Spermatozeugmata, not to be confused with spermatophores, that also transfer sperm, are compound structures (parasperms with attached eusperms) known only in certain “mesogastropods”: Loxonematoidea? (Abyssochrysidae), Littorinoidea (Littorinidae), Triphoroidea (Triphoridae and Cerithiopsidae), Tonnoidea (Ranellidae), Janthinoidea (Epitoniidae and Janthinidae), and doubtfully Cypraeoidea (Cypraeidae). This pattern of taxonomic occurrence does not match that of any other character known, their morphology is diverse, and it is concluded that the spermatozeugmata in these taxa are not all homologous and that, like spermatophores, they have evolved repeatedly. Littorinid spermatozeugmata have frequently been studied after fixation and shrinkage of the parasperms (“nurse cells”), during which the eusperms drop off. Spermatozeugmata are not a synapomorphy linking the Triphoroidea and Janthinoidea. Records of spermatophores (except in the “pulmonate” suborder Stylommatophora) since Robertson (1989) are updated.