Fig. 11. Traces of two landmarks (tripod arms) in two arm-fixed coordinate systems, reconstructed for the left elytron in Melolontha hippocastani. (A,B) Traces of two arms in the arm P-fixed system; (C,D) Traces of two arms in the arm V-fixed system. A and C show traces of the referent arm in its own fixed system, while B and D show traces of another arm in the former system. The reference arm-fixed system rotates together with the elytron about the body-fixed axis, while the other arm turns about the radius-vector of the reference arm. Each arm may be set as the reference one. Zero pitch, 4 episodes, 90 frames.