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. The Thysanura are recognizable by their elongate feelers and tail-processes (cerci). Campodea Machilis and Lepisma - to which belongs the "silverfish" (q.v.) - are the best known genera. (See also HEXAPODA and APTEPA.)