Male.

Left: Overlying, fused mantle lobes removed to expose thin, transparent, colourless shell through which several internal organs can be discerned.
Right: Shell removed; internal organs clearly visible through the very thin, transparent mantle.
Visible visceral features (numbered to accord with features in image 17) include:
1: mantle skirt left after cutting. Males have a large penis below the skirt on the right of the animal (see images 19 & 25)
3: bright orange or brown, bipectinate osphradium that tests the water quality of the inhalent current and, possibly, filters out large debris before the current reaches the ctenidium.
4: large, pale orange or yellow, unipectinate ctenidium (gill) with very long filaments.
5: white, left shell-muscle.
6: white, right shell-muscle.
8: convoluted hypobranchial gland that shows as a series of irregular white bands on the mantle. It secretes mucus for trapping and cementing particulate matter from the inhalent current before it is expelled.
9: kidney.
11: testes (ovaries in females).
12: round, opaque white, acid-producing repugnatory glands located in the mantle near the edge of the shell where they would discourage predatory invasion of the viscera contained within it.
13: digestive gland. (Prostate in this species is an unobtrusive, narrow tube.)

Male. Shell length 5.8mm. Isle of Lewis, Scotland. April 2018. Leg. D. McKay & S.Taylor.