and MERMITHIDAE. Gmelin (1788) divided the genus Gordius into Gordius and Filaria. Dujardin (1842) named the genus Mermis and considered it belonged among the nematodes. Creplin (1847) separated the genus Chordodes from Gordius. Villot in his monograph (1874) referred all 34 of the then known species of GORDIACEA to Gordius, but Chordodes was accepted and clearly defined by Janda (1893). Camerano (1897) added the genera Paragordius and Parachordodes. Camerano's (1915) revision listed 113 species which he considered valid. Most of the taxonomic studies of GORDIACEA in America have been made by Montgomery (1898-1907). May (1919) described the families GORDIIDAE and CHORDODIDAE and studied the life cycles of Gordius robustus Leidy and Paragordius varius (Leidy). G. W. Muller (1927) split the genus Parachordodes into Parachordodes and Gordionus. Heinze (1933-1937) erected the genera Beatogordius (1934), Paragordionus (1935), Chordodiolus (1935) and Euchordodes (1937), and four subfamilies (1935) of CHORDODIDAE. Heinze (1937) also developed new techniques in preparing specimens (especially the cuticula) for study. Dorier (1930) showed that larvae of GORDIACEA may encyst on vegetation and infect their host by mouth. Many species of GORDIACEA have been named without sufficient description to distinguish them. Identification must be based on details of the extremities and especially on the minute structure of the cuticula: its areolae, pore canals, furrows, tubercles, bristles.