The Echinoid Directory

• Test circular to oval in outline with thin but rounded margin.
• 5 gonopores.
• Petals broad and open distally.
• Five simple perradial food grooves on oral surface extending only about half way to the margin (to end of second post-basicoronal plates).
• Ambulacral and interambulacral zones of equal width at ambitus.
• Basicoronal circlet pentastellate with interambulacral plates projecting.
• Plates of posterior interambulacrum disjunct in type species; continuous in other species. Plating in lateral and anterior paired interambulacra continuous adorally but with extremely narrow contact between primordial and second plates.
• Periproct oral, towards posterior margin (submarginal in type species). Opening bounded by second or third pairs of interambulacral plates.

Middle to Late Eocene of south eastern USA.

Scutella mississippiensis Twitchell, 1915, p. 124, by original designation.

• P. conradi (Cotteau, 1889); Middle Eocene, south eastern USA.
• P. mississippiensis (Twitchell, 1915); Middle Eocene, southen USA.
• P. palmeri Osborn et al., 2013; Middle Eocene, eastern USA.
• P. plana (Conrad 1865); Middle Eocene, south eastern USA.

Clypeasteroida; Scutellina; Scutelliformes; Protoscutellidae.

Presumed paraphyletic by exclusion of more derived protoscutellids.

Differs from Mortonella in having simple rather than bifurcating food grooves. Distinguished from Periarchus by its simple, non-bifurcating food grooves and periproct opening more marginal and behind first post-basicoronal plates.

Kier, P. M. 1980. The echinoids of the Middle Eocene Warley Hill Formation, Santee Limestone, and Castle Hayne Limestone of North and South Carolina. Smithsonian Contributions to Paleobiology 39, 1-102, pls 1-22.

Osborn, A. S., Mooi, R. & Ciampaglio, C. N. 2013. A New Species of Protoscutella (Echinoidea, Clypeasteroida, Protoscutellidae) from the Middle Eocene (Lutetian) Santee Limestone in Berkeley County, South Carolina. Southeastern Geology 49, 119-131.