License, verbatimCC0
The Metropolitan Museum of Art: Open Access, Creative Commons Zero (CC0). Flagged isPublicDomain=true in the museum's own record.
José Guadalupe Posada. A skeleton holding a bone and leaping over a pile of skulls while people flee, from a broadside entitled 'Las bravisimas calaveras Guatemaltecas', ca. 1907 (a later impression). The Metropolitan Museum of Art.