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Rhipidogorgia, rip-i-dō-gor′ji-a, n. a genus of alcyonarian polyps of fan-like shape.

Every Alcyonarian colony is developed by budding from a single parent zooid.

Formerly all corals in which tabulae are present were classed together as Tabulata, but Tubipora is an undoubted Alcyonarian with a lamellar stolon, and the structure of the fossil genus Syringopora, which has vertical corallites united by horizontal solenia, clearly shows its affinity to Tubipora.

The structure of the zooid of Heliopora, however, is that of a typical Alcyonarian, and the septa have only a resemblance to, but no real homology with, the similarly named structures in madreporarian corals.

In the Alcyonarian forms belonging to this great group these tentacles are always eight in number, and fringed on both sides.