On pls. IX to XVI are illustrated the series of masks from the cave recently discovered in Mexico, which are in the Museum of the American Indian, Heye Foundation. They fall into two classes, those on pls. IX to XII being ornamented with turquois mosaic, and so nearly alike in workmanship that they might well be the product of one artist, while the masks on pls. XIII to XV are different in character, the mosaic pieces being larger and coarser, and considerable stone other than turquois was employed in the decoration. They are all in a damaged condition and lack the chin. All the mosaic incrustations are set in a bed of gum. [Illustration: FIG. 15] The best-preserved specimen is illustrated in colors on pl. IX; it is 7½ inches high, and 6¾ inches wide. Bands of light and dark turquois will be observed on the forehead and temples. Around the lower margin of the face is a band of blackish to dark-brown stones. On the sides of the mask are two large black discs made of a composition resembling charcoal and sticky clay. This substance is present in a number of the other masks, and we venture the conjecture that it may be the material used by the goldsmiths in modeling figures to be cast in gold. Sahagun describes it as follows: The master gives them the charcoal, which they grind very fine. And when it is ground they add a little clay, the glutinous earth which they use in their pottery. They mix the charcoal with the clay and stir it, and knead it in such manner that the two substances constitute one solid mass. And when they have the mass prepared, they shape it into thin discs which they expose to the sun.... For two days these objects dry, and become very hard. When the charcoal is well dried and very hard, it is cut, then carved by means of a little scraper of copper.[91] The tip of the nose, as well as the chin, is gone. There are traces of red paint over the mouth and in the circular spaces on each side of the nose. When the specimen was received, the missing section of the lower part of the face was covered with a band of tin, as in the mask (pl. XVI) from which the mosaic has disappeared. From this circumstance we believe that the objects in this cave deposit were used by the Indians after the Spanish conquest, possibly until comparatively recent times. Our reasons for this belief will be found in the chapter translated from Motolinia in our conclusion. If we assume that at certain intervals during centuries the Indians resorted to the cave to worship in secret their ancient gods, we can explain the worn condition of nearly all of these specimens. Undoubtedly they were preserved and treasured for many generations, revered as precious relics of a lost but not entirely forgotten civilization. There is not the slightest reason for doubting their origin in pre-Spanish times. [Illustration: PL. XXIV SHIELD OF WOOD WITH MOSAIC DECORATION MUSEUM OF THE AMERICAN INDIAN HEYE FOUNDATION, NEW YORK]