A drawing of a scene before a classical altar, executed in pen, ink and wash on blue paper, with touches of white heightening. To the left of the sheet, a river god reclining before a portico, other figures standing to right. The outlines have been pricked. Inscribed at the bottom right in a later hand: 'p polidoro caravaggio.' Arthur Popham attributed the sheet to Francesco Salviati (1510–63); however an attribution to his student Giuseppe Porta (1520–75) is now commonly accepted.