ORDER LITHOGLYPTIDA KOLBASOV, NEWMAN & HØEG 2009

Diagnosis: Monophyletic in molecular analyses. Females with sac-like mantle; operculum without neck, with wide aperture, opercular bar less than aperture length; labrum big, saddle-like; mouth cirri developed; thorax without long dorsal processes, sets of thoracic lappets without cuticular border; gastric mill absent. Cypris larvae with developed thorax and thoracopods. Burrow aperture elongated, slit-like.