The classification of insects has passed through many changes and with the growth of detailed knowledge, an increasing number of orders has come to be recognized. Handirsch (1908) and Wilson and Doner (1937) have reviewed the earlier attempts at classification and here we need only note that the foundations of a modern system were laid by Brauer (1885), who recognized the fundamental division of the class into the group- the primitively wingless Apterygota and the winged or secondarily apterous Pterygota. In 1908 Handirsch published a more revolutionary system, incorporating recent and fossil forms, which gave the Collembola, Thysanura and Diplura the status of three independent Arthropodan classes and considered as separate orders such groups as the Sialoidea, Raphidioidea, Hetereoptera and Homoptera.