[en] An examination of the motions of the optical spiral tracers in the Perseus arm reveals a clear kinematic separation between the inner and outer sides of the arm. Those objects on the inner or near side have a mean velocity residual (ΔV=V/sub obs/-V/sub model/) of -10.7 km s^-1 while those on the outer or far side have a mean positive residual of +7.0 km s^-1. These velocity residuals are interpreted in terms of the linear density-wave theory as streaming motions between the sides of the arm. Plausible solutions for the amplitudes of the noncircular motions yielded 10 to 20 km s^-1 and 7 to 15 km s^-1 for the radial and tangential components, respectively. These results are about twice the amplitudes suggested by the theory