Besides the waterways already named, there are the Sabine, forming the western boundary; and the Pearl, the eastern boundary; the Calcasieu, the Mermentau, the Vermilion, Bayou Teche, the Atchafalaya, the Boeuf, Bayou Lafourche, the Courtableau River, Bayou D'Arbonne, the Macon River, the Tensas, Amite River, the Tchefuncte, the Tickfaw, the Natalbany River, and a number of other smaller streams, constituting a natural system of navigable waterways, aggregating over 4000 miles long.