A peculiar form of pipe, which may be a variant of the Sioux type, is found in a limited area in the upper Mississippi valley. These pipes usually have bases with long projecting spurs, but the bowl is smaller than the stem hole and very low. It is surrounded by a broad, thin disk sometimes as much as three and a half inches across. Some of these “disk pipes” suggest the shallow-bowled pipes of the Asiatics, but the form is certainly prehistoric. Pipes of this type are rare, and were probably made for ceremonial use. One of the sacred pipes of the Omaha is of this sort. Although all the Mexican Indians were predominantly cigarette-smokers, ancient clay pipes of elbow type have been found in the valley of Mexico (Pl. IV, No. 5). They are not mentioned by any of the early Spanish writers, but the specimens found are unquestionably of native workmanship, and are probably prehistoric. The commonest form has a bulb-shaped bowl and a rather thick stem flattened on the bottom, so that the pipe will stand upright. The occurrence of elbow pipes in a limited area, far from any other in which they were known, is difficult to account for. Some of these pipes resemble forms in use in the southeastern United States and lower Mississippi valley. Elbow pipes were also used on the Northwest Coast and in Alaska, but they were introduced into these regions after the discovery of America. The Alaskan Eskimo apparently learned the practice of smoking from the natives of Siberia, and their pipes are of Asiatic type, with very small bowls (Pl. VI, No. 1). Their best pipes are made from walrus tusks, and are often elaborately etched. The tusk is usually split lengthwise and the halves joined in such a way that they can be taken apart to obtain the juice distilled in smoking. The juice was mixed with fungus ashes for chewing or with the smoking tobacco. Poorly made pipes of Eskimo form were used by the Athapascan tribes of interior Alaska, who were taught to smoke by the Eskimo. The Indians of the Northwest Coast chewed tobacco in ancient times, but did not smoke it. The more northern tribes may have adopted smoking from Asia by way of the Eskimo, but their pipes show little resemblance to the Asiatic forms, and they probably learned the practice from white visitors. The natives of this region are expert carvers, and nearly all their pipes are decorated with figures of men or totemic animals. Wood is the favorite material (Pl. VI, No. 2), but bone and antler are also used and some of the tribes make very elaborate pipes of black slate (Pl. VI, No. 3). The slate pipes are much sought after by collectors, and many of them seem to have been made for sale rather than use.