We may imagine that the first aborigine to discover the possibilities of the stone ornament, selected an unusually soft claystone, punched a hole through it with a thorn, and the material being very soft, the rim between the perforation and the upper part gave way and the stone was lost. Meantime, other natives, seeing and admiring this new ornament, followed his example. Presently, it was ascertained that slate and sandstone, while harder to drill, retained their shape and were more serviceable than softer clay-stones. Somebody discovered that it was well to make two perforations in the oval stone. Again, that by grinding the edge of the stone one could change the form, and thus the objects shown in Fig. 291 came into use. A stone of near the desired shape was worked accordingly, and flat discs remained as more or less circular or rectangular ornaments. Thus, slate and shale, rectangular in the natural state, were made into rectangular or square ornaments and tablets. [Illustration: FIG. 295. (S. about 1–2.) Five specimens, two of which are ovate, two pointed, and the upper one to the left is spade-shaped. But the upper one was broken and afterwards ground down, so that its present form is no indication that the original form is spade-shaped. Collection of Peabody Museum, Cambridge, Mass. ] On the folder herewith presented as Fig. 292, I have drawn all the forms of polished stones of the problematical and ornamental class. That is, all of them that have been brought to my attention. There will be few specimens illustrated in this section that are not included in the figure mentioned. My aim in presenting so many of these is to include all the types. Some odd-shaped problematical forms may be considered as the result of individual fancy on the part of prehistoric man, and not true types. The outlines shown in Fig. 292 are illustrated, further on in the chapter, by specimens either full size, half-size, or less. To the left are the letters indicating the various rows, while the numbers refer to type specimens. Readers should bear in mind that the numbers represent illustrations and not pages.