First in interest in the writer’s collection is a large life-sized mask of white cedar which was covered with mosaics of turquois and other stones set in a thick gum or pitch with which it was coated. Three greatly elongated straight projections answer for the nose and the two lips. Holes were cut for the eyes and two small ones on the sides for the thongs which bound it to the head. A large cavity in the forehead was evidently the setting of the crowning stone of the collection, though of what nature this was we unfortunately are unable to surmise, as it evidently became loosened and dropped out years before its discovery. Along the sides of the face are depressions in the coating of gum for regularly shaped stones about half an inch long by three-eighths of an inch in width, arranged in parallel rows--none of which remain at present. The rest of the surface, as noted, was covered with small turquois mosaics, a number of which are in place today.[92] _Skull Masks_ The two final masks to be described are the skull masks in the Ethnographical Museum in Berlin, and in the British Museum, London. On pl. XVIII is represented the Berlin example, which has been described by Uhle and illustrated in colors, three-fourths natural size.[93] Only the front of the skull has been used, and it was incrusted with sky-blue to pale slabs of turquois. The mask is 6⅝ inches in height. Our illustration is a photograph of the lithograph published by Uhle. The skull mask in the British Museum (pl. XIX) has been illustrated many times, and is one of the best-known pieces of Mexican mosaic. It has also been repeatedly described, so that it is not necessary to present a detailed description at this time. Suffice it to say that the back of the skull has been cut away, and the front covered with five broad transverse mosaic bands, alternating from the top downward, of lignite (not obsidian, as all writers have described it, we are informed by Joyce) and turquois. The inside is lined with leather, on which traces of red paint still remain. _Shields_ Richly decorated shields or chimallis played a prominent part in certain phases of the life of the ancient Mexicans. Mrs. Nuttall, in her interesting and instructive study, “On Old Mexican Shields,”[94] has pointed out that “all authorities agree that the shields were of two kinds. The first consisted of the military shields used for protection in warfare by all grades of warriors; the second comprised the shields carried, for display only, in religious dances and festivals.” In this study Mrs. Nuttall has made the following classification of shields, based on an extended examination of the chronicles of early writers: 1. Plain, unadorned war-shields (_yaochimalli_) of several kinds, used by the common soldiers.