Hemiasterine spatangoids with:
- ovate outline and gibbous profile;
- plastron protamphisternous, with plates 5.a.2 and 5.b.2 enlarged but unequal and with markedly oblique median suture. Labral plate contacting only plate 5.b.2 (usually disjunct);
- episternal plates biserially offset;
- petals long and straight; weakly sunken to almost flush;
- apical disc variable - ethmolytic or ethmophract;
- peripetalous fasciole present.