As to function, they may be classed as personal ornaments, as money, and as material for mnemonic records.
PERFORATED SHELLS.
Under this head I shall examine briefly the manner of piercing or altering the smaller varieties of shells preparatory to stringing. The multitudes of perforated shells exhumed from the graves of our ancient tribes afford a fruitful field of study, and our large collections of more recent specimens serve to illustrate the manner in which they were employed.
In Plate XXXII illustrations are given showing the various methods of manipulation and perforation. In North America the Marginella, the Oliva, and the Cyprea seem to lead in importance.
Fig. 1 represents an Oliva, the apex of which has been broken away and the rough edge ground down, producing a passage for a thread, which may be introduced through the natural aperture below. This is a common method of perforation in many widely separated districts, and with a considerable variety of shells. The specimen figured is from a mound in Cocke County, Tenn. It is an Oliva literata from the Atlantic coast.
Fig. 2 shows a very usual method of treating small univalves. The most prominent part of the lower whorl is ground down until the wall is quite thin, and a small round hole is then drilled through it. The specimen illustrated is a large Olivella biplicata, obtained from the island of Santa Rosa, Cal.
Figs. 3 and 4 illustrate specimens from Mexico. Some thin-bladed implement, probably of stone, has been used to saw a slit or notch in the first convolution of the shell near the inner lip. Fig. 3 has one of these perforations, and Fig. 4 has two. The shell is the Oliva literata, from the Atlantic coast.
Fig. 5 is simply one-half of an Olivella biplicata with the interior parts extracted. It is made by cutting the shell longitudinally and drilling a central perforation. The specimen figured is from San Miguel Island, Cal.
Fig. 6 illustrates the manner of breaking out a disk preparatory to making a bead. This disk, when perforated, is frequently used by the Indians of the Pacific coast without additional finish.
Fig. 7 shows two examples of beads made from small specimens of the Olivella biplicata; both extremities are ground off, leaving a rather clumsy cylinder. The originals are from graves on the island of Santa Rosa. Such beads are frequently worn at the present time.