Centre left: O. muricata rhinophore has maximum of 12 lamellae. Tubercles are club-shaped with broad top. White southern form of O. muricata.
Centre right: Adalaria proxima rhinophore has maximum of 19 lamellae. Club-shape and torpedo-shape tubercles on the mantle have a narrow rounded apex. White Orkney form of A. proxima.

Drawings from Alder & Hancock (1845-1855) uncoloured except A. proxima rhinophore of southern yellow form..