they had vanished into the ground, whenever one of us, no matter how
cautiously, tried to approach them.

News of Apaches was again afloat, and one day a Mexican officer called
at the camp obviously in pursuit of Apaches from whom he had recently
taken twelve horses: but unfortunately the men had escaped. The
presidente of Casas Grandes had been advised of the killing of two
Americans near San Bernardino by some Apaches, and had also ordered
some men to look for the miscreants in the sierra.

Having thoroughly investigated the caves, we turned our attention to
the mounds, which are very numerous in this part of the country. They
are always covered with grass, and sometimes even trees grow on
them. When excavated they disclosed the remains of houses of a type
similar to that of the cave-dwellings. Some of the mounds were high
enough to justify the supposition that the houses had two stories,
each six or seven feet high, and containing a number of rooms. From
the locality in which the mounds were found it becomes at once
evident that the houses which once stood there were not destroyed by
inundations and covered by diluvial deposits. The mounds are composed
of gravelly cement and fine debris of house walls, and the rooms left
are completely filled with this material. It is easy to imagine how
the mounds were formed by the gradual demolition of the ceilings,
plastering, and roofs, forming a heap which to-day appears as shapely
as if it had been made by man for some definite purpose.

The houses were communal dwellings, each consisting of one room,
which generally was not quite ten feet square. The walls, eight
to nine inches thick, built of a mixture of clay and earth, were
fairly well preserved in places. In one house, which had unusually