Ketubot 41: Partial Payments and a Goring Ox

Closing the chapter, with a new mishnah. If someone stole, and then comes clean, he doesn't have the pay the additional fine (eg: 2x the object stolen. Basically, those compensation packages that include payment plus fine, the perpetrator can be exempted from the knas (fine). Why isn't rape on this mishnah? Also, the second half of the mishnah takes us into the Laws of Damages, and a goring ox.