On page 210 it gives the illustration of a man tied to a stake, under which illustration it says: “Prometheus tied by Zeus to the stake (or cross) and exposed to the Eagle: Rescue by Hercules (A vase found at Chiusi, now in Berlin.
... For observe that in some of the older pictures, as, for instance, in the vase of [page 211] Chiusi (see illustration on page 210), Prometheus is not chained to a rock but tied to a pole, that is, to a σταυρός or cross, and Greek authors frequently use expressions such as the verb ἀνασκολοπίζεσθαι (Aeschylus) and ἀνασταυροῦσθαι (Lucian) which mean ‘to be crucified.’”