The posterobasal portion of the axillary membrane, joining the hind margin of the wing to the thorax, forms two basal lobes called the calypteres (sing. calypter; squamae, squamulae). The proximal lobe, called the lower calypter, begins as a narrow, membranous ligament arising from the furrow between the scutellum and the postnotum and ends where the more distal lobe, the upper calypter, folds sharply over it.