The style of this sheet is close to that of drawings executed by Salviati early in his career such as the two copies after Raphael in the Louvre (C. Monbeig Goguel, Francesco Salviati o la Bella Maniera, exhib. cat., Rome, Villa Medici and elsewhere, 1998, pp. 31-33, figs. 1 and 2). These drawings show the same type of red chalk crosshatching delineated with strong outlines. In particular the sheet of Jupiter and Ganymede shows the same treatment of the face in close hatching with a prominent ear.
Similar drawings, most of which are also copies of other masters, are in Brunswick, in the Louvre and in Poitiers (C. Monbeig Goguel, op. cit., nos. 2, 3, 6 and 10).
Giorgio Vasari recounts in his Life of Vasari that when he arrived in Rome in the winter of 1530-1 to join his friend Francesco Salviati they 'devoted themselves in company all that winter to the study of art, with much profit, leaving no noteworthy work, in a palace or in any other part of Rome, that they did not draw' (G. Vasari, Lives of the Painters, Sculptors and Architects, London, 1996, II, p. 560).
The composition is based on a lost drawing by Raphael, in which Hercules is similarly gripping the lion's head in his left arm, known through a chiaroscuro woodcut by Niccolò Vicentino (Bartsch XII, 17). That design was also used, with slight differences, by Giulio Romano in a fresco in the Sala dei Cavalli in the Palazzo Te, Mantua (K. Oberhuber in Giulio Romano, exhib. cat., Mantua, Palazzo Te, 1989, p. 151).