Studies of Carboniferous cephalopods, principally from Arkansas, but also from Kentucky, Indiana, Oklahoma, Texas, and Utah, have resulted in the recognition of 6 new genera: Reticycloceras (type species, R. croneisi, n. sp.) and Mitorthoceras (type species, M. perfilosum, n. sp.) which are orthoconic nautiloids, and Paracravenoceras (type species, P. ozarkense, n. sp.), Fayettevillea (type species, F. planorbis, n. sp.), Pygmaeoceras, (type species, Gastrioceras pygmaeum Mather, 1915), and Axinolibus (type species A. modulus, n. sp.) which are ammonoids.