1)  Coins of the Civil Wars - These coins, all denarii except for a few known aurei, were struck from the revolt of Gaius Julius Vindex in March of 68 until shortly after the final victory of Vespasian in December of 69.  They generally have inscriptions alluding to "Good Fortune", Rome, Liberty, the Senate, Mars, the Roman People, Peace, Harmony, or Jupiter.  One remarkable series revived types of Augustus and Divus Augustus types in a wish for the return of the original style of "principate", where the emperor was merely a "first among equals" rather than an autocrat.  The coins, mostly very rare, were issued in the provinces of Spain, Gaul, Germany, and Africa.  The main imperial mint at Rome was always in the hands of the reigning emperor and therefore never issued any anonymous types.

     2)  Anonymous Quadrantes - These coins, which are generally rather scarce, are anepigraphic on the obverse and bear only "S C" on the reverse.  The types are varied, with animals, personifications, and gods forming the majority.  Many of them resemble types of Domitian and from find evidences they are believed to be from the time of Domitian (81-96) until Antoninus Pius (138-161).  No reason is known for not bearing the name of the issuing emperor, although speculation centers on their being issued at Rome by the Senate on special occasions.

     3)  Coins of the Mines - These quadrantes, which are very scarce, seem to have been struck for circulation only in the mine districts of Dardania, Pannonia, and Dalmatia.  Not all mine coins are anonymous, as some bear the portraits and inscriptions of Trajan, Hadrian, and Antoninus Pius.  However the anonymous variety, featuring obverses of Roma, Diana, Sol, and Mars are more commonly encountered.  Reverse inscriptions on both varieties refer to the mining districts:  "METALLI PANNONICI", "METALL VLPIANI PANN", "DARDANICI", "MET NOR", "METAL AVRELIANIS", "METALL VLPIANI DELM", and "METAL DELM".  The reverse design is often Moneta or Aequitas, a stag, cuirass, Ceres, or simply the inscription alone.  They date in the early-to-mid second century (Trajan to possibly Marcus Aurelius, although no portrait pieces of Aurelius are known).

     4) "Coins of the Interregnum" - Two theories exist on these coins:

    a) When Aurelian was murdered near Byzantium in the late summer of 275, his wife Severina survived and there is substantial evidence from the coins to believe that she may have continued to strike (and rule?) during the so-called 'Interregnum' when the Senate and the Army were paralyzed with fear and remorse, respectively.  That period lasted approximately four months before Tacitus accepted the throne.  Severina's coins of Alexandria dated in the final year of the reign of Aurelian comprise the bulk of that mint's coinage, and her final issues at other mints, which were usually restricted to a few officinae, were struck at all officinae.  Finally, she was the only Empress to strike coins bearing the legend "CONCORDIAE MILITUM", and those coins were her last issue.  A very odd series of sestertii (avg. wt. 15.7 gms) and dupondii were struck of a single type which have an obverse insciption of "GENIVS P R" (Head of the Genius of the Roman People) and a reverse inscription of "INT VRB S C" (Inscription within a wreath).  Those anonymous coins are believed by some to have been issued by the Senate during the "Interregnum", although not with certainty.

    b) The coins described above may have been issued by Gallienus for his return to Rome from Greece in 266.  This theory rests largely upon the resemblance of the portrait to Gallienus and the fact that "INT VRB" may have represented "INTROITVS VRBIS" (roughly - "the entrance to the city").

     5)  Constantinian Commemoratives - These generally common AE3/4's and AE4's were struck in conjunction with the construction of the new capital city of Constantinopolis, and can be closely dated to the period from 330 to 346.  They generally feature personifications of the cities of Rome and Constantinopolis, although the army and the Roman People also are glorified on some of the scarcer issues.  The most common reverses are of the wolf and twins, and victory.  They take their name from Constantine I, the founder of Constantinopolis.

     6)  Pagan Civic Coinages under Maximinus II - These anonymous AE3's and AE4's of Nicomedia, Antioch, and Alexandria feature obverse types such as Serapis, Ceres, Jupiter, the Genius of Antioch, and the Genius of Alexandria.  Generally scarce, they are considered to have been struck during the last persecution of the Christians by Maximinus II (ruled 309-313 - last persecution was from the fall of 311 until early 313).  The most common type, that of "IOVI CONSERVATORI" was struck at Antioch.  In weight they range from 1/12 to 1/8 of a contemporary follis.  Although having aspects of a civic coinage, these coins were probably struck at the imperial mints in the above cities.