Lionesse, Lyonesse, or Lionés, a tract of land between Land's End and the Seilly Isles, now submerged "full forty fathoms under water."  It formed a part of Cornwall.  Thus Sir Tristram de Liones is always called a Cornish knight.  When asked his name, he tells Sir Kay that he is Sir Tristram de Liones; to which the seneschal answers, "Yet heard I never in no place that any good knight came out of Cornwall."—Sir T. Malory, History of Prince Arthur, ii. 56 (1470). (The Reader's Handbook of Famous Names in Fiction, Allusions, &c., Brewer, 1899)