Fig. 12 shows a rather peculiar method of treating _Cyprea_ shells by the tribes of the Pacific coast and the Pacific islands. The prominent part of the back is cut or ground away, and the columella is partially or wholly removed, a passage the full size of the natural aperture being thus secured. This is also an ancient as well as a modern method of treatment. [Illustration: PL. XXXII--PERFORATED SHELL BEADS. (1/1)] Small bivalve shells are prepared for stringing by drilling one or more holes in the center or near the margin, according to the manner in which they are to be strung. Such beads have been in almost universal use by primitive peoples, both ancient and modern. Shells with natural perforations, such as the _Fissurellas_ and _Dentalia_, are extensively employed by the west coast peoples, and foreign varieties of the latter have been largely imported by Europeans, and from very early times have been used by the tribes of all sections. The natural perforation of the _Fissurella_ is often artificially enlarged, and additional perforations are made near the margin. Examples may be seen in Plate XLIX. I shall include under the head of beads all small objects having a central or nearly central perforation, made for the purpose of stringing them in numbers. In shape, they range from straw-like cylinders, three, four, and even five inches long, with longitudinal perforations, to thin, button-like disks, two or more inches in diameter. In general the cylinders are made from the columellæ of univalves, and the disks from the outer walls of the same, or from the shells of bivalves. Of course, there are forms that fall under no classification, such as disks with perforations parallel with the faces, or cylindrical forms with transverse perforations, while many small, pendant-like objects, of varied shapes, are strung with the beads, and might be classed with them; but these are exceptions, and can be described along with the classified objects most nearly resembling them. The grinding down and the perforating of natural shells is easily accomplished, so that any savage could afford to decorate his person with this jewelry in profusion. But the class of beads illustrated in Plates XXXIII, XXXIV, and XXXV could not have been made without the expenditure of much time and labor, and doubtless owe their existence, in a measure, to mercenary motives. As they were made from the walls or columellæ of massive shells, they must have been broken or cut out, ground smooth about the edges, and perforated; this, too, with most primitive tools. DISCOIDAL BEADS.