Abstract

Three localities in southern Illinois and western Kentucky have yielded about 270 tiny crinoids, all belonging to two new species of Allagecrinus. A. coronarius, n.sp., is from the Shetlerville Member of Renault Formation and the Ridenhower (Paint Creek) Formation, low in the Chester Series; A. elegantulus n.sp., is from the Cave Hill Member of Kinkaid Limestone, high in the Chester. Ontogeny progresses from armless forms to eight-armed forms, to one specimen with 14 arms. Phylogeny of the genus shows progressive decrease in height and increase in width of the calyx. The Chester species are compared with Lower Carboniferous species of Scotland.

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