This is a unique saddle from the 1970's called the Easy Seat. It came and went and almost nobody noticed.
I was lucky enough to get an original a couple of years ago. It is pretty neat. I used it for about a year. In fact, it wasn't any more comfortable than a normal seat. Maybe if I had a prostrate infection or hemorrhoids, it would be a different story.
Anyway, I saw this on ebay today and thought you would get a kick out of it.