I still see this photo as two turtles and I've outlined them, the male in red (like their eyes), the female in black for no good reason at all...
Note the male turtle's extended neck, in the stone, as well as this photo below...
"Mating takes place throughout the spring and summer...Box turtle males can be very aggressive with their mating. When the male mounts the female he often will try to bite her head and front legs..."
"Reproduction: There is some variation between the courtship rituals of the subspecies. The courtship of both T.c.carolina and T.c.major is divided into three phases: a circling, biting, shoving phase; a preliminary mounting phase; and a copulatory phase...(T)he actual copulation is the same in all subspecies, with the male standing somewhat upright, leaning the concave part of his plastron against the back of the female's carapace. It is in this balanced position that the male fertilizes the female with his penis. Males sometimes fall backwards after copulation, and if they can't right themselves they die of starvation..." http://nationalzoo.si.edu/Animals/ReptilesAmphibians/Facts/FactSheets/Easternboxturtle.cfm