TL;DR: The tonnacean genus Thalassocyon Barnard is removed from the Cymatiidae and placed in the Ficidae on the basis of shell morphology, the reduced periostracum and the details of the radula.
Abstract: Summary The tonnacean genus Thalassocyon Barnard, 1960 contains only two species, T. bonus Barnard, 1960 from deep water off South Africa and T. mi Dell, 1967 from deep water off northern New Zealand. The genus is removed from the Cymatiidae and placed in the Ficidae on the basis of shell morphology, the reduced periostracum and the details of the radula.