=American Fresh-water Pearls.=--The facts cited by Mr. George F. Kunz in his paper, published in the Report of the United States Fish Commission, on the Fresh-water Pearls and Pearl Fisheries of the United States, give considerable importance to this feature of our natural history. The mound explorations attest that fresh-water pearls were gathered and used by the prehistoric peoples of the country "to an extent that is astonishing. On the hearths of some of these mounds in Ohio the pearls have been found, not by hundreds, but by thousands and even by bushels--now, of course, damaged and half decomposed by centuries of burial and by the heat of superficial fires." The narratives of the early Spanish explorers make several mentions of pearls in the possession of the Indians. For a considerable period after the first explorations, however, American pearls attracted but little attention, and "for some two centuries the Unios [or 'fresh-water mussels'] lived and multiplied in the rivers and streams, unmolested by either the native tribes that had used them for food, or by the pioneers of the new race that had not yet learned of their hidden treasures." Within recent years the gathering of Unio pearls has attained such importance as to start economical problems warranting and even demanding careful and detailed inquiry. The first really important discovery of Unio pearls was made near Paterson, N. J., in 1857, in the form of the "queen pearl" of fine luster, weighing ninety-three grains, which was sold to Eugénie, wife of Napoleon III, for twenty-five hundred dollars, and is now worth four times that amount. As a result the Unios at Notch Brook, where it was found, were gathered by the million and destroyed. Within a year fully fifteen thousand dollars' worth of pearls were sent to the New York market. Then the shipments gradually fell off. Some of the best American pearls that were next found were at Waynesville, Ohio, where Mr. Israel H. Harris formed an exceedingly fine collection. It contained more than two thousand specimens, weighing more than as many grains. Among them were one button-shaped on the back and weighing thirty-eight grains, several almost transparent pink ones, and one showing where the pearl had grown almost entirely through the Unio. In 1889 a number of magnificently colored pearls were found at different places in the creeks and rivers of Wisconsin, of which more than ten thousand dollars' worth were sent to New York within three months. These discoveries led to immense activity in pearl hunting through all the streams of the region, and in three or four seasons the shells were nearly exhausted. The pearl fisheries of this State have produced at least two hundred and fifty thousand dollars' worth of pearls since 1889. Another outbreak of the "pearl mania" occurred in Arkansas in 1897, and extended into the Indian Territory, Missouri, Georgia, and other States.