58 
ANTHROPOLOGY: H. J. SPINDEN 
Proc. N. a. S. 
notation or at least no evidence of any such count has come down to us. 
There was, however, a permutation cycle of 260 days based on 20 names, 
that show etymological correspondence to the 20-day names of the Mayas, 
and 13 numbers. The historical records were mostly recorded in a year- 
bearer system. Structurally the Mexican year began with the month 
Toxcatl because this was the month that had as its initial day the particular 
day giving its name to the year. 
The day-for-day correlation of the Aztecan calendar and the Gregorian 
calendar is based on the recorded position of a few days in both counts 
and on statements of the beginning days of the Aztecan months. These 
statements have constantly to be corrected as of a definite year owing to 
the retrogression of the 365-day Aztecan year in relation to the 365.25 
day Julian year. 
In the correlation as finally effected, the Aztecan year 3 Calli began 
ostensibly on a day 1 Calli, the first of the month Atlcaualco, but with 
the significant day 3 Calli as 1 Toxcatl. The day 1 Calli 1 Atlcaualco 
corresponded to February 12, 1521, Julian calendar, or February 22, 
Gregorian calendar. 
A highly important fact develops when the Mayan and Aztecan calen- 
dars are brought together after each has been correlated to the Gregorian 
day. This fact is the practical identity of the two time counts which 
has never before been assumed or demonstrated. It should be sufficient 
to remove any doubts engendered by unavoidable adjudication qf evi- 
dence where authorities are in conflict. 
The Aztecan year bearers, Calli, Tochtli, Acatl, and Tecpatl are equiva- 
lent to the Mayan days Akbal, Lamat, Ben, and Eznab, that in the ar- 
chaic Mayan calendar could occupy the position 1 Pop. But the Yucatan 
year bearers Kan, Muluc, Ix, and Cauac come one day later than these 
days. Therefore, the Mayan year bearers, Kan, Muluc, Ix or Cauac, 
should have numbers one in excess of the equivalent Aztecan year bearers. 
But it is clear that the Mayan year 6 Kan does not equal an Aztecan year 
5 Calli, instead it equals a year 3 Calli. This discrepancy is not funda- 
mental since the two years do not begin at equivalent positions in the 
tropical year. This initial day 6 Kan 1 Pop of the Mayan year 6 Kan 
fell on August 3, 1521, and in the Aztecan yfear 3 Calh found its practical 
equivalent in the first day of the month Tlaxochimaco that began with 
5 Calli on August 1. More exactly 6 Kan equals 6 Cuetzpalin, the second 
day of the Aztecan month Tlaxochimaco, corresponding to August 2. 
We find, therefore, that the permutation cycles of the two calendars come 
within a day of exactly coinciding. The mathematical possibilities in- 
volved in this essential agreement would seem to assure the truthfulness 
of the Mayan correlation. 
It is expected that this new possibility of turning Mayan and Mexican 
dates into the Gregorian calendar will open a new field for investigation. 
