I am happy to report that Simeon von Pumpernickel has been located. As I suspected, he was making an effort to break into show business, and to that end he mailed himself to my sister who was on a movie set at the time. Fortunately he arrived there safely, but he's not going to be in pictures any time soon. Naughty monkey.
Here he is enjoying some convivial simian conversation with my sister's monkey, Charles Clarence.
So, all you would-be rising stars out there, be forewarned: YOU CANNOT MAIL YOURSELF TO STARDOM. Just FYI.