent orifice
labial palp
ordinary filament