Part T, Echinodermata 2 (Revised), vol. 3, ch. 3, p. 160–225
Journal: Treatise on Invertebrate Paleontology
Year: 2011

Cup large, more or less 5-sided, commonly rather low and wide. Basals forming more or less horizontal underside of cup and commonly part of sides. Radials steep. Radial articular facets separated or laterally in contact. Arms unknown. Column cylindrical or proximally pentagonal; proximal part not widening toward cup. Uppermost columnal enlarged as a 5-sided proximale included in cup, with proximal end reaching the central cavity, and with articular facet toward surrounding basals, forming steep