A quick look at the respective RIC introductions to the eastern coinage of Trajan Decius and Trebonianus Gallus shows that there is some uncertainty about the total number of officinae in the
, , , , IIV, IV
On antoniniani of Gallus we also encounter VI and VII alongside IV and IIV:
, , , , IV, VI, IIV and VII
Back in 1936, Karl Pink proposed four marked officinae at
In 1977 an important paper was published by W.E. Metcalf on a hoard of
i. IV and IIV are retrograde variants of VI and VII (six and seven)
Everything comes down to the interpretation of mint marks IIV and IV. Pink came to his total of four officinae because he read these as 3 and 4 respectively, 'perhaps because there was no mark for the fifth officina '. This would imply that mint marks VI and VII do not stand for six and seven, but are 'irregular variants of IV and IIV (four and three) ', something that RIC finds conceivable. But why use IIV and IV alongside the perfectly adequate mint marks and ? That seems to be very unpractical and hard to understand, to say the least. Is it not much more likely that it is the other way around: IV and IIV are retrograde variants of VI and VII, six and seven?
ii. Decius ' and Gallus ' tetradrachm coinage at the
After the emperor Philip 's demise in AD 249, the number of offinae in the
, , , , /E, S, Z
The system of pellets that was introduced on the final issue of tetradrachms of Philip I now proved difficult to maintain, which is why officinae 6 and 7 adopted Greek numerals S and Z in stead of the unpractical mint marks and . This system of mint marks ranging from to Z was continued into the reign of Gallus.
iii. Mint mark VI was used by officina 6 during the reign of Gallus
Two of Gallus ' tetradrachm issues show without question that mint mark VI was used by officina 6. Both obverse and reverse bear the officina mark, and on these coins VI on the obverse is combined with mint mark S on the reverse Greek numeral S with certainty indicating officina 6. These systems of mint marks had to be logical and easily recognizable within the mint. It is therefore inconceivable that mint mark VI was used by officina 6 on tetradrachms, while at the same time it was used by officina 4 on antoniniani.
iv. The missing officina 5
There are no
There are Decius tetradrachms from officina 5, showing mint marks and E, but it is interesting to see that there are no known Gallus tetradrachms from officina 5. In other words, Gallus ' provincial coinage at the
 For the sake of clarity I only mention the names Decius and Gallus in this short discussion, but of course these mint marks also appear on coins of their family members like Herennia Etruscilla, Herennius Etruscus, Hostilianus and Volusianus.
 K. Pink 'Der Aufbau der rφmischen Mόnzprδgung in der Kaiserzeit ' in: NZ 69 (1936) 14; P. LeGentilhomme, 'La trouvaille de Nanterre ' in: RN 5, vol. 9 (1946) 67; RIC IV part iii p. 118, 155.
 W.E. Metcalf 'The
 Metcalf, p. 84, n.13.
 RIC IV, part iii, in the introduction to the eastern coinage of Gallus, p.155.
 Metcalf claims that there are tetradrachms that combine mint marks IV and IIV with S and Z (p.85, n.13). However, I could not find any published coins to support this statement.
 Prieur 666 and 667.
 I am indebted to Tom Vossen for this idea.