Abstract:
The echinoids are described from the middle Eocene Warley Hill Formation, Santee Limestone, and Castle Hayne Limestone of North and South Carolina. Twenty-seven species are present including the following new taxa: Eurhodia baumi, Eurhodia rugosa ideali, Eurhodia rugosa depressa, Eupatagus wilsoni, Eupatagus lawsonae, Linthia harmatuki, Agassizia wilmingtonica Cooke inflata, and Protoscutella mississippiensis (Twitchell) rosehillensis. Three zones are identified: the earliest characterized by Protoscutella mississippiensis (Twitchell) and Santeelampas oviformis (Conrad), a "middle zone" with Linthia harmatuki and the youngest species of Protoscutella, and a "late zone" with large numbers of Periarchus lyelli (Conrad) and Echinolampas appendiculata Emmons. The "early zone" is considered early middle Eocene, the "middle zone" middle Eocene and the "late zone" probably late middle Eocene. The three species of Protoscutella appear to represent an evolutionary series-P. mississippiensis (Twitchell) to P. conradi (Cotteau) to P. plana (Conrad)-characterized by the shifting of the periproct nearer to the peristome.
The echinoids lived in well-aerated sediments in a tropical sea.
