If a bishop is present during the Eucharistic Liturgy, then a deacon carries the Bishop’s special staff which is surmounted by a golden cross between two golden serpents. This staff is different from the pastoral staff which the bishop uses at other times to indicate his role as an apostolic shepherd.
1246 Johannes Troyer, The Cross as Symbol & Ornament Collected, Drawn and Described (United States: Westminster, 1961): p. 60. 1247 PG. 67:689.