The coat of arms recalls the founding of Mexico City, then called Tenochtitlan. The legend of Tenochtitlan as shown in the original Mexica codices, paintings, and post-Cortesian codices, does not include a snake.t is a modified version of the national coat of arms, with the addition of the full official name of the country Estados Unidos Mexicanos, in a semi-circular accommodation in the upper part of the seal. Current and past Mexican peso coinage have had the seal engraved on the obverse of all denominations.