The whole source code of Ardor3D is here:
http://ardorlabs.trac.cvsdude.com/Ardor3Dv1/browser#trunkThe Mesh class is in the "ardor3d-core" subproject.
Ardor3D is not "my" project, I'm only an active contributor, I ported its JOGL renderer from JOGL 1.1.1a to JOGL 2.0 and I still use this engine in my own game.
If you plan to use Ardor3D, you can look at this complete example that displays an MD2 model:
http://ardorlabs.trac.cvsdude.com/Ardor3Dv1/browser/trunk/ardor3d-examples/src/main/java/com/ardor3d/example/pipeline/SimpleMd2Example.java