[Illustration: Fig. 10. Puma shaped metate of gray andesite, from Rio Joca--¼.] The largest specimen in the McNiel collection is 2 feet long, 18 inches wide, and 12 inches high. A similar piece has been illustrated by De Zeltner. The usual office of these metates is considered to be that of grinding corn, cocoa, and the like. The great elaboration observed in some examples suggests the idea that perhaps they were devoted exclusively to the preparation of material (meal or other substances) intended for sacred uses. A high degree of elaboration in art products results in many cases from their connection with superstitious usages. Speculating upon the use of these objects, De Zeltner mentions a mortar “whose pestle was nothing but a round stone, which still shows traces of gold here and there. It was evidently with the help of this rude instrument that the Indians reduced the gold to powder before fusing it.”[13] The implement or pestle used in connection with these mealing tablets in crushing and grinding is often a simple river worn pebble, as mentioned above, but is more usually a cylindrical mass of volcanic rock, worked into nearly symmetric shape. _Stools._--The stool-like appearance of some of the objects described as metates suggests the presentation in this place of a group of objects that must for the present be classed as stools or seats, although their true or entire function is unknown to me. They are distinguished from the mealing stones by their circular plate, their sharply defined, upright, marginal rim, and the absence of signs of use. [Illustration: Fig. 11. Stool shaped object carved from gray, minutely cellular basalt--⅓.] [Illustration: Fig. 12. Stool with columnar base, carved from gray basaltic rock--⅓.] Two of these objects are from the vicinity of David. The largest and most interesting is illustrated in Fig. 11. It is carved from a piece of vesicular basaltic tufa and is in a perfect state of preservation. The height is 6 inches and the diameter of the top 10 inches, that of the base being a little less. The slightly concave upper surface is depressed about half an inch below the upright marginal band. The periphery is a little more than an inch in width and is decorated with a simple guilloche-like ornament in relief. The disk-like cap is connected by open lattice-like work with the ring which forms the base. The interior is neatly hollowed out. The open work of the sides consists of two elaborately carved figures of monkeys, alternating with two sections of trellis work, very neatly executed. The other specimen is somewhat less elaborate in its sculptured ornament.