Diagnosis (see O’Loughlin & Maric 2008). Body flattened, with well-defined ventral sole. Dorsal surface of body invested by imbricating scales. Ventral sole soft, surrounded by tube feet. Mouth and anus dorsally turned.
Remarks. For synonymy, discussion, and a key to genera of Psolidae see O’Loughlin & Maric (2008), with removal of ‘lacking calcareous towers’ from point one emended in O’Loughlin & Whitfield (2010). The authors recommend here that ‘thin calcareous’ also be omitted from the point one description of the sole to allow for the inclusion of Ceto which has a thicker, leathery sole. The diagnosis of Psolidae above does not admit Neopsolidium Pawson, 1964. There are no Australian species of Echinopsolus, Lissothuria or Ekkentropelma.