Mantle removed except yellow anterior (7).
1: operculum.
2: dark ventral surface of epipodium.
3: pale dorsal surface of epipodium.
4: sole of foot.
5: side of foot.
6: head.
7: anterior of mantle.
8: ?.
9: rectum.
10: ?.
11: pericardium, sac containing the heart.
12: right kidney.
13: digestive gland (mostly concealed by 14).
14: gonads (inactive; in September). Colour similar in both sexes,
except February- May when ovaries green and testes pink or
cream. www.marlin.ac.uk/species/detail/1324
15: columellar muscle.
Photograph interpreted with Fretter and Graham (1994, in Crothers, 2001, .).
Menai Strait, Wales. September 2016.