Mrs. McCarty argues that the judge should have granted her motion for judgment notwithstanding the jury's verdict for the defendant. But she failed to move for a directed verdict on the issue of the defendant's negligence, and that is a prerequisite to judgment n.o.v. Fed.R.Civ.P. 50(b). It is true that she made a motion for a directed verdict on the issue of her contributory negligence, which was denied, and that the defendant made a motion for a directed verdict on the issue of its negligence, which was also denied, but these motions were not equivalent to the motion she failed to make. Even if she had been innocent of contributory negligence as