†family Helminthochitonidae Van Belle 1975 (mollusk)
Aculifera - Paleoloricata - Helminthochitonidae
Parent taxon: Chelodina according to R. D. Hoare 2002
Sister taxa: Gotlandochitonidae, Preacanthochitonidae, Scanochitonidae, Septemchitonidae
Subtaxa: Diadelochiton Helminthochiton
Distribution:
• Permian of Greece (1 collection), United States (2: Nevada)
• Carboniferous of United States (5: Ohio, Oklahoma, Pennsylvania, Texas)
• Devonian of Australia (1), Germany (2), the United Kingdom (2)
• Ordovician of United States (5: Kentucky)
Total: 18 collections each including a single occurrence