Patagium

·noun One of a pair of small vesicular organs situated at the bases of the anterior wings of lepidopterous insects. ·see ·Illust. of Butterfly.

II. Patagium ·noun In bats, an expansion of the integument uniting the fore limb with the body and extending between the elongated fingers to form the wing; in birds, the similar fold of integument uniting the fore limb with the body.