Division Bacillariophyta Engl. & Gilg (1919) see Phylum Bacillariophyta Engl. & Gilg (1919)
   Class Coscinodiscophyceae Round & R.M. Crawford (1990) - radial centrics
     Subclass Coscinodiscophycidae Round & R.M. Crawford (1990)
       Order Coscinodiscales Round & R.M. Crawford (1990)
         1 Family Coscinodiscaceae Kütz. (1844)
         2 Family Rocellaceae Round & R.M. Crawford (1990)
         3 Family Aulacodiscaceae (Schütt) Lemmerm. (1903)
         4 Family Gossleriellaceae Round (1990)
         5 Family Hemidiscaceae Hendey (1937)
         6 Family Heliopeltaceae H.L. Sm. (1872)