MIDI on OS X
In order for CoreMIDI to work with Jack MIDI, a CoreMIDI-to-JACK-MIDI bridge is required. This feature is available on versions equal to or greater than version 0.89 of JackOSX.
MIDI ports show up in Ardour's MIDI connection matrix in multiple locations. Bridged CoreMIDI ports as well as JACK MIDI ports that have been created by other software clients will show up under the "Other" tab. Bridged CoreMIDI hardware ports show up under the "Hardware" tab.
There are multiple options for connecting MIDI ports outside of Ardour.