Scald milk with onion, mace, and parsley; remove seasonings. Melt butter, add flour, salt, pepper, and gradually the milk; then add eggs, slightly beaten. Put a layer of fish on buttered dish, sprinkle with salt and pepper, and add a fewdrops of lemon juice. Cover with sauce, continuing until fish and sauce are used, shaping in pyramid form. Cover with crumbs, and bake in hot oven until crumbs are brown.