1 to 1: ovipositor. 2: tip of ctenidium.
Restrained gastropods will, with patience, well directed lighting and luck, provide good views or macro-photographs of the head, tentacles and, within the mantle cavity, the ctenidium, anus, and penis or oviduct opening and ovipositor.
Full article of Anatomy of marine gastropods without dissection. below image 2 2 Gastropod anatomy. Transparent sole of Janolus hyalinus on undersurface of water.