Suborder Ophiacanthina O’Hara et al., 2017

Diagnosis

Abradial genital plate without conspicuous ridges or perforations. Arm spines smooth or with lateral thorns. Dorsalward increase in size of spine articulations. Lateral arm plates commonly with constriction leading to raised distal portion. Generally row of small perforations (putatively associated with arm spine innervation) in shallow vertical furrow on inner side of lateral arm plates.