AQUILA----and Aquila legionaria.----See Eagle.
An aquila (plural: aquilae) was the standard of a Roman legion topped with an eagle, which was carried by a special grade legionary known as an Aquilifer (aquila-bearer). One eagle standard was carried by each legion. The eagle standard was extremely important to the Roman military, beyond merely being a symbol of a legion. A lost standard was considered an extremely grave occurrence, and the Roman military often went to great lengths to both protect a standard and to recover it if lost; for example, see the aftermath of the Battle of the Teutoburg Forest, where the Romans spent decades attempting to recover the lost standards of three legions.
Source: http://en.wikipedia.org/wiki/Aquila_(Roman).