and regulated the inner life of the clan. A land system somewhat similar to that of the Mexican calpulli existed among the Mixtec in so far as land appears to have been hereditary in families but could not pass outside the local group. Below the members of the calpulli ranked certain freemen who farmed the lands of the lords on payment of a rental (in kind), and, finally, a class of serfs who were bound to the soil and probably represented the remnants of the early agricultural population. The Mexican social system therefore comprised a landed aristocracy who paid no definite taxes, but owed service to the king; associated with them was a military nobility who held lands at the king’s goodwill, and whose tenants paid royal taxes. Lower in rank were the calpulli freemen, who paid taxes in common; still lower, the tax-paying rent-holders, and finally the serfs, who paid taxes only to their feudal lords. In addition to these there was the official class, their sons and descendants, who, ranking as warriors and noble, paid no definite taxes, but contributed their personal services and formed the suite of the ruler. The office-holders were known by the generic name of Tecutli, and the positions which they occupied were essentially military in origin; four of them were placed as overseers of the four districts into which the city was divided for administrative purposes, and acted as representatives of the Tlacatecutli, or ruler. Besides these there were the judicial officials, treasurers, and a whole host of overseers, of whom the lowest in rank, as in Peru, exercised supervision over a few families only. The travelling merchants constituted a peculiar and privileged class, and will be considered later when the subject of trade is discussed. The expansion of the power of Mexico brought many other cities under its influence, and these were obliged to furnish tribute in kind, and were also liable to military service. In important cities a governor, Petlacalcatl, was placed, with a tax-gatherer, Calpixque, under him; in less important districts a governor or a Calpixque resided in the principal city, and the tribute was collected in the surrounding towns by subordinate officials. Apart from a general supervision there was very little interference with the tributary cities; the original rulers were rarely displaced, but continued to govern according to the local laws, and, with the exception that certain lands were often reserved for the use of the Mexican crown, the property of the conquered was respected. The rather loose nature of the suzerainty exercised by Mexico over its dependents made revolt a frequent occurrence, but this was hardly regarded as a drawback, owing to the ceremonial nature of war and its function in providing victims for sacrifice. Tribute was generally paid by a town or district in common, and consisted of local produce and manufactures (Fig. 18). Produce-tribute, which was