Urechinine holasteroids with:
- thin test;
- orthosternous plastron (labral plate followed by single symmetrical sternal plate). Labral plate may be separated from sternal plate by ambulacral plates;
- ambulacral plates I.a.4 and V.b.4 extended behind episternal plates and incorporated into subanal fasciole;
- no rostral plate;
- pores outside phyllodes single;
- apical disc with single anterior genital plate;
- periproct supramarginal; somewhat sunken.