Abstract: A survey of the Late Permian ammonoids which serve as reference for  the
   Chidruan Stage shows that = apparent faunal sequence can be established by evolutionary
   lineages of these fossils.  Cephalopods of this age are telatively rare and have received less
   detailed treatment than other Permian faunas probably for this reason, the known variety is
   not as great as is that from older and younge beds.  Cyclolobids, with higbly developed am-
   monitic sutures, appear to be the best reference for age assignment.  The Permian Otocerataceae,
   important as precursors of diverse Triassic stocks, are also of value.