“Prehistoric objects of unknown use whose most typical form is that of a double-convex or double-concave lens. The perimeter is a circle and the sides range from considerably convex through plane to deeply concave. The diameter varies from 1 in. to 8 in., the thickness from one fourth of an inch to 6 inches, very rarely passing these limits; the two dimensions have no definite relation to each other. Some specimens are convex on one face and plane on the other; but when one face is concave the other is also. Of the latter form many have a secondary depression at the centre; others have a perforation which is sometimes enlarged until the disc becomes a ring. They are made principally of very hard rock, as quartz, flint, jasper, novaculite, quartzite, porphyry, syenite, and the like, though stone as soft as marble, sandstone, barite, and even steatite was sometimes chosen. No type of relics is more difficult to classify than these discs. The name first given them, and by which they are still commonly known, is ‘chunky stones,’ from the native name of the game played with analogous discs by Southern Indians. But the description of the game, considered in connection with the great variation in size and material of the specimens, shows that only a small percentage of them could have been thus utilized. Culin believes that a limited number may be definitely regarded as ‘chunky stones.’ He recognizes three types: (1) perforated (least common); (2) symmetrical, unperforated; (3) asymmetrical, unperforated. A similar diversity is observed in the stones used in the analogous Hawaiian game of _maika_.[44] From the smooth, symmetrical, highly polished ‘chunky’ stone they merge by insensible gradations into mullers, pestles, mortars, pitted stones, polishing- and grinding-stones, hammers, sinkers, club-heads, and ornaments, for all of which purposes except the last they may have been used in some of their stages, so that no dividing-line is possible. They present various styles and degrees of finish. Many retain their natural surface on both sides with the edge worked off by grinding or pecking, the latter marks possibly resulting from use as hammers. The sides may be ground down while the edge remains untouched; or, when made from a thick pebble, the sides may be pecked and the edge ground. Some specimens which are entirely unworked require very close examination to distinguish them from others whose whole surface has been artificially produced. It is possible, however, to arrange a large number of specimens from one locality in a regular series from a roughly chipped disc to a finished product of the highest polish and symmetry. The finest specimens, in greatest numbers, come from the states south of the Ohio River, and from Arkansas eastward to the Atlantic. The territory within a radius of one hundred miles around Chattanooga, Tennessee, and for about the same distance around Memphis, is especially rich in them.