Bath tub spout collar ...

[myopicdystrophy]

I got the chrome cover off with a lot of effort - but I was left with this mystery! There's no set screws - the tiny hole on the bottom is where the little finish screw held on the cover. Has anybody seen these before and have an idea on how to remove it? It's an American Standard probably from the 1970s ... thanks for any help!

Here are the picture links:
http://www.flickr.com/photos/112635248@N06/11574682045/
http://www.flickr.com/photos/112635248@N06/11575013324/
http://www.flickr.com/photos/112635248@N06/11575013554/
http://www.flickr.com/photos/112635248@N06/11575017054/
http://www.flickr.com/photos/112635248@N06/11574687675/

We have a friend moving in so I'm trying to get this ready for her! Thanks again.