accessing usb device - opening a directory

im using ofxDirList which works beautifully with folders on my macintosh hd. im sure it would work just as well on an external hd if i know the name of it before i compile or enter the name at runtime. but if i want the user to add a usb to the mac themselves neither of us will know the name (nor would i want them to enter the name). my plan was to use the shortcut to the external on the desktop but that doesnt seem to appear in the desktop directory when i access it from my program.

is there a way i can get a list of all external device names (or all drive names) so i could allow the user to select theirs and access the files?

edit: just asked my uni supervisor and apparently there is a hidden folder in mac hd called volumes which holds all the drives. yay.