License, verbatimCC0
The Metropolitan Museum of Art: Open Access, Creative Commons Zero (CC0). Flagged isPublicDomain=true in the museum's own record.
Stefano della Bella. A triton and a siren fighting at center, their legs as scrollwork, a swan to right, the grotesque head of an old man below, plate 6 from "Friezes, foliage, and grotesques" (Frises, feuillages et grotesques), ca. 1638–43. The Metropolitan Museum of Art.