Cephalon: with opisthoparian sutures; glabella usually subrectangular or quadrate, sometimes broad-based, tapering forward, lateral furrows on glabella often faint or absent; palpebral furrows and eye ridges often present; eyes often medium sized, but variable; genal spines typically present.
Thorax: up to 10 segments.
Pygidium: medium to large, broadly transverse, semicircular, subrectangular, or subtriangular; furrows often faint or absent; axis often persist along nearly full length, sometimes extending into terminal spine, or a pair of lateral spines extending from 1st and 2nd pleural field (Kaolishaniidae)