The Zone Map delineating the above districts is hereby declared to be a part of this ordinance. The zoning district boundary lines are intended generally to follow street center lines, existing lot lines and the like, as indicated on the Zone Map. Where a zoning district boundary line does not coincide with any such line as above set forth, its location or relation to another boundary line is indicated on the Zone Map by means of figures expressing distance in feet from a street side line or other boundary line.