Bulletin of Zoological Nomenclature 227 PROPOSED USE OF THE PLENARY POWERS TO DESIG-NATE A TYPE SPECIES FOR THE GENUS " ANCYLUS " MiJLLER, 1774 (CLASS GASTROPODA) IN HARMONY WITH ESTABLISHED NOMENCLATORIAL PRACTICE By BENGT HUBENDICK {RiksmUfSeum, Stockholm, Sweden) (Commission's reference Z.N.(S.)240) The object of the present application is to seek the assistance of the International Commission on Zoological Nomenclature, through the use of its plenary powers, in securing that the type species of the genus Ancylu^ Miiller (O.F.), 1774 (Class Gastropoda), shall be the species commonly accepted as such and to avoid the confusion which would result from the strict application of the normal rules in this case. That confusion would be extremely serious, for imder the normal rules it would be necessary to abandon the term " Ancylus-See " which is imiversally used to denote a well-known former limnic stage of the Baltic and is so deeply entrenched in the Uterature of European geology that its abandomnent would be open to the strongest possible objection and must, indeed, be regarded as entirely impracticable. 2. The generic name Ancylus was first published in 1767 by GeofiFroy on pages 13 and 124 of his Traitd sommaire des Coquilles . . . qui se trouvent aux Environs de Paris. Geoffiroy placed what he regarded as one species only in this genus but he did not cite it under a binominal name. The description which he gave is so vague that the species which he had in mind might have been either the species now commonly treated as having already been named Patella lacustris Linnaeus, 1758 {Syst. Nat. (ed. 10) 1 : 783) or the later named species Ancylus fluviaiilis Miiller (O.F.), 1774 {Verm, terrestr. fluviat. Hist. 2 : 201). Geoffroy stated however that the species in question was the only one knoA\Ti in the neighbourhood of Paris and this suggests that that species was the common Ancylus fluviatilis Miiller. This inference is supported by the fact that Geoffroy cited (1) Lister (1678, Hist. Anim. Angl. : 151, pi. 2, fig. 32), (2) Gualtieri (1742, Iiidex Test. Conch. : pi. 2, fig. AA), and (3) d'Argenville (1780, Conch. 2 : 1, pis. 8, 27), for the figures given by all of these authors appear to represent the foregoing species. On the other hand, Geoffroy cited also the description of Patella lacustris pubUshed by Linnaeus in 1746 (Faun, svec. (ed. 1) : 369) and again in 1758 {Syst. Nat. (ed. 10) 1 : 783). There has however been discussion in the past as to the identity of the species to which Linnaeus appUed this name. Jeffreys (1862, Brit. Conch. 1 : 123), for example, and Woodward (B.B.) (1903, J. Conch. 10 : 361) pointed out that the descrip-tion given by Linnaeus apphed as well to the species Ancylus fluviatilis Miiller as to that to which the name Patella lacustris Linnaeus, 1758, is commonly appUed ; the figures cited by Liimaeus appear to depict Ancylus fluviatilis Miiller, and that species alone is represented in the Linnean collection. It was for reasons of this order that nearly one hundred years ago Forbes & Hanley (1852, Hist. Brit. Moll. 4 : 188) and Hanley (1855, Ipsa Linnaei Conchylia : Bull. zool. NomencL, Vol. 6 (Jxiiy, 1952)
Proposed use of the plenary powers to designate a type species for the genus Ancylus Muller, 1774 (Class Gastropoda) in harmony with established nomenclatorial practice
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