Bulletin of Zoological Nomenclature 297 PROPOSED SUPPRESSION UNDER THE PLENARY POWERS OF THE FAMILY-GROUP NAME " SEGUENZICERATIDAE " SPATH (L.F.), 1924 (CLASS CEPHALOPODA, ORDER AMMONOIDEA) By W. J. ARKELL, M.A., D.Sc, F.R.S. {Sedgwick Museum, Cambridge University, Cambridge) (Commission's reference : Z.N.(S.) 931) The object of the present apphcation is to ask the International Commission to use its Plenary Powers to suppress the family-group name seguenzicera-TiDAE Spath (L.F.), 1924 {Pal. ind. (n.s.) 9 Mem. 1) : 13 (type genus : Seguenziceras Levi, 1896). The grounds for this application are set out below. 2. In an apphcation submitted in October 1950 I asked the Commission to give a Ruling on the question whether the reputed name Arieticeras Quenstedt, 1883, possessed the status of availabihty and therefore whether it invahdated the later name Arieticeras Seguenza, 1885. The question of principle involved was considered by the International Congress of Zoology at Copenhagen in 1953, and in the light of the decision then taken, the Commission has since ruled that Arieticeras Quenstedt, 1883, possesses no status of availabihty and consequently that the name Arieticeras Seguenza is not to be rejected as a junior homonym. In announcing this decision in Opinion 337 {Ops. Decls. int. Comm. zool. Nomencl. 10 : 109 — 124) pubhshed on 17th March 1955, the Commission placed the name Arieticeras Seguenza on the Official List of Generic Names in Zoology, at the same time placing the invahd substitute name Seguenziceras Levi, 1896, on the Official Index of Rejected and Invalid Generic Names in Zoology. 3. In September 1954 Mr. Hemming, as Secretary to the Commission, informed me that it was desired to obtain decisions from the International Commission in regard to the family-group name aspects involved in any applications concerning ammonite nomenclature which had been pubUshed in May 1951 in Triple-Part 6/8 of volume 2 of the Bulletin of Zoological Nomenclature. In aU except the present case the apphcation of the rules adopted by the Copenhagen Congress made it possible to formulate recommenda-tions which were in harmony with current nomenclatorial practice. 4. In the present case the difficulty arises from the unfortunate decision by the Copenhagen Congress that a family-group name is not to be rejected when the name of its type genus is rejected as being (as in the present case) a junior objective synonym of some other generic name (1953, Copenhagen Decisions zool. Nomencl. : 36, Decision 54(1 )(a)). I have already protested Bull. zool. Nomencl. Vol. 11, Part 9. December 1955.
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