Structure of the internal skeleton of the metathorax of Aphrophora. (A) Ventral view of the left half of the metathorax and proximal joints of the left hind leg. The box on the inset drawing indicates the area drawn in detail. The ventral cuticle of the thorax (orange) and the muscles were removed to reveal the pleural arch (red), linking the lateral edge of the coxa of the left hind leg (green) ventrally to the articulation of the left hind wing dorsally. (B) Dorsal view to show the left pleural arch curving ventrally from the hinge of the left hind wing to the lateral hinge of the thoraco-coxal joint of the left hind leg. The large tendon of the trochanteral depressor muscle is also shown.