The posterior left part of a fossil skull, found by Mr. G. Pelster of Oosterbeek in a heap of gravel that was dredged up at the Loowaard along the Rhine, upstream from Arnhem, is reported on. It is identified as being a Hippopotamus, probably the Late Pleistocene H. incognitus Faure, 1984. The single anatomical difference from the recent hippo observable in the fossil piece, consists of a funnel-shaped indentation in the squamosal, directly in front of the posterior base of the no longer present jugal arch, probably an extra implementation of a part of the masseter muscle.