Subclass †Heterostraci Lankester, 1868
   Family †Cyathaspididae Kiaer, 1932, nom. praeval.
     Subfamily †Poraspidinae Denison, 1964
       1 Genus †Homalaspidella Strand, 1934 [paraphyletic]
       1.n.1 Genus †Faberaspis Elliott, Lassiter & Blieck, 2018
       1.n.2 Genus †Poraspis Kiaer, 1930