Preheat the oven to 375°. In a bowl, mix the mayonnaise with the lemon juice, scallions and jalapeño and season with salt and pepper. Spread the bread crumbs on a rimmed platter. Generously brush each ear of corn with the mayonnaise mixture and roll in the bread crumbs to coat. Put the corn on a large, rimmed baking sheet and bake for about 35 minutes, or until browned and crisp. Serve at once.