The tonalpohualli (count of days) was the sacred almanac of the Mexicas. This ritual calendar was registered in the tonalamatl (book of days), a green-fold bark paper or deerskin codex from which a priest (called tonalpouque) cast horoscopes and predicated favorable and unfavorable days of the cycle. The almanac year comprised of 260 days, each of which was assigned a date by intermeshing one of 20 day-signs, represented graphically with a glyph, and a number from 1 to13, represented by dots so that no two days in the cycle could be confused. The almanac year was thus made up of 20 13-day weeks, with the first week beginning on 1-Crocodile and ending on 13-Reed, the second week running from 1-Ocelot to 13-Deaths' Head and so on. A god or goddess was believed to preside over each day-sign, as shown in the following chart.
The Center of the Disc - Tonatiuh
Tonatiuh's Face is the face of the sun, Lord of Heaven, around which takes place all daily and periodic phenomena. The crown, nose-pendant, ear-rings and necklace are magnificent, as must be the ornaments characteristic of this deity. The hair is blond, due to the golden appearance of the sun. The wrinkles on the face show age and maturity. And the tongue, stuck out is the form of an obsidian knife, indicates that the diety demands to be fed with blood and human hearts.
First Ring - from Center. Four Olin representing the Earthquake Epoch or Sun. The four epochs represented inside the square portions of this symbol correspond to the four previous epochs also called suns.
Second Ring - The second ring from the center is composed of 20 named days contained in one month, also used for naming years. Each year starts on one of four of these 20 days.
Twenty Days of the Aztec Month
Snake - Coatl
Lizard - Cuetzpallin
House - Calli
Wind - Ehecatl
Crocodile - Cipactli
Flower - Xochitl
Rain - Quiahuitl
Flint - Tecpatl
Movement - Ollin
Vulture - Cozcacuauhtli
Eagle - Cuauhtle
Jaguar - Ocelotl
Cane - Acatl
Herb - Malinalli
Monkey - Ozomatli
Hairless Dog - Itzquintli
Water - Atl
Rabbit - Tochtli
Deer - Mazatl
Skull - Miquiztli
Third Ring - Sun Rays - Chalchihuite Ornaments - Splashed Blood Symbols
Outer Ring - Dedication Plate - Herbs with Buds - White Scrolls - Flame Sign - Xiucoatl's Tail