[Kingdom] Animalia Linnaeus, 1758 - animals Grade Enterozoa Grade Cœlomata Phylum Echinoderma Branch Ambulacrata Class Echinoidea (Leske, 1778) - sea urchins and sand dollars Grade Autechini Branch Petalosticha Order Spatangidæ Gray, 1825 Genus Pourtalesia Agassiz, 1869