Inner surface of roof of opened mantle cavity (1). Air is moved in and out of the mantle cavity by the snail lowering and raising the floor of the cavity (2) to reduce or increase the air pressure in the cavity relative to that of the atmosphere. The oxygenated blood (haemolymph) is circulated to the rest of the body by the heart (3 auricle, 4 ventricle) near the mantle cavity.
Faeces from the rectum (5) and urine brought from the kidney (6) by the ureter are deposited in the mantle cavity from which they are expelled with the exhalent current out of the pneumostome.

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