How to add many pictureboxes in a list from a form in c#

I need help. I want to add 200 of picturebox in a list in c#.This i s the code i used but no working. Says that out of arrange.

   List<PictureBox> imagini = new List<PictureBox>();

            foreach (Control c in this.Controls )
            {
                if (c is PictureBox)
                {
                    imagini.Add();
                }
            }