Vestigial wings are wings on a creature, which cannot be used to fly becasue the wings are too small to lift the creature. For example, the Hydra has wings that are too small to be used for flight. These wings can be used, however, for appearence: they can make the dragon seem larger than it truely is, or be used for display in the sense of attracting a mate. Vestigial wings are leathery or scaly in all known dragon cases.
- Drake, Ernest. Dragonology Field Guide to Dragons. China. Candlewick Press, 2007, pgs. 17, 25.