Browser question: what is the name for the button that gives a "vertical history"?

I’m talking about the button next to the Back (left arrow) and Forward (right arrow) buttons. The one that allows you to quickly select a page you visited 5 clicks ago.

Is there a name for that? It appears to have been removed from the default settings in IE9 and Firefox 11, and I’d like to figure out if it can be restored. Hard to do a Google search without knowing what it’s called, though.