Three hundred and fifty representatives of Palmatolepis glabra Ulrich & Bassler, collected from a single sample of the late Devonian Saverton shale of Illinois, are used to illustrate intraspecific variability in conodonts. The main types of variation are discussed, and the various morphologic features are evaluated for taxonomic use. The study indicates that a conservative philosophy of speciation and careful study of large numbers of individuals must be applied to conodont species if they are to attain widespread use by the general stratigrapher.

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