In 1975 the North Sea beach at Scheveningen was raised about 1 m with sand dredged from the North Sea bottom about 20 km northwest of Scheveningen at a sea depth of 20-26 m. Molluscs were very abundant in this sand, and among them were many species quite unusual in the material washed ashore on (this part of) the Dutch coast. In this paper a general introduction is given, together with the first part of the systematical chapter, in which for each species the questions whether or not it lived at the dredging place and what its influence might be on future material washed ashore on the beach at Scheveningen,is discussed.