Abstract

Shell tubules etched into the shell by mantle extensions are known from numerous higher bivalve taxa but were so far unknown from Condylocardiinae. Shell tubules of Condylocardia share a number of characteristics with Cardita but are distinctly different from arcoid tubules in diametre, penetration depth and shape. These differences are hypothesised to indicate different functions, origins, and perhaps involvement of different cell types in these taxa. However, further assessment requires histological examinations of the mantle, which was not available for the present study. See addendum for some additional information.