Mesothems are cyclic, chronozonally defined depositional intervals in basins, with thin, unconformity-bounded shelf equivalents. If eustatically controlled, as has been suggested for British Namurian mesothems, mesothemic cycles should be recognizable in distant but contemporaneous intervals. This appears to be the case in the mid-Carboniferous of the Ozark shelf region, where the record of thin, shallow-shelf deposits, punctuated with lacunae, is compatible with the Namurian mesothemic model. In the Ozark shelf succession, equivalents of only 9 of the 19 ammonoid zones of the British Namurian are represented. According to the mesothemic model, parts of a few additional zones may be discovered on the Ozark shelf, but a complete sequence will be represented only in the Ouachita Basin to the south.