Scald and shell the shrimp, seasoning highly the boiling water. Put the lard into a large kettle and, when hot, add the flour, making a brown Roux. When quite brown, without a semblance of burning, add the chopped onion and the parsley. Fry these, and when brown, add the chopped bay leaf; pour in the hot oyster liquor and the hot water, or use the carefully strained liquor in which the Shrimp have been boiled. When it comes to a good boil, and about five minutes before serving, add the Shrimp to the Gumbo and take off the stove. Then add to the boiling hot liquid about two heaping tablespoonfuls of the “File, ” thickening according to taste. Season again with salt and pepper to taste. Serve immediately with Boiled Rice.