Shops and stores and service establishments, limited to the following: apparel, bakery, barber, beauty, book, dry-cleaning, confectionery, drug, florist, specialty food, gift, laundry, jewelry, millinery, print and newspaper, tailor, ice cream and sandwich shops and caterers, photographers and photo supplies, restaurants, theaters, clinics, cocktail lounges, public and private substations and transportation terminals, provided that not more than 20% in the aggregate of the land area of any one M-4 District shall be used for such purposes.