After Parker, 1982 and “The CAS Echinoderm webpage”, 1998

<==o Atelostomata
   |--o Cassiduloida
   |  |-- Echinolampadidae
   |  |-- Cassidulidae
   |  |-- Pliolampadidae
   |  |-- Apatopygidae
   |  `-- Neolampidae
   `--o Spatangoida
      |-- Holasterina Durham & Melville, 1957 sensu Parker, 1982 [Holasteroida Durham & Melville, 1957 sensu The Echinoid Directory, 2004]
      `--o Aphisternata
         |-- Toxasteridae
         |-- Hemiasteridae
         |-- Palaeostomatidae
         |-- Pericosmidae
         |-- Schizasteridae
         |-- Aeropsidae
         |-- Brissidae
         |-- Spatangidae
         |-- Loveniidae
         `-- Asterostomatidae

Reference(s):