Ventral view. Anterior of animal at right of image. Right of animal at top of image.
The white sole is approximately circular when fully spread and attached to glass.
The thick peripheral border of the mantle skirt (1) appears whitish, failing to transmit the mustard colour of its dorsal surface.
The rest of the translucent mantle skirt (2) distorts to blue-green the emerald green of its dorsal surface which is backed by the white of the shell .
Small vessels carry oxygen-depleted, colourless blood from the visceral mass through gaps between the muscle bundles of the pedal retractor muscle and through the green mantle skirt (3) to the efferent pallial vessel.
The large, peripheral, efferent pallial vessel (4) carries oxygen-depleted, blood round the entire animal between zones 1 & 2 of the mantle skirt.
Blood in the efferent pallial vessel travels forwards on both sides of the animal, that on the right passes round in front of the head to the left where two vessels (5) carry the blood into the nuchal cavity (6) where it passes through the ctenidium (7) to be oxygenated and then recirculated by the heart to the body.
See also images 24 Testudinalia testudinalis. Littoral. Moray Coast, Banffshire, Scotland. May 2017. Leg. S. Taylor. and 25 Testudinalia testudinalis. Shell length 13.9mm. Littoral. Moray Coast, Banffshire, Scotland. May 2017. Leg. S. Taylor. .
APPENDIX re range advance/retreat: flic.kr/p/2jW74ig