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creek and river where limestone is the country rock, since 
in nearly all instances the Unios secrete pearls when this 
favorable condition exists. 
The great quantities of Unio pearls that existed in pre- 
historic times is evidenced by the Little Miami Valley, ex- 
plored by Prof. Frederick W. Putnam and Dr. Charles 
L. Metz, and more recently by Warren K. Moorehead. who 
carried on operations for Prof. Putnam. The former pro- 
cured over 60,000 pearls, nearly two bushels, drilled, un- 
doubtedly of Unio origin, all of them, however, decayed 
or much altered, and of no commercial value. In 1884, 
the former scientists examined the Marriott Mound, where 
they found nearly 100 Unio shells, and among other objects 
of special interest six canine teeth of bears, that were per- 
forated by a lateral hole near the edge at the point of the 
greatest curvature of the root, and by passing a cord 
through this, the tooth could be fastened to any object or 
worn as an ornament. Two of these teeth had a hole bored 
through near the end of the root on the side opposite the 
lateral perforation, and the whole countersunk in order to 
receive a large spherical pearl, about $ inch in diameter. 
When the teeth were found, the pearls were in place, al- 
though chalky from decay. Upward of 250 pearl beads 
were found, concerning which they say: ‘‘ The pearl beads 
found in the several positions mentioned are natural pearl, 
probably obtained from the several species of Unios in the 
Ohio River. In size they vary from jo inch to 3 inch in 
diameter, and many arespherical. They are neatly drilled, 
and. the larger from opposite sides. These pearls are now 
chalky and crumble on handling, but when fresh they 
would have formed brilliant necklaces and pendants.”’ 
The find of Mr. Moorehead is exhibited in the Anthro- 
pology Building of the World’s Fair, and belongs to the 
collection that is to be made the permanent one of the 
city of Chicago, to be shown ultimately in the Fine Arts 
Building, Jackson Park. 
