THYSANURA  , the name applied by P . A .

Latreille to the primitive wingless insects known as springtails and bristletails . Sir J . Lubbock (Lord Avebury) separated the springtails as a distinct order, the Collembola, and by many students this separation has been maintained . It is better, on the whole, to regard the Thysanura and Collembola as sub-orders of a single order, the Aptera (q.v.) . The Thysanura are recognizable by their elongate feelers and tail-processes (cerci) . Campodea (q.v.) Maclzilis and Lepisma—to which belongs the " silver-fish " (q.v.)—are the best known genera .