No building, structure, or dwelling may be erected on a lot of land not fronting on a street, which lot contains less than 20,000 square feet in area or has less than the minimum area and frontage on a right-of-way required for the zone in which it is located, unless such building, structure, or dwelling is accessory only to some existing building, structure, or dwelling, and no dwelling may be erected on a lot fronting on a street, which lot contains less area and less frontage on a street than the minimum area and frontage required for the zone in which said parcel or lot of land is located, as set forth in § 198-705.1.1 through 705.1.7 herein, except that where a lot was recorded at the Registry of Deeds at the time this Zoning Bylaw was adopted, in which case, the provisions of § 198-201, applying to narrow and irregular lots, shall apply.