Division Haptophyta Hibberd
   Class Prymnesiophyceae D.J. Hibberd (1976) see Class Coccolithophyceae Rothm. (1951)
     Subclass Prymnesiophycidae (D.J. Hibberd) Cavalier-Sm. (1986) see Class Prymnesiophyceae D.J. Hibberd (1976)
       "Holococcoliths"
         Family Calyptrosphaeraceae Boudreaux & Hay (1969)
           ?Genus †Orastrum F.H. Wind & S.W. Wise, in S.W. Wise & F.H. Wind, 1977