The mollusks are removed from the river bottoms in various ways and by many forms of apparatus. In the shallow streams the fishermen simply wade out in the water and pick up the shells by hand. If not readily visible from the surface, the shells may be located with the bare feet or by the use of a water-telescope. Where the water is too deep for wading, the fishermen work from small boats, and use garden rakes or other convenient inplements. Where pearling has developed into more of an industry, special forms of rakes and drags are employed. A shoulder rake, with a handle twelve to twenty feet in length, is used extensively under the ice in frozen rivers, and in lakes and other places where the water is still and from eight to fifteen feet in depth. This is simply an overgrown or enlarged garden rake, armed with twelve or fifteen iron teeth about five inches in length. A wire scoop or basket is attached to receive the catch as it is pulled from the bottom by the teeth, and when this scoop is well filled it is lifted and the contents dumped on the ice or into the skiff. This method is laborious, and is employed only where the water is shallow and the mollusks are abundant. Scissor tongs—similar to those used by oystermen on the Atlantic coast—are also employed in some localities, especially in Arkansas, where it is estimated that 1700 pairs were manufactured and sold in 1899 and 1900, at about $7 each. In the large streams of the Mississippi Valley, with their slow and steady currents, and where the Unios are taken largely for their shells to be used in button manufacture, the most popular form of apparatus since 1896 has been the crowfoot drag. This ingenious contrivance consists of a cross-bar of hollow iron tubing or common gas-pipe, six or eight feet long, to which are attached, at intervals of five or six inches, stout twine or chain snoods or stagings, each about eighteen inches in length. To each of these are attached three or four prongs or “hooks,” about six inches apart. These “hooks” are four-pronged, and are made of two pieces of stout wire bent at right angles to each other. According to the depth of the water, from twenty-five to seventy-five feet of three quarter inch rope is attached to the drag for the purpose of towing it behind the boat, which is permitted to drift down the stream with the current. This contrivance costs about $3, and each fisherman generally has at least two of them, as well as a wide flat-bottom boat costing $5 or $10.