Diagnosis
provided by World Register of Marine Species
Articulata with cup thin walled, hollow, formed by basals and radials; infrabasals absent; basals fused or with 1 to 3 sutures. Radials 5, separated by distinct sutures. Arms undivided, except in Calamocrinus, where the first division occurs between brachials 8 to 15, first division never at primibrachial 2. Arms branch exceptionally at brachial 4 in Dumetocrinus and Gephyrocrinus. Arms considerably narrower than radials, completely separated laterally; radial articular facet narrower than width of ossicle. Nonmuscular articulations smooth synostosial), primibrachials 1 and 2 united by synostosis. First pinnule on brachials 2 to 6. Tegmen covered by small polygonal plates. Column homeomorphic, long, slender, without nodals or cirri. Columnal articulations typically symplectial proximally with radiating crenulae, grouped in more than 5 crenular units (except in Laubiericrinus, the only genus with pentamerous symplexies); symplexies sometimes with areolar depressions or piercings. Facets of distal columnals tending to reduced or densely arranged vermicular crenulae, commonly with juvenile symplectial pattern around lumen. Attachment to substrate by expanded terminal disk, no radix.
- license
- cc-by-4.0
- copyright
- WoRMS Editorial Board
- bibliographic citation
- Hess H. (2011). Hyocrinida. <em>In: Hess H, Messing CG, Ausich WI (Eds.), Treatise on Invertebrate Paleontology, Part T, Echinodermata 2 Revised, Crinoidea, vol. 3. University of Kansas Press, Lawrence, Kansas.</em> 172–179.
- contributor
- Messing, Charles, C.G.
