In a pdf of the museum collection I found on the web I quote: "ZODIAC DISC WITH PERGAEAN ARTEMIS
Marble
D: 91 cm.
Roman Period, 2nd century A.D.
Perge - 1.28.77
A greyish white marble disc in the shape of a shield carrying the 12 signs of the Zodiac
upon it, one of which has been lost, when it was damaged. In the middle there is the bust of Artemis Pergaia
with a crescent resting upon her shoulders and some ritual symbols and personifications around the border
of this central figure. The head of the Goddess today is missing."