Phylum Porifera Grant, 1836 - sponges Subphylum Hexactinellida Schmidt, 1870 see Class Hexactinellida Schmidt, 1870 Class Amphidiscophora F.E. von Schulze see Subclass Amphidiscophora Schulze, 1886 Order Amphidiscosida Schrammen, 1924 Family Pheronematidae Gray, 1870 Genus Platylistrum F.E. von Schulze, 1904