IV. Cyrtoctenus gen. nov., a large late Palaeozoic Arthropod with pectinate Appendages

Synopsis It is confirmed that the type species of the genus Glyptoscorpius Peach 1882 is a subjective synonym of Adelophthalmus Jordan and Meyer 1854. Species which have been referred to Glyptoscorpius are reviewed and their present taxonomic position defined. Cyrtoctenus gen. nov., type species Cyrtoctenus peachi sp. nov., is designated to accommodate forms bearing five pairs of specialised abdominal appendages of which the first is comb-like. Four species of Cyrtoctenus from Devonian and Carboniferous rocks in Scotland, England, Belgium and Czechoslovakia are recognized. The structure and affinities of these forms are discussed with special reference to the comb-like appendages and their ornamentation in relation to these features in other arthropods. In particular the development of filaments and fulcra from different types of scales is discussed. The characters of the new genus are found to be so distinctive as to require the creation of the new order Cyrtoctenida for its accommodation.