Abstract

The family Lyracystidae n.fam. and genus Lyracystis n.gen. are proposed for the holotype and one paratype of the Middle Cambrian eocrinoid Gogia? radiata Sprinkle, the Burgess Shale “Arms” from the same unit, and many additional partial and more complete specimens of this eocrinoid collected from the Burgess Shale since 1975. A second species, Lyracystis reesei n.gen. and n.sp. is described from a single partly complete specimen from the similar-aged Spence Shale of northern Utah. Lyracystis has three wide V-shaped arms bearing numerous long straight brachioles in the notch, a partly organized theca having larger and smaller ridged plates with epispires, and a very long multiplated stalk made up of rounded or spiny small plates. Lyracystis is the longest-stalked, suspension-feeding echinoderm known from the Middle Cambrian. The three remaining paratypes of Gogia? radiata and four new specimens with possible branched brachioles from the Burgess Shale are renamed Gogia stephenensis n.sp.

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