Beatrix Potter Perpetual Birthday Calendar. This fabulous slim appointment format perpetual Birthday calendar features delightful illustrations created by the lady most famous for her Peter Rabbit creation! The calendar is perpetual, meaning that the calendar can be used year after year as the days of the week are not assigned to each individual day. This calendar will make a great gift for any busy family with lots of Birthdays to remember and those of us who don’t look forward to copying Birthday and other anniversary calendar entries from one calendar to the next at the end of every year!