Salmacis and Hermaphrodite
The story is from Ovid's Metamorphoses IV. Spying on Hermaphroditus as he bathes, the nymph Salmacis is consumed with passion; later she captures him in her embrace and their bodies become one - half-male, half-female. This is one of a number of studio variants based on an original by Albani in the Louvre and is especially close to an example in the Galleria Sabauda, Turin.