Πρυτανεία

When lengthened and feminine [this word means] a certain number of days; but in the neuter nobody has said clearly what it means. Some said it is a sum of money, which those involved in litigation paid, out of which which the jurors' fee was given to the six-thousand [sc. jurors]. But prytaneiai [are] a number of days. There were ten every year, because the tribes [were] also ten. The Athenians followed the lunar year: each of the ten tribes held office for 35 days, and from the lunar-year were left 4 days out, that [the Athenians] assigned to the first four tribes which were chosen to take the prytaneia. And first each of the four [tribes] had a prytaneia equivalent to 36 days, while the remaining six [tribes] had instead [one lasting] 35.
The prytaneia is therefore a number of days, 36 or 35. And every tribe holds the prytaneia [sc. in turn]. But among the other Attic writers prytaneia [are sums of] money, which both of the parties in involved in litigation paid, both the accused and the accuser.