consul B. C. 20, is a false reading in Dio Cassius (55.30) for Silianus.
The full name of this consul was A. Licinius Nerva Silianus [NERVA, LICINIUS, No. 7].
William Smith. A Dictionary of Greek and Roman biography and mythology. London. John Murray: printed by Spottiswoode and Co., New-Street Square and Parliament Street. In the article on Soranus, we find: "at this present time (1848)" and this date seems to reflect the dates of works cited. 1873 - probably the printing date.