NEW YORK — The ingenue look played a leading role on both sides of the Atlantic this season. Marc Jacobs, for example, seemed to be following a muse who was part schoolgirl, part French maid and part Olive Oyl. He did cute, saucy little dresses, some with inset trompe l’oeil collars, and offbeat little coats and jackets with big buttons. Here, his slightly naughty schoolgirl in a piped and pleated dress. For more on the season, see pages 6 and 7.