My macbook air (running raring ubuntu linux) has 1 usb plug. I have a usb powered fan tray which has 4 other usb connection. This not only keeps things cool on my lap but expands my ability to plug in toys 
I can't seem to figure out what port the arduino is on when plugged into one of the fan tray usb ports!
When I plug the arduino into my macbook air's single usb port the arduino is mounted as serial port /dev/ttyACM0.
When I plug the fan tray in that mount point doesn't exist and I can't find where the arduino is (it has power).
I've tried searching dmesg and lsusb to no avail. is issue has something to do with the fan tray being recognized as a true usb connection while the arduino is considered serial.
Thoughts, direction? thanks