has been discovered at some depth, and it may be that several such were constructed during the process of building in order to give solidity to the mass; but it is more likely that the outer layer represents an addition to the original building. Other evidence of phases in construction have been discovered in some of the mounds, in cases where an entire building has been filled solid in order to support a later edifice above it. Growth by accretion of this nature was a feature of many of the Maya sites, as will be seen later. It is probable that this mighty pyramid was approached by a stairway on its western face from the "path of the dead." The general assemblage of the lesser mounds seems to exhibit more evidence of design than many Mexican ruins, and the whole site bears the stamp of considerable antiquity as well as long-continued occupation. In particular is to be noticed a tendency to group the mounds round quadrangular courts, a tendency which, as will be seen later, is characteristic of the Zapotec area. The district from early times bore the reputation of a burial-ground of great sanctity, and the lesser mounds were at first believed to be burial-tumuli (whence the name "path of the dead" given to the sunk roadway). Excavation however, as far as carried out, seems to prove that the greater number supported buildings of a residential nature, many of them of an unusually complex ground-plan. The walls were of lava fragments and adobe, dressed with mortar. The roofs of the larger apartments were supported on pillars, probably of wood, of which the rectangular bases, similar in construction to the walls, have been found. Stone-carving is practically non-existent, probably for the same reason that there are no well-dressed stone facings, viz. unsuitability of local material; but the interiors were ornamented with frescoes in beautiful colours in which plant motives play an important part.
