Comó llamar a constructores de clases base

Cómo llamar a constructores de clases base

 

class Point2D
{
  public int X;
  public int Y;

  public Point2D (int X, int Y)
  {
    this.X X;
    this.Y y;
  }
  public virtual void PrintToConsole()
  {
    System.Console.WriteLine("({0}, (1})", X, Y);
  }
}
class Point3D : Point2D
{
  public int Z;

  public Point3D (int X, int Y, int Z) : base (X, Y)
  {
    this.z = Z;
  }

  public override void PrintToConsole()
  {
    System.Console.WriteLine("({0}, {1}, {2})", X, Y, Z);
  }
}
class MyMainClass
{
  public static void Main()
  {
    Point2D My2DPoint = new Point2D(100, 200);
    Point3D My3DPoint = new Point3D(150, 250, 350);
    My2DPoint.PrintToConsole();
    My3DPoint.PrintToConsole();
  }
}