It is grublike without distinct sclerites on thorax or abdomen and without urogomphi. Legs are short but have six segments, as is usual in Adephaga. There is only one tarsal claw. Most of the body segments each have a dorsal transverse row of spinulae which is interrupted at the midline. At a minimum there are such rows on the metathorax and abdominal segments 1-6.
Eyes are absent.
There is a soft epipharynx projecting anteriorly. In the past, this has been mistaken for a labrum. The nasale is truncate, the labial palpi are reduced to vestiges, and the maxillae and prementum bear fringed membranes. These highly modified beetles have been moved from place to place among the Coleoptera. At first they were grouped with other wood-dwelling beetles of somewhat similar appearance, and therefore, among the Polyphaga .