Mephibosheth - Also called Merib-baal (and Meri-baal, probably by a clerical error, 1 Chronicles 9:40). The two names seem to have the same meaning: Bosheth, shame, being the equivalent for Baal, and Mephi (scattering or destroying, being equivalent to Merib (contending with). Compare Ish-bosheth and Esh-baal, Jerub-baal and Jerub-besheth.
He fell on his face - In fear. Such generosity to a fallen rival as David showed in restoring him his paternal property seemed to him scarcely credible.