17 Rissoella diaphana COMPARE Rissoella opalina

17 Rissoella diaphana COMPARE Rissoella opalina

Rissoella opalina has 1: cephalic tentacles deeply and widely bifid. 2: snout slightly bifid. 3: operculum. 4: white hypobranchial gland with U shaped end, flounced margin, scattered brown blotches and brown oval at its end. Bretagne, France. © M. Cochu.