There is a sign missing in Eq. (2b) which should read (Formula Presented) Since publication we have become aware of previous work where symplectic structures and/or constants of motion have been found in the ordinary differential equations describing the rigid body motion of particles in Stokes flow. hese include the sedimentation of three spheres [1], the motion of many particles driven by external torques [2,3], Keplerian orbits of a pair of edimenting discs [4], and the motion of an active sphere in a stream [5,6]. We regret our failure to cite these papers in the context of our Eq. (4). © 2020 American Physical Society. American Physical Society.