A STORY partly or wholly underground, but having one-half or more of its clear height (measured from finished floor to finished ceiling) below the CURB LEVEL; except that where the CURB LEVEL has not been legally established, or where every part of the building is set back more than twenty-five feet from a street line, the height shall be measured from the adjoining grade elevation. Cellars shall not be counted as STORIES in measuring the height of buildings. (See BASEMENT.)