Clarke, John R. 1998. Looking at Lovemaking: Constructions of Sexuality in Roman Art 100 B.C.-A.D. 250. University of California Press, Berkeley. ISBN 0-520-20024-1
This is an extensive study of Roman art depicting sexual activity, much of it overtly pornographic. Of the entire (enormous) corpus of material, Clarke has only identified two images that may depict or imply sexual activity between women. Both are part of a series of wall paintings at the Suburban Baths in Pompeii (ca. A.D. 62-79), and the physical condition of the paintings makes interpretation difficult and uncertain.
Both occur in the same location (apodyterium 7) and are scenes 5 and 7 in the series there. The framing of the scenes implies ridicule of sexual activity between women, but it must be considered who the intended audience was (men visiting prostitutes) and the social implications of sexual roles and practices in Roman society.
Scene 5 shows a female figure (identifiable by wearing a breast-band while otherwise naked) reclining on her elbow in bed, turned toward a figure standing beside the bed and with her leg raised to rest on the standing person’s shoulder.
The sex of the standing person can’t be determined from the body, which is indistinct due to damage, but Clarke interprets the person as female based on the hairstyle, and because the person’s skin is depicted as pale and similar in color to the reclining woman. In this genre of art, men are systematically depicted with darker skin than women. Clarke also argues that in this sequence of paintings, there is an increasing degree of “perversion” (according to Roman attitudes) in each successive scene. Given this, the placement of scene 5 in the sequence would be unexpected if it represented a prelude to a standard male-female sex act. Clarke further speculates that among the obscured details, the standing woman may be wearing a dildo (and he provides a number of literary references to such a practice in a Roman context).
Following Scene 6, involving a m/m/f threesome with the man in the middle simultaneously penetrating and being penetrated, Scene 7 increases the number of participants and sex acts. The bed contains two men and two women. From the left, a man anally penetrating a second man, who in turn is receiving fellatio from a woman, who in turn is receiving cunnilingus from a second woman.