Abstract. Paradoxostoma ? cretacea Bonnema (1941), is shown to belong to the deep sea cyprid genus Aratrocypris Whatley et al (1985). The implications of the discovery of this genus, hitherto known only from the Palaeocene to Recent, in the Upper Cretaceous of the Netherlands are discussed with respect to the palaeodepth of the Dutch Chalk Sea and to the origin and palaeozoogeographical history of Aratrocypris. The new species Aratrocypris gigantea, from the Recent and Aratrocypris maddocksae from the Cainozoic, are described from the North Atlantic and other, nomina nuda species are described or discussed from the same area.