On or before the first day of June in each year, the commissioner of the land office shall prepare and transmit to the clerks of the several counties in which the same are situated, lists of all the forfeited lands in the several townships therein, and of all the unsold university, school, and state building lands which he may have cause to believe are improved, together with proper forms of returns and certificates of appraisement, to be forthwith distributed by such clerks respectively to the several supervisors of townships to whom the same may be directed.