An electric machine for arrangement in a transmission housing, having an adapter device, an axle connected to the adapter device, a rotor arranged on the axle by a bearing device so as to be rotatable about the axle, and a stator which surrounds the rotor in a circumferential direction and which is arrangeable spaced apart from the rotor, and at least partially fixable, in the adapter device, wherein the adapter device partially covers the rotor and/or the stator.