diota - What does it mean?

Noun

A Greek'' had recently discovered a vessel of ''terra cotta'' containing some small bronze coins of ''Naxos'', of the finest die, exhibiting the head of the bearded ''Bacchus'' in front, and a ''diota on the reverse, with the legend ??????: we bought ten of these.

The reasons for introducing these two devices are obvious; but the case of the diota, which is commonly placed horizontally under the feet of the owl, requires a separate explanation. Corsini says, in a dissertation of his Fasti Attici, that it is supposed by dome to refer to the amphora of oil, which was presented to the conquerors at the Panathenæa; but is himself of opinion, that it intended to denotes the manufacture of vessels in terra cotta, for which the Athenians were celebrated.

On the shore here I found three handles of Greek unpainted diotæ , on which magistrates? names are stamped.