The Borden Formation in northeastern Kentucky contains a signifiant, largely undeseribed,
Osagean (upper Tournaisian to lower Viséan) ammonoid succession. Lower Osagean strata
in the Nancy Member contain a diverse Pericyclus Zone assemblage characterized by
Muensteroceras oweni (Hall), M. parallelum (Hall), Kazakhstania colubrella (Morton), Imitoceras
ixion (Hall), and Masonoceras kentuckiense Work and Manger.  This interval, which ranges into
the basal Cowbell Member, was referred to the Muensteroceras owe i Assemblage Zone by
Gordon and Mason (1985) and Gordon (1986) and indicates correlation to the lower Ivcorian
Stage of the Belgian Tournaisian succession.  The succeeding middle Osagean interval in the
middle and upper part of the Cowbell Member contains Merocanites drostei Collinson and
Dzhaprakoceras which presumably represent the lower, or Tournaisian  (upper Courceyan or
lower Chadian), portion of the Fascipericyclus-Ammonellipsites Zone.  An even higher middle
Osagean assemblage with Polaricyclus bordenensis new species and Winchelloceras allei
(Winchell, 1862) occurs in the upper part of the Nada Member, near the top of the Borden
Formation, and is the basis for the current report.