Many biomimetic legged robots exist, but their leg designs appear to be arbitrarily chosen. Here, we examine the performance difference between a canine-inspired rear leg in its normal configuration versus the same leg in a transverse-mirrored configuration. A quadrupedal robot was built to test this hypothesis; the robot was successfully able to walk in with both rear-leg configurations. Successful telemetry of energy and localization data was also demonstrated. Both experimental and simulation results confirm that the transverse-mirrored configuration is faster and more efficient. In experiment the robot achieved speeds of up to 0.4 m/s versus 0.33 m/s, and specific resistances of 3.9 versus 5.1 in transverse and normal experiments, respectively. It is suggested here that the transverse-mirrored configuration, which engages the knee spring more than the normal configuration, be used in designs which require higher speeds and greater efficiencies.