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EAGLE (Aquila), called the "King of Birds", and consecrated to Jupiter as the minister of his lightning, is a type which is often seen standing on a thunderbolt, a globe, a laurel-wreath, a palm branch, an altar or the prow of a ship.
On a denarius of the Terentia gens, struck by Varro, naval pro-questor of Pompey the Great (Pompeius Magnus), the reverse shows the emblems of Pompey's power by sea and land, consisting of a sceptre between a dolphin and an eagle. (Illustrated by the woodcut above).
At the consecration of Emperors, an eagle was set free from among the flames of the funeral pyre. Flying into the air it was supposed to bear the soul of the deified emperor to heaven. For this reason, on the reverse of some posthumous imperial coins with the bare head of the Emperor or the veiled head of the Empress (Augusta) on the obverse, there is shown an eagle in full flight with the emperor or empress on its back. - See CONSECRATIO.
Antoninus Pius and Marcus Aurelius struck coins with the reverse design of an Eagle standing in the middle between an owl and a peacock, the attributes of Jupiter, Minerva and Juno. There is a brass medallion of Antoninus Pius, in the Cabinet de France, which more clearly shows the meaning of this remarkable group. On the reverse of this medallion, which has no legend, Jupiter is seated in the centre with Minerva, also seated, on his right, and Juno on his left. A coin of Vespasian exhibits a similar type of the three shrines of the Capitoline Triad, in which stood the three statues of these deities, each with it's attendant bird occupying the same relative position as on the first coin described in this paragraph.
The coin pictured at the top of this article, showing the eagle standing on a thunderbolt, is from a denarius of the Emperor Domitian in the collection of Alex (FORVM STAFF).