Pteralia of the Paleozoic Insect OrdersPalaeodictyoptera, Megasecoptera andDiaphanopterodea (Paleoptera)

For an understanding of insect evolution the structure of the wing base is of major significance. However, the fossil record o pteralia in extinct orders is extremely scanty. This paper is concerned with the wing bases of certain Paleozoic Paleoptera, namely, Palaeodictyoptera, Megasecoptera and Diaphanopterodea rom the Upper Carboniferous (Namurian) of Czechoslovakia, the Upper Carboniferous (Stephanian) of France, and the Lower Permian of Czechoslovakia and Kansas. Independently of the Neoptera, the Diaphanopterodea acquired the ability to flex the wings backwards over the abdomen. In this respect, the order is of special interest, and an attempt is made here to compare the pteralia o the Diaphanopterodea with those of extant Ephemeroptera. Our present knowledge of the wing base in Paleozoic Paleoptera is restricted to the axillary plate o several palaeodictyopteran adults (Kukalova, 96o, 969-7o), and palaeodictyopteran nymphs (Woot