The length of arc or circumference for the cross-section of the red blood cell has been determined for the normal range of dimensional values for mammalian red cells. Graphs for arc length vs. diameter and vs. cross-sectional area, for fixed thickness, are included. The graphs give an indication of the rates of change of the geometrical parameters contained therein. A special case of Fick's Law, based on the model geometry utilizing the Oval of Cassini, is presented for the mammalian red cell. The ratios of surface area to volume necessary for a complete Fick's Law formulation, are given for the normal range of dimensional values for the mammalian red cell.