[Kingdom] Animalia Linnaeus, 1758 - animals
   Grade Enterozoa
     Grade Cœlomata
       Phylum Echinoderma
         Branch Tentaculata Eschscholtz, 1825
           Class Blastoidea Say, 1825
             Order Elœacrina
               1 Genus Elœacrinus
               2 Genus Pentatrematites Sowerby, 1828