The notion of relativistic, or “particle” rotator, which is the system of four “beingrössen” centered on a moving point in Minkowski space, has recently been introduced to describe kinematically the average motion of extended particles in space time. In this paper, we further study this system as such and show its similarity with the bilocal theory introduced by Yukawa. The special example of the hyper-spherical rotator is treated in detail by replacing the original beingrössen variables with comlex traid variables and relativistic Euler angles.