Bilaminate structure of foot clearly distinguished on melanistic specimens as ventral sole-layer is white and dorsal layer black. Two layers do not precisely coincide; to anterior of snout (1) the dorsal layer, like the snout, is deeply and widely bifid exposing large ‘V’ of white sole-layer (2) .
At anterior, lobe-tip of black upper-layer may be well behind sole edge (3), close to it (4), or extend beyond it (fig. 14 ). Shell height 1.95 mm, Weymouth, England, April 2012.