28.1 Rissoa membranacea.

28.1 Rissoa membranacea.

Males have a large, whitish penis attached behind the right tentacle. When not in use, it is recurved to fit into the shorter mantle cavity, as in this image where it is seen (1) through the semi- transparent shell. Mediterranean form. Sublittoral. Novigrad, Croatia. November 2017. Leg. © A. Petani.

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