 The pygidium carries backward directed spines on its margins, where it curves back towards the midline.In the subgenus "Agnostus (Agnostus)", the axis of the pygidium is relatively narrow, ending 
pointed, or narrowly rounded, and furrows crossing the pygidial axis are weak at best.The subgenus "Agnostus (Homagnostus)" has a broadly rounded termination of the axis extending nearly to posterior border furrow.