25 U.S.C. § 348a
The period of trust on lands allotted to Indians of the Klamath River Reservation, California, which expired , and the legal title to which is still in the United States, is reimposed and extended for a period of twenty-five years from : Provided, That further extension of the period of trust may be made by the President, in his discretion, as provided by section 348 and section 391 of this title.