Audacity doesn't recognize PreSonus Firestudio

I’ve had a Presonus Firestudio Mobile, and I’ve been able to use it with Reaper and Garage Band on my MacBook Pro, but Audacity has never recognized it, and has never showed it in Audacity preferences, either as an input or output device. This has been true no matter which version of Mac OS X I’ve run (10.6, 10.7, and 10.9). Audacity does work with the MacBook Pro’s mic or line input.

Should I be able to use my FireStudio with Audacity?
If so, does anyone know what I need to do to resolve this problem?

Thank you!

Could this be as simple as plugging in the sound device, let the Mac recognize it and then start Audacity?