I04 Shell Life 



iridescent, marked witli fine irregular grooves which 

 run from the beak to the lower margin. The cardinal 

 tooth is small and erect, whilst the laterals are long 

 and plate -like. The white animal has a short 

 excurrent siphon, and a bluish foot streaked with 

 white. The fringe of tentacles around the mantle 

 is shown in the figure, where will also be seen one 

 tentacle above the foot developed abnormally as 

 compared with the others. When the creature 

 crawls along it waves this tentacle about, appar- 

 ently using it as a sense-organ, feeling its way and 

 ascertaining the presence of food. It is a southern 

 species, its distribution here being restricted to 

 Dorset, Devon, Cornwall, the Channel Islands, and 

 the south and west of Ireland. Like the Montagu- 

 shells previously described, it has a preference for 

 the company of a creature belonging to an entirely 

 different class of animal life. In this case the mess- 

 mate is a sino^ular crustacean, known as Gebia stellata, 

 that burrows in muddy sand. No doubt the Lepton 

 acts, to some extent at least, as a scavenger, feeding 

 upon the excretions and surplus food of Gebia, whilst 

 the flatness of its shell enables it to keep out of 

 the way as the Gebia scuttles up and down his 

 burrow. 



The Shining Coin-shell (Z. nitidiim) is a much 

 smaller species, as will be seen on reference to the 

 figures, which are of the natural size. It differs from 

 squamosum by the shell being less flat, less thin, 

 with the beaks more prominent, and the animal 

 appearing to be more gelatinous. The lower edge 

 of the shell is less straight, and the fine rib-marks 

 run only in one direction — that is concentrically. 



