The notices shall be headed “notice of hearing” in letters not less than one inch in height and shall contain a description of the territory proposed to be annexed and a statement of the time and place of the hearing. In lieu of the description the boundaries of territory proposed to be annexed may be shown by means of a diagram printed upon the notice. The notices shall be posted not less than ten days prior to the date set for the hearing. In addition to the notices the board shall direct its clerk to publish a notice once a week for two successive weeks in the newspaper of general circulation circulated in the district and another in the territory proposed to be annexed that the board deems most likely to give notice of the hearing to the inhabitants of each.