The purpose of this revised application, as in Case 3829, is to conserve the current usage of the generic name Halitherium Kaup, 1838 and the specific name of its type species, Pygmeodon schinzii Kielmeyer & Jäger, 1835 (currently Halitherium schinzii), for a taxon of fossil sirenians from Europe, by designating a neotype for this nominal species. The name Halitherium schinzii has been used in a substantial body of literature extending over nearly two centuries to the near exclusion of other names. Stability of nomenclature will be served by designating the holotype of Kaupitherium gruelli Voss & Hampe, 2017 as neotype of P. schinzii as well as of Halianassa studeri Studer, 1887 under the ICZN Commission's plenary power, thereby rendering Kaupitherium Voss & Hampe, 2017 and K. gruelli Voss & Hampe, 2017, along with Halianassa Meyer, 1838 and Halianassa studeri Studer, 1887, junior objective synonyms of Halitherium Kaup, 1838 and H. schinzii (Kielmeyer & Jäger, 1835), respectively.