None of said securities shall be authorized except upon a finding by the State Bond Commission that there has been filed with it a request for such authorization, which is signed by or on behalf of the Commissioner of Transportation and states such terms and conditions as said commission, in its discretion, may require. Each series of said securities shall be authorized by a written determination which is signed by a majority of the members of the State Bond Commission and filed in the office of the Secretary of the State and sets forth the principal amount of the securities of such series and a description of the purpose or several purposes for which such securities are authorized. Such description may specify a part or parts of a particular project or particular projects enumerated in § 13a-185 but shall be sufficient if made merely by a reference to any of the numbered subdivisions of either subsection of said § 13a-185.