def _fix_ocean_basins_50_v4_1_0(self, df):
    """fix ocean basins 50 for naturalearth v4.1.0

    - Mediterranean Sea and Ross Sea have two parts: renamed to Eastern and Western
      Basin
    """

    new_names = {
        14: "Mediterranean Sea Eastern Basin",
        30: "Mediterranean Sea Western Basin",
        26: "Ross Sea Eastern Basin",
        29: "Ross Sea Western Basin",
    }

    # rename duplicated regions
    for idx, new_name in new_names.items():
        df.loc[idx, "name"] = new_name

    return df