"This would appear to be purely mythological, but the fact that all these imaginary antediluvian periods consist of a certain number of cycles, shows that this fable was invented subsequent to the time when the Mexicans had attained a knowledge of cycles, years and of the approximate _length_ of the solar year. It seems, therefore, probable that the mythological representation is in some way connected with celestial phenomena, and it is accordingly, found that the days designated in the parallelograms A and C, as 4 Ocelotl, and 4 Quiahuitl, correspond respectively, (on the assumption that the first year of the cycle corresponds with the 31st of December,) with the 13th of May and 17th of July, old style, or 22d of May and 26th of July, new style. And these two days 22d of May and 26th of July, are those, according to Gama, of the transit of the sun by the zenith of the city of Mexico, which, by the observations of Humboldt, lies in 19° 25' and 57" north latitude and in 101° 25' 20" west longitude from Paris. The two other days 4 Ehecatl, and 4 Atl, do not correspond either in the first year of the cycle or in the year 13 Acatl, with any station of the sun or any other celestial phenomena. "There are three other hieroglyphics contained within the interior circumference or representation of the sun, which indicate the dates of some celebrated feasts of the Aztecs. The three following indications or hieroglyphics are found immediately below the figure of the sun. The first of these, designated by the letter H, is placed between the parallelograms C and D, and consists of two squares of five oblongs each, indicating the Aztec numeral 10. The symbol of the day is not annexed, but the whole of the central figure is itself the sign Olin Tonatiah, and the hieroglyphic of the day Olin, as delineated on the stone among the other emblems of the days, is on a small scale and abbreviated form of that central and principal figure of the stone. The day designated here, is consequently, 10 Olin. Below this, and on each side respectively of the great vertical ray of the sun, are found the hieroglyphics of the days 1 Quiahuitl, and 2 Ozomatli. Of the last mentioned days,--10 Olin corresponds in the first year of the cycle, with the 22d day of September, new style;--1 Quiahuitl with the 28th of March, and 2 Ozomatli with the 28th of June, as will be seen by the table at the end of this description of the calendar.