Phylum Porifera Grant, 1836 - sponges
   Class Demospongea Sollas, 1875 see Class Demospongiae Sollas, 1885
     Subclass †Lithistida Schmidt, 1870
       Order Tetralithistida Lagneau-Hérenger, 1962
         Suborder Tetracladina Zittel, 1878
           Family Theonellidae Lendenfeld, 1903
             Subfamily †Phymaplectiinae Reid, 2004
               1 Genus †Phymaplectia Hinde, 1883
               2 Genus †Thamnospongia Hinde, 1883