Article: Stem morphology of the Recent crinoid Chladocrinus (Neocrinus) decorus

The modern crinoid Chladocrinus (Neocrinus) decorus (Wyville Thomson) has a column which is divided into a short proximal growing region, and a longer distal portion in which the arrangement of columnals remains constant. Lumen shape is pentagonal just beneath the cup but is circular for most of the length of the stem. Articular facet morphology shows considerable variation proximally but is constant in the dististele except between nodals and infranodals, where articulation is synostosial rather than symplexial. Cirri are quite different from the column, being elliptical with elliptical lumina and synarthrial articulation between cirral ossicles. Lumen shape is more constant than columnal outline or facet morphology, so it is concluded that the Russian system of naming morphogenera, which emphasizes lumen shape, is preferable to that of Moore (1939a), which stresses columnal outline.