In a bowl, mix cornmeal, flour, baking powder, and salt. Whisk in milk and eggs until blended, then whisk in butter.
Place a nonstick griddle or a 12-inch nonstick frying pan over medium heat (350°); when hot, coat lightly with oil and adjust heat to maintain temperature. Spoon batter in 1/3-cup portions onto griddle and cook until pancakes are browned on the bottom and edges begin to look dry, about 2 minutes; turn with a wide spatula and brown other sides, 1 1/2 to 2 minutes longer. Coat pan with more oil as necessary to cook remaining pancakes.
Serve pancakes as cooked or keep warm in a single layer on baking sheets in a 200° oven for up to 15 minutes.