a genus of insects, belonging to the order of vermes testacea. The body is oblong, flat beneath; creeping; mouth placed below; vent behind, surrounded with a fringe; two feelers, retractile. There are several species.—The argo, or lemon doris, has an oval body, convex, marked with numerous punctures, of a lemon colour, the vent beset with elegant ramifications. It inhabits different parts of our seas, called about Brightelmstone the sea-lemon. See Plate XCII.