LEFT: Ctenidium removed, at larger scale.
RIGHT: animal removed from shell and black pigment rubbed off translucent mantle.
1: mantle rim with thin, yellowish upper layer and thick, white lower layer.
2: left columellar muscle.
3: comb-like ctenidium (gill).
4: osphradium for testing water quality before it reaches the gill. In this species it has a structure similar to the ctenidium. Early workers misinterpreted it as a second smaller ctenidium (Jeffreys, 1867).
5: very extensive white hypobranchial gland lining the entire roof of the mantle cavity to the right of the ctenidium.
6: digestive gland.
7:intestine.
8: ovotestes.