Specimen removed from shell 12,1mm long.
Left: viscera viewed through transparent mantle with pigment coating scraped off. (Roof of nuchal cavity removed.)
Right: mantle removed from viscera.
The gonads are situated between the viscera and foot. Just before and during breeding they may spread up and over much of the viscera, but they are usually hidden, apart from a small section (1), on an animal removed from the shell. If the mantle is taken off a female, her ovaries may rapidly expand as the ova absorb water and the constraint of the mantle is removed (2).
APPENDIX re range advance/retreat: flic.kr/p/2jW74ig