The steady flow induced between two offset plates rotating at angular velocity bounding a fluid-saturated porous medium in a system uniformly rotating at angular velocity is studied. The problem is governed by a Reynolds number R, a porosity parameter , and representing the ratio of Coriolis to inertial forces. Details of the loci of centers of rotation projected onto the mid-plane are found, and sample similarity profiles covering a range of parameters are given in graphical form. A formula is derived to compute spiral angles as a function of gamma and sigma.