; class Stelleroidea, subclass Ophiuroidea)
An order of brittle-stars in which the ambulacral groove is covered by the lateral arm-plates. The dorsal and ventral arm-plates are well developed. Large radial shields, buccal shields, and genital plates are present in the disc. The order is known from the Silurian to the present.
Subjects: Zoology and Animal Sciences.