Subclass †Heterostraci Lankester, 1868 Family †Cyathaspididae Kiaer, 1932, nom. praeval. Subfamily †Poraspidinae Denison, 1964 Genus †Homalaspidella Strand, 1934 [paraphyletic] 1 †Homalaspidella borealis Denison, 1963 2.1-n †Homalaspidella nitida [sister group to excluded taxa]