Abundant silicified polyplacophorans from numerous localities in the Ordovician in Kentucky and other localities in Virginia, Wisconsin, and Minnesota are described systematically. New species are: Spicuchelodes cressmani, Calceochiton floweri, Preacanthochiton baueri, Orthriochiton recavus, Helminthochiton blacki, H. marginatus, and Alastega martini; new genera and species are: Listrochiton weiri, Litochiton crebatus, and Amblytochiton incomptus; and new families are Litochitonidae and Alastegiidae. Hemithecella expansa Ulrich and Bridge in Butts, 1941 and Chelodes cf. C. mirabilis (Butts, 1926), from the Chepultepec Formation in Virginia are also described. Comparisons are made with Chelodes whitehousei Runnegar, Pojeta, Taylor, and Collins, 1979 from Australia and Calceochiton hachitae Flower, 1968 from New Mexico.
Listings of the fauna associated with the chitons are given for the Kentucky occurrences; taphonomic discussions of these are included.