Wash eggplants, wipe dry, and remove green tip. Cut a lengthwise slice from each. Scoop out inside and reserve, leacving a wall 1/2 inch thick. Invert shells in a shallow baking pan. Pour in 1 inch of water. Bake in 400 oven for 20 minutes (or until half done.).
Chop pulp and saute with onion in 1/4 cup margarine. Add bread crumbs, tuna, and seasonings. Spoon into eggplant shells and place in a shallow baking dish.
Mix bread cubes with melted butter. Sprinkle around edge of tops. Bake uncovered in 350 for 20 minutes.