Abstract
In an Appendix to the Actiniæ of the Challenger Expedition, R. Hertwig. 1882, described a peculiar genus, Porponia, with two species, P. elongata and P. robusta, which he characterises in the following manner: “Actiniarien (Hexactinien?) mit 2 Schlundrinnen ohne Ringmuskel, mit dünnwandigen Tentakeln, deren Basen auf der äusseren Seite durch spangenförmige Verlängerungen des Mauerblatts gestützt werden.” Partly owing to the badly preserved material, however, he did not venture to indicate definitely its systematic position, though he considered it conceivable that it represented a transitional form between the Zoanthidæ and the true Actiniæ, or Hexactiniæ.

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