Diagnosis
provided by World Register of Marine Species
Isocrinida with arms long, slender; branching mostly isotomous. Facets of brachials with well-developed muscle fossae. Whorls of mostly circular cirri at regular intervals along the pentaradiate column. Facets of columnals with petaloid pattern. Cryptosymplectial to synostosial articulation beneath cirrinodals as preformed rupture point (autotomy plane) between nodal and infranodal; in Proisocrinidae all columnal articulations symplectial and attachment by cementing disk.
