28 Tonicella marmorea

28 Tonicella marmorea

Intermediate valve. Sublittoral, Orkney. February 2015. Leg. P. Lightfoot per J. Porter.
The white articulatum on intermediate valves ii to viii projects forwards as a pair of gently curved, wide, short (front to rear) apophyses (1) separated by a narrow jugal sinus (gap) (2) that is less than 25% length of an apophysis.

marinvert.senckenberg.science/image-browse/