The structure of the ctenidium in the Megangulus venulosa (Tellinidae: Veneroida) was histomorphological examined. The outer ctenidium lacks the outer lamina and the inner lamina of outer ctenidium (ILO) upturns from the ctenidial axis (CA). The outer lamina of inner ctenidium (OLI) descends from CA to the ventral bend (VB) and the inner lamina of inner ctenidium (ILI) ascends from VB. ILO is attached to the fixed-membrane of ILO (FML) which develops between the filament and the longitudinal vessel running along the edge of FML. ILI and OLI are attached to the inner-laminar connecting membrane. The laminae are composed of the ordinary filaments (OF). Each OF is joined together by the interfilamentar junctions which form an intra-plical band, and is attached to the interfilament connecting membrane composed of the lacunar tissue of the interfilamentar junctions.
Megangulus venulosa
Fixed-membrane of the inner lamina of outer ctenidium
Inner-filament connecting membrane
Interfilamentar junction of the form of an intra-plical band
Lacunar tissue of the interfilamentar junction
Ordinary filament