Cheirocrinidae

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Treatise on Invertebrate Paleontology, part T, vol. 2 (1978):

• Crown pendent or recumbent on stem, with imperfect to perfect bilateral symmetry developed in the plane of the E ray and BC interray. Cup with basal circlet subtriangular in outline consisting of four, three, or one plates which bears all or part of the stem impressions at apex of triangle and is muscularly hinged along base of triangle with radial plates; median (E) radial compound, with inferradial forming middle part of all hinge contact with basal and superradial connected broadly to narrowly with inferradial or disconnected by intervention of adjoined edges of large lateral (A,D) radials; B and C radial compound, in some genera with infer- and superradial elements of each distinct, but in others with superradials fused together and in one genus (Senariocrinus) with inferradials fused in accompaniment with unfused superradials, lateral radials (A,D) large and undivided, oppositely placed with respect to the plane of bilateral symmetry. Median (E-ray) arm unbranched or isotomously divided; lateral arms multiple, characterized by the compound proximal axillary brachials that form main-axil series and more or less numerous axil-arms with heterotomously developed unbranched ramules produced alternately from abanal and adanal sides of the axil-arms (except in Chiropinna). Anal tube composed of stout, transversely crescentic plates arranged uniserially with inner (ventral) side covered by irregular, thin, small plates. Stem formed of modertaely thin, discoidal columnals.

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