Doris, a genus of gasteropod molluscs in the sub-order Nudibranchiata, the type of a family called Doridæ, and sometimes popularly Sea- lemons. The body has an elongated oval form, a flat ventral and more or less arched dorsal surface, a whitish, yellowish, or brownish colour, and usually a warty skin. Two retractile club-shaped tentacles on the back of the head, and feathery respiratory processes, sometimes retrac- tile, round the anus, are also marked characteristics. There is no distinct mantle or adult-shell, but the skin of the back is slightly broadened out over head and 'foot,' and limy particles occur in the skin. The radula is broad, and many-toothed. Numerous species occur in British and other seas, but more abundantly in the southern hemisphere. Some of them attain a considerable size. Few of them inhabit deep water. They crawl on rocks, seaweeds, &c., where they are often left by the tide; or swim in a reversed position, the foot, made concave by muscular action, serving to buoy them up. Some of them are pretty and interesting inmates of the aquarium.