Division Bacillariophyta Engl. & Gilg (1919) see Phylum Bacillariophyta Engl. & Gilg (1919)
   Subdivision Bacillariophytina Medlin & Kaczmarska (2004) see Subphylum Bacillariophytina Medlin & Kaczmarska (2004)
     Class Mediophyceae Medlin & Kaczmarska (2004) - bipolar centrics
       1 Order Chaetocerotales Round & R.M. Crawford (1990)
       2 Order Biddulphiales Willi Krieg. (1954)
       3 Order Cymatosirales Round & R.M. Crawford (1990)
       4 Order Thalassiosirales Glezer & I.V. Makarova (1986)
       5 Order Triceratiales Round & R.M. Crawford (1990)
       6 Order Hemiaulales Round & R.M. Crawford (1990)
       7 Order Lithodesmiales Round & R.M. Crawford (1990)
       8 Order Toxariales Round (1990)
       9 ?Order Ardissoneales Round (1990)