I have the same functionality under Menu button (the three dots) - Share - Send to other devices (with a Firefox icon). When I press that I get a list of device

I have the same functionality under Menu button (the three dots) - Share - Send to other devices (with a Firefox icon). When I press that I get a list of devices connected using Firefox sync and can send the tab to my computer. If I share a URL from other apps, like Chrome, there's an "Add to Firefox" option available also. Using Firefox 48.0 on Android, it auto updates so it should be the latest version.