Differences in the position of the brachioles on the ambulacra, and the number of hydrospires, indicate that species of this widespread genus inhabited two separate environments: carbonate shelf, and biohermal. Ten valid species are recognized, including two new: O. celticus and O. saltensis. Species erroneously assigned to Orophocrinus by earlier authors are removed, and junior synonyms of valid species are listed. A key to species is offered, diagnostic characters are tabulated, and phylogeny, ontogeny, and functional morphology are discussed in detail.