Copan, Altar U, 1 to 2 2 Caban 0 or 20 Pop. " " U, 51 to 52 3 Eb 0 or 20 Pop. Temple of the Cross, Q 2 P 3 11 Caban 0 or 20 Pop. " " " " F 12 E 13 9 Ik 0 or 20 Chen (J.T.G.) " " " " E F 9 9 Ik 0 or 20 Yax or Zac. The month glyph of the last example looks like Zac. If it is Yax it proves Goodman's theory by calculation. Thus we see that in three out of four cases in the Dresden Codex and in three cases out of four in the Inscriptions where the context is such as to throw light on the question, the evidence is in favor of concluding that the months began with a day 0 or 20 and not with a day 1. Moreover in the single case in the Codex which tends to prove the contrary, it is interesting to see that the month glyph, Xul, is somewhat different from the other Xul glyphs, while in the doubtful case in the inscriptions, if the month glyph had been Chen and not Mol, it would have agreed with the dates before and after it. In other words, the calculations both before and after the date in question would be quite accurate if the month were Chen and if, therefore, the beginning day were 0 or 20, while the glyph of Mol makes the calculation after that date inaccurate. All the evidence taken gives a very strong presumption in favor of Goodman's theory that the month began with 0 or 20. It is also interesting to notice that of the other dates given above where the calculation does not help us, three of these are 0 or 20 Pop (provided we have identified the number glyph correctly, which is certainly none of the known glyphs for any of the numbers 1 to 19). This date would not be significant if 20 Pop were the last day of the month, but it would be very significant if it were the beginning day of the month, that is the beginning day of the New Year. I think, therefore, that it is safe to assume as a good working hypothesis that the beginning days of the month were designated as 0 or 20, and the last day of the month as 19.