There is hereby authorized to be appropriated, out of the Federal aid to wildlife restoration fund established by the Act entitled “An Act to provide that the United States shall aid the States in wildlife-restoration projects, and for other purposes”, approved September 2, 1937, as amended (16 U.S.C., secs. 669–669i), for the 1956 fiscal year and for each fiscal year thereafter, an amount equal to 20 per centum of the accumulated unappropriated receipts in such fund on August 12, 1955, until the accumulated unappropriated receipts in such fund on such date have been appropriated and expended. Funds appropriated under the authority of this section shall be made available to the States in accordance with the provisions of, and under the apportionment formula set forth in, such Act of September 2, 1937, and shall be in addition to the funds appropriated under section 3 of such Act [16 U.S.C. 669b].