18(4)If it appears to the Superintendent, or if he has any reason to suppose, from the annual statement that the value placed by an insurer upon any of its real estate is too great, he may either require such insurer to secure an appraisement of such real estate by one or more competent valuators, or may himself procure such appraisement at the expense of the insurer, and the appraised value, if it varies materially from the statement made by the insurer, may be substituted in the annual report of the Superintendent.