“…In some dendrochirote holothuroids the pharyngeal skeleton is not unlike the calcareous oral ring and the associated ambulacral plates of some edrioasteroids-an analogy regarded by FELL (1965) as suggesting that the Edrioasteroidea, like the Holothuroidea, descended from a common echinozoan stock. The inclusion of edrioasteroids in Pelmatozoa has been questioned by MATSUMOTO (1929), LAMEERE (1931), andFELL (1965), who consider that their pelmatozoan features are purely secondary responses to adoption of a sessile mode of life. Reasons for including them (and Cyclocystoidea) in the Echinozoa are given in Part U of the present Treatise.…”