absolutely their idols, as if it were a hundred years ago (that they had had them).[112] Hernándo Ruiz de Alarcon, in his treatise on the superstitions of the natives of New Spain, relates that when they went to the hills or other remote places where their idols were hidden away, or to certain piles of stones where they often made offerings and sacrifices, they carried there offerings which were sometimes copal incense wrapped in _quauhamatl_, a kind of white paper made from the bark of a soft tree. This work, written in 1620, is entitled, _Tratado de las Supersticiones y Costumbres Gentilicas que oy viuen entre los Indios Naturales desta Nueva España_, and was published for the first time in 1892 by the Museo Nacional of Mexico. The present writer has noted such stone piles, particularly in Yucatan. It is probable that we have here an explanation of the existence of our deposit of mosaic-incrusted wooden shields and masks, which leads us to hope that still further discoveries of this character may be made. The climatic conditions in certain parts of the highlands of Middle America, where this deposit was found in a cave, favor this assumption. There are great sections of comparatively dry, wind-swept, almost desert plains, treeless hill-slopes, and ravines, where the chief vegetation is cacti in the lower altitudes, while higher up pines and oaks abound. Here wooden objects should be indefinitely preserved in ancient tombs or in caves, protected by a covering of loose, dry earth, the condition under which our collection was found. The discovery of this remarkable collection of mosaics emphasizes the fact that the investigation of the archeology of Mexico is hardly commenced, in view of the vast amount of material hidden under the ruins of thousands of ancient settlements and burial places, and probably in countless caves, which still remain untouched by the archeologist. As revealed by the surprising results of Thompson’s dredging in the sacred cenote in Yucatan, a wealth of archeological material also lies buried in the mud under the waters of sacred wells and lakes. This is notably so in the case of Lake Chapala, on the borders of Michoacan and Jalisco in Mexico,[113] and of Lake Amatitlan in Guatemala, where thousands of pottery vessels and other objects have been recovered from the bottoms of the lakes by divers, and from the mud when the waters have receded from the shores during times of extreme drought. These objects had been thrown into the waters as offerings to the gods.