Noctua, the owl:

A seldom mentioned constellation that was once placed on the end of the tail of Hydra, the sea-serpent. The origins of the constellation are unknown, but an image of it appears in the American astronomer Elijah Burritt's Atlas, part of his Geography of the Heavens. Noctua seemed to replace the earlier constellations of Turdus Solitarius, the solitary thrush and John Flamsteed's Hermit Bird. All of these constellations are no longer recognized by astronomers.